Rift Valley fever in Madagascar : infection risks for the abattoir staff in Antananarivo

Abstract

The first Rift Valley fever (RVF) epizootic was reported in Madagascar in 1990-1991. A serological survey was conducted in Antananarivo main slaughterhouse to determine the risks of infection by the RVF virus among workers in January 1995. In 12 out of 126 workers (9.5%), RVF IgG antibodies were detected in association with RVF IgM antibodies in 11 cases. All positive individuals worked in the first section of the slaughter line. The 11 RVF IgM positive workers represented 48% of the staff in that area. It is most likely that they were infected by an aerosol during the slaughter of a viremic animal. They did not show any clinical symptoms. Another serological survey conducted in 40 bovines every week in the abattoir from October 1994 to January 1995 showed a 7.0% RVF IgG prevalence rate. Only one animal was reported RVF IgM positive early December 1994. Preventive measures such as mandatory mask wearing on the slaughter line and if possible vaccination of high risk staff are recommended.