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Pitfalls on live wildlife auctions:

wildlife diseases

21 September 2012

There are two major pitfalls concerning wildlife diseases which should be taken into consideration when buying wildlife. The one concerns buying wildlife from or moving them to regions with a known prevalence of some diseases and the other with buying wildlife which can introduce diseases to a wildlife ranch because they do not yet show the clinical symptoms of such diseases at the time of buying, or because the symptoms are nor recognized by the buyer.

The first pitfall centres around the myth that it is possible to introduce a founding population of springbok that is resistant to heartwater disease by buying it privately or on live wildlife auctions from a region where this disease is endemic. Springbok from regions where heartwater disease is endemic usually sell for much higher prices than springbok from other regions. On live wildlife auctions the record price per animal for a springbok that is resistant to heartwater disease was R22 000 up to 2011, compared with R2400 for a springbok from regions that are free of heartwater disease. The mean price per animal for a heartwater-resistant springbok in 2011 on live wildlife auctions was R1392 compared with R8952 (6.4 times more) for a springbok from a heartwater disease region. Moreover, it is usually futile to buy springbok that are free of heartwater disease and relocate them to a region where this disease is endemic. Because the ewe does not transfer her resistance to heartwater disease to her lamb, it is also futile to buy a heartwater-resistant founding population of springbok.

In South Africa, heartwater disease is transmitted through the bite of the common variegated tick Amblyomma hebraeum which carries the rickettsial parasite Ehrlichia ruminatum. The tropical variegated tick Amblyomma variegatum is also a carrier of this parasite but it only occurs in the extreme north-eastern parts of Namibia and further north. This parasite infects the ticks in a cyclic manner when they feed on wildlife that have developed heartwater disease. In South Africa the common variegated tick occurs in the bushveld and Lowveld but not in grasslands and the more western and southern regions. Wildlife that develop heartwater disease experience blood leaks from the tissues, causing blood to accumulate in the soft tissues, heart sac, lungs, brain and body cavities as a straw-coloured fluid. Infected wildlife show rapid and excessive blinking of the eyes, stagger around, develop seizures, make uncoordinated paddling motions with the legs, lie down on the side and sometimes develop diarrhoea and breathing problems before dying.

Treatment with oxytetracycline is only possible in captivity during the early signs of the disease. Young lambs in captivity from five to eight weeks old can be vaccinated but there currently is no vaccine that is available commercially. Moreover on extensive wildlife production areas, the lambs and calves of receptive wildlife will have to be captured and kept in captivity for the duration of the process. Successful vaccination requires repeated treatment and therefore cannot be done other than in captivity. Wildlife that are not resistant to heartwater disease should be vaccinated at least six weeks before being moved into a region where heartwater is endemic. The best option is not to expose susceptible wildlife to this parasite and not to bring wildlife that are susceptible to heartwater disease to regions where they do not occur naturally. Except for the springbok, the blesbok and black wildebeest are especially susceptible to heartwater disease. Other wildlife in which the disease has been recorded include the blue wildebeest, African savanna buffalo, eland, giraffe, sable antelope and steenbok, but in them the symptoms are usually relatively mild.

A second major pitfall is buying sick wildlife which are still developing diseases and do not yet show the clinical symptoms. The biggest nightmare of any wildlife rancher is an outbreak of an infective disease in his wildlife. Early in the 20th century rinderpest, for example, caused enormous losses under livestock and wildlife in South Africa and the rest of Africa. Foot-and-mouth disease is caused by a virus and can infect a large variety of wildlife. Although the mortality rate due to this disease is not as high in wildlife as in livestock, an outbreak of this disease will stop the export of all agricultural products from the infected region. The first symptom of an infection is the appearance of small, white lesions in the mouth and between the hooves. Confirmation of the disease can only be done in an approved veterinary laboratory. When sub-clinically infected wildlife are purchased on live wildlife auctions the disease can develop and spread over an entire wildlife ranch. Wildlife diseases can also impact on the hunting industry which currently forms the backbone of the wildlife industry because no product of a wild animal will be allowed to be removed from a ranch where foot-and-mouth disease, buffalo disease (corridor or east coast fever) and bovine tuberculosis occurs. Moreover, diseases such as rabies, black quarter disease, Corynebacterium infection, brucellosis, malignant catarrhal fever, swine fever, canine distemper, horse sickness, botulism, red-water, Cytauxzoonosis and nagana all occur in wildlife. In addition, disease conditions such as mange are spread by mytes.

Diseases in wildlife that can threaten human health are an additional danger. The occurrence of bovine tuberculosis, for example, influences the export of wildlife meat and can expose humans that are ill or weak to tuberculosis. Other diseases that are being monitored for transmission to humans include corridor disease, foot-and-mouth disease, canine distemper, rabies and swine fever. Hunters who hunt for the pot and who slaughter and cut up their own hunted meat are especially exposed to possible infection from these diseases because the carcasses are usually not handled under the supervision of a trained meat inspector.

It has recently been found that the distribution of wildlife to regions in which they did not occur naturally and the fragmentation of ecosystems such as grasslands and forests in the past 30 to 40 years have been responsible for the distribution of all the major pandemic diseases from wildlife to humans. This includes the distribution of viral diseases such as HIV AIDS, the Nipah virus and avian flu. Such a pandemic can cause enormous damage and financial losses. The importation of wildlife from areas with endemic diseases undoubtedly can create major problems for humans, the wildlife and livestock of South Africa and can also threaten food security. It therefore has become vital that veterinary examinations be done on all the wildlife that are being sold on live wildlife auctions to certify that they are free from diseases. These examinations should also include external and internal parasites while the disease status of the region from which the wildlife came should also be taken into consideration. No transport permits should be granted for moving wildlife from regions with known endemic diseases to ones where these diseases are not known to occur. Buying wildlife that seem pretty is not always wise and the best approach remains that any wildlife rancher should concentrate on stock that are native to a given region. Losses due to uninformed purchases can expose the existing wildlife on a ranch to immeasurable harm. However, informed disease management is not yet part and parcel of the wildlife industry as it should be.

 

References:

Anonymous 2007. Heartwater. Center for Food Security and Public Health. Ames: Iowa State University.

Anonymous 2012. Diseases shared by animals and humans. Kruger Park Times. http://www.krugerpark.co.za/krugerpark-times-2-8-diseases-shared-by-animals- and-humans

Cloete, F 2012. Tendense van lewende wildverkope 2011. Game & Hunt 18(2): 18 - 20.

Oberem, P and P Oberem 2011. A guide to animal diseases in South Africa. Pretoria: Briza Publications.

Verdoorn, G H 2011. Bek-en-klou-seer bedreig ons wild. S A Hunter, July: 40.

By: Prof J du P Bothma

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