Chikungunya Outbreak, French Polynesia, 2014

To the Editor: Chikungunya virus (CHIKV), an arthropod-borne virus (arbovirus) of the family Togaviridae, genus Alphavirus, is transmitted by mosquitoes of the Aedes genus, especially Ae. aegypti and Ae.albopictus (1).The main clinical manifestations of CHIKV infections are sudden high fever, headache, back pain, myalgia, arthralgia affecting mainly the extremities, and rash.CHIKV emerged in the Pacific region in New Caledonia in March 2011.Additional outbreaks occurred in Papua New Guinea in June 2012; Yap State (Federated States of Micronesia) in August 2013; Tonga in April 2014; and American Samoa, Samoa, and Tokelau in July 2014 (2).Phylogenetic analysis of CHIKV strains showed the existence of 3 lineages: West African, Asian, and East/ Central/South African (1).French Polynesia is a French territory in the South Pacific, with 270,000 inhabitants living on 5 archipelagoes.Arboviruses are a common cause of outbreaks in French Polynesia: the last dengue virus (DENV) outbreaks caused by DENV-1 and DENV-3 occurred in 2013 (3), and DENV-1 still circulates.French Polynesia also experienced the largest Zika virus (ZIKV) outbreak ever reported during October 2013-April 2014 (4).In May 2014, CHIKV infection was detected for the first time in French Polynesia in a traveler returning from Guadeloupe, (5) where a chikungunya outbreak was ongoing (6).In late September 2014, an increasing number of patients with fever and rash who tested negative for DENV and ZIKV by real-time reverse transcription PCR (RT-PCR) were recorded by the French Polynesia Department of Health on the south coast of Tahiti, French Polynesia's main island.Serum samples collected from 19 of these patients were tested for CHIKV by RT-PCR using previously reported primers and a probe (7).Seven of the 19 (37%) were positive; all 7 were autochthonous.The first specimen that tested positive for CHIKV had been collected from a patient on September 25, and by October