WHO, WER and Epidemiological Bulletin

"Although Rift Valley fever has been confirmed in the current outbreak affecting humans and livestock in Kenya and Somalia, it is evident that other causes have contributed to the high rate of haemorrhagic symptoms and deaths among both humans and animals. Laboratory investigations at the WHO Collaborating Centres at Kenya Medical Research Institute in Nairobi, National Institute for Virology in Johannesburg and at Centers for Disease Control and Prevention in Atlanta have tested specimens from Kenya and Somalia for a wide range of infectious agents but so far the only clear diagnosis is RVF which has been confirmed by virus isolation or implicated through the demonstration of specific IgM antibodies in a 30-40% of samples tested.

Preliminary epidemiological studies have shown that the flooded areas of north-eastern Kenya are most likely to have suffered mainly from Rift Valley fever and that the virus may have reached the area some time in November-December 1997. The disease is widespread but presenting with typical RVF symptoms which are in general mild in humans but causing abortions in sheep, goats and camels. Animal vaccination, which would be the most efficient control measure for RVF, is not considered feasible under the current conditions in the affected areas. Severe haemorrhagic disease is not common for RVF and the absence of RVF virus antibody in about two-third of viral haemorrhagic fever cases tested in the laboratory is a further indication that another infectious or toxic agent is involved. Contrary to the RVF outbreak [as a whole], the severe cases of haemorrhagic illness have occurred in localized clusters. Unfortunately, these clusters have been reported in remote flooded areas in the northeast near the border with Somalia which are very difficult to reach. WHO and the Task Force in Nairobi are now establishing a base in Garissa for further investigations of the cases of haemorrhagic fever.

The international team coordinated by WHO will include members from Epiet, Paris, Epicentre of Medecins Sans Frontieres, the National Institute for Virology in Johannesburg, Centers for Disease Control and Prevention and the US Army Medical Research Institute of Infectious Diseases, FortDetrick. The team will be equipped with a locally rented helicopter to access areas otherwise difficult to reach. The establishment of the team has been made possible thanks to financial support of WHO and the Department for International Development, United Kingdom."--Martin Hugh-Jones <mehj2020@vt8200.vetmed.lsu.edu> ON ProMED-mail <promed@usa.healthnet.org>