Surveillance of emerging diseases: challenges and contradictions

Abstract

In the final chapter, François Roger justifies the essential yet ambiguous role of health surveillance at the heart of global governance concerns. It should make it possible to detect what seems to be becoming more and more unpredictable as early as possible. This surveillance is not without contradictions, and analysis of the epidemiological transitions which have accompanied the socioeconomic development of societies shows this. Health surveillance must address the challenges that reveal the complexity of the problem at hand. It is also crucial to know what should be monitored. Anticipation requires keeping an eye on the signals which herald the possible emergence of a disease and not the emergence of the diseases themselves. These signals are mixed, as are the mechanisms of emergence. What are they? The evolution of biological diversity, agricultural practices, antibiotic use? On what level do they need to be observed? Moreover, how can we prevent these signals, which are weak and uncertain, from replacing the dangers themselves in collective fears?

Full text

Serge Morand, Muriel Figuié, eds
Emergence
of infectious diseases
Risks and issues for societies


5.Surveillance of emerging
diseases: challenges
and contradictions
François Roger
Are we now on the brink of a fourth global epidemiological upheaval? The first,
which took place in the Neolithic era, was associated with the domestication of animals
and the establishment of larger permanent human settlements. The next two upheavals
were linked to urbanization and commercial trade and led to “microbial unifications”, one
beginning in the fifth century in Eurasia, the other starting in the fifteenth century in the
New World. Pandemic influenzas, viral haemorrhagic fevers in animals and humans, and
antimicrobial resistance are, rightly or wrongly, emerging or feared ‘microbial storms’
induced by a broad range of environmental and socioeconomic factors and increasingly
frequent and intense contacts between humans and animals. In this context, it has become
necessary to assess all of the factors involved in epidemiological dynamics, including
not only biological factors (which all too often are the only factors considered) but also
economic, social and environmental factors, and particularly the decline of biodiversity.
Moreover, surveillance and control systems must be developed based on risk assessments
integrating human and social dynamics, including the cost-effectiveness of these systems
and how they are perceived and accepted by livestock farmers, health professionals, and
society as a whole.
While the International Commission on Stratigraphy (International Union of Geological
Sciences) has not officially validated the term ‘Anthropocene’, it is increasingly being used
by researchers and the media to describe a period where, “for two generations, humanity
has become a geological force on a global scale, altering human and ecosystem health51”
(Steffen etal., 2015). In animal health, profound changes in livestock farming practices in
many regions of the world, combining genetic standardization with high domestic animal
densities, and in parallel the destruction of natural habitats in certain areas, could lead to
the emergence and spread of new diseases. This Anthropocene era may also be linked to
a sixth mass extinction of animal and plant species (Ceballos etal., 2015; Kolbert, 2015),
one much more rapid than past extinctions and with a major impact on biodiversity that
could play a role in the occurrence of infectious events.
51. The starting point of the Anthropocene is a particular topic of debate: while some authors consider it
to have begun with the Industrial Revolution, others wish to go back to the Neolithic era, or even earlier
(Lewis and Maslin, 2015).

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EMERGENCE OF INFECTIOUS DISEASES
Two major and opposing trends have been shaping the evolution of infectious diseases
over the past two decades:
– First, United Nations international agency programmes, particularly the public health
objectives of the Millennium Development Goals (Dye, 2014), and animal health
programmes focusing on strengthening veterinary services (OIE52), alongside research
institutions and centres are contributing to a reduction in the incidence of certain diseases
(even eradication, as for rinderpest53) and the strengthening of public and veterinary health
systems, although results continue to vary significantly across regions and diseases.
– Second, environmental, climatic and zootechnical changes and the internationaliza-
tion of goods and trade are favouring the emergence, spread and maintenance of new
human, animal and zoonotic diseases. These disturbances also are inducing increased
interference and interactions between ‘epidemiological compartments’, meaning between
human groups, domestic and wild animal populations, and the environment. Lastly, the
development of antimicrobial resistance is now leading some authors to sound the alarm
on the risks of what could be a public health ‘time bomb’.
This has led to the development and strengthening of management capacities, namely the
surveillance and control of infectious diseases. More efficient health surveillance is deemed
indispensable to react swiftly to an emergence, but also to measure the effectiveness
of control measures implemented (for example, vaccinations). It is difficult to anticipate
abrupt outbreaks of infectious diseases, although monitoring certain biological and
non-biological determinants (human behaviour, social events) of diseases and health
statuses can warn of the risk of emergence (Olson etal., 2015). The outbreaks, epizootics
and epidemics of bluetongue, a ruminant disease in northern Europe, Ebola fever in West
Africa, and the H5N1 strain of highly pathogenic avian influenza, etc. were not anticipated.
Nor was the emergence of AIDS, which can be considered as a true black swan (Paté-
Cornell, 2012), meaning that the emergence of the HIV virus from the equatorial forest
was a completely unforeseen event (see below).
Epidemiologic rupture or transition?
“Global disease burden has continued to shift away from communicable to non-commu-
nicable diseases and from premature death to years lived with disability. In sub-Saharan
Africa, however, many communicable, maternal, neonatal, and nutritional disorders remain
the dominant causes of disease burden.” (Murray etal., 2012)
Alongside global changes, including upheavals in terms of land use and globalization,
biodiversity’s role in health is discussed in Chapter 1 by Serge Morand. He examines
52. OIE PVS Pathway, http://www.oie.int/en/support-to-oie-members/pvs-pathway/
53. http://www.oie.int/en/for-the-media/press-releases/detail/article/no-more-deaths-from-rinderpest/


5.Surveillance of emerging diseases: challenges and contradictions
the ambivalent role of biodiversity loss, which research indicates may favour or hinder
emergence. However, according to the author there is a confusion of scale in numerous
studies, i.e., between actual emergence (e.g., primary transmission between a reservoir
and a host) and spread (role of movements, globalization of trade). More broadly, there
is a need to clearly distinguish between the potential emergence of pathogens (detected
through analyses, monitoring, etc.) and the emergence of a disease in its clinical and
epidemiological forms. Many questions remain with regard to the relationship between
biodiversity loss and disease. However, a recent meta-analysis (Civitello etal., 2015)
suggests that the maintenance of biological diversity reduces disease risks. If this is the
case, health, and its corollary, health protection, could be added to the list of ecosystem
services provided by biodiversity.
The role of wildlife, which is frequently associated with emergences (avian influenza
and wild birds; Ebola and bats and great apes; SARS and bats and civets), probably
should be qualified (Tompkins et al., 2015). Furthermore, certain diseases also impact
amphibians, birds and mammals (Grogan et al., 2014). For example, the Ebola virus
disease had devastating consequences for great ape conservation plans in Central Africa
(Bermejo etal., 2006); white-nose syndrome decimated bat colonies in the United States
(Boyles etal., 2011), which could lead to major farm losses due to the positive role
played by bats in relation to crop pests; canine distemper (a disease of domestic dogs)
infected lions in East Africa (Viana etal., 2015); bovine tuberculosis, an animal disease
transmissible to humans (zoonosis), affects cats and other species in southern Africa (de
Garine-Wichatitisky etal., 2013); rabies and canine distemper (Gordon etal., 2015) affect
Ethiopian wolves, considered an endangered species (red list) by the International Union
for Conservation of Nature (IUCN). Wildlife conservation policies should more fully consider
these risks of infection in keeping with the “One Health” concept, which advocates for
a global approach to human, animal and environmental health. More specifically, better
defined research and surveillance strategies are needed at the interface between wildlife
and domestic animals (Wiethoelter etal., 2015).
We propose to distinguish between epidemiological, global, major and above all infectious
and parasitic ruptures (or upheavals, or shocks) – of which there have been three since
the first during the Neolithic agricultural revolution 11,000 to 12,000 years ago – and
epidemiologic transitions, which pertain rather to recent, modern transformations of
societies in terms of demographics, technologies, and health (shift from infectious
diseases to chronic, degenerative diseases) and which are continuing with the economic
development of societies (Table 2).
Over the past two centuries, numerous countries experienced a significant drop in mortality
combined with a considerable increase in life expectancy as they developed. In terms of
public health disease burden, chronic diseases (generally non-infectious) have replaced
acute infectious diseases. There are several reasons for this: improved hygiene and care,
vaccinations and antibiotic treatments, biosecurity on farms, improved nutrition and
food security. However, urbanization, more sedentary lifestyles, dietary changes, etc.
accompany these transitions towards primarily non-infectious and chronic pathologies.

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EMERGENCE OF INFECTIOUS DISEASES
However, bacteria, viruses and parasites continue to exist, and infectious diseases are
particularly pernicious in the Global South, in both human and animal populations. For
animal diseases, there is considerable geographic diversity, with sharply contrasting
situations between developed countries, countries in transition and middle-income
countries, and the poorest countries, principally in Africa, which are the most dependent
on livestock farming and most at risk from a health perspective (Perry etal., 2013).
Consequently, we also could apply the concept of epidemiologic transition, initially
developed in public health,54 to animal health, and say that there are transitions between
an ensemble of parasitic and infectious diseases predominating in traditional systems
and a pathology related to livestock intensification.
A study (Jones etal., 2013) shows that agricultural intensification and environmental
changes – and the evolution of the link between the two – are correlated with the risk of
emerging zoonoses. Some authors suggest that micro-organisms may also play a role
in the development of important chronic diseases in developed countries and those in
54. The concept of epidemiologic transition was proposed by Omran (1971).
Table 2. Epidemiologic ruptures and transitions: a preliminary typology
Epidemiologic ruptures
(or upheavals or shocks)
Epidemiologic transitions
Periods Neolithic (agricultural revolution), fifth
century (Africa-Asia including Europe)
then fifteenth century (New World)
Since the end of the 19th century
Geography Regions (Middle East, China, etc.),
continents
Countries undergoing demographic
and economic transitions; achieved
for developed countries, underway for
middle-income countries and emerging
economies (BRICS)
Mode Gradual (domestication) or brutal
(colonization of the New World). Also
“exchanges” (e.g., syphilis) towards
Europe
Gradual over several generations
Diseases Wide spread of infectious diseases
(microbial pools, new viruses for
immunologically naive populations)
Move from parasitic, infectious
diseases to chronic, degenerative
diseases
Impacts Major impact on societies (e.g.,
epidemiologic shock on the Americas)
Increased life expectancy
Present day Potential rupture? Consequence of
climatic, ecological and therapeutic
changes (antibiotic resistance)
Epidemiologic transitions continuing in
middle-income countries and emerging
economies: towards a globalization
of health?


5.Surveillance of emerging diseases: challenges and contradictions
Box 2. Pathocenosis
The concept of pathocenosis – based on the notion of biocenosis but applied to
a community of diseases – proposed by Grmek in 1969 aims to provide a logical
framework to analyse these transitions and disease emergence. A recurring but
controversial theme in epidemiology linked to this concept is that each pathoge-
nic agent occupies an ecological niche, and its elimination leaves room for new
pathogens. According to Lloyd-Smith (2013), the elimination of a pathogen leads
to a vacant niche that could be re-invaded by the original pathogen. However,
if other pathogens attempt to move in, other factors intervene in a dialectic of
competition and evolutionary adaption without necessarily leading to the emer-
gence of a new disease.
transition, for example heart diseases, cancers and diabetes (Rosenthal, 2015). The use
of antibiotics is rising sharply in livestock farming worldwide, causing the development of
transmissible resistance in bacteria affecting humans. Van Boeckel etal. (2015) estimate
that antimicrobial consumption will increase by 67% by 2030, linked particularly to the
growing demand for meat products in middle-income countries. Given the major risks posed
by this surging and uncontrolled use of antibiotics in animal production and health, as
well as in individual medicine, self-medication and public health, coupled with weak new
product development, Woolhouse etal. (2015) liken antimicrobial resistance to climate
change and suggest that an intergovernmental group similar to the Intergovernmental
Panel on Climate Change (GIEC) should be created.
Will the history of infectious diseases soon come to an end with the latest upheavals
correlated with a massive loss of biodiversity? Or are we going through a new
epidemiological rupture (new viruses jumping the species barrier and causing new diseases
in first epidemic and then endemic forms; antimicrobial resistance)? Or is it the case that
epidemiologic transitions are continuing in public and animal health, varying with the
economic situations of countries? Influenza viruses, responsible for animal and human
influenza, could contribute to this discussion; new strains appear regularly, sometimes
jumping the species barrier between birds and mammals, including humans, and causing
epizootics or epidemics or even panzootics and pandemics.
What ever happened to the seventh pandemic?
“Massive deadly epidemics have disappeared. They have been replaced by just one: the
proliferation of humans themselves.” Cool Memories 1980–1985, Jean Baudrillard, 1987
A possible influenza pandemic was reported in the sixteenth century in Europe and
Africa. The twentieth century witnessed the Spanish influenza pandemic of 1918–1919

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EMERGENCE OF INFECTIOUS DISEASES
caused by the H1N1 virus (over 40 million dead); the 1957 Asian influenza caused by the
H2N2 virus (1 to 4 million dead); and the Hong Kong flu in 1968 caused by the H3N2 virus
(1 to 2 million dead). The appearance in the twenty-first century of the panzootic and
zoonotic H5N1 avian influenza revived the threat of a major pandemic. The H5N1 virus, a
strain highly pathogenic for birds, is transmitted to humans with very high rates of case
fatality (mortality/morbidity) but with thus far very low overall mortality. However, due to
the genetic plasticity of influenza viruses and the possibility of recombination with other
strains, researchers, experts and international agencies rapidly launched a pandemic risk
alert. H1N1 influenza A (H1N1pdm09), which emerged in 2009, had a pandemic character
in terms of geography and contagiousness but its mortality rates cannot be compared
to the pandemics of the twentieth century. As mortality linked to the influenza virus is
mainly due to secondary infections (Jamieson etal., 2013), improved hygiene and care of
flu patients has certainly contributed to the overall reduction in mortality during the last
pandemics. However, given the weakness of health systems in some countries and the
unpredictability of certain highly pathogenic strains (for example, H7N9 in China, which
is proving to be weakly pathogenic in birds but highly pathogenic in people), it would be
unwise to let down our guard.
While some authors55 consider that the emergence of highly pathogenic H5N1 avian
influenza overall led, in terms of public health, to “much ado about nothing”, it should be
noted that the disease had major direct and indirect socioeconomic impacts on livestock
farms in countries of the Global South (Alders et al., 2014). These impacts are linked
to the disease itself, but also to the responses of different stakeholders in the poultry
sector, to consumers, and to the measures taken by governments. H5N1 is now endemic
in many Asian countries and in Egypt, and since 2015 has re-emerged in Africa with
serious consequences for poultry value chains. Some authors argue that we will never
again be faced with a devastating influenza pandemic due to effective early warning and
surveillance programs, better care for patients and secondary infections, etc. However,
given the recent multiplication of bird and pig zoonotic strains, particularly in China
where livestock farming conditions facilitate the spread and genetic evolution of these
viruses, and the economic and health risks for the least developed countries, continued
vigilance is necessary (Von Dobschuetz et al., 2014). Bluetongue disease and Ebola
haemorrhagic fever, which never should have left their natural areas – respectively the
inter-tropical region and the forest of Central Africa – should incite us to be cautious in
terms of projections.
For Brender and Gilbert (Chapter 2), WHO actually emerged as an international organization
by restructuring itself through the management of a pandemic, influenza A(H1N1)pdm09,
and of the pandemic risk of H5N1 avian influenza. This crisis made it possible to strengthen
links between health sectors and start developing the ‘One Health’ approach (Pfeiffer etal.,
55. “It is not necessary to set fire to the planet due to some zoonotic infection, nor to spend billions of euros,
nor to create a governmental crisis; ultimately it is ‘much ado about nothing’”. Raoult, 2015.


5.Surveillance of emerging diseases: challenges and contradictions
2013). In animal health, this panzootic had a positive effect on the overall strengthening
of veterinary capacities in many countries through programmes and projects financed
and implemented by international agencies and donors. These avian influenza epizootics
led animal health sector managers to further develop dialogue with livestock farmers
(Alders etal., 2014).
Recently, WHO was sharply criticized for its management of the ongoing Ebola epidemic
in West Africa. An expert report dated 7 July 2015 emphasizes that the organization
indeed failed to “provide an urgent public health response to a grave epidemic” (Maurice,
2015). Twenty-some recommendations have been proposed to re-establish “WHO as the
lead guardian of global public health”. Among these recommendations is a proposal
to strengthen GOARN,56 a global outbreak alert and response network. Jeremy Farrar,
the Director of Wellcome Trust, vigorously supports this idea and emphasizes that this
mechanism “should be truly independent, outside any political influence” (Maurice, 2015).
The management of infectious diseases at the international level requires robust and
interconnected international agencies. The One Health paradigm ratified by OIE and
United Nations agencies (FAO, WHO, UNICEF), which postulates that the epidemiological
dynamics and interplay of actors conditioning the health of animal and human populations
should be studied in their ecological, socioeconomic and political context at the interface
of human health, animal health and ecosystem health, should facilitate this management.
The real or imagined consequences of an epidemic or epizootic, fear of a pandemic,
media coverage and the hype that can follow must be held up against the reality of health
and epidemiological data (morbidity, mortality, and lethality rates, economic and social
impacts) by a broad range of medical scientists working in both animal and public health.
The Horseman on the Roof
“What?” said the young man, “You don’t know? Where are you from? It’s cholera. It is the
finest case of Asiatic cholera that has ever been seen! Go there one more time,” he said,
holding the vial. “Trust me, I am a doctor.”
The Horseman on the Roof, Jean Giono, 1951.
The “plague” in Athens in 430 BC was a major epidemic in ancient Greece. It has been
the subject of discussion in recent years among doctors, microbiologists, epidemiologists,
paleo-pathologists and other experts who debate the origin and etiology of this disease.
A priori from Ethiopia, this infectious disease, characterized by a gastrointestinal
haemorrhagic-like fever, could have been typhus, influenza, a viral haemorrhagic fever
like Rift Valley fever or, some argue, even Ebola (Olson etal., 1996). Animal mortality was
56. http://www.who.int/ihr/alert_and_response/outbreak-network/en/. At the end of 2014, CIRAD offered
GOARN its expertise in the fields of ecology, epidemiology and veterinarian sciences for certain zoonoses.


EMERGENCE OF INFECTIOUS DISEASES
reported during the same period. The events are recounted by the Greek politician and
historian Thucydides (fifth century BC), who considered that fear and panic both disrupted
Greek society at the time and amplified the spread and consequences of this disease.
The destructive nature of fear is without doubt a signature of the plagues which have
since taken societies by surprise: the black plague (Yersinia pestis) in medieval times,
AIDS in the 1980s, pandemic influenzas and Ebola virus today. The cholera epidemics of
the nineteenth century in Europe and North America share several similarities with the
ongoing Ebola epidemic in West Africa: inadequate health services, populations’ fear
and beliefs about the means of contamination, riots, unrest and suspicion of the medical
community (Sheard, 2014). While Ebola killed fewer people during the epidemic in West
Africa (since 2014) than many endemic diseases like malaria or measles during the same
period of time, it had an amplifying effect on other diseases (e.g., malaria) and more broadly
on health (for example, refusal to go maternity clinics for fear of contamination; Hessou,
2014). More broadly, for Ebola, the public health crisis was transformed into a multi-
sectoral crisis affecting people’s food security and livelihoods and national economies
while threatening the geopolitical stability of the region (FAO-CIRAD, 2015).
Against this backdrop, to act more effectively on the chains of transmission, the cooperation
of sociologists and anthropologists would have been warranted from the start of field
interventions during the Ebola epidemic in Guinea, Liberia and Sierra Leone (Chandler
etal., 2015; Brown etal., 2015). More broadly, an understanding of epidemics, surveillance
and disease control can benefit from multidisciplinary approaches that do not limit
themselves to biological and medical sciences (Stärk and Morgan, 2015).
Black swans and perfect storms
“What complicates everything is that which does not exist works hard to make everyone
believe otherwise.”
Vendredi ou les limbes du Pacifique, Michel Tournier, 1966
Black swan and perfect storm are two buzzwords in the English-language press,
which often uses them as shorthand to describe financial and weather-related disasters. In
probability theory, they refer respectively to a ‘rare event’ (black swan57) which can have
wide ranging consequences if it occurs, and to a convergence of apparently unrelated,
rare circumstances that drastically aggravate a situation (perfect storm, or ‘worst-case
scenario’).
The emergence of an animal pathogen with zoonotic potential can be a rare event in
terms of probability. An example is the zoonotic form of Ebola, with the original animal-
57. Referring to black swans which had been assumed to be non-existent in Europe until they were discovered
in Australia. The use of the term ‘black swan’ was proposed by the philosopher Nassim N. Taleb in the field
of finance.


5.Surveillance of emerging diseases: challenges and contradictions
to-human transmission for the index case being a rare event (Pigott et al., 2014). The
subsequent human-to-human spread, facilitated by weak health systems and ineffective
international coordination, can cause, as shown by the epidemic still underway in January
2016 in West Africa. Highly localized outbreaks of vector-borne diseases (the first case of
West Nile fever on the American continent in the Bronx Zoo in New York in 1999; Lanciotti
etal., 1999), a new influenza strain on a livestock farm (Baudon etal., 2014), or a disease
emerging in wildlife (Wiethoelter etal., 2015) may also be considered as rare events.
The wide spread of an emerging pathogen in a new socioeconomic system (Ebola in
West Africa), and the risk of an antibiotic resistance ‘pandemic’, can be seen as perfect
microbial storms underway or in the making. This notion of a perfect storm converges
with the concept of emergence in its first, philosophical definition, namely, “the whole
is greater than the sum of its parts”.58
❚ Can a black swan or perfect storm be predicted?
Paté-Cornell (2012) argues that while the attack on the twin towers of the World Trade
Center in New York on 11 September 2001 was not a black swan – there were warning
signals that could have been analysed – the emergence of AIDS in the 1980s truly was
one, as was the Ebola haemorrhagic fever outbreak in West Africa in 2014 (Osterholm
etal., 2015).
Major virus detection campaigns (USAID PREDICT-1 followed by PREDICT-259 which will
also explore possible determinants more deeply) in ecosystems considered to be hotspots
of biodiversity – and consequently of viruses (South-east Asia, Central Africa) – and the
metagenomic analysis of the biodiversity of viromes are not analogous to surveillance,
but rather a snapshot of a community of pathogens at a specific point in time. Yet will
these viruses jump the species barrier, locate a receptive host community and foster the
emergence of a disease? The exploration of these ‘viral loads’, as well as of environmental
and human behaviour parameters within ecosystems, could help define priorities for the
surveillance of pathologies.
Current research is not adequately addressing the complexity and interdependence of
the environmental, biological, economic and social dimension of pathogen emergence.
This is considerably limiting our capacity to anticipate, prevent and respond to the
emergence of infectious diseases. However, prediction and simulation models are
becoming increasingly sophisticated (Heesterbeek etal., 2015). They combine the
spatial and temporal dimensions of population-based, individual-based, social (contact
networks), economic, etc. mathematical models, but they should be handled with caution:
“All models are wrong, but some are useful” (Box, 1976). This underscores the need to
58. http://plato.stanford.edu/entries/properties-emergent/
59. http://www.usaid.gov/what-we-do/global-health/pandemic-influenza-and-other-emerging-threats/
programs


EMERGENCE OF INFECTIOUS DISEASES
better communicate the limits of these models to decision makers and health managers,
especially with regard to one type of modelling, risk analysis.
Risk analysis, which does not consist in predicting events, but rather in understanding the
probability of possible scenarios, is a probabilistic modelling tool – unlike the scenario
planning method described by Patrick Zylberman in Chapter 3 – developed in the veterinary
and then medical fields, and which should be consolidated, particularly with regard to
its communication component. Indeed, too few tangible studies on the communication
of risk have been conducted (Figuié and Fournier, 2008). Risk analysis involves both
scientists, who estimate and assess risks and propose alternative scenarios to mitigate
these risks, and managers in charge of developing control strategies. A lack of effective
communication between these stakeholders, as well as with the general public and the
media, limits the relevance and effectiveness of these models and fuels confusion and
misunderstanding about the risks involved.
For certain diseases such as influenza, the prediction of the occurrence of a new strain
seems unrealistic given current knowledge about mutations and recombinations of
influenza viruses and the tools available.60 Surveillance systems capable of detecting rare
events and the precursors of these events are needed. They require innovative methods
to detect and identify an unusual event capable of generating epidemics or epizootics.
Syndromic surveillance, non-specific surveillance based on the collection of data that
can be outside the medical field,61 could enable the early detection of emergences or the
warning signs of emergence. These approaches also are being studied to warn of the risk
of an imminent terrorist attack.62
Surveillance at all costs?
“Hidden diseases are the most difficult to treat.”
Chinese proverb
Health surveillance is a field that requires input from a wide range of disciplines: pathology,
epidemiology, microbiology-immunology, sociology, economics, anthropology, modelling,
ecology, communication sciences, etc. It is not the prerogative of epidemiologists alone, who
contribute to the definition and evaluation of surveillance systems through methodological
input (samples, statistical and epidemiological analyses) and the proposal of new collection,
analysis and assessment methods (Goutard etal., 2012; Vergne etal., 2012; Collineau etal.,
60. In time, the Chaos Theory (modelling of deterministic chaotic systems) could nevertheless be an
interesting method (https://www.ncbi.nim.nih.gov/pmc/articles/PMC2465602/). Tools have also been
developed to assess the pandemic potential of the H7N9 strain and other influenza viruses (https://doi.
org/10.1017/S0950268815001570).
61. Triple-S guidelines on syndromic surveillance: www.syndromicsurveillance.eu/Triple-S_guidleines.pdf.
62. American CDC: http://emergency.cdc.gov/bioterrorism/).


5.Surveillance of emerging diseases: challenges and contradictions
2013; Delabouglise etal., 2015). A surveillance system based only on laboratories and
information systems, which are now very powerful but rely on equipment that is expensive
to obtain and maintain, cannot be sustainable, particularly in the difficult socioeconomic
context of countries in the Global South. The key issue remains access to the field and
to ‘epidemiological units’, which are individuals or groups of animals or people, for the
collection at the source of health information and samples in sufficient quantities and
quality and on a regular basis to be able to derive elements for monitoring and alerts. It is
also clear that the information which is compiled and analysed must be regularly provided
back to system stakeholders for the system to operate in an optimal manner. Innovations
in this field, particularly in the least developed countries and the most isolated regions, are
critical (Goutard etal., 2015). These include in particular participatory approaches which
rely, in animal health, on the knowledge of livestock farmers, for example.
Surveillance leads to action. In animal health, this involves vaccination, treatment, and
quarantine measures, as well as slaughtering and controlling animal movements, etc. If
these interventions have negative or adverse effects, this reduces the effectiveness of
surveillance and the involvement of stakeholders, or induces the emergence of parallel
systems. The actual (in the case of slaughtering) or feared (dissension within social
networks) risks of sanctions following the suspicion of animal or zoonotic diseases do
not encourage livestock farmers to report suspicions or become part of a surveillance
network. Alongside a top-down approach, in which no consultation process is involved,
it may be interesting to use participatory approaches developed in the social sciences.
This would enable discussions, communication, negotiations and a sharing of knowledge
in order to lead to the joint identification of priorities and socially acceptable solutions.
Participatory surveillance thus could certainly supplement a surveillance system by
addressing the shortfalls identified by evaluation processes. These approaches also
render it possible to avoid surveillance systems that stigmatize farmers. They made it
possible to identify the last outbreaks of rinderpest before the disease was eradicated
from the planet (see inset 2).
In the big data era, weak signals can be detected and identified within a huge mass of
data to alert, anticipate (Olson etal., 2015) and contribute to non-specific syndromic
surveillance. For animals in the Global South, however, we are dealing rather with small
data, although the extraordinary coverage of mobile networks holds some promise for the
potential to collect data that could be used in a surveillance framework in collaboration
with livestock farmers. Numerous recent initiatives in this area in public and animal health
and through One Health approaches for the surveillance of zoonoses confirm the value
of this tool. However, digital surveillance raises a certain number of confidentiality and
ethical questions given that mechanisms guaranteeing the rights of citizens (for example,
data protection and freedom of information) are currently lacking in numerous countries.
The evaluation of surveillance systems is essential for their improvement (Calba etal.,
2015). Beyond technical elements (efficiency of data transmission), such evaluations
must consider economic issues – what are the benefits, what utility can be drawn from a

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EMERGENCE OF INFECTIOUS DISEASES
system which is by definition long-term in nature, how can it be measured? – as well as
social, even psychological questions regarding the populations involved, whether in public
health or animal health for livestock farmers and animal sector actors. Surveillance can
effectively lead to ostracism and stigmatization for target populations whether in human
health (for example, the start of the AIDS epidemic) or animal health (the identification
of a herd with tuberculosis, or an industry infected by a pathogen, can have significant
social consequences). For wildlife, an effective surveillance system can have indirect
consequences for traditional hunters and the bush meat supply chain.
Broadening the battlefield
“But in all frankness, how long can we maintain the wall separating the department of
biology from the departments of law and political science?”
Sapiens: A Brief History of Humankind, Yuval Noah Harari, 2015
While the Global North is broadly protected from the incursion and spread of known
pathogens thanks to effective health systems, the Global South is more exposed and
less equipped to fight epidemics and epizootics, and especially endemic and enzootic
diseases, whether recognized or neglected. Global attention is focused on emerging
diseases, but neglected diseases – meaning ones neglected by public authorities, donors,
the scientific community, and the private sector – affecting vulnerable populations in the
Global South have major medical, economic and social impacts. The 17 tropical diseases
and a subgroup of eight zoonoses the WHO considers neglected are also neglected in
terms of surveillance. The official, ratified extension of this concept to strictly animal
diseases should be examined, as greater attention on the part of donors, decision-makers
and researchers would enable better investments in animal health in cold spots (Perry
etal., 2013), meaning areas where the most vulnerable populations live.
Opposition between the vision of donors and politicians and the interests of livestock
farmers may limit the effectiveness of surveillance and control. For example, foot-and-
mouth disease, an animal disease that is highly contagious but causes little mortality,
hampers regional and international trade. The management of this disease may be imposed
although livestock farmers in countries where the disease is enzootic (sub-Saharan
Africa, South-east Asia) do not consider the disease important, even though it has
indirect economic consequences (production losses) (Bellet etal., 2012). In addition to
incorporating participatory approaches that can help improve surveillance and control
systems in certain contexts, when possible these systems should, rather than focusing
on a single disease, be able to monitor diverse health conditions and be capable of
detecting unexpected events. More broadly, and this was emphasized for the ongoing
Ebola epidemic in West Africa, surveillance mechanisms should be better integrated
into overall health systems (Dhillon and Yates, 2015) and not be dependent on funding
obtained through time-limited projects. Surveillance requires permanent mobilization.

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5.Surveillance of emerging diseases: challenges and contradictions
For a surveillance system to operate smoothly, it must be based on a network of
stakeholders: patients, livestock farmers, health professionals, etc. Under this framework,
the One Health concept adopted by international regulatory agencies (OIE and UN agencies)
and supported by major donors can be applied to surveillance, particularly to zoonoses
and health conditions linked to the environment. One Health surveillance would have
the advantage of being able to pool strengths and resources. In Cambodia, the fact that
avian influenza was detected first in people before the infected farms which caused the
human cases is indicative of important weaknesses in the field of veterinary surveillance.
Are we moving towards a new end of infectious diseases, like that announced in 1967 by
the United States Secretary of Health, or are epidemiologic transitions continuing with the
gradual replacement of infectious diseases by chronic diseases as countries develop? Or
are we on the verge of an epidemiological rupture with the emergence of new pathogens
hitherto ‘buried’ in certain ecosystems and animal reservoirs, including intensive livestock
farms and, in parallel, the efficacy of antimicrobials reaching its limits?
We do not understand all of the parameters of diseases and we can only partially, or on
a very short term basis, predict the occurrence of new diseases. Appropriate surveillance
systems can help us understand and analyse ecological changes and epidemiological
trends while improving the control of emerging and endemic diseases. Such systems must
be efficient, specific and non-specific, syndromic and etiological, operating on diverse
geographic scales, but also firmly rooted in the field in the most vulnerable regions,
collecting health information as well as environmental, climatic, and behavioural metadata.
“Why does health, regularly described as a global public good [or global common good, see
Chapter 4] – remain an area where international inequalities are so profound?” (Gadreau, 2014).
South-South and North-South cooperation in the fields of public health and animal health must
be strengthened through joint research platforms, health networks, and integrated surveillance
systems. The joint action of international agencies is crucial. Avian influenza, for example,
enabled a “return to an integrated human and animal health approach” (Vagneron, 2015)
between WHO, OIE and FAO and to set down the concrete foundations of One Health in action.
Four of the Millennium Development Goals (MDG), launched in 2000 for a 15-year period,
refer explicitly to health. Despite significant progress, the burden of infectious diseases,
in general endemic and for some neglected, remains heavy, particularly in the least
developed countries. For the period after 2015, when the MDGs will be replaced by a new
set of poverty reduction and sustainable development goals (Sustainable Development
Goals, SDG, 2015–2030), the Director-General of WHO (Dye, 2014) is focusing on five
aspects of the fight against infectious diseases:
– study of the biological links between infectious and non-infectious diseases;
– control of infections in urban areas;
– improvement of the response to international health threats;
– expansion of vaccination programmes for children to prevent acute and chronic diseases
in adults;
– development of universal health coverage.

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EMERGENCE OF INFECTIOUS DISEASES
However, the post-2015 health era must not neglect the improvement of animal health
which, combined with strengthening the productivity of livestock farming, is a major lever
for poverty reduction (Pradère, 2014), and must broaden its vision of health by integrating
sectors and disciplines outside the strictly medical field.
Even though some risks are known – antimicrobial resistance, unceasing evolution of
influenza viruses – it is difficult to see what the future holds. Major rupture based on
increasingly frequent emergences? Transition and end of infectious diseases? Either way
we must have warning systems and be able to respond in real time.
A multi- and interdisciplinary approach to health, combining biological, human, social
and mathematical sciences, is essential, whether to address the interdependence of
animal, human and environmental health (One Health) (Lapinski etal., 2015) or to be
able to transfer research outputs to decision-makers, particularly in the field of health
management.