albopictus was less susceptible to DEN virus, leading us to consider Ae. Moreover, as demonstrated by the rates of disseminated infection obtained, Gabonese Ae. albopictus appears to be a better vector for CHIK virus than Ae. albopictus showed a higher susceptibility to CHIK virus than Ae. aegypti collected in Libreville to transmit CHIK and Dengue virus. An experimental study was conducted in the laboratory, using experimental infections to determine the ability of Ae. To assess the respective roles of Aedes albopictus and Aedes aegypti in Dengue and chikungunya transmission in Libreville, we proceeded in two steps. In Libreville, Aedes albopictus and Aedes aegypti are potential vectors of CHIK and DEN viruses. Rainfall in Libreville, Gabon from September 2006 to September 2007 (grey bars) and monthly numbers of suspected Chikungunya cases in Gabon, March 2006вЂ“September 2007 (black curve). However, new CHIK cases were confirmed in November 2007 in Lastourville, Ogoue Lolo province (south-east Gabon).ДЇigure 1. Since August 2007, no suspected cases have been recorded in Libreville despite the start of the rainy season in September of that year. During the peak of the May outbreak, CHIKV transmission was also recorded in Bitam, the capital of the Woleum Ntem province (north Gabon).

The transmission decrease observed in June was presumably due to the end of the rains and corresponding decrease in vector density-both Aedes albopictus adult abundance and oviposition rate are closely correlated with rainfall. From April 2007 through May 2007, 5,000 additional cases were retrospectively included by the Gabon health authorities after further analysis ( Figure 1). From May 2007 through September 2007, 13,802 suspected cases were recorded in health centers and 829 patients were hospitalized, though fortunately no deaths occurred. The Gabon Ministry of Public Health commissioned a crisis committee to manage the outbreak patients were identified as suspected CHIK cases if they presented with a sudden fever over 39вЊ which lasted for more than 48 h in spite of anti-malarial treatment, in addition to a headache and severe joint and muscle pain, with or without a rash. When malaria diagnosis tests (blood thick smear, slide or malaria CoreВ® rapid test) were performed, the results were negative and CHIKV was identified from patient blood samples as the main causative agent. The majority of patients were presumptively treated for malaria with no symptom improvement. In April 2007, an outbreak of Dengue-like symptoms occurred in Libreville where Aedes albopictus was first detected in December 2006. such as Aedes aegypti or the recently discovered Aedes albopictus as a primary vector. During the last 6 years, the urban cycle has tended to play an increasing role in CHIKV transmission in Central Africa, bringing into question the participation of urban Aedes sp. In central Africa, this spreading vector was first collected in 2000 in Cameroon, in 2003 in Equatorial Guinea, and in 2006 in Gabon. In recent times, the Asian tiger mosquito Aedes albopictus has succeeded in colonizing some parts of sub-Saharan Africa. During the late 1970s, serological surveys conducted in Gabon revealed a CHIKV exposure seroprevalence of 8.5% in urban Libreville (the capital of Gabon), rising from 20% to 44% in rural areas. Rural outbreaks were found to be heavily dependent upon the densities of these sylvatic mosquitos, which increase during periods of heavy rainfall. including Aedes africanus, Aedes furcifer, Aedes luteocephalus, Aedes neoafricanus, Aedes taylori. The Chikungunya virus was classically isolated from several sylvatic Aedes sp. In Africa, while recent serological surveys suggest a high prevalence of Togaviridae, Flaviviridae and Bunyaviridae and there is recent evidence of CHIKV circulation in Republic Democratic of Congo and Cameroon, detailed information about CHIKV circulation remains imprecise. This mutation has favored improved transmissibility of the virus by the mosquito Ae. Sequence analysis of the virus genome revealed that these recent outbreaks were caused by a new variant characterized by a mutation in the E1 envelope glycoprotein gene (A226V). albopictus was identified as the major vector in La Reunion Island and Europe. Though previously considered to be a vector with poor efficiency, Ae. A CHIKV outbreak began in Kenya in 2004, spread to populated islands in the Indian Ocean and later jumped to India, and Europe вЂ“. First isolated in Tanzania in 1952, Chikungunya virus (CHIKV), an Alphavirus member of the Togaviridae, is now a world-wide public health problem.

Software Iteman