Zaïre ebola virus (ZEBOV): in Gabon, ZEBOV outbreaks occurred in 1994, 1996, 1997 and 2001; 29 primary human cases were generally contaminated by direct contact with 33 and concurrent infections of DENV and CHIKV have been reported in towns affected by the two outbreaks. 34 Dengue fever and the severe form of the disease, dengue hemorrhagic fever (DHF), are caused by the world's most prevalent mosquito-borne virus. 37 DENV is carried by Aedes aegypti mosquito, which is strongly affected by ecological and human drivers, but also influenced by climate (temperature, humidity and solar radiation). 37 Although DENV was known to circulate among mosquitoes within limited areas in West Africa and East Africa, dengue fever first emerged among the African population during the epidemic of Nigeria in 1964-1968, 38 then in Senegal in 1980 39 and Burkina Faso and Kenya in 1982. 40, 41 Since then epidemic manifestations were recorded in East Africa (Mozambique, Sudan, Djibouti, Somalia, Eritrea), in Senegal and more recently in Gabon. 34, 42 It seems that dengue fever is on the edge of emergence in Africa with the potential appearance of the devastating DHF that is yet to be observed on the continent. Yellow Fever Virus (YFV): Gabon is officially designated as an infected country. A YFV outbreak occurred in 1994 in Ogooue-Ivindo Province, North East of Gabon with 44 cases reported. 43 More recently, in 2009, Cameroon reported a laboratory-confirmed case of yellow fever (YF). 44 YF has become an important public health issue because of its case-fatality rate of 50% and the estimated 200,000 cases and 30,000 deaths that occur each year worldwide. Also, despite the efficiency of the YF vaccine and its inclusion in the national vaccination program, human populations situated in remote areas have a limited access to the public health system.