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Identification of the Ebola virus in Gabon in 1994

1997; Elsevier BV; Volume: 349; Issue: 9046 Linguagem: Inglês

10.1016/s0140-6736(05)60984-1

1474-547X

Jacques P. Amblard, Paul Obiang, Samuel Edzang, Christophe Préhaud, Michèle Bouloy, B. Le Guenno,

Viral Infections and Vectors

Gabon has been struck twice during 1996 by the Ebola virus. One epidemic began in February in the village of Mayibout, 70 km north of Makokou, the main town of the Ogoue-Ivindo province.1AnonymousOutbreak of Ebola haemorrhagic fever in Gabon officially declared over.Wkly Epidemiol Rec. 1996; 71: 125-126Google Scholar Among the 37 cases, 21 died. The second outbreak was from July to December around the town of Booué, 200 km west of Makokou,2AnonymousEbola haemorrhagic fever.Wkly Epidemiol Rec. 1996; 71: 320PubMed Google Scholar and reached Libreville and Johannesburg. It caused 52 cases and 40 deaths. We report here the virological confirmation of a previous outbreak of Ebola haemorrhagic fever in Gabon. In November, 1994, unexplained deaths were reported in two gold-mining camps, Mekouka and Andock. During December, the number of cases increased in the two camps and some appeared in the nearby village of Minkebe. These three places are situated in deep rain forest along the Nouna river, 100 km north-west of Makokou, and can be reached only by canoe. A team from the Ministry of Health was sent and blood samples collected in Makokou Hospital and in Minkebe. The main clinical symptoms were fever, abdominal pain, black diarrhoea, and conjunctival injection. Two diseases were suspected, mercury poisoning and yellow fever. The first eight samples from acutely ill patients were sent to military hospitals in France. The concentrations of mercury in sera were too low to support mercury poisoning. Six of these samples were tested at the Pasteur Institute for yellow fever IgM and found negative. A retrospective analysis detected a high titre of Ebola IgM in four of them. Unfortunately, the volumes were too low and the storage conditions too bad to allow viral isolation. A second set of samples had been collected in Minkebe on Dec 27, 1994. Among 33 persons complaining of at least one symptom of fever, headache, or diarrhoea, two men (34 and 28 years old) had haemorrhagic fever. They had been evacuated to Makokou where one died and the other recovered. We isolated Ebola viruses from both sera. Furthermore, Ebola specific IgM was detected in 9 sera (27%). We have sequenced the whole nucleocapsid gene of this Ebola Gabon 1994 strain and a part of the envelope genes has been sequenced in Marburg Fceinz Feldmann, Viktor Volchkov, personal communication). It is very closely related to the Zaire strain isolated in 1976 (Yambuku) and 1995 (Kikwit) with less than 1·5% divergence in both nucleotide sequences. The sequences of the PCR amplified genes of the samples collected in February, and October, 1996, during the last outbreaks in Gabon are nearly identical to this 1994 strain. This epidemic has been primarily reported as a yellow fever outbreak on serological results obtained on other samples but without isolation of the virus.3AnonymousYellow fever.Wkly Epidemiol Rec. 1995; 70: 163PubMed Google Scholar Sylvatic yellow fever is often associated with mild forms of the disease or may be symptomless.4Monath T Monath T The arboviruses, epidemiology and ecology. Chapter 51. CRC Press, USA1989Google Scholar Here we have proof of the cocirculation of both viruses but the clinical symptoms and virological results suggest that the 44 reported cases with 28 deaths5AnonymousYellow fever.Wkly Epidemiol Rec. 1995; 71: 64Google Scholar were due to Ebola. The impact of the 1994 outbreak had increased the surveillance of unusual diseases in the Makokou region and allowed a rapid recognition of the following epidemics. These early warnings have probably limited the number of cases.