Article

Industrial livestock production and global health risks

Figures

Content may be subject to copyright.
Pro-Poor Livestock Policy Initiative
A Living from Livestock
Research Report
1
June 2007
Industrial Livestock Production
and Global Health Risks
J. Otte, D. Roland-Holst, D. Pfeiffer, R. Soares-Magalhaes,
J. Rushton, J. Graham and E. Silbergeld
1. Abstract
Because of human and livestock population growth, changes in livestock production, the
emergence of worldwide agro-food networks, and significant changes in personal mobility,
human populations increasingly share a global commons of disease risk, among themselves and
with domestic and wild animal species. To elucidate the linkage between livestock production
and global public health, this paper draws upon recent experiences provided by different
influenza A virus (IAV) incursions into domestic livestock populations, the most notable one being
the ongoing HPAI H5N1 epidemic that originated in Asia, which now also affects Africa and
which has led to outbreaks in the Near East and in Europe.
Livestock production has significantly changed over the past decades with industrial systems and
their associated value chains being dominant in developed countries and becoming increasingly
important in developing countries where traditional livestock production still provides an important
source of income for a large share of the population. Industrial systems are characterized by
large numbers of animals of similar genotype being raised, predominantly in confinement, for one
purpose with rapid population turnover at a single site. This paper provides evidence suggesting
that without commensurate private and public investments in bioexclusion and biocontainment
measures these industrial systems can result in increased animal and public health risks.
Risks to animal and public health arising from livestock production are a local and global
externality that may not be properly reflected in the costs of production and the authors argue
that more equitable distribution of these costs requires well informed public intervention to shape
PPLPI Research Report
2
private incentives for the implementation of biosecurity so that livestock production aligns with
public health interests.
2. Introduction
Recent emergence of contagious human diseases from animal populations, such as Nipah virus
infection in 1999, SARS in 2002 and the current epidemic of highly pathogenic avian influenza
(HPAI) caused by H5N1, from which nearly 200 people have died since 2004, have heightened
public awareness of possible linkages between wild animal populations, livestock production and
global public health. Because of human and livestock population growth, changes in livestock
production, the emergence of worldwide agro-food networks, wild animal trade, and significant
changes in personal mobility, human populations increasingly share a global commons of
disease risk, among themselves and with other animal species.
It is, therefore, not surprising that three out of four emerging pathogens affecting humans over
the past ten years have originated from animals or animal products (Taylor et al., 2001). HPAI
offers a recent example of how a new viral challenge has possibly emerged from wildlife, by first
adapting to domestic livestock and then circulating within these populations with the risk of
acquiring the ability to infect humans and and of sustained human-to-human transmissibility. The
case of HPAI also highlights how conditions of animal husbandry and the livestock supply chain
can influence health risks for human populations worldwide. While individual countries have
taken steps to contain outbreaks and to dissemination of HPAI, pathogens can move by
unregulated and unrecognized pathways, such as on airborne dust, in animal wastes utilized in
agriculture, in ballast water on ships, and in migrating wild animals. It is imperative to understand
the formal and informal networks of exchange in order to develop evidence-based policies to
anticipate and prevent emergence of novel zoonoses.
To elucidate the linkage between livestock production and the global commons of disease risk,
we draw upon recent experiences provided by different influenza A virus (IAV) incursions into
domestic livestock populations, the most notable one being the ongoing HPAI H5N1 epidemic
that originated in Asia, which now also affects Africa and with outbreaks having been recorded in
the Near East and in Europe.
This paper reviews changes in food animal production that have occurred over the past decade,
and then summarizes the current understanding of the emergence of distinct influenza viruses.
Direct and indirect evidence, drawn primarily from HPAI outbreaks in areas of high poultry
density, is presented on aspects of biosecurity and biocontainment that are relevant to the
transmission of influenza viruses in industrial poultry production systems. Incentives associated
PPLPI Research Report
3
with the management of animal and public health risks are discussed based on the evidence
presented.
3. Changes in Food Animal Production
As countries have become more affluent, demand for livestock-derived food has substantially
increased, leading to a major transformation of global animal food production. The linkages
between sub-sectors of the animal industry, such as feed manufacturers, breeding companies,
livestock keepers and processors, as well as production practices have changed significantly
over the past decades, with potentially serious consequences for disease risks. These changes
include significant increases in livestock populations and densities, concentrated industrial food
animal production, using fewer but more productive livestock breeds and lines, with, in the case
of poultry and pigs, hybrid animals providing the end product, specialization in and vertical
integration of stages of production (e.g. breeding, raising, finishing), and major changes in the
design of animal housing facilities.
Industrial food animal production involves high throughput animal husbandry, in which thousands
of animals of similar genotypes are raised for one purpose (such as pigs, layer hens, broiler
chickens, ducks, turkeys) with rapid population turnover at one site under highly controlled
conditions, often in confined housing, with nutrient dense, industrial feeds replacing access to
forage crops. In the US, these facilities are known as animal feeding operations (AFOs).
Concentrated animal feeding operations (CAFOs) are a type of AFO, which have a regulatory
definition in the US as facilities that have animals stabled or confined for at least 45 days out of
any 12 month period and holding at least 1,000 animal units (AUs) (1 AU = 1000 pounds body
weight).
Globally, pig and poultry production are the fastest growing and industrializing livestock sub-
sectors with annual production growth rates of 2.6 and 3.7 percent over the past decade (Table
1). As a consequence, in the industrialized countries, the vast majority of chickens and turkeys
are now produced in houses in which between 15,000 and 50,000 birds are confined throughout
their lifespan. Increasingly, pigs and cattle are also raised under similar conditions of
confinement and high density. The trend towards industrialization of livestock production can
also be observed in developing countries, where traditional systems are being replaced by
intensive units at a rate of 4.3 percent of animal holding units per year, with much of that
increase occurring in Asia, South America and North Africa (CAST, 1999). In developing
countries a large proportion of industrial units are sited in or close to human population centres.
Over the same time, the human population has grown by almost 700 million people, again, with
PPLPI Research Report
4
much of this growth occurring in the developing world and in particular affecting urban
populations.
Table 1: Changes in global human population, pig and poultry inventories, and production and
international trade of pig and poultry meat between 1996 and 2005.
1996 2005 Annual growth (%)
Human population 5,762 6,451 1.1
Inventory
Pigs (million) 859 963 1.1
Poultry (million) 14,949 18,428 2.1
Production
Pig meat (thousand tons) 79,375 103,226 2.6
Poultry meat (thousand tons) 56,408 81,856 3.7
International trade
Pig meat (thousand tons) 6,398 9,557 4.0
Poultry meat (thousand tons) 5,359 9,234 5.3
Source: FAOSTAT
Industrialization of food animal production has led to major increases in livestock productivity,
which are to a large extent the result of genetic progress and the development of diets tailored to
specific stages of production. For poultry and pigs, industrial production is organized in stages
which separate primary breeders, multipliers and producers (often contract farmers). A small
number of globally operating companies form the apex of the breeding pyramid. Different
production stages are often undertaken at different sites, leading to significant movement of live
animals, at times across national borders. In 2005, for example, more than 25 million live pigs,
i.e. more than 2 million pigs per month, were traded internationally (FAOSTAT). In the US, there
is a huge movement of unfinished animals, for example feeder pigs from the Carolinas to the
Cornbelt. In 2001, 27 percent of pigs in the US were moved from one state to another (or more)
(Hennessy, 2004). Investigations in relation to the recent HPAI outbreak in the UK revealed that
links in poultry production within one enterprise between facilities located in the UK and in
Hungary involved movement of hatching eggs, birds and poultry products four times before the
final product reached retail (Lucas, 2007). Animal slaughter operations have also become
concentrated, leading to larger average distances for transport to slaughter (Burrell, 2002; MLC,
2001).
The consolidation of poultry and pig production for reasons of competitive advantage has also
affected the geography of food animal populations. Over the past 60 years, the geographic
distribution of both pig and poultry production in the US, for example, has become more
clustered, with poultry production now being highly concentrated in the southeastern states and
pig production concentrated in some of these same states, as well as in the Midwest. Similar
trends have occurred worldwide with pig and poultry populations increasingly concentrated in
PPLPI Research Report
5
particular locations which are often geographically coincident. An approximate overview of the
global distribution of poultry and pig population densities is provided by Figure 1. With the
geographical concentration of pig and poultry production, there has been an associated increase
in global trade and movement of pig and poultry meat products, which over the past decade has
increased at an average annual rate of 4.0 and 5.3 percent, respectively (Table 1). Although
trade can be considered safe when conducted in line with OIE regulations, poultry trade has
been implicated in the cross-border spread of H5N1 in Asia and Africa (Kilpatrick et al., 2006).
Figure 1: Global poultry (top) and swine (bottom) distributions.
FAO 2007
Industrial pig and poultry production with its geographic intensity and being coincident for the two
species, and with the regular movement of animals between production stages provides
significant opportunities for interactions between large populations of confined poultry and / or
PPLPI Research Report
6
pigs and thus has potential consequences for the development and transmission of some
zoonotic disease agents. The proximity of thousands of confined animals increases the
likelihood of transfer of pathogens within and between these populations, with consequent
impacts on rates of pathogen evolution. Furthermore, animals held in confinement produce large
amounts of waste, which need to be disposed of. Much of this waste, which may contain large
quantities of pathogens, is disposed of on land, posing an infection risk for wild mammals or
avians. Poultry house waste is also utilized in aquaculture, a form of food animal production,
which results in the creation of artificial wetlands and thereby increases direct opportunities for
contact with wild avians.
4. Emergence of Novel Influenza A Viruses
Evidence suggests that non-domesticated aquatic birds are the primary reservoir of influenza A
viruses (IAVs) and probably all IAVs of mammals have ancestral links to avian lineages (Webby
and Webster, 2001). An important feature of IAVs is their capacity to undergo molecular
transformation and to adapt to new host populations1 and thereby acquire the potential to cause
major disease outbreaks. One way of classifying IAVs into sub-types is on the basis of their
haemagglutinin (HA) and neuraminidase (NA) antigens. Known hosts for different IAV HA and
NA types are presented in Table 2.
Table 2: Known hosts for different HA and NA influenza A virus subtypes.
Host Role in
epidemiology HA Subtype NA Subtype
Waterfowl Reservoir All 16 subtypes All 9 subtypes
Domestic ducks Reservoir Wide rangea Wide rangea
Humans Reservoir
Spillover H1, H2, H3,
H5, H7 N1, N2, N3, N7
Pigs Reservoir
Spillover H1, H3,
H4, H9 N1, N2
Horse Reservoir H3, H7 N7, N8
Cattle Reservoir H3 N2
Cat, Tiger Spillover H5 N1
Whale Reservoir H3, H13 N2, N9
Seal Reservoir H4, H7 N7
Chicken & Turkey Reservoir
Spillover H9
H1, H5, H6, H7 N1, N2, N3, N7, N9
Source: Adapted from Webster et al., 2006; and Li et al., 2003
1 Two distinct genetic processes underlie antigenic transformation of IAVs: antigenic drift and antigenic shift.
Molecular changes result from point mutations in the viral haemagglutinin (HA) and neuraminidase (NA)
glycoproteins. Antigenic changes occur in conjunction with the selection pressure applied by the host immune
response. Less frequent, but of potentially far greater impact is the process of antigenic shift, which can result
when a single cell is infected by two distinct IAVs giving rise to progeny viruses containing genetic material from
both parental viruses. This reassortment can completely change the molecular profile of IAVs and thereby
facilitate virus spread through a host population, potentially giving rise to major epidemics.
PPLPI Research Report
7
Another criterion for classifying IAVs is their pathogenicity, i.e. their ability to cause disease in
experimentally inoculated chickens. Thus virulent viruses leading to severe disease and high
levels of mortality are classified as highly pathogenic AI (HPAI) while viruses causing much
milder disease (primarily mild respiratory disease, depression and reduction in egg production in
laying birds) are classified as low pathogenicity AI (LPAI).
To date, only IAVs of the H5 and H7 subtype have been shown to cause HPAI, but not all H5 and
N7 IAVs are highly pathogenic. Current evidence suggests that HPAI viruses are not endemic in
wild bird populations and only arise as a result of molecular changes from low pathogenicity IAVs
(LPAI) that occur after introduction into domestic poultry from wild birds (Capua and Alexander,
2004), although one outbreak of HPAI H5N3 that could not be linked to domestic poultry has
been recorded in terns in South Africa in 1961.
Evidence suggests that introduction of LPAI viruses into domestic poultry populations usually
occurs as a result of direct or indirect contact with wild waterfowl or domestic ducks. Various
incursions of LPAI virus into domestic poultry have been reported over the past decade, mostly in
North America and Europe, but also in Mexico, Chile and Pakistan, details of which have been
compiled by Capua and Alexander (2004). In Mexico, 1994, a LPAI H5N2 virus mutated into a
HPAI virus and spread to Guatemala in 2000 and to El Salvador in 2001, presumably via trade
(ibid). LPAI H5N2 is now established in domestic chicken populations in Central America. In
both, the 2003 H7N7 HPAI epidemic in the Netherlands (Stegeman et al., 2004) and the 2004
H7N3 HPAI epidemic in British Columbia, Canada (Power, 2005), it appears that LPAI infections
in poultry preceded the emergence of HPAI in different poultry houses on the same commercial
farms. In Italy, the 1999/2000 H7N1 HPAI epidemic was preceded by 199 reported outbreaks of
LPAI H7N1 in the same region. On the other hand, between the mid-1990s and 2004 H7N2
LPAI virus appears to have been endemic in parts of the US, linked to live poultry markets,
without conversion to an HPAI virus.
Overall, over the past 10 years reports of HPAI have increased dramatically with ten distinct
minor or major epidemics reported worldwide since 1997 while 14 outbreaks have been recorded
over the preceding 40 years. It is however important to acknowledge the limits in detection and
reporting of HPAI and LPAI outbreaks when attempting to interpret this apparent increase in
disease incidence.
In addition to the apparent increase in outbreaks caused by H5 and H7 LPAI and HPAI viruses,
H9N2 LPAI virus has also spread through domestic poultry populations in the 1990s and become
endemic in commercial poultry in China, the Middle East and elsewhere. H9N3 outbreaks are
said to have occurred in China in 1994 (Yingjie, 1998, quoted in Capua and Alexander, 2004).
PPLPI Research Report
8
Pigs may potentially assume an important role in the emergence of novel IAVs as they can be
infected by either avian or human viruses (Kida et al., 1994; Schulz et al., 1991). Gilchrist et al.
(2007) note the proximity of concentrated poultry and swine operations as a source of disease
risk from IAVs although so far there have only been reports of AI viruses from poultry in pigs and
not vice-versa. Classical H1N1 swine influenza viruses are very similar to the virus implicated in
the 1918 – 1919 human influenza pandemic and circulate predominantly in the US and Asia.
H3N2 viruses of human origin have been isolated from pigs in Europe and the Americas shortly
after their emergence in humans (Webby and Webster, 2001) and are now endemic in pigs in
southern China (Peiris et al., 2001), where they co-circulate with H9N2 viruses with the potential
of reassortment with H5N1.2 In the USA, outbreaks of respiratory disease in swine herds have
been caused by IAVs which arose from reassortment of human H3N2, classic swine H1N1 and
avian viral genes (Zhou et al., 1999)
Thus, it appears that IAVs are now fairly widespread in commercial poultry (and to a lesser
extent pig) populations and that highly pathogenic strains are emerging or being detected with
growing frequency. This may be due to the substantial increase in poultry numbers (25 percent)
over the last decade and / or to changes in poultry production, as well as to enhanced diagnostic
capacities and better disease reporting and / or to changes in poultry production (Capua and
Alexander, 2006). Although the specific role of CAFOs in the emergence of novel diseases is not
well understood, the US Council for Agriculture, Science and Technology (CAST, 2005) warns
that a major consequence of modern industrial livestock production systems is that they
potentially allow the rapid selection and amplification of pathogens.
5. Biosecurity and Disease Transmission in Industrial Systems
Biosecurity has been broadly defined as any practice or system that prevents the spread of
infectious agents from infected to susceptible animals, or prevents the introduction of infected
animals into a herd, region, or country in which the infection has not yet occurred (Radostits,
2001). More specifically, farm biosecurity combines ‘bioexclusion’, i.e. measures for preventing a
pathogen from being introduced to a herd/flock, and ‘biocontainment’, which addresses events
after introduction, i.e. the ability for a pathogen to spread amongst animal groups within a farm or
of being released from the farm (Dargatz et al., 2002). The majority of farms devote most
resources to bioexclusion although large multiunit farms also invest in biocontainment to prevent
spread to other units.
2 For instance, in 1999, IAV subtype H9N2, was isolated from two girls in Hong Kong, who recovered from
influenza-like illnesses (Peiris et al., 1999).
PPLPI Research Report
9
Disease transmission between farms depends on the combination of individual bioexclusion
practices and biocontainment measures. The importance of the latter is largely determined by
the magnitude and direction of resource (and waste) flows across and between farm populations.
In the livestock sector, these flows can be complex because of specialization at different stages
of animal production and processing and intricate formal and informal market chains. Large
scale production at all stages is highly concentrated, with small numbers of large, intensive
facilities and even fewer responsible enterprises. Larger facilities are often assumed to
implement more advanced biosecurity measures, but the intensity of their operations also poses
higher risks for infection and pathogen propagation. Over one cycle of 10,000 broilers for
example, around 42 tons of feed and 100,000 l of water have to be supplied to the birds, and
unless stringent measures are taken these remain potential routes of introduction, while around
20 tons of waste will be produced requiring disposal.
The design and operational requirements of large scale poultry and swine houses also result in
compromises of biosecurity. Because confinement of thousands of animals requires controls to
reduce heat and regulate humidity, poultry and swine houses are ventilated with high volume
fans that result in considerable movement of materials into the external environment (Jones et
al., 2005) and dust emissions, visible (particles >10 microns) and invisible (particles <10
microns), from poultry barns housing thousands of birds can be substantial. Measurement of
aerosol emissions from a broiler operation revealed a million fold elevated concentration of
aerosolized invisible dust near a poultry barn fan as compared to outdoor air in a semi-rural area
(Power, 2005). These particles have the potential to remain suspended in the air for up to
several days, and, depending on prevailing winds, poultry barn dust could be found several
kilometers from its source. Although little is known about the survival of IAVs on dust particles,
high concentrations of infectious AI virus have been detected in air samples from an infected
barn while low levels of virus were detected in one of nine samples some 800 m from an infected
barn. However, it was not determined if this sample of virus was infectious (Power, 2005).
Other pathogens have been shown to readily move in and out of poultry and swine houses.
Pathogen entry was demonstrated in a recent study of Campylobacter-free broiler flocks, housed
in sanitized facilities, using standard biosecurity measures, and fed Campylobacter-free feed and
water. Seven out of ten flocks became colonized with Campylobacter by the time of slaughter
and two flocks were colonized by Campylobacter strains genetically indistinguishable from
strains isolated from puddles outside of the facility prior to flock placement (Bull et al., 2006).
Although the route of entry was not determined, this study clearly shows that some pathogens in
the immediate environment of a poultry facility have a high chance to overcome standard
bioexclusion measures. Contaminated air exiting the house via ventilation systems becomes a
source of Campylobacter to the external environment and microbes may be carried some
distance by wind and surface water transport. Campylobacter strains with identical DNA
PPLPI Research Report
10
fingerprints to those colonizing broilers have been measured in air up to 30 m downwind of
broiler facilities housing colonized flocks (Lee et al., 2002).
Insects are another means for pathogen entry to and exit from poultry houses. Research carried
out during an HPAI outbreak in Kyoto, Japan in 2004, found that flies caught in proximity to
broiler facilities where the outbreak took place, carried the same strains of H5N1 influenza virus
as found in chickens of an infected poultry farm (Sawabe et al., 2004). A study in Denmark
found that as many as 30,000 flies may enter a broiler facility during a single flock rotation in the
summer months (Hald et al., 2004).
Evidence that bioexclusion measures of (at least some) large-scale industrial poultry operations
are not impenetrable by IAVs is provided by reviewing the HPAI H5N1 outbreaks reported to OIE
(www.oie.int). HPAI H5N1 for instance has been reported to have caused outbreaks in large-
scale industrial poultry units with supposedly high biosecurity standards in South Korea (a
300,000 bird unit), Russia (two 200,000 bird units) and Nigeria (a 50,000 bird unit) in 2006, and
in the UK (a 160,000 turkey unit) in 2007. Moreover, large(r) industrial-type flocks appear to be
overrepresented in the list of HPAI H5N1 outbreaks reported to OIE vis-à-vis outbreaks in
backyard / village flocks in relation to their respective shares of total national flocks. Around 40
percent of the HPAI H5N1 outbreaks in domestic poultry reported to OIE between late 2005 and
early 2007 occurred in poultry units of 10,000 birds or more (more than 25 percent occurred in
units of more than 10,000 birds), while, even in many OECD countries, e.g. Germany, France,
UK and Belgium, less than 10 percent of flocks consist of more than 10,000 birds. It is likely that
some of this overrepresentation of large industrial-type flocks in reported outbreaks is due to
ascertainment bias because outbreaks are more likely to be detected and reported in large-scale
operations than in backyard systems3. Nevertheless, it demonstrates that, whatever the source
of the virus (wild avians, backyard poultry, other commercial units), bioexclusion measures
implemented by some large-scale industrial poultry units, including those in industrialized
countries, may be insufficient to protect against H5N1 incursion when challenged.
This empirical evidence of sub-optimal biosecurity of a proportion of commercial operations is
substantiated by direct observations and points to a need for greater oversight and or regulation
of biosecurity of industrial poultry production. For instance, Power (2005) reports that more than
three quarters of commercial broiler and table egg farms in Fraser Valley, Canada, had indicated
in a survey that they did not provide disinfection footbaths nor required a change of clothes /
coveralls by employees on entering their barns. In Maryland, US, Price et al. (2007) found that
3 But note that assuming a lag of 8 to 10 days between infection of a flock and notable increase in mortality and a
45-day cycle for broilers, between 15 and 20 percent of infections of broiler flocks are expected to go undetected.
PPLPI Research Report
11
most poultry workers are provided little or no protective clothing or opportunities for personal
hygiene or decontamination on site, and that they take their clothes home for washing.
Once IAVs have entered industrial production facilities they can be transferred between
operations by contaminated shipping containers and trucks. Given that a gram of infected faeces
can contain as many as ten billion infectious virus particles, a small amount of contaminated
faecal material or litter adhering to boots, clothing or equipment may be sufficient to transmit
virus from an infected to a susceptible flock (Power, 2005). Biocontainment of IAV, once poultry
are infected thus poses a substantial challenge, even in countries with advanced animal-health
services and depends on early detection of outbreaks and action before the virus has spread
widely in infected premises.
6. HPAI Epidemics in Densely Populated Poultry Production Areas
The 1999-2000 H7N1 epidemic in northern Italy, the 2003 H7N7 epidemic in the Netherlands and
the 2004 H7N3 epidemic in Fraser Valley (British Columbia, Canada) highlight the difficulties
faced by animal health authorities when HPAI infects flocks in densely populated poultry
production areas (DPPAs). Table 3 provides a summary of these three epidemics.
Table 3: Summary of HPAI outbreaks in densely populated poultry production areas.
Italy1
1999 – 2000 Netherlands
2003 Canada
2004
Farm type Industrial Backyard /
hobby Industrial Backyard /
hobby Industrial Backyard /
hobby
Farms in the
affected area 3,271 na 1,362 17,431 app. 800 533
Farms declared
infected 382 10 233 22 42 11
Infection risk 12% na 17% 0.1% app 5% 2%
Farms
depopulated all in 5,500 km2 1,255 17,421 410 533
Proportion farms
depopulated 100% 92% 100% app 50% 100%
Birds culled app 16 million app 30 million 13.6
million 17,977
1 Figures are for Veneto and Lombardia, the hardest hit provinces, source: Capua pers. comm..
In all three epidemics animal health authorities noted the high density of poultry farms with
frequent contact between farms by trucks and surprisingly low levels of biosecurity practiced by
some operators as having been associated with the considerable spread of virus (Capua et al.,
2002; Stegeman et al., 2004; Power 2005). Retrospective analysis of between-flock
transmission in two distinct outbreak areas in the case of the Netherlands and of an H7N3 LPAI
epidemic in Italy in 2003-2004 estimated reproduction ratios (Rh, the average number of
PPLPI Research Report
12
secondary infections caused by 1 infectious flock) of 6.5, 3.1 and 2.9 respectively (Stegeman et
al., 2004; Capua and Marangon, in press) prior to the implementation of control measures. This
clearly indicates that standard bioexclusion and biocontainment measures in a number of the
predominantly industrial flocks were insufficient to prevent disease spread, and that disease
detection or reporting was delayed. For caged layers, for example, Capua and Alexander
(2006b) cite a ‘flock incubation period’ of up to 18 days, which, in areas with intense between-
farm traffic, provides sufficient time extensive movement of the virus.
Control of the three epidemics was only achieved through massive depopulation of commercial
and backyard / hobby flocks (vaccination was not applied). Retrospective analysis of the Dutch
outbreak also revealed that between-flock transmission continued even after the implementation
of strict movement controls in the affected areas. The authors conclude that containment of the
epidemic was more likely to be the result of the depletion of susceptible flocks by depopulation
than the reduction of the transmission rate through biocontainment measures (Stegeman et al.,
2004).
The lower probability of infection of backyard / hobby flocks compared to that of industrial flocks
in the Dutch and Canadian epidemics, in which samples were collected from backyard / hobby
flocks in the vicinity of infected industrial flocks, is consistent with findings from the HPAI
epidemic in Thailand in 2004 and the 2002 outbreak of Newcastle disease in Denmark (Otte et
al., 2007) and suggests that commercial transactions are an important route for disease
transmission between industrial farms.
7. The Animal:Human Interface
Over the past 100 years, the sudden emergence of antigenetically different strains of IAVs
transmissible among humans leading to human influenza pandemics has occurred in 1918
(H1N1, Spanish flu), 1957 (H2N2, Asian flu), and 1968 (H3N2, Hong Kong flu) (Webby and
Webster, 2001). Studies on these pandemic viruses have shown that all three contained an
avian component (Capua and Alexander, 2006b).
A number of studies demonstrate that IAVs from animals can move across the animal:human
interface in the context of food animal production and processing, and therefore, livestock
keepers and people otherwise in close contact with live animals are the most likely group to act
as ‘bridge’ for IAVs between livestock and human communities at large (Saenz et al., 2006),
should an IAV acquire the capability of sustained human-to-human transmission.
Myers et al. (2006), for example, report that swine farmers had higher titres of H1N1 and H1N2
antibodies and greatly elevated risks of seropositivity to these two influenza A viruses (35.3 and
PPLPI Research Report
13
13.8 odds ratios respectively), as compared to community referents. A comprehensive study of
the outcome of exposure to H5N1 has been conducted in Hong Kong during the 1997 outbreak
(Bridges et al., 2002). In this study, 1,525 poultry workers and 293 government workers involved
in culling activities and disease investigations were assessed for risk factors for seropositivity.
Only occupational tasks involving contact with live poultry were associated with increased risks of
seropositivity, and the probability of carrying H5 antibodies increased with increased numbers of
such occupational contacts from around 3 percent at the low end to nearly 10 percent at the high
end. A study in Italy found anti-H7 antibodies in 3.8 percent of serum samples from poultry
workers during the period in 2003 when LPAI H7N3 was circulating (Puzelli et al., 2005). A study
of H7N7 infection among persons reporting influenza-like symptoms was conducted in the
Netherlands in association with the 2003 H7N7 HPAI epidemic (Koopmans et al, 2004). H7 virus
was detected by PCR in ocular swabs of 86 of 453 persons (18.9 percent) calling into the health
department. The highest detection rates were found in poultry cullers (41.2 percent), followed by
veterinarians (26.3 percent) and farmers and their family members (14.7 percent).
Fortunately, thus far, the recent HPAI viruses do not easily infect humans, have not acquired
sustained human-to-human transmissibility and only the Asian HPAI H5N1 appears to have a
high case fatality in infected humans. Increased exposure of humans to avian IAVs undoubtedly
increases the likelihood that avian and human influenza viruses infect the same individual, which
could facilitate the emergence of a ‘novel’ virus, but the molecular changes required for efficient
transmission of IAVs among humans remain poorly understood. Thus, in a ferret model (used to
investigate the transmissibility of human influenza viruses) two H5N1 avian-human reassortant
viruses and one H3N2 human-avian reassortant virus exhibited reduced replication efficiency
and no transmission, suggesting that H5N1 viruses may require further adaptive steps in order to
develop pandemic potential (Maines et al., 2006), the likelihood of which remains unknown.
8. Management of Animal and Public Health Risks
Animal and public health risks have a complex relationship with economic incentives. Some
responses to market and regulatory signals elevate infection risk, including the scope and term of
disease incubation, while others reduce risk levels. Generally speaking, incentives for risk
reduction are associated with a ‘virtuous cycle’ of product quality, reputation, and profit.
Behaviours that increase risk usually arise from uncertainty, loss aversion, or illicit profit
incentives.
Although the effects of HPAI primarily become evident in domestic poultry, disease outbreaks
have repercussions that go far beyond primary producers. These repercussions are to a large
extent a result of public and private responses to the (real or perceived) risk of the disease and
PPLPI Research Report
14
its potential effects rather than to the actual, direct on-farm impact. Thus, any control programme
needs to take into account this plurality of stakeholder reactions and interests as well as their
potential to contribute to, and their incentives to undermine control programmes. It must be
recognized that some individuals and enterprises may actually gain from an animal disease
outbreak affecting others.
Disease risk can be considered as the outcome of an initial process of infection, followed by
within farm / flock transmission, exposure of other actors in the production process, and reaction.
The magnitude of each of these processes can be positively or negatively affected by economic
incentives and policy interventions. For example, the risk posed by an infectious disease related
to food animal production may be influenced by:
Providing incentives and introducing regulations to promote adoption of practices that
reduce the probability of initial outbreaks (e.g. bioexclusion measures);
Introduction of incentives and standards that facilitate early detection, on-farm
containment, and eradication;
Establishing incentives and standards to reduce release from farms and other routes of
exposure of others (e.g. biocontainment measures); and
Developing strategies to mitigate disease impact, for example through emergency or
preventive vaccination in high risk areas.
It would seem logical that ‘private’ decision makers will primarily focus on bioexclusion and less
so on on-farm biocontainment, since the latter is only relevant once the pathogen has been
introduced into their facilities, and as they are likely to believe that their bioexclusion measures
are sufficient to prevent that from happening.
A critical issue of incentives and disincentives relates to early detection of disease incursion.
The importance of early detection cannot be overstated as the magnitude of disease epidemics
is exponentially related to the time elapsed between pathogen introduction and implementation of
control measures. Timely reaction heavily relies on early detection and disclosure by those in
daily contact with livestock, however current disease control policy tends to encourage individual
behaviour along the old adage ‘shoot, shovel and shut up’. Incentive systems need to be
devised that encourage ‘good behaviour’ while penalizing ‘bad behaviour’. A dilemma in the
latter will be that the required disincentives may run counter to the need for incentives for early
disclosure. Compensation schemes that offer equal compensation for lost animals, irrespective
of timing of disclosure fail to create an incentive consistent with the policy objective of early
reaction (Graming et al., 2006). Likewise, depopulation of entire premises in the event of
selected pathogen entry into a poultry house, for example, does not offer an incentive for
PPLPI Research Report
15
reporting the latter or for major investments in within-farm biocontainment (let alone between-
farm biocontainment).
Compensation for depopulation usually only covers (partial) costs to producers that are directly
affected by the depopulation measures, while the other costs of disease control measures, such
as movement restrictions, on other market participants are not normally covered. Unless an
appropriate balance is struck between the control and compensation systems, farmers in a
quarantined area may have an incentive to introduce disease onto farms with consequential
depopulation and partial compensation rather than to suffer the indirect impacts of disease
control measures.
As it can be more profitable to raise or move animals for ‘finishing’ to locations where animal feed
is abundant, e.g. close to feed mills, than to continuously move feed over large distances, areas
of high livestock density have emerged in a number of regions worldwide. Semi-vertical
integration of production processes, where a large company supplies young stock and feed,
while farmers provide animal housing and labour, has often not been accompanied by systematic
spatial planning of the units in the system. Although spatial concentration is convenient from an
organizational point of view, as illustrated in the case of the HPAI outbreaks in DPPAs, it has
serious drawbacks for the control of epidemic diseases. In the European Union (EU), location-
specific disease risks, as for example determined by concentration of production units or
proximity to wildlife reservoirs, are not factored into the cost of production because the current
tax-financed system of disease outbreak response acts as a free insurance of last resort, and
thereby results in the generation of avoidable amounts of ‘risky’ production (Jansson et al.,
2006). The same authors show that although moving to risk-based compulsory insurance for
FMD, financed by the livestock sector, would not result in major relocation of dairy production
within the EU, it would lead to a fairer distribution of disease control costs between member
countries and between consumers and producers. Location of poultry and pig production, which
does not rely on the availability of grazing land, might however shift in response to a risk-based
insurance system.
The benefits of freedom from highly contagious diseases are shared by all market participants,
i.e. non-exclusive, and therefore have similarities with common property resources. But as
achievement and maintenance of disease freedom is heavily dependent on individual behaviour,
livestock keepers may become locked into a ‘Nash equilibrium’ in which no one has anything to
gain by unilateral action. Public intervention is required to align individual and societal interests,
but to do so successfully requires detailed understanding of the individual incentives of market
participants and of the full set of consequences of potential interventions.
PPLPI Research Report
16
9. Conclusions
Intensification of food animal production is an entrepreneurial response to the increasing demand
for food of animal origin, at times supported by public investment. Satisfying current global
demand for poultry meat by traditional systems would require a dramatic expansion of the poultry
population as meat offtake per bird per year in traditional systems is about one tenth that of
industrial systems (a similar ratio would hold for egg production). Therefore, from the point of
view of meeting the growth in demand, the world has to depend upon some of the technologies
of large scale industrial type production. However, as CAST (2005) states “the cost of the
increased production efficiency of these industrial systems is the necessity for heightened
biosecurity and improved surveillance to safeguard global public health.” Hennessy et al. (2004)
have shown that the risk of infectious disease can create decreasing returns to scale, when
technology is otherwise increasing returns to scale. The same holds true for waste disposal.
Thus, once these externalities are factored into the production costs of industrial systems, the
economically optimum size and siting of operations may change.
Concentration of food animal production and the unregulated ‘evolution’ of densely populated
livestock production areas not only result in major environmental burdens, but also generate
significant animal and public health risks. Recent experience has shown that disease
containment in these areas is extremely difficult, and in the case of outbreaks can result in the
ethically rather questionable destruction of millions of healthy birds. An unrecognized aspect of
industrial food animal production concerns worker exposures (Price et al, 2007) to zoonotic
diseases. Saenz et al. (2006), using mathematical transmission models, show that when CAFO
workers comprise more than 15 percent of a community they may act as IAV amplifiers for the
community as a whole.
Although understandably H5N1 is currently of major global concern, IAVs in general in poultry
and swine, kept whichever way, should be closely monitored internationally as human exposure
to ‘silently’ circulating IAV is just as likely (or unlikely) to lead to emergence of a potentially
pandemic strain as exposure to HPAI.
The trend towards division of labour (within and between countries) for different stages of food
production and processing increases the risk of pathogen transfer over large distances even if
production facilities are not highly concentrated. An example of this effect is the Longtown
livestock market during the 2001 foot-and-mouth disease epidemic in Great Britain which acted
as a source of infection for many different herds and flocks, and thereby resulted in the spread of
infection to several geographically dispersed areas in the country (Gibbens and Wilesmith,
2002). The risk of pathogen transfer via animal movements could be significantly reduced by
enforcement of minimum time intervals between movement of animals onto and off farms
PPLPI Research Report
17
While the role of industrial food animal production in the emergence of drug resistant bacteria is
beyond doubt, its role in the emergence of novel virus strains requires further investigation. As
all parasites, viruses face a life-history trade-off between persistence, i.e. host survival, and
fecundity, i.e. host exploitation (Galvani, 2003). Maximising fecundity may lead to an increase in
virulence and in a number of avian influenza outbreaks, highly pathogenic viruses have indeed
emerged after multiplication in large flocks of chickens. However, as HPAI viruses have
occasionally been reported before the development of large-scale industrial poultry production,
the latter are not a pre-requisite for the emergence of virulent strains.
Policy makers in both developing and developed countries appear to accept that large-scale
industrial farms have higher standards and self-discipline in biosecurity, while smallholders need
more rigorous public oversight. The realities of animal health, economic incentives, and the
public interest in disease prevention are far too complex for simple rules of thumb like this to be
optimal for society. Only a comprehensive, evidence-based approach to risk management can
sustain a safe food supply. Although it is in the self-interest of individuals to enhance their
bioexclusion measures, biocontainment has a strong collective action component requiring public
intervention. Thus, at least initially, it might be more cost-effective for public authorities to ensure
that the small share of large industrial operations, which is responsible for a large share of
resource, product and waste flows implements high biosecurity standards.
Given the proven difficulties of containing the spread of HPAI in areas of high flock density, the
wisdom of creating poultry production zones, as envisaged by some governments, seems at
least questionable unless these are properly planned and adequate land is provided to allow
appropriate dispersal of units. To be effective, such zones would require careful planning of all
aspects of food animal production following the principles of ‘industrial ecology’, which focuses
on closing cyclical processes and reducing transfers. Development of such solutions requires a
10 to 20 year time horizon and institutionalized collaboration between a large number of
stakeholders (de Wilt et al., 2000). Shorter term health risk-based decisions on siting of
industrial production units should be based on application of tools akin to those developed to
assess the cumulative impacts of multiple CAFO facilities in a watershed subunit as described by
Osowski et al. (2001).
PPLPI Research Report
18
10. References
Bridges, C. et al. Risk of influenza A (H5N1) Infection among Poultry Workers, Hong-Kong,
1997-1998. J Infect Dis 2005; 192:1318-1322
Bull, S. et al. Sources of Campylobacter spp. Colonizing Housed Broiler Flocks During Rearing.
Appl Env Microbiol 2006; 72:645-652
Burrell, A. Animal Disease Epidemics: Implications for Production, Policy and Trade. Outlook on
Agriculture 2002; 31(3):151–60
Capua, I. et al. The 1999-2000 Avian influenza (H7N1) Epidemic in Italy: Veterinary and Human
Health Implications. Acta Tropica 2002; 83:7-11
Capua, I. and D.J. Alexander. Human Health Implications of Avian Influenza Viruses and
Paramyxoviruses. Eur J Clin Microbiol Infect Dis 2004; 23:1-6
Capua, I. and D.J. Alexander. Avian Influenza: Recent Developments. Avian Pathology 2004;
33(4):393-404
Capua, I. and D.J. Alexander. Avian Influenza Infection in Birds – a Moving Target. In: Influenza
and Other Respiratory Viruses 2006a; 1:11-18
Capua, I. and D.J. Alexander. The Challenge of Avian Influenza to the Veterinary Community.
Avian Pathology 2006b; 35(3):189-205
Capua, I. and S. Marangon. The Use of Vaccination to Combat Multiple Introductions of
Notifiable Avian Influenza Viruses of the H5 and H7 Subtypes between 2000 and 2006 in
Italy. Vaccine 2007, in press
CAST. Animal Agriculture and the Global Food Supply. Task Force Report 135, 1999; 92pp
CAST. Global Risks of Infectious Animal Diseases. Issue Paper 28, February 2005; 15pp
Dargatz, D.A. et al. An Introduction to Biosecurity of Cattle Operations. Vet Clin North Am Food
Anim Pract 2002; 18:1–5,
de Wilt, J.G. et al. Agroproduction Parks: Perspectives and Dilemmas. Innovation Network
Rural Areas and Agricultural Systems 2000; http://www.agro.nl/innovationnetwork
FAO. Gridded Livestock of the World, 2007. Rome: Food and Agriculture Organization of the
United Nations, Animal Production and Health Division (in press)
Galvani, A. Epidemiology Meets Evolutionary Ecology. TRENDS in Ecology and Evolution
2003; 18(3):132-139
Gibbens, J.C. and J.W. Wilesmith. Temporal and Geographical Distribution of Cases of Foot-
and-Mouth Disease During the Early Weeks of the 2001 Epidemic in Great Britain. Vet
Rec 2002; 151:407-412
Gilchrist, M. et al. The Potential Role of Concentrated Animal Feeding Operations in Infectious
Disease Epidemics and Antibiotic Resistance. Environmental Health Perspectives 2007;
115:313-316
PPLPI Research Report
19
Graming, B.M. et al. Incentive Compatibility in Risk Management of Contagious Livestock
Disease. In: The Economics of Livestock Disease Insurance. CABI Publishing 2006, pp.
39-52
Hald, B. et al. Flies and Campylobacter Infection in Broiler Flocks. Emerg Inf Dis 2004; 10:1490-
1492
Hennessy, D. et al. Infectious Disease, Productivity, and Scale in Open and Closed Animal
Production Systems. Center for Agricultural and Rural Development, Working Paper 04-
WP 367 2004, 37pp.
Jansson, T. et al. Modelling the Impact of Compulsory Foot and Mouth Disease Insurance in the
European Union. In: The Economics of Livestock Disease Insurance. CABI Publishing
2006, pp. 233-251
Jones, T. et al. Environmental and Management Factors Affecting the Welfare of Chickens on
Commercial Farms in the United Kingdom and Denmark Stocked at Five Densities.
Poultry Sci 2005; 84:1155-1165
Kida, H. et al. Potential for Transmission of Avian influenza Viruses to Pigs. J Gen Virol 1994;
75:2183-2188
Kilpatrick, A. et al. Predicting the Global Spread of H5N1 Avian Influenza. Proceedings of the
National Academy for Sciences of the USA 2006, 103:19368-19373
Koopmans, M. et al. Transmission of H7N7 Avian Influenza A Virus to Human Beings During a
Large Outbreak in Commercial Poultry Farms in the Netherlands. Lancet 2004; 363:587-
593
Lee, M. et al. Class 1 Integron-associated Tobramycin-Gentamicin Resistance in Campylobacter
jejuni Isolated from the Broiler Chicken House Environment. Antimicrob Agents
Chemother 2002; 46(11):3660-3664
Li, K.S. et al. Characterization of H9 Subtype Influenza Viruses from the Ducks of Southern
China: A Candidate for the Next Influenza Pandemic in Humans? J. Virol. 2003;
77(12):6988-6994
Li, K.S. et al. Genesis of a Highly Pathogenic and Potentially Pandemic H5N1 Influenza Virus.
Nature 2004; 430:209-213.
Lucas, C. Bird flu's Link with the Crazy Trade in Poultry. Financial Times. 26 February 2007.
Maines, T.R. et al. Lack of Transmission of H5N1 Avian-Human Reassortant Influenza Viruses
in Ferrets. Proceedings of the National Academy of Sciences of the US 2006;
103:12121-12126
MLC The Abattoir and Meat Processing Industry in Great Britain. Supplement to the 1999
edition. 2001 Meat and Livestock Commission, PO Box 44, Winterhill House, Snowdon
Drive, Milton Keynes, MK6 1AX, UK
Myers, K. et al. Are Swine Workers in the United States at Increased Risk of Infection with
Zoonotic Influenza Virus? Clinical Infectious Diseases 2006; 42:14-20
PPLPI Research Report
20
Osowski, S. et al. A Watershed-Based Cumulative Risk Impact Analysis: Environmental
Vulnerability and Impact Criteria. Environmental Monitoring and Assessment 2001;
66:159-185.
Otte, J. et al. HPAI Risk, Biosecurity and Smallholder Adversity. In: Proc. of the WPSA Asian
Pacific Federation Working Group on Small-Scale Family Poultry Farming Symposium,
Bangkok, Thailand 2007, pp 1-8
Peiris, M. et al. Influenza A H9N2: Aspects of Laboratory Diagnosis. J Clin Microbiol 1999;
37:3426-3427
Peiris, M. et al. Co-circulation of Avian H9N2 and Contemporary ‘Human’ H3N2 Influenza
Viruses in Pigs in Southeastern China: Potential for Genetic Reassortment? J Virol
2001; 75:9679-9686
Price, L.B. et al. Neurologic Symptoms and Neuropathologic Antibodies in Poultry Workers
Exposed to Campylobacter jejuni. Accepted in J Occ Env Med, Feb, 2007).
Power, C. The Source and Means of Spread of the Avian influenza Virus in the Lower Fraser
Valley of British Columbia During an Outbreak in the Winter of 2004 – An Interim Report,
Feb 2005. Available at: http://www.inspection.gc.ca
Puzelli, S. et al. Serological Analysis of Serum Samples from Humans Exposed to Avian H7
Influenza Viruses in Italy between 1999 and 2003. The Journal of Infectious Diseases
2005; 192 BRIEF REPORT
Radostits, O.M. Control of Infectious Diseases of Food-Producing Animals. In: Herd Health:
Food Animal Production Medicine, 2001, 3rd Edition, Saunders Company
Saenz, R.A. et al. Confined Animal Feeding Operations as Amplifiers for Influenza. Vector
Borne and Zoonotic Diseases 2006; 6(4):338-346
Sawabe, K. et al. Detection and Isolation of Highly Pathogenic H5N1 Avian influenza A Viruses
from Blow Flies Collected in the Vicinity of an Infected Poultry Farm in Kyoto, Japan,
2004. Am J Trop Med Hyg 2006; 75:327-322
Schulz, U. et al. Evolution of Pig Influenza Viruses. Virology 1991; 183:61-73
Stegeman, A. et al. Avian Influenza A Virus (H7N7) Epidemic in the Netherlands in 2003:
Course of the Epidemic and Effectiveness of Control Measures. J Infect Dis 2004;
190:2088-2094
Taylor, L.H. et al. Risk Factors for Human Disease Emergence. Phil Trans R Soc Lond B Biol
Sci 2001; 356:983-989
Webby, R.J. and R.G. Webster. Emergence of Influenza A Viruses. Phil Trans R Soc Lond B
2001; 356:1817-1828
Webster, R.G. et al. H5N1 Outbreaks and Enzootic Influenza. Em Inf Dis 2006; 12(1):3-8
Zhou, N.N. et al. Genetic Reassortment of Avian, Swine, and Human Influenza A Viruses in
American Pigs. J. Virol 1999; 73(10):8851-8856
PPLPI Research Report
21
11. Disclaimer, Acknowledgements & Contacts
PPLPI Research Reports have not been subject to independent peer review and constitute views
of the authors only. This paper has significantly benefited from insightful comments provided by
Les Sims, Mo Salman and Martin Upton. The authors would also like to acknowledge the
responsiveness to requests for information on HPAI outbreaks in Italy and Canada by Ilaria
Capua and colleagues of the Istituto Zooprofilattico Sperimentale delle Venezie and of Susan
Wilson of the Canadian Food Inspection Agency. For comments and / or additional information,
please contact:
Joachim Otte and Jonathan Rushton
Food and Agriculture Organization - Animal Production
and Health Division
Viale delle Terme di Caracalla, 00153 Rome, Italy
E-mail: joachim.otte@fao.org and
jonathan.rushton@fao.org
PPLPI website: http://www.fao.org/ag/pplpi.html
David Roland-Holst
Rural Development Research Consortium
223 Giannini Hall, University of California Berkeley, CA
94720 - 3310 USA
E-mail: dwrh@rdrc.net
Dirk Pfeiffer and Ricardo Soares-Magalhaes
Royal Veterinary College - Epidemiology Division,
Dept. Veterinary Clinical Sciences
Hawkshead Lane, North Mymms, Hatfield, Herts,
AL9 7TA, UK
E-mail: pfeiffer@rvc.ac.uk and magalhaes@rvc.ac.uk
Jay Graham and Ellen Silbergeld
Johns Hopkins University Bloomberg School of Public
Health - Department of Environmental Health Sciences
615 N. Wolfe St., Baltimore, MD 21205, USA
E-mail: jgraham@jhsph.edu and esilberg@jhsph.edu
... Bushmeat and backyard farming increase the risk of zoonoses due to the possible spread of diseases from wild animals. Modern intensive farming also contributes to the risk of zoonoses, despite the assumption that modern intensive farming methods have increased biosecurity and biocontainment [6,7,[11][12][13][14][15][16]. ...
... Diseases from outside farms can still enterfor instance, via personnel, veterinarians, and transportation teams. Additionally, diseases from within farms can spread to outside locations via animal waste, treated or untreated contaminated water, air, transportation, and the consumption of animals [15,16,[19][20][21]. Evidence shows, for example, that avian influenza outbreaks occur frequently in large-scale farms, even though this zoonosis naturally occurs in wild birds [14,16]. ...
... The second aim of this research was to investigate whether people are willing to take protective measures to decrease the risk of zoonotic outbreaks. As controls, such as biosecurity, do not eradicate the risk of zoonoses [13,15], we focused on the solution of reducing the consumption of animal products [6]. As such, a protective measure that people can take to decrease the risk of zoonoses is to reduce their consumption of animal products (i.e., meat, dairy). ...
Article
Full-text available
Zoonoses have become more frequent and intense. As intensive animal farming plays a role in the emergence of zoonoses, the increase in intensive animal farming increases the risk of future zoonotic outbreaks. This raises the question of to what extent people are aware that intensive animal farming poses a risk to zoonoses. Furthermore, if people would be made aware, would they be willing to take protective measures, such as reducing their animal food consumption? This was investigated in a representative descriptive study of 1009 Dutch citizens. We measured participants’ perception of the risk of intensive animal farming and their perception of the way animals are treated. We measured their willingness to consume fewer animal products and their opinions on governments banning intensive animal farms. Additionally, participants estimated the percentage of meat from intensive farms that they consume. The main results showed that most participants were aware that zoonoses can occur through intensive animal farming, but not where their meat comes from. The majority of participants were willing to change their animal consumption behavior if this could reduce future zoonotic outbreaks.
... Notably, the current study reports fast Campylobacter (and core microbiota) screening under farm conditions. The decision-action gap is crucial in intensive farming systems such as poultry production, where the high throughput of animal husbandry presents a high risk of developing and transmitting zoonotic agents [49][50][51]. Campylobacter infection is one of the ...
... Notably, the current study reports fast Campylobacter (and core microbiota) screening under farm conditions. The decision-action gap is crucial in intensive farming systems such as poultry production, where the high throughput of animal husbandry presents a high risk of developing and transmitting zoonotic agents [49][50][51]. Campylobacter infection is one of the the last century's most widespread foodborne infectious diseases, and poultry has been considered the origin of 80% of human cases [52,53]. Thus, our study yields two main results. ...
Article
Full-text available
Campylobacter is recognised as one of the most important foodborne bacteria, with a worldwide health and socioeconomic impact. This bacterium is one of the most important zoonotic players in poultry, where efficient and fast detection methods are required. Current official culture methods for Campylobacter enumeration in poultry usually include >44 h of culture and >72 h for identification, thus requiring at least five working shifts (ISO/TS 10272-2:2017). Here, we have assembled a portable sequencing kit composed of the Bento Lab and the MinION and developed a workflow for on-site farm use that is able to detect and report the presence of Campylobacter from caecal samples in less than five hours from sampling time, as well as the relationship of Campylobacter with other caecal microbes. Beyond that, our workflow may offer a cost-effective and practical method of microbiologically monitoring poultry at the farm. These results would demonstrate the possibility of carrying out rapid on-site screening to monitor the health status of the poultry farm/flock during the production chain.
... There is broad consensus that a OH approach promoting animal and plant health enhances biosecurity in food production systems. This, in turn, protects human and animal health by reducing the spillover of infectious agents (9,16,44), as well as by limiting the animal and plant diseases that impact production systems and the availability of food products (45). The possibility that SARS-CoV-2 may have initially spilled over from wildlife to wildlife farms or wildlife markets, where biosecurity measures are often rudimentary, and the knowledge that this has been the source of previous pandemics, highlights the need for an interdisciplinary OH approach also to biosecurity, based on increasing awareness and capacity among all actors along food value chains, from the producer to the consumer. ...
Research
Full-text available
Policy brief in support to the Pandemic treaty discussion at the WHA special meeting Nov 29 to Dec 1 2021
... Worldwide meat supply will have to almost double by 2030 to address the growing population, which is reflected in the increasing intensive livestock farming rates of the preceding years (Steinfeld, 2004). However, industrial farming is accused of significantly contributing to climate change, consuming natural supplies (Steinfeld, 2004) and triggering outbreaks of contagious human diseases originating from animal populations (Otte et al., 2007). Meanwhile, the socio-economic crisis of the outbreak of COVID-19 (the disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) has brought enormous changes in the global society and economy, and devastating effect on global health systems (Nicola et al., 2020). ...
Article
Background The very recently released EFSA's scientific opinion on the safety of dried (whole or ground) Tenebrio molitor larvae (yellow mealworm) considering their uses in various food products and the following approval by The Standing Committee on Plants, Animals, Food and Feed, brought T. molitor into the spotlight. This is EFSA's first opinion on edible insects as a novel food pursuant to Regulation (EU) 2015/2283. Scope and approach This review aims to summarize existing information regarding the features that may corroborate the sustainability and increase the acceptability of T. molitor larvae as food ingredient. Towards this end, aspects related to rearing and farming conditions, nutrient content and technological approaches for the recovery of protein and lipid fractions are addressed. Special emphasis was posed on their protein techno-functional properties and the development of new T. molitor larva-based food products. Key findings and conclusions The larvae of yellow mealworm are considered among the most promising alternatives to address the predicted deficiency of conventional food protein. Owing to their notable protein, lipid, vitamin, and mineral content, they could serve as future ingredients for industrial purposes (e.g. substitutes of traditional animal sources) bringing environmental and economic advantages. Several methods of T. molitor larvae protein extraction have been studied leading to different characteristics of the final protein preparations. Compared to conventional protein sources the protein fraction of T. molitor has not been much investigated with respect to its physicochemical and techno-functional properties, the knowledge of which is essential to allow their effective inclusion in food formulations.
Article
The importance of studying the economic impact of animal health on the livestock industry, the veterinary service and the economic and food security of the country as a whole has long been recognized worldwide. The article substantiates the structured components of animal health. Each of the components and individual features are considered. Animal health economics has the following components: economics of planning veterinary measures, management and financing of the state veterinary service, analysis of animal health policy. Although economics and epizootology together with the organization of veterinary business are separate branches of knowledge, but their association forms the same economics of animal health, which provides effective management of animal health, forms a policy of financing the veterinary service at various levels and financing anti-epizootic measures. as well as analysis of animal health policy analysis.
Article
The world is facing challenges from both new and re-emerging diseases and Influenza virus is one of the main causes of such diseases. The virus has the ability to mutate into a form that spreads efficiently among animals and humans. Swine influenza is a highly contagious and economically important disease of pigs. It is caused by type influenza viruses with main subtypes of H1N1, H1N2, H3N2 and H3N1. These are the main subtypes in endemic areas in pig populations. Human and avian influenza viruses can infect pigs and can give rise to novel reassortants. The virus enters in to the respiratory tract through different routes and attaches to the epithelial cells on the lining of the tract and replicates. Replication of the virus and action of immune cells together disrupts the cells on the lining of the respiratory tract. The disease has short incubation period with clinical signs of fever, lethargy, anorexia, weight loss, and coughing, sneezing, nasal and ocular discharge, conjunctivitis and labored breathing. Influenza A viruses infects a large variety of animal species including humans, pigs, horses, sea mammals and birds. Transmission of the virus from pigs to humans is not common. People with regular exposure to pigs are at increased risk of swine flu infection. Swine flu rarely passes from human to human. Symptoms of zoonotic swine flu in humans are in general, namely chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and discomfort. The Centers of Disease Control and Prevention recommends real time polymerase chain reaction as the method of choice for diagnosing H1N1. Prevention of swine influenza has three components: prevention in swine, prevention of transmission to humans, and prevention of its spread among humans. If a person becomes sick with swine flu, antiviral drugs used in human influenza treatment are not generally administered to swine, but Antibiotics may be used to control secondary infections.
Article
Full-text available
Antimicrobial resistance (AMR) can be highlighted as one of the most significant health concerns among the last decades, for which antimicrobial drug use in food-producing animals has contributed as one of the major drivers. Food-producing animals are one of the most important and rapidly expanding commercial agricultural sectors worldwide but there is currently limited knowledge on the temporal and geographical distribution of scientific research on antimicrobial resistance in food-producing animals. We provide a global overview of the spatial and temporal trends of scientific knowledge on AMR in food-producing animals. Peer-reviewed papers of AMR on food-producing animals were retrieved from the Web of Science, systemized and dissected. The final validated dataset contained 1341 occurrences observations covering the 1957–2018 period. There has been a shift of research efforts, both geographically and temporally, emphasizing regional differences in food animal production and changing practices in the food production industry. It becomes evident that many regions have been poorly surveyed, wherein intensified sampling and testing efforts should be most valuable. This systematization of knowledge will be crucial in helping to determine how to optimally allocate limited resources available for AMR monitor and control, aiding in the prediction where the threat of new resistant infections will be greatest. AMR research in food-producing animals in developing countries is markedly growing, reflecting changes in food animals production systems but also posing a particularly significant threat, not only due to intensive animal production, but also exacerbated by poor sanitation. We highlight that the use of antibiotics in food producing animals is pervasive, calling for urgent action. These findings raise the possibility to finetuning key priorities on AMR global issues.
Article
The article study the foundation, stages of formation and development of the animal health economy. The main scientific schools and their contribution to the development of animal health economics are highlighted. It is established that the economics of animal health is a dynamic and relatively new field of research, currently little explored are economic tools that cover the problems of animal health and the functioning of the veterinary service. Currently, new priority areas for the development of animal health economics are the study of the economics of livestock systems and animal health problems due to the impact of these systems, in particular transboundary emergent animal diseases. Undoubtedly, one of the main criteria for sustainable livestock is animal welfare and biosecurity, which are priorities of the "One World, One Health" concept established by the FAO, OIE and WHO Triumvirate in 2009. It is the consolidation of these criteria and the laws of economics will ensure the sustainable development of animal husbandry. It is extremely necessary to establish its own scientific school, which will take into account the world experience, realities and features of veterinary medicine and animal husbandry and be implemented in modern science and livestock production of Ukraine. Since Ukraine has for many years stood aside from the development of such areas of economic research as animal health economics and relied on the outdated system of determining the economic efficiency of veterinary measures, which inherited from the planned economy, it is now necessary to start its own scientific school. take into account the world experience and realities and features of the field of veterinary medicine and animal husbandry of our country. In the dynamically developing livestock industries (poultry farming, pig farming) there are already own economic features of veterinary services and animal health management, which do not fully correspond to world trends and promising areas of veterinary management. Therefore, it is already necessary to offer production economic approaches and methods of financing anti-epizootic measures, ensuring the health of livestock, veterinary management, forecasting the feasibility of treatment taking into account the political, social, economic, economic and environmental characteristics of Ukraine.
Article
Full-text available
A highly pathogenic avian influenza virus, H5N1, caused disease outbreaks in poultry in China and seven other east Asian countries between late 2003 and early 2004; the same virus was fatal to humans in Thailand and Vietnam. Here we demonstrate a series of genetic reassortment events traceable to the precursor of the H5N1 viruses that caused the initial human outbreak in Hong Kong in 1997 (refs 2-4) and subsequent avian outbreaks in 2001 and 2002 (refs 5, 6). These events gave rise to a dominant H5N1 genotype (Z) in chickens and ducks that was responsible for the regional outbreak in 2003-04. Our findings indicate that domestic ducks in southern China had a central role in the generation and maintenance of this virus, and that wild birds may have contributed to the increasingly wide spread of the virus in Asia. Our results suggest that H5N1 viruses with pandemic potential have become endemic in the region and are not easily eradicable. These developments pose a threat to public and veterinary health in the region and potentially the world, and suggest that long-term control measures are required.
Article
Full-text available
Pandemic strains of influenza A virus arise by genetic reassortment between avian and human viruses. Pigs have been suggested to generate such reassortants as intermediate hosts. In order for pigs to serve as 'mixing vessels' in genetic reassortment events, they must be susceptible to both human and avian influenza viruses. The ability of avian influenza viruses to replicate in pigs, however, has not been examined comprehensively. In this study, we assessed the growth potential of 42 strains of influenza virus in pigs. Of these, 38 were avian strains, including 27 with non-human-type haemagglutinins (HA; H4 to H13). At least one strain of each HA subtype replicated in the respiratory tract of pigs for 5 to 7 days to a level equivalent to that of swine and human viruses. These results indicate that avian influenza viruses with or without non-human-type HAs can be transmitted to pigs, thus raising the possibility of introduction of their genes into humans. Sera from pigs infected with avian viruses showed high titres of antibodies in ELISA and neutralization tests, but did not inhibit haemagglutination of homologous viruses, cautioning against the use of haemagglutination-inhibition tests to identify pigs infected with avian influenza viruses. Co-infection of pigs with a swine virus and with an avian virus unable to replicate in this animal generated reassortant viruses, whose polymerase and HA genes were entirely of avian origin, that could be passaged in pigs. This finding indicates that even avian viruses that do not replicate in pigs can contribute genes in the generation of reassortants.
Chapter
This book on the economics of livestock disease insurance is organized into three major parts. Following an introduction (chapters 1-2), part II (chapters 3-8) includes a variety of discussions about what is known about how to build a livestock insurance programme. It begins with a look at the conceptual basis for government involvement in the management of livestock diseases, including prevention, control, regulation and eradication. This discussion is picked up by looking at incentive compatibility and insurability conditions in the private sector, emphasizing how livestock disease management is unique. Compensation is also examined, including what losses should be compensated, choosing a method to value the losses, determining the portion of losses to compensate, and outlining a potential role for insurance. Finally, the complexity of the risks at the farm level is demonstrated using a model that evaluates revenue insurance. Part III (chapters 9-20) offers a diverse discussion about disease management issues and programmes in Australia, Canada, Europe and the USA. These chapters include more discussion about how to build economically sound insurance programmes, and observations are based on modelling or observing case studies. The book has a subject index.
Article
The rapid expansion and increasing mobility of human populations make understanding the evolution of parasite virulence a public health priority. The potential for the swift evolution of virulence in response to changes in host ecology has motivated the integration of evolutionary ecology with epidemiological theory, as part of the emerging field of evolutionary epidemiology. Virulence is the product of complex interactions among evolutionary, ecological and epidemiological processes. Recent models that incorporate ideas from both evolutionary ecology and epidemiology generate predictions that could not be made by either discipline alone. These models predict that the ecological or evolutionary changes affecting population dynamics of disease, such as spatial structuring, within-host dynamics, polymorphism in host resistance, host longevity and population size, impose selection on virulence. As disease incidence increases, it becomes particularly important to take into account the implications of infection by multiple parasite strains. Evolutionary epidemic models also identify the potential importance of immune evasion and optimal virulence for the selection of sex in parasites. Thus, merging epidemiology with evolutionary ecology has widespread potential to help us answer evolutionary questions and to guide public health policy.
Article
The outbreak of a highly infectious animal disease in a disease-free area is an ever-present risk. Recent epidemics in European livestock populations illustrate that the cost in terms of eradication, lost production and trade disruption may be high. In this paper, the implications for the meat and livestock industry, government policy and international trade rules are considered. The need for strict biosecurity and effective contingency plans is stressed. Options such as private insurance, animal tracing systems and emergency vaccination are discussed. Current measures for controlling animal disease epidemics raise various social and ethical issues that complicate the policy makers' task.
Article
In late summer through early winter of 1998, there were several outbreaks of respiratory disease in the swine herds of North Carolina, Texas, Minnesota, and Iowa. Four viral isolates from outbreaks in different states were analyzed genetically. Genotyping and phylogenetic analyses demonstrated that the four swine viruses had emerged through two different pathways. The North Carolina isolate is the product of genetic reassortment between H3N2 human and classic swine H1N1 influenza viruses, while the others arose from reassortment of human H3N2, classic swine H1N1, and avian viral genes. The hemagglutinin genes of the four isolates were all derived from the human H3N2 virus circulating in 1995. It remains to be determined if either of these recently emerged viruses will become established in the pigs in North America and whether they will become an economic burden.