An anthrax outbreak in the Kruger National Park (KNP) claimed at least 65 animals in September 2010. The actual deaths could be much higher as carcasses are not easily found and the park has only one dedicated team on the ground.
The first case was noted in May, and since then, the disease has spread along the rivers and spruits in the northern parts of the park (Shingwedzi area), a pattern typically associated with anthrax.
"While anthrax may evoke horror images of letter bombs and terror attacks, it is not a disease generally associated with human deaths. In the KNP, anthrax poses no threat to tourists as people can only be infected through contact with an infected animal," says At Dekker, lab technician of the state veterinary department based in Skukuza.
According to Dr Valerius de Vos (professor extraordinary), veterinary ecologist and renowned anthrax expert, the disease is an integral part of the eco-system and, though the present outbreak is closely monitored, it is not regarded as something out of the ordinary.
Anthrax is an acute disease and is caused by the bacteria Bacillus anthracis. The bacteria form spores that can survive for many years, even centuries.
It is believed one of the ten plagues mentioned in the Bible refers to anthrax. Dr de Vos, who, while he was employed in the KNP and had studied the disease for 40 years, found spore on 250 year old bones in the Pafuri area.
Anthrax is endemic to the Pafuri region of Kruger and has its own peculiar pattern and cycles as observed by Dr de Vos over many years. An infected animal sets the cycle in motion, which is then sustained and spread by blow flies and animals feeding on infected foliage. Animals with a phosphate and calcium shortage do tend to chew on old bones.
Anthrax outbreaks occur in 10 to 20 year intervals in Kruger, depending on several factors such as rainfall and population density. The last outbreak was towards the end of 2009 in the Pafuri region north of the Levuvhu river when about 150 animals died.
While most animals are susceptible to the disease, kudu, waterbuck, roan antelope and buffalo are more vulnerable to infection due to their feeding habits. Birds cannot be affected, but vultures, especially, are known as carriers of the spore.
After feeding on an infected carcass, vultures wash themselves and defecate in shallow, stagnant pools and so shed millions of spores in the water where the spores then usually settle at the bottom of the pool.
The herd activity of buffalo in these pools stirs the spores to the surface where, mostly the bigger bulls drink. This year, notably half of the number of carcasses found was buffalo.