Author(s): Marie Christine Jaffar-Bandjee 1 , Duksha Ramful 1 , Bernard Alex Gauzere 1 , Jean Jacques Hoarau 1 , Pascale Krejbich-Trotot 1 , Stephanie Robin 1 , Anne Ribera 1 , Jimmy Selambarom 1 , Philippe Gasque [[dagger]â ] 2
anti-TNF-[alpha]Î±; arthritis; Chikungunya; chloroquine; encephalitis; immunology; methotrexate; mosquito; neutralizing antiserum; vaccine
Chikungunya: a re-emerging worldwide epidemic
Chikungunya (CHIK) is a re-emerging mosquito-borne disease due to an alphavirus (arbovirus) of the Togaviridae family [1,2] . The alphavirus group comprises 29 viruses, six of which can cause human joint disorders (arthralgia evolving to arthritis), namely Chikungunya virus (CHIKV; in Africa, Indian Ocean, India and Southeast Asia), O'âNyong-Nyong virus (in Africa), Semliki forest virus (in Africa, Asia and Europe), Ross River virus (in Australia and the Pacific), Sindbis virus (cosmopolitan) and Mayaro virus (in South America and French Guyana)  . The tropical disease CHIK is transmitted by the Aedes mosquito and is characterized by fever, headache, rashes and debilitating arthralgia  . CHIK was initially believed to be mainly an incapacitating disease and nonfatal, but severe forms and deaths have been reported on the Indian Ocean island of La RéÃ©union  and in India  . A total of 3 years after the 2005-2007 epidemic, as the main feature of the disease remains the persistence of chronic arthralgia, the disease is now recognized as a major public health issue [2,7] .
Chikungunya virus was first isolated in Tanganyika (now Tanzania) in 1953 [4,8] . Epidemics were then reported in West Africa [9-11] , the Central African Republic  and in Southern Africa  . Many outbreaks were reported in Southeast Asia and the Western Pacific  , Indonesia  and India  . Neither Europe nor the Americas experienced outbreaks of CHIKV during these years. The last epidemic wave of CHIK in the Indian Ocean emerged in Kenya (Lamu) in July 2004, then reached the Comoros in January 2005, and the Seychelles in March 2005, followed by Mauritius. Serologic studies showed a high attack rate, with a prevalence of 75% in the population of Lamu  , and 63% in Comoros  . The virus reached La RéÃ©union in March-April 2005, with a prevalence of over 38% (266,000 cases)  . For the first time, deaths were directly or indirectly attributed to CHIKV (254 in La RéÃ©union)  . Afterwards, several outbreaks expanded to India  and Southeast Asian countries. In India, it is estimated that more than 1.4 million people in 13 states were infected. Moreover, imported cases of CHIK in exposed travelers from the affected areas were observed in most countries in Europe, the USA, Canada, Hong Kong and, more recently, in China  . In Italy, where Aedes albopictus is present, an outbreak of more than 200 cases occurred in the Ravenna region during the summer of 2007  . Previous phylogenetic studies showed that CHIKV strains were clustered into three distinct genotypes separated primarily by location into West African, Central/East/South African and Asian genotypes [23,24] . Earlier outbreaks in Southeast Asia, India and Indonesia prior to 2004 were caused by strains of the Asian genotype  . Explosive epidemics in the Indian Ocean...