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African buffalo were introduced into a wildlife conservancy in the southeast of Zimbabwe in an effortto increase the conservancy's economic viability, which is primarily based on eco-tourism. The buffalo were infected with SAT serotypes (SAT-1, SAT-2 and SAT-3) of foot and mouth disease (FMD) virus, and in order to isolate the conservancy and prevent the transmission of FMD to adjacent populations of domestic livestock, the conservancy was surrounded by a double-fence system, 1.8 m in height. The intention was to prevent the movement of both wildlife and domestic animals across the perimeter. However, two years after the buffalo were introduced, FMD occurred in cattle farmed just outside of the conservancy. Using serological and molecular diagnostic tests, epidemiological investigations showed that it was most likely that antelope (impala or kudu), infected through contact with the buffalo herd within the conservancy, had jumped over the fence and transmitted the virus to the cattle.

Quantification of the risk that African buffalo (Syncerus caffer) (isolated within wildlife conservancies in Zimbabwe by a double fencing system) would infect cattle outside the conservancies with foot-and-mouth disease (FMD) virus was assessed by scenario-pathway analysis. Of the five scenarios considered, the greatest annual risk (1:5000) for cattle would be from antelope jumping over the outer perimeter fence of the conservancy and infecting cattle on the outside. The other transmission scenarios (including air-borne transmission) had a FMD risk that was low to very low. Risk management would include means to prevent the escape of antelope from the conservancies and restriction of cattle density in the proximity of the perimeter fence.

Pestiviruses were isolated from three eland (Taurotragus oryx) in Zimbabwe. The viruses were characterised by typing with monoclonal antibodies and by partial genetic sequencing. All were similar to bovine viral diarrhea viruses commonly isolated from cattle. This suggests that bovine viral diarrhea virus can spread from cattle to eland.

The prevalence of antibody to the viruses of bovine virus diarrhoea (BVD), bovine herpes virus typel (BHV1), rift valley fever (RVF), bovine ephemeral fever (BEF) and bluetongue (BT) and to Leptospira sp. was determined in wildlife populations in Zimbabwe. Evidence of infection with BVD virus was found in 14 of the 16 species examined but was greatest in eland Taurotragus oryx, nyala Tragelaphus angasi and bushbuck Tragelaphus scriptus. Persistent infection with BVD virus was found in 1 of 303 antibody-free eland but not in the smaller sample of 102 antibody-free buffalo Syncerus caffer. Antibody to BHV1 was widespread, being found in 10 of 16 species with the highest prevalence being in buffalo and eland. Antibody to RVF was most prevalent in black rhino Diceros bicornis and white rhino Ceratotherium simum, buffalo and waterbuck Kobus ellipsiprymnus. Both BEF and BT were widespread in all the species examined. Evidence of infection with Leptospira sp. was found in 7 species. Infections were due to up to 3 of 8 different serovars.

Four wild African ruminants, eland (Taurotragus oryx), giraffe (Giraffa camelopardalis), kudu (Tragephalus strepsiceros strepsiceros), and blue wildebeest (Connochaetes taurinus), were experimentally infected with the rickettsia Cowdria ruminantium, the tickborne agent causing heartwater in domestic ruminants. The infections were established, and C. ruminantium was transmitted to naive small ruminants by the vector Amblyomma hebraeum when transmission attempts were made at days 128 (eland and wildebeest), 85 (giraffe), and 24 (kudu) post infection. These wild ruminants, which are natural hosts for the tick vector, and which commonly occur within heartwater-endemic areas of Africa, are likely to play important roles in the epidemiology of heartwater as reservoirs of C. ruminantium infection. These findings also demonstrate that considerable risks are associated with the translocation of wild ruminants from heartwater-endemic areas to heartwater-free areas such as the northern and southern American mainlands, which have large populations of susceptible domestic and wild ruminant hosts and tick species that are capable of transmitting the disease.

An outbreak of foot-and-mouth disease (FMD) occurred during April 1991 in a trypanosomiasis sentinel cattle herd by the Rifa River to the east of Lake Kariba, Zimbabwe. Despite the cattle having been vaccinated biannually for the previous five years the disease was severe. The viruses isolated from the affected animals were typed as FMD virus type SAT 1. Free-living African buffalo (Syncerus caffer) which had been using the same watering place as the affected cattle were sampled and FMD type SAT 1 virus was isolated. Partial nucleotide sequencing of the gene coding for the capsid protein 1D (VP1) of one of the viruses isolated from cattle and two of the viruses isolated from buffalo demonstrated a close relationship between the three viruses. Since no other cattle were present in the area and no outbreaks of SAT 1 had occurred in Zimbabwe since 1989, it was concluded that the disease had been transmitted from buffalo to cattle.

Between 1989 and 1992, 7970 wild ungulates, comprising 14 different species, were tested for antibodies to types SAT 1, SAT 2 and SAT 3 foot-and-mouth disease (FMD) virus. Of these 1.2% were found to be positive and these included impala (Aepyceros melampus), eland (Taurotragus oryx), waterbuck (Kobus ellipsiprymnus) and sable (Hippotragus niger). All the positive animals were either from the wildlife areas where buffalo (Syncerus caffer) occur or from ranches where clinical FMD had occurred in cattle. The role of these animal species in the current epidemiology of FMD in Zimbabwe is discussed.