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The primary vector at the origin of the 2007 outbreak in Libreville, Gabon is identified as Aedes albopictus, trapped around the nearby French military camp. The Chikungunya virus was isolated from mosquitoes and found to be identical to the A226V circulating human strain. This is the first field study showing the role of the recently arrived species Aedes albopictus in Chikungunya virus transmission in Central Africa, and it demonstrates this species' role in modifying the epidemiological presentation of Chikungunya in Gabon.

Outbreaks of Ebola virus haemorrhagic fever have been reported from 1994 to 1996 in the province of Ogooué Ivindo, a forest zone situated in the Northeast of Gabon. Each time, the great primates had been identified as the initial source of human infection. End of November 2001 a new alert came from this province, rapidly confirmed as a EVHV outbreak. The response was given by the Ministry of Health with the help of an international team under the aegis of WHO. An active monitoring system was implemented in the three districts hit by the epidemic (Zadié, Ivindo and Mpassa) to organize the detection of cases and their follow-up. A case definition has been set up, the suspected cases were isolated at hospital, at home or in lazarets and serological tests were performed. These tests consisted of the detection of antigen or specific IgG and the RT-PCR. A classification of cases was made according to the results of biological tests, clinical and epidemiological data. The contact subjects were kept watch over for 21 days. 65 cases were recorded among which 53 deaths. The first human case, a hunter died on the 28th of October 2001. The epidemic spreads over through family transmission and nosocomial contamination. Four distinct primary foci have been identified together with an isolated case situated in the South East of Gabon, 580 km away from the epicenter. Deaths happened within a delay of 6 days. The last death has been recorded on the 22nd of March 2002 and the end of the outbreak was declared on the 6th of May 2002. The epidemic spreads over the Gabon just next. Unexplained deaths of animals had been mentionned in the nearby forests as soon as August 2001: great primates and cephalophus. Samples taken from their carcasses confirmed a concomitant animal epidemic.

During the last outbreak of Ebola virus haemorrhagic fever that occurred concurrently in Gabon and Congo, several primary foci were identified in the Ogooue Ivindo province (Northeast Gabon), where previous outbreaks had occurred. A 48-year-old woman living in Franceville located 580 Km from the epicentre presented fever with haemorrhagic signs. She was evacuated to Libreville where Ebola infection was suspected. Diagnosis was confirmed at the Centre International de Recherches Médicales of Franceville on the basis of detection of specific antibodies. Symptoms had already subsided by the time diagnosis was documented. An epidemiological investigation was undertaken to identify the source of contamination and detect secondary cases. No human or nonhuman primate source of contamination could be formally identified. Direct contact with the virus reservoir could not be ruled out. No secondary cases were detected. The favourable outcome, absence of secondary, and failure to identify a source of contamination suggest that epidemiologically undefined cases may go unnoticed during and outside of outbreaks.