Rabies: A neglected zoonotic disease
Rabies is a zoonotic disease (a disease that is transmitted from animals to humans), caused by the rabies virus, of the Lyssavirus genus, within the family Rhabdoviridae. Domestic dogs are the most common reservoir of the virus, with more than 95% of human deaths caused by dog-mediated rabies.
The virus is transmitted in the saliva of rabid animals and generally enters the body via infiltration of virus-laden saliva from a rabid animal into a wound (e.g. scratches), or by direct exposure of mucosal surfaces to saliva from an infected animal (e.g. bites). The virus cannot infiltrate intact skin. Once the virus reaches the brain, it further replicates, resulting in presentation of clinical signs from the patient. There are two clinical manifestations of rabies – furious (classical or encephalitic) and paralytic. Furious rabies is most common form of human rabies, accounting for approximately 80% of cases.
With the exception of Antarctica, rabies is endemic on all continents. Of the tens of thousands of deaths occurring annually due to rabies, 95% of cases are reported in Asia and Africa.
Dog-mediated human rabies disproportionately affects poor rural communities, particularly children, with the majority (80%) of human deaths occurring in rural areas, where awareness and access to appropriate post-exposure prophylaxis is limited or non-existent.
The true burden of the disease is likely to be underestimated due to chronic underreporting and political neglect in many developing countries. Improved reporting systems are required to address the lack of accurate data and validate these estimates in a number of regions.
Rabies is a 100% vaccine-preventable disease. Countries embarking on rabies elimination programmes have successfully experienced marked reductions, often progressing to the elimination of rabies. Elimination programs often revolve around mass dog vaccination campaigns, where at least 70% of the dog population should be covered in order to break the cycle of transmission in dogs, and to humans.
Safe, effective vaccines can also be used for pre-exposure immunization in people. Post-exposure prophylactic vaccinations are required for treating individuals who have had no previous immunisation. The reduced volume required by intradermal vaccines, in comparison to the intramuscular vaccine results in cost savings of 60-80%. Intradermal vaccination may be a more cost-effective option for high-flow clinics where the disease is endemic.