Hooo-Hooo Volume 11 Nr 1 - Page 4

WildLife Group of the SAVA HemorrhagiC Septaceamia IN AFRICAN BUFFALO Dr Rick Last BVSc; M.Med.Vet (Pathology)Specialist Veterinary Pathologist Vetdiagnostix –Veterinary Pathology Services Introduction Hemorrhagic septicaemia (HS) is an acute, often peracute, highly fatal form of septicaemic pasteurellosis associated with certain serotypes of Pasteurella multocida, namely serotypes B:2 and E:2 (Carter and Heddleston system). Clinical disease is most commonly reported in cattle, water buffaloes and American bison with infrequent natural disease documented in pigs, sheep, goats, camels, elephants, horses, donkeys, various species of deer and yaks. The first reported cases of hemorrhagic septicaemia in African Buffalo in South Africa were in 2011. Since this time there have been increasing numbers of cases documented in African buffalo which have coincided with logarithmic growth of the game industry. Historically, type B occurred in Asia and type E in Africa, with Egypt having both types. South Africa was mostly free of it, and so it is notifiable when found. Onderstepoort therefore included type E in the cattle Pasteurella vaccine, in the early 1980’s, when there was a spill-over of HS in cattle due to type E from Botswana 1 . Type B was however later found in Zimbabwe 4 , and in Namibia 6, but not in SA, until the current outbreak of type B in wildlife, mostly in buffaloes in 2008. (Maryke Henton – Vetdiagnostix, Personal Communication). 4 Epidemiology Cattle, water buffaloes and bison are known reservoirs of infection with a small percentage of healthy animals harbouring small numbers of P. multiocida B:2 or E:2 in their tonsils/nasopharynx 2, 3, 5, 7, 8 . A similar scenario is suspected in African buffalo, although one should also consider increased contact between buffalo and cattle with the growing intensification in the game industry and therefore, increased opportunity for transmission between cattle and buffalo and vice-versa. Bacteria are shed from carrier animals during periods of stress. Common stressors include: high temperatures and humidity, concurrent infections and poor nutrition. Clinical disease is more common during rainy seasons in summer rainfall areas (moisture, temperature and humidity, promoting bacterial survival in the environment), with bacteria being maintained in intervening periods in the nasopharyngeal areas of carrier animals. Stress induced recrudescent infections in carrier animals with extensive proliferation and spread of the bacteria to susceptible in-contact animals is the most common trigger for outbreaks 2, 3, 5, 7, 8 . Transmission occurs by direct contact or through fomites, with buffalo becoming i