The epidemiology of African swine fever in Cameroon

The epizootiology of African swine fever in the North West, South West and West Provinces of Cameroon was studied between 1982 and 1988. The enzootic area of ASF was determined using the data from a serological survey and interviews with pig farmers and it covered the southern parts of the N. W. and S. W. Provinces and all of the West Province except the districts of Malantouen and Massangam where pigs are not kept. The highest prevalence of seropositive pigs for ASF antibody was in the West Province where 10. 2% of the pigs sampled between January-June 1988 were positive. Restriction enzyme analysis and restriction enzyme site mapping of genomes of isolates from different parts of the enzootic area failed to distinguish between the 1982, 1985, 1987 and 1988 isolates but the 1986 isolate differed from the others in two fragments occurring within the last 10Kbp from the right terminus and another occurring within the central region of the genome (89-91Kbp). The restriction enzyme fragments of the genomes of the Cameroon viruses were similar to the West and South West African isolates from Senegal (Dakar/59), Zaire (Katanga/67) Angola (Angola/70; Angola/72) and Namibia (Namibia/86-1), and were also very similar to the recent European isolates from Malta (1978), Sardinia (1978,1982), Italy (1983), Portugal (1984) and Belgium (1985). In contrast, the Cameroon isolates were genetically very different from the East and South East African isolates from Tanzania, Malawi, Zambia and Mozambique. The genome of the CAM/82 isolate remained unchanged when the virus was passaged in either domestic pigs or PBM cultures. The Cameroon virus isolates shared the same haemadsorption antigens with the recent European isolates and those from Angola and Namibia. They also produced the same lesions and clinical signs in infected domestic pigs which were similar to those produced by some recent European isolates when inoculated into domestic pigs. No evidence for the presence of soft ticks of the Ornithodoros moubata complex was found during a survey of ASF carried out between 1985 and 1988 in the West Province and southern parts of the North West and South West Provinces of Cameroon. The absence of warthogs (Phacochoerus aethiopicus) from these areas was also recorded.