Hemorrhagic Fevers : Few Clues after 25 Years

ABSTRACT

There is a high prevalence of Ebola antibodies found in the Kenya population; related to geographical area and season; although the clinical disease was never found and the virus was not isolated. A field study was carried out in 7 hospitals in western Kenya; 1986 -1987 (including surveillance studies in suspect areas); to intensify collection and transport of samples; testing facilities; patient observation with record keeping and follow-up. This study involved 1109 admitted patients with fever and/or bleeding; 155 contacts of haemorrahagic fever antibody (Hfab) patients; and 916 people in suspect areas. Respectively 160;44 and 80 persons were found Hfab positive mainly to Ebola; using an indirect immunofluorescent assay. From 676 viral cultures no virus was isolated. A relationship between antibody titres and ecological factors; social habitat; age; sex or season was not found. The non-specificity of IF testing was demonstrated by 1) the disagreement between the results of two reference laboratories; 2) the unpredictability of the titre conversation course; and 3) by proving a significant cross-reactivity with Borrelia burgdorferii antibodies; Plasmodium falcparum antibodies and Salmonella typhi antibodies. Renewed testing in 1995 of 90 positive sera (with low titres) showed 19 sera to be positive by Elisa (2 in Zaire; 1 in Sudan; 9 in Reston and 7 in Cote d'Ivoire) from which 4 were confirmed by IFI 2 in Reston and 2 in Cote d'Ivoire. These findings are more proof that non-human virulent strains of Filoviridae; especially Ebola virus; are around in Kenya