Reasons why dog-mediated rabies remains endemic in affected regions across Africa, despite low virus prevalence, have been revealed, thanks to a UK-led study.
The research, led by the University of Glasgow, is based on data from tracing the disease in more than 50,000 dogs in Tanzania from 2002 until 2016.
Dog-mediated rabies is transmitted through bites and scratches and is almost always fatal unless immediately treated with a post-bite course of injections that prevents the infection from taking hold.
An international team of researchers, led by Professor Katie Hampson at the University of Glasgow, has found new information about how the pathogen can persist at less than 0.15% of the dog population annually.
To understand the virus dynamics, researchers tracked rabies transmissions, dog population densities, disease incidence and vaccination campaigns in a large population of domestic dogs in Serengeti.
Writing in Science, they write that the mobility and behaviour of individual rabid dogs means the virus can disperse and circulate at this low virus prevalence. A small proportion of infected dogs act as “super spreaders”, travelling more than 10km, biting other animals and bringing new virus lineages to different communities.
Prof Hampson said: “The virus uses a clever strategy for low level persistence, which makes its dynamics harder to both detect and predict. But these new mechanistic insights also show why scaling up dog vaccination is so necessary.”
The team says the processes that underpin the persistence and prevalence of rabies operate on much smaller scales than those typically modelled for the disease and that it is often down to the behaviour of a few individual infected dogs.
Over the 14-year study period, the researchers pinpointed hundreds of introductions from neighbouring villages that sustained circulation across the region.
Although the variability in rabid dog biting behaviour means most introductions do not take off, some outbreaks that do last for years.
Mancy R, Rajeev M, Lugelo A et al. Rabies shows how scale of transmission can enable acute infections to persist at low prevalence. Science 28 April 2022
Leave a Reply