Rabies has been one of the most feared diseases throughout human history and has the highest human case-fatality proportion of any infectious disease. Every year over 7 million people receive post-exposure prophylaxis, and an estimated 55,000 people die from rabies. Over 99% of these deaths occur in developing countries where rabies is endemic in domestic dog populations. However, the impacts of canine rabies are often overlooked, largely because human rabies deaths are now extremely rare in Western Europe and North America, where mass vaccination successfully eliminated the disease from domestic dog populations.
Although canine rabies has been successfully eliminated from Western Europe and North America, in the developing world someone dies every ten minutes from this horrific disease, which is primarily spread by domestic dogs. A quantitative understanding of rabies transmission dynamics in domestic dog populations is crucial to determining whether global elimination can be achieved. The unique pathology of rabies allowed researchers to trace case-to-case transmission directly during a rabies outbreak in northern Tanzania. From these unusual data, they generated a detailed analysis of rabies transmission biology and found evidence for surprisingly low levels of transmission. They also analysed outbreak data from around the world and found that the transmission of canine rabies has been inherently low throughout its global historic range, explaining the success of control efforts in developed countries. However, they show that when birth and death rates in domestic dog populations are high, such as in the study populations in Tanzania, it is more difficult to maintain population-level immunity in between vaccination campaigns. Nonetheless, although the level of vaccination coverage required is higher than would be predicted from naïve transmission models, global elimination of canine rabies can be achieved through appropriately designed, sustained domestic dog vaccination campaigns.
Transmission dynamics and prospects for the elimination of canine rabies. PLoS Biol. 2009 Mar 10;7(3):e53
Rabies has been eliminated from domestic dog populations in Western Europe and North America, but continues to kill many thousands of people throughout Africa and Asia every year. A quantitative understanding of transmission dynamics in domestic dog populations provides critical information to assess whether global elimination of canine rabies is possible. We report extensive observations of individual rabid animals in Tanzania and generate a uniquely detailed analysis of transmission biology, which explains important epidemiological features, including the level of variation in epidemic trajectories. We found that the basic reproductive number for rabies, R0, is very low in our study area in rural Africa (approximately 1.2) and throughout its historic global range (<2). This finding provides strong support for the feasibility of controlling endemic canine rabies by vaccination, even near wildlife areas with large wild carnivore populations. However, we show that rapid turnover of domestic dog populations has been a major obstacle to successful control in developing countries, thus regular pulse vaccinations will be required to maintain population-level immunity between campaigns. Nonetheless our analyses suggest that with sustained, international commitment, global elimination of rabies from domestic dog populations, the most dangerous vector to humans, is a realistic goal.
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Coldwater and tropical fish are the third most popular pet in the UK after cats and dogs. Over 3 million homeowners have a pond in their garden and many of these are stocked with fish, some of which, like koi carp, are very expensive. As Keith Way describes in this article in Microbiology Today (pdf) a whole host of viruses are in the environment just waiting to infect them with harmful diseases:
