[Show abstract][Hide abstract] ABSTRACT: The major histocompatibility complex (MHC) influences immune response to infection and vaccination. In most species, MHC genes are highly polymorphic, but few wild canid populations have been investigated. In Ethiopian wolves, we identified four DLA (dog leucocyte antigen)-DRB1, two DLA-DQA1 and five DQB1 alleles. Ethiopian wolves, the world's rarest canids with fewer than 500 animals worldwide, are further endangered and threatened by rabies. Major rabies outbreaks in the Bale Mountains of southern Ethiopia (where over half of the Ethiopian wolf population is located) have killed over 75% of wolves in the affected sub-populations. In 2004, following a rabies outbreak, 77 wolves were vaccinated, and 19 were subsequently recaptured to monitor the effectiveness of the intervention. Pre- and post-vaccination rabies antibody titres were available for 18 animals, and all of the animals sero-converted after vaccination. We compared the haplotype frequencies of this group of 18 with the post-vaccination antibody titre, and showed that one haplotype was associated with a lower response (uncorrected P < 0.03). In general, Ethiopian wolves probably have an adequate amount of MHC variation to ensure the survival of the species. However, we sampled only the largest Ethiopian wolf population in Bale, and did not take the smaller populations further north into consideration.
[Show abstract][Hide abstract] ABSTRACT: Tanzania's iconic national park must not be divided by a highway, say Andrew Dobson, Markus Borner, Tony Sinclair and 24 others. A route farther south would bring greater benefits to development and the environment.
[Show abstract][Hide abstract] ABSTRACT: Mass vaccination of owned domestic dogs is crucial for the control of rabies in sub-Saharan Africa. Knowledge of the proportion of households which own dogs, and of the factors associated with dog ownership, is important for the planning and implementation of rabies awareness and dog vaccination programmes, and for the promotion of responsible dog ownership. This paper reports the results of a cross-sectional study of dog ownership by households in urban and rural communities in the United Republic of Tanzania.
Fourteen percent (202) of 1,471 households surveyed were identified as dog-owning, with an average of 2.4 dogs per dog-owning household. The percentage of dog-owning households was highest in inland rural areas (24%) and lowest in coastal urban communities (7%). The overall human:dog ratio was 14:1. Multivariable logistic regression revealed that households which owned cattle, sheep or goats were much more likely to own dogs than households with no livestock. Muslim households were less likely to own dogs than Christian households, although this effect of religion was not seen among livestock-owning households. Households were more likely to own a dog if the head of the household was male; if they owned a cat; or if they owned poultry. Dog ownership was also broadly associated with larger, wealthier households.
The human:dog ratios in Tanzania are similar to those reported elsewhere in sub-Saharan Africa, although cultural and geographic variation is evident. Estimation of the number of owned dogs, and identification of household predictors of dog ownership, will enable targeted planning of rabies control efforts.
BMC Veterinary Research 02/2008; 4:5. · 1.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Summary • As outbreaks of infectious diseases have emerged as a threat to small populations, conservation managers are increasingly making decisions regarding whether and how to intervene in such situations. Past controversies and lack of knowledge and firm guidelines may inhibit this process. We present data on a vaccination campaign against a rabies outbreak in endangered Ethiopian wolves as a case study of a disease-control intervention in a threatened population. • Ethiopian wolves on the periphery of the outbreak area were trapped to administer a dose of injectable rabies vaccine and to assess the magnitude and duration of the immune response. The expansion of an established population monitoring programme allowed us to assess the factors influencing the probability of capturing particular animals and to evaluate the overall success of the intervention. • All wolves sampled 1 month after vaccination had protective levels of serum antibody titres. A booster dose administered within 1–6 months appeared to be necessary to maintain these levels. Females were less likely to be trapped than expected, if dispersing females were included in the population. Animals captured in the first trapping session were more likely to be recaptured if the pack was trapped again. • The intervention was successful in halting the spread of the rabies outbreak and had few short-term impacts on the population of wolves and non-target species. • Synthesis and applications. Demographic, spatial and behavioural heterogeneities within populations may affect vaccine uptake or delivery and thus the efficacy of vaccine-based interventions. Managers of populations of threatened species should ensure that disease-control programmes are carefully designed to maximize information gained on all aspects of an intervention, and thus to evaluate its outcome and impact. Dissemination and discussion of results is crucial in order to apply what has been learnt to similar scenarios in the same or related populations.
[Show abstract][Hide abstract] ABSTRACT: The complex pathogen-host-vector system of the tick-borne louping-ill virus causes economic losses to sheep and red grouse in upland United Kingdom. This paper examines the spatial distribution, incidence and effect of control measures on louping-ill virus in the Bowland Fells of Lancashire. Seroprevalence in sheep at the beginning of the study varied within the area and was affected significantly by the frequency of acaricide treatment. There was a clear decrease over 5 years in the effective force of infection on farms implementing a vaccination programme, irrespective of acaricide treatment regime, however, only one third of farms apparently eliminated infection. On farms where vaccination did not occur or where vaccination was carried out intermittently, the estimated force of infection was variable or possibly increased. Thus, as befits a complex host-pathogen system, reductions in prevalence were not as dramatic as predicted; we discuss the potential explanations for these observations.
Epidemiology and Infection 09/2007; 135(6):963-73. · 2.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although detailed, long-term scientific studies provide potentially crucial information for conservation, they are rare. Moreover, there is often a disjunction between scientists and managers that can affect whether scientific results are applied to help solve conservation problems. Long-term studies can promote increased communication between scientists and managers and hence offer an opportunity for constructive engagement between the two groups. We examined direct and indirect impacts of a 30-year study, the Serengeti Cheetah Project (SCP). Much of what is currently known about wild cheetahs comes from the SCP. In particular, the SCP has demonstrated that cheetahs have a combination of semisociality and ranging patterns that is unique among mammals. This system arises because cheetahs need to be mobile to avoid predators and competitors, yet maintain access to prey; this results in densities much lower than for other large carnivores and a requirement for large areas of heterogenous and connected habitat. The SCP started as a research project, but expanded into a national program, developing capacity for carnivore conservation within Tanzania. Long-term studies such as the SCP are uniquely placed to establish effective working relationships between scientists and managers, engage local and national institutions, and strengthen national capacity for biodiversity conservation. This process is best realized through the establishment of frameworks for conservation that seek to align scientific research with management needs. Long-term studies also play an important role in identifying international priorities for conservation. Nonetheless, the integration of science and management in conservation is a two-way process that requires concerted efforts by both sides to improve and maintain dialogue. Ultimately, conservation depends on people, and maintaining a commitment to a particular area over many years-such as through implementation of a long-term research project-helps establish mutual trust and respect, particularly when combined with development of local and national capacity for scientific research and conservation management.
[Show abstract][Hide abstract] ABSTRACT: Recent outbreaks of rabies and canine distemper in wildlife populations of the Serengeti show that infectious disease constitutes a significant cause of mortality that can result in regional extirpation of endangered species even within large, well-protected areas. Nevertheless, effective management of an infectious disease depends critically on understanding the epidemiological dynamics of the causative pathogen. Pathogens with short infection cycles cannot persist in small populations in the absence of a more permanent reservoir of infection. Development of appropriate interventions requires detailed data on transmission pathways between reservoirs and wildlife populations of conservation concern. Relevant data can be derived from long-term population monitoring, epidemic and case-surveillance patterns, genetic analyses of rapidly evolving pathogens, serological surveys, and intervention studies. We examined studies of carnivore diseases in the Serengeti. Epidemiological research contributes to wildlife conservation policy in terms of management of endangered populations and the integration of wildlife conservation with public health interventions. Long-term, integrative, cross-species research is essential for formulation of effective policy for disease control and optimization of ecosystem health.
[Show abstract][Hide abstract] ABSTRACT: The conventional objective of vaccination programmes is to eliminate infection by reducing the reproduction number of an infectious agent to less than one, which generally requires vaccination of the majority of individuals. In populations of endangered wildlife, the intervention required to deliver such coverage can be undesirable and impractical; however, endangered populations are increasingly threatened by outbreaks of infectious disease for which effective vaccines exist. As an alternative, wildlife epidemiologists could adopt a vaccination strategy that protects a population from the consequences of only the largest outbreaks of disease. Here we provide a successful example of this strategy in the Ethiopian wolf, the world's rarest canid, which persists in small subpopulations threatened by repeated outbreaks of rabies introduced by domestic dogs. On the basis of data from past outbreaks, we propose an approach that controls the spread of disease through habitat corridors between subpopulations and that requires only low vaccination coverage. This approach reduces the extent of rabies outbreaks and should significantly enhance the long-term persistence of the population. Our study shows that vaccination used to enhance metapopulation persistence through elimination of the largest outbreaks of disease requires lower coverage than the conventional objective of reducing the reproduction number of an infectious agent to less than one.
[Show abstract][Hide abstract] ABSTRACT: This paper reviews the broader benefits of canine vaccination to human and animal health and welfare with an emphasis on the impacts of mass dog vaccination against rabies in countries of the less-developed world. Domestic dogs are the source of infection for the vast majority (>95%) of cases of human rabies worldwide, and dogs remain the principal reservoir throughout Africa and Asia. Canine vaccination against rabies has been shown to dramatically reduce the number of cases in dogs, the incidence of human animal-bite injuries (and hence the demand for costly post-exposure prophylaxis) and the likely number of human cases, primarily in children. Further benefits include the mitigation of the psychological consequences of rabies in a community, improved attitudes towards animals and animal welfare and reduced livestock losses from canine rabies. Mass vaccination has recently been used in the conservation management of wild carnivore populations threatened by transmission of rabies and canine distemper virus from domestic dog populations. Vaccination of wildlife hosts directly may also provide an option for mitigating infectious disease threats. The development of integrated control measures involving public health, veterinary, wildlife conservation and animal welfare agencies is needed to ensure that control of canine diseases becomes a reality in Africa and Asia. The tools and delivery systems are all available--all that is needed is the political will to free the world from the ongoing tragedy of these diseases.
[Show abstract][Hide abstract] ABSTRACT: Infectious diseases pose an important extinction risk for a number of endangered carnivore populations. Wild canids are particularly susceptible to generalist pathogens transmitted from domestic dogs – particularly rabies virus and canine distemper virus (CDV). Here we present a review of rabies as a threat to Ethiopian wolves, an endangered canid restricted to a few isolated Afro-alpine ranges in the Ethiopian highlands, and the impact of rabies on the largest population in the Bale Mountains. In the Bale Mountains, two confirmed rabies outbreaks among Ethiopian wolves in 1991–1992 and 2003–2004 were each responsible for over 70% mortality among focal packs and a third rabies outbreak was suspected in 1990. This review also presents an integrated disease management strategy for Ethiopian wolves combining long-term population monitoring, disease surveillance, conventional and emergency vaccination programs, and advanced modelling techniques.
[Show abstract][Hide abstract] ABSTRACT: With rabies emerging as a particular threat to wild canids, we report on a rabies outbreak in a subpopulation of endangered Ethiopian wolves in the Bale Mountains, Ethiopia, in 2003 and 2004. Parenteral vaccination of wolves was used to manage the outbreak.
[Show abstract][Hide abstract] ABSTRACT: For pathogens transmitted by biting vectors, one of the fundamental assumptions is often that vector bites are the sole or main route of host infection. Here, we demonstrate experimentally a transmission route whereby hosts (red grouse, Lagopus lagopus scoticus) became infected with a member of the tick-borne encephalitis virus complex, louping ill virus, after eating the infected tick vector. Furthermore, we estimated from field observations that this mode of infection could account for 73-98% of all virus infections in wild red grouse in their first season. This has potential implications for the understanding of other biting vector-borne pathogens where hosts may ingest vectors through foraging or grooming.
Proceedings of the Royal Society B: Biological Sciences 06/2004; 271 Suppl 4:S202-5. · 5.29 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The spatial ecology of golden jackal Canis aureus was studied on farmland adjacent to the Bale Mountains National Park in southern Ethiopia during 1998–2000. Three adult and four subadult jackals were captured in leg-hold traps and radiotagged. The range size of the adult jackals varied from 7.9 to 48.2 km2 and the subadults from 24.2 to 64.8 km2 . These ranges are the largest recorded for this species. Range overlap of the tagged jackals averaged 54%, which, in conjunction with observations of associations between individuals, suggested that all the tagged jackals belonged to one social group. Tagged jackals were observed alone on 87% of occasions despite the extensive overlap in individual ranges. Pairs consisting of a male and female were the most commonly observed group and larger groups were seen on only five occasions. Jackals in this population appeared less gregarious than observed elsewhere. The jackals used all the habitats available to them, particularly at night when they foraged in Artemesia and Hypericum bush and farmland. During the day they were more frequently found in Hagenia and Juniper woodland and their diurnal resting sites were characterized by thick cover. This is the first detailed study of golden jackals in a human-modified landscape in Africa and further demonstrates the flexibility in behaviour and ecology exhibited by this species throughout its range.RésuméOn a étudié l’écologie spatiale du chacal doré, Canis aureus, sur une ferme voisine du Parc National des Bale Mountains, dans le sud de l’Éthiopie, entre 1998 et 2000. On a attrapé trois adultes et deux sub-adultes dans des pièges à mâchoires et on les a èquipés d’émetteurs radio. La taille du territoire des chacals adultes variait de 7,9 à 48,2 km2 et celle des sub-adultes de 24,2 à 64,8 km2. Ces territoires sont les plus vastes rapportès pour cette espèce. Le recouvrement des territoires des chacals marqués était en moyenne de 54%, ce qui, compte tenu des observations d'associations entre les individus, laisse supposer que tous les chacals marqués appartenaient au même groupe social. Les chacals marqués ont été observés seuls à 87% des occasions malgré cet important recouvrement des territoires individuels. Les paires composées d'un mâle et d'une femelle étaient les groupes les plus souvent observés, et on n'a vu de groupes plus importants qu’à cinq occasions. Les chacals de cette population semblent moins grégaires qu'ailleurs. Les chacals fréquentaient tous les habitats disponibles, particulièrement la nuit lorsqu'ils se nourrissaient dans les buissons d’Artemisia et d’Hypericum et sur les terres des fermes. Pendant la journée, on les observait plus fréquemment dans les forêts d’Hagenia et de genévriers, et leurs sites de repos se caractérisaient par une épaisse couverture. Ceci est la première étude détaillée de chacals dorés dans un paysage modifié par l'homme en Afrique; elle démontre une fois de plus la flexibilité du comportement et de l’écologie dont fait preuve cette espèce dans toute son aire de répartition.
[Show abstract][Hide abstract] ABSTRACT: The spatial ecology of the white-tailed mongoose Ichneumia albicauda was studied during November 1998 to February 2000 on farmland adjacent to the Bale Mountains National Park in southern Ethiopia. Four male and one female white-tailed mongooses were captured and radiotagged. The average range size was 3.2 km2 for three adult males and 2.6 km2 for the female which is larger than previously recorded in savannah habitat. Asymptotic range size was reached at approximately 50 locations for the males and twenty locations for the female. The ranges of the three adult male mongooses overlapped on average only 2% whereas the single female range overlapped with two adjacent males by 81 and 25%, respectively. Twenty per cent of mongoose sightings were of groups that consisted of a male and female. Diurnal resting sites were found amongst rocks or in empty buildings. The mongooses foraged on grassy areas within woodland and bush during nocturnal activity periods. We conclude that white-tailed mongoose social organization in this agricultural landscape was similar to other solitary mongooses and was characterized by a mosaic of exclusive male ranges overlapping a separate mosaic of smaller female ranges.RésuméDe novembre 1998 à février 2000, on a étudié l’écologie spatiale de l‘ichneumon, Ichneumia albicauda, dans une ferme voisine du Parc National des Bale Mountains, en Éthiopie. On a capturé quatre mangoustes mâles et une femelle que l'on a équipés d'un émetteur radio. La taille moyenne du territoire était de 3,2 km2 pour les trois mâles adultes et de 2,6 km2 pour la femelle, ce qui est plus grand que ce qui a été rapporté pour les habitats de savane. La taille asymptotique du territoire était atteinte à environ 50 endroits pour les mâles et 20 pour la femelle. Les territoires des trois mâles adultes se recouvraient en moyenne sur seulement 2%, alors que celui de la femelle recouvrait ceux des deux mâles voisins sur 81% et 25% respectivement. 20% des observations de mangoustes concernaient des groupes composés d'un mâle et d'une femelle. Les sites de repos diurnes se trouvaient dans des rochers ou des bâtiments inoccupés. Les mangoustes se nourrissaient dans des zones herbeuses dans les forêts ou les broussailles, pendant des périodes d'activité nocturne. Nous concluons que l'organisation sociale des ichneumons dans ce paysage agricole était semblable à celle des autres mangoustes solitaires et se caractérisait par une mosaïque de territoires exclusifs de mâles recouvrant une autre mosaïque de territoires de femelles, plus petits.
[Show abstract][Hide abstract] ABSTRACT: There exist many tick borne infections that are of either economic or public health interest. Mathematical models have previously been used to describe the dynamics of these infections. However it has recently come to light that there is an alternative mechanism for the transmission of these diseases that has not been considered in a modelling framework. This is transmission through ticks co-feeding on non-viraemic hosts. This paper extends a simple mathematical model to include this alternative transmission mechanism. The model is used to describe the dynamics of Louping ill virus in red grouse (the viraemic host) and hares (the non-viraemic host). However, these results are applicable to many other systems. The model is analysed using joint threshold density curves. It is found that the presence of a non-viraemic host allows the virus to persist more readily than it would in the presence of a host that simply amplified the tick population. More importantly, if the level of non-viraemic transmission is high enough the virus can persist in the absence of the viraemic host. This result has important implications for the control of tick borne diseases.
Journal of Mathematical Biology 03/2004; 48(2):119-34. · 2.39 Impact Factor