Page 75 - VHSA - Onderstepoort 100 Years - Part 3

ONDERSTEPOORT 100
Tuberculosis (caused by Mycobacterium bovis) became a major threat to African buffaloes in the Kruger National Park and KwaZulu-Natal Parks in the 1990s. Potgieter, Stoltsz and co- workers assisted the veterinary authorities to develop a protocol for breeding ‘clean’ calves from T. parva-infected buffalo cows in a vector-free area. The molecular diagnostic tests (see below) developed by B.A. Allsopp and colleagues were employed for the detection of parasite DNA, in case in utero transmission of the infection occurred. Species-specific DNA probes have been developed that are capable of detecting carrier infections of parasites of the Theileria parva-group, Theileria mutans, Theileria taurotragi, Theileria buffeli and an unknown Theileria sp. of buffaloes. These
tests showed much promise as additional diagnostic tools to evaluate the success of breeding Corridor disease-free buffaloes from areas where the disease is endemic.
The success of this project led to great demand by the game industry for disease-free African buffaloes for commercial game farming in South Africa. The buffaloes in the KwaZulu-Natal parks are free
from foot and mouth disease but are infected with the Theileria parasite that causes Corridor disease in cattle. It is obvious that if such animals could be cleared of their carrier status they could be used
to satisfy the commercial demands. Stoltsz and colleagues were unable to sterilize several buffaloes of their infection with the latter parasite by using the chemotherapeutic remedies primaquine, halofuginone, parvoquone and buparvoquone. It has also been shown that the indirect fluorescent antibody test is not sufficiently sensitive to declare buffaloes in an endemic area free from infection with Corridor disease.
By 1999/2000 the breeding of Corridor disease-free buffaloes by farmer/entrepreneurs had expanded dramatically, especially in the Phalaborwa district where large establishments had sprung up. Judging from the rigorous testing, by Stoltsz and his colleagues, of such animals for the carrier- state of Corridor disease, the breeding protocols that had been developed by the Animal Health directorate appeared to be effective, as most calves born to breeding herds tested negative for the Theileria parva-group of parasites.
So-called Corridor disease-free buffaloes, thought to be of Addo Elephant Park origin, which were sold and then introduced to a cattle farm were, however, responsible for an outbreak of classical Corridor disease, the farmer concerned loosing about 200 head of cattle. The veterinary authorities therefore placed a moratorium on the movement of all buffaloes in this country unless the animals had been subjected to a battery of tests. A convenient diagnostic test package, the ‘Buffalo Package’ was developed by the OVI to test Lowveld buffaloes for all four of the diseases potentially carried by them, i.e. bovine tuberculosis, foot
and mouth disease, bovine brucellosis and Corridor disease.
It has been found that older buffaloes in the Kruger National Park have such low antibody titres (< 1/180) to T. parva in the IFAT that they would normally be regarded as uninfected. To test their immune status to Corridor disease five such animals were challenged with a tick-derived Theileria parva lawrencei stabilate. There was no clinical response, indicating that they were solidly immune.
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Protozoology
1908-2008
Years