An outbreak of West Nile fever among migrants in Kisangani, Democratic Republic of Congo

In February 1998, an outbreak of acute febrile illness was reported from th e Kapalata military camp in Kisangani, the Democratic Republic of Congo. Th e illness was characterized by an acute onset of fever associated with seve re headache, arthralgia, backache, neurologic signs, abdominal pain, and co ughing. In 1 individual, hemorrhagic manifestations were observed. The neur ologic signs included an altered level of consciousness, convulsions, and c oma. Malaria was initially suspected, but the patients showed negative bloo d films and failed to respond to antimicrobial drugs. A total of 35 sera co llected from the military patients in the acute phase were tested for the p resence of IgM against vector-borne agents. Serum IgM antibodies against We st Nile fever virus were found in 23 patients (66%), against Chikungunya vi rus in 12 patients (34%), against dengue virus in 1 patient (3%), and again st Rickettsia typhi in 1 patient (3%). All sera were negative for IgM antib ody against Rift Valley fever virus, Crimean Congo hemorrhagic fever virus, and Sindbis virus. These data: suggest that infections with West Nile feve r virus have been the main cause of the outbreak.