Animal rabies

Transmission of animal rabies is similar to that of human rabies, with virus-laden saliva from infected animals entering the body through wounds or by direct contact with mucosal surfaces. Following access to the muscle cells at the wound site, peripheral nerves and subsequently the central nervous system, the virus travels retrogradely from the CNS via peripheral nerves to various tissues, most importantly the salivary glands, from which it is shed, completing the transmission cycle.

Though the major burden of human rabies is attributed to dog-mediated transmission, a wildlife (sylvatic) cycle of rabies also exists, with wild animals (e.g. bats, raccoons and foxes) serving as the maintenance host of the virus.

Dog rabies is characterized by clinical manifestations, including changes to normal behaviour, such as:

  • Biting without provocation
  • Eating abnormal items such as sticks, nails, faeces, etc.
  • Running for no apparent reason
  • Vocal changes (e.g. hoarse barking and growling) or inability to produce sounds
  • Excessive salivation or foaming from the mouth

Dog vaccination in Tanzania ©Sarah Cleaveland

Investment in eliminating the risk of rabies at its source is the most cost-effective measure. Vaccination of at least 70% of dogs in areas at risk is now accepted as the most effective way of preventing human rabies deaths. However, in many parts of Asia and Africa the vaccination coverage (of generally 30-50%) established in dog populations is not high enough to break the transmission cycle of the disease and early discontinuation of rabies control programmes can lead to costly re-emergence of the disease.