Viral haemorrhagic fever surveillance in Kenya, 1980-1981

Following two cases of Marburg virus disease in Kenya in 1980, viral haemorrhagic fever surveillance was undertaken in western Kenya. Over a 21-month period investigations, including virus isolation attempts, patient and contact serology, visits to areas where suspected cases occurred, interviewing family members and neighbours of suspected cases and following up any additional illnesses in these areas, were carried out. During the study two cases were found that were likely to have been Ebola haemorrhagic fever based on rising antibody titres or positive serology in contacts. Diagnoses of hepatitis A, hepatitis B, malaria, bacterial septicaemia or other causes were arrived at in 24 cases. No diagnosis could be made in 26 instances. 741 human sera were tested for antibodies against Marburg, Ebola, Congo haemorrhagic fever, Rift Valley fever or Lassa fever viruses by indirect fluorescence. Eight sera were positive for Ebola virus antibodies, all of which were from suspected cases or contacts of suspected cases. Two sera were antibody positive to Congo virus and one had antibodies against Rift Valley fever virus. No Marburg or Lassa virus antibodies were detected.