Seasonal Foot and Mouth Disease and its Control in Malawi

Abstract

During the 19 years between 1957 and 1975 seven out of eight FMD outbreaks in Malawi began during the dry season. Movement restrictions on animals and animal products, supplemented by various immunization procedures were used as control measures. The earliest immunization method used was aphthization and it was applied in combination with vaccines when they became available. However, the virus replication during aphthization was hazardous and there were doubts about the efficacy of attenuated vaccines, so these methods were superseded by the use of inactivated vaccines. Disease control procedures were routinely withdrawn after the end of each outbreak, but this policy was changed in 1969 when an annual prophylactic vaccination regime was implemented. It was initiated during a period when there was no FMD in the country and timed to have maximum effect during the dry season. The work was monitored by serum and probang surveys for carrier animals and analysis of the results shows that the measures employed were effective in the control of virus spread. It was possible to eradicate the virus from the areas studied, but new outbreaks were caused by fresh introductions of virus.