WildLife Group of the SAVA
Investigation of a suspected anthrax case in a Greater Kudu cow :
How to go About it to Improve the Potential for a Diagnosis
By : Dr Luca Mendes ( BVSc , MVetSci Cons . Med .)
Case Summary
A Greater Kudu ( Tragelaphus strepsiceros ) cow was found dead at a private game ranch in the Makana District of the Eastern Cape . The animal had been seen the day before with no obvious abnormality . An initial inspection of the carcass revealed a moderate haemorrhagic discharge from her nostrils and anus . Based on the ecology and epidemiology of the disease in Southern Africa ( Bengis , 2013 ), Anthrax ( Bacillus anthracis ) was initially suspected as the aetiological agent . On-site peripheral blood smears stained using Diff-Quick ( Kyron Laboratories , South Africa ) revealed highly suspicious , short chains of large , anthrax-like bacilli . However , further blood smears stained using polychrome methylene blue ruled out anthrax . A full post mortem was subsequently performed , which revealed a severe , generalised necro-haemorrhagic syndrome . Although further sample results were inconclusive , histopathology suggested a clostridial infection . The carcass was safely disposed of by incineration and there were no further mortalities of kudu on the ranch .
Background Information
Anthrax Ecology Anthrax is an infectious disease of wild and domestic animals and humans , caused by a Gram positive , nonmotile , endospore forming bacterium . A combination of exotoxins causes widespread damage to the reticulo-endothelial system and vasculature , resulting in varying degrees of haemorrhage and oedema and ultimately death . Ruminants and hind gut fermenters are most susceptible ( Bengis , 2013 ). In southern Africa , kudu play an important role in the ecology and epidemiology of anthrax ( Bengis , 2013 ; Clegg et al ., 2007 ; de Vos , 1990 ; Braak & de Vos , 1990 ).
Kudu Cow History Four weeks prior to death , the cow had been moved over 1800 km from Thabazimbi , in the north of South Africa , to the ranch . The relocation saw the animal being moved from a ranch in a savannah ecosystem to the arid sub-tropical thicket of the Eastern Cape .
Prior to death , this cow had appeared to adapt to the new surroundings and had been frequently observed eating browse and supplementary feed . She also had no vaccination history .
Investigation of the Carcass
Initial Assessment Prior to handling the carcass , basic protective clothing ( overalls and gum boots ) and disposable latex gloves were put on .
Mild to moderate haemorrhagic discharge was noted from her nostrils and anus while signs of paddling motions were observed in the sand . She was in average body condition ( score : 2.5 out of 5 ), with an expected level of external parasites for the region ( predominantly Amblyomma and Rhipicephalus spp . ticks ).
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