Silent Circulation of Ross River Virus in French Polynesia

• We investigated the prevalence of Ross River virus in French Polynesia
• Sera of 593 blood donors were collected from July 2011 to October 2013
• 34.40% of blood donors had immunoglobulin G antibodies against Ross River virus
• We report silent circulation of Ross River virus in French Polynesia

SummaryObjectivesRoss River is an emerging mosquito-borne disease in the Western Pacific. Ross River virus (RRV) circulation has been sporadically reported in some Pacific Island Countries and Territories but never in French Polynesia. To determine if RRV has circulated locally among the French Polynesian population, we conducted a seroprevalence study on blood donors.MethodsSera of 593 blood donors were collected from July 2011 to October 2013 and tested by ELISA for the presence of RRV-specific Immunoglobulin G (IgG) antibodies.ResultsA total of 204 (34.40%) blood donors were found seropositive for RRV. Among the 132 blood donors that were born in French Polynesia and had never travelled abroad, 56 (42.42%) had RRV-specific IgGs.DiscussionOur results support the existence of autochthonous RRV transmission and suggest that this pathogen has silently circulated in French Polynesia. These findings raise the question of possible undetected circulation of RRV in other Pacific Island Countries and Territories.

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