Ebola-Zaire and Ebola-Sudan

In 1976 there was a sudden large-scale epidemic of 2 different Ebola viruses in Maridi (South Sudan) and in Yambuku, on the Ebola river in North Congo. The mortality rate in Yambuku was very high (280 deaths out of 318 cases = 88%) and slightly lower in Sudan (53%). In 1977 there was one fatal case in Tandala, North Congo. New major outbreaks occurred in 1979 in Nzara (South Sudan), in 1995 in Kikwit, Congo and in 2003 in Kelle, Congo Brazzaville. The virus, which emerged in Kikwit, very closely resembled that in Yambuku (less than 1.6% difference in RNA, which is very little). This is a sign of a genome which is not under selection pressure, suggesting a stable ecological niche between epidemics. The Sudanese virus isolates of 1976 and 1979 were also almost identical.

In December 1994, 44 people were infected in Minkouka (northeast Gabon). In February 1996, 37 people were infected with Ebola virus in the isolated village of Mayibout, in the same area on the Ivindo river. In this case it was suspected that people were infected after eating infected chimpanzee meat. In October 1996 a similar outbreak was seen in Gabon in Booué and then in Makokou. There were approximately 60 cases. An infected doctor was flown over to South Africa and there caused a fatal secondary case in a nurse. This illustrates how easily pathogenic organisms can be spread in this age of rapid transport. The Gabonese virus isolates were identical to those in Congo. Asymptomatic infections occurred in Gabon in a number of people. In the autumn of 2000 there was a large scale epidemic of Ebola-Sudan in Gulu in the north of Uganda. After this there were cases in other districts (Masindi, Mbarara). There were 425 cases with 224 deaths. In December 2001-January 2002 numerous cases were reported in Gabon and in neighbouring Congo. Multiple cases emerged again in April 2002 in Gabon. Early in 2003, a large scale epidemic occurred in Mbomo and Kelle, a very remote and rural area of Congo Brazzaville, just south of Odzala National Park. It started by a large scale die-off among the lowland gorillas in the park. The disease flared up again in the same area, in November the same year, but was contained before New Year 2004. In May 2004, Ebola haemorrhagic fever appeared again in Sudan, in the area of Yambio.

Category: Medical Subject Notes , Medicine Notes