Rabies in greater Kudu Antelope in Namibia

Namibia is one of the countries where both dog rabies as well as wildlife rabies commonly occur. Since 1977, the country has experienced two epidemics of rabies in kudu antelope, manifesting in recurring cycles (Figure 20), with the second epidemic persisting until today, to aa point where rabies in kudu can be regarded as endemic. This phenomenon of rabies in kudu is unique to Namibia and does not occur in any other part of natural range of this antelope species in the rest of Africa. The disease is responsible for large numbers of fatalities in the Namibian kudu population, resulting in severe economic losses to the game farming and hunting industry. There is no indication that the disease in kudu will abate any time soon. Although genetic studies of the RABV isolated from kudu suggest that the rabies virus affecting kudu may originate from jackal, epidemiological surveys, clinical observations and transmission experiments confirm that non-bite transmission of rabies in kudu, through direct or indirect contact, is possible. This route of infection may be the most important mode of transmission and spread of the disease in kudu, also explaining the serious extent of the disease once it flares up in a susceptible population. Intra-muscular vaccination using a commercial inactivated vaccine has been shown to be effective in protecting kudu against rabies but it remains a costly method with practical limitations and no information on the duration of immunity available so far. Experiments have delivered definite proof that protective immunity against rabies can be achieved in kudu using an oral vaccine, but methods and protocols need to be improved in order to achieve protective immunity in a sufficient number of animals. Different types of suitable bait were developed and their uptake by kudu tested successfully. It should therefore be possible to further develop this approach into an effective delivery method for the rabies vaccine. Serological tests required to effectively monitor the immune response to rabies vaccines, validated for the use in this species, need to be developed. Taking everything into consideration, it should be possible develop the necessary tools, methods and protocols to effectively protect kudu antelope against rabies, within the foreseeable future.