An outbreak of African swine fever in the southern region of Malawi.

An outbreak of African swine fever (ASF) was first detected in December 1989 in the southern region of Malawi. During 1990 the outbreak reached epidemic proportions: by August 1990, over 31,000 pigs (45%) from a population of 70,000 in the affected areas had died or been slaughtered. In affected villages this accounted for 83% of the pigs present. The outbreak probably originated in the central region of Malawi, where ASF is enzootic. Virus isolates from the southern and central region outbreaks in 1989-1990 were indistinguishable using DNA restriction fragment pattern analysis. The rapid spread of the disease and the difficulty experienced in halting this spread are discussed. Important factors included the type of pig husbandry (mainly scavenging without penning) and the fact that veterinary field staff lacked the mobility to ensure the observance of restrictions. New initiatives will be required--in particular, raising public awareness and developing community participation--if ASF is to be controlled in the future.