Download Integrating human and wildlife health: the case of

2017_77: Integrating human and wildlife health: the
case of nonfatal rabies in Africa
Supervisors: Professor Rosie Woodroffe ([email protected]), Professor
Christl A. Donnelly (Department of Infectious Disease Epidemiology) and Dr Pierre
Nouvellet (Department of Infectious Disease Epidemiology)
Department: Zoological Society London / Medicine
Policymakers increasingly recognise the public health impact of zoonotic diseases
such as avian influenza and SARS. At the same time, conservationists increasingly
recognise the impact on endangered wildlife of diseases such as chytridiomycosis and
canine distemper. In some cases, the same pathogens threaten both human and
wildlife health: for example Ebola has caused mass mortality in both people and
gorillas.
Rabies is a major threat to human, livestock, and wildlife health. Persisting mainly in
domestic dog populations, rabies kills an estimated 60,000 people a year, and has
also devastated populations of endangered species such as Ethiopian wolves and
African wild dogs.
Rabies has major impacts because it can cause extremely high mortality, a pattern
which characterises its epidemiology. Nevertheless, experiments show that some
domestic dogs can abort rabies infection, becoming immune to subsequent challenge
(1). In parts of Africa, a high proportion of unvaccinated domestic dogs, and wild
carnivores, have circulating rabies antibodies (e.g., 2, 3) suggesting that such nonfatal
exposure may be commonplace. Such acquired immunity could alter estimates of the
vaccination coverage needed to control rabies; however models of rabies dynamics
typically do not include acquired immunity (e.g., 4).
This project will explore the implications of nonfatal rabies exposure for efforts to
protect human and wildlife health in East Africa. Combining mathematical modelling
with fieldwork at an existing study site, where domestic dog vaccination is being
expanded across a site with long-term monitoring of African wild dogs (5), the
studentship will address four questions:
(i) Are naturally seropositive domestic dogs immune to rabies? This question will be
addressed by blood-sampling domestic dogs before, and shortly after, routine
vaccination, to seek evidence of anamnestic responses in seropositive dogs.
For more information on how to apply visit us at www.imperial.ac.uk/changingplanet
Science and Solutions for a Changing Planet
(ii) In modelled domestic dog populations, how does including acquired immunity
influence rabies dynamics, including projected outcomes of sustained and sporadic
vaccination campaigns?
(iii) Does domestic dog vaccination reduce exposure to rabies virus in African wild
dogs? This question will be addressed by screening existing and newly-collected blood
samples from wild dogs, as domestic dog vaccination expands across the study area.
(iv) In modelled African wild dog populations, how does including an immune class
influence rabies dynamics? Does sustained or sporadic domestic dog vaccination
benefit wild dogs by reducing rabies exposure, or harm them by reducing natural
immunization?
1. M. Fekadu, in The Natural History of Rabies, G. M. Baer, Ed. (1991), 191-378.
2. K.C. Prager et al., Rabies and canine distemper virus in wild and domestic
carnivores in northern Kenya: Are domestic dogs the reservoir? EcoHealth 9, 483
(2013).
3. R. Woodroffe et al., Contact with domestic dogs increases pathogen exposure in
endangered African wild dogs (Lycaon pictus). PLoS One 7, e30099 (2012).
4. P. Nouvellet, et al., Rabies and Canine Distemper Virus Epidemics in the Red Fox
Population of Northern Italy (2006-2010). PLoS One 8, e61588 (2013).
5. R. Woodroffe, C.A. Donnelly, Risk of contact between endangered African wild dogs
Lycaon pictus and domestic dogs: opportunities for pathogen transmission. J Appl
Ecol 48, 1345-1354 (2011).
For more information on how to apply visit us at www.imperial.ac.uk/changingplanet