An outbreak of chikungunya in southern Thailand from 2008 to 2009 caused by African strains with A226V mutation

SummaryObjectivesTo elucidate clinical and molecular characteristics of chikungunya fever (CHIK fever) from the 2008–2009 outbreak caused by chikungunya virus (CHIKV) in southern Thailand.MethodsThree hundred and eighty-one sera from 332 patients with acute febrile illness were tested for anti-CHIKV IgM antibody by ELISA. A molecular analysis of these sera was performed using a semi-nested reverse transcriptase polymerase chain reaction (RT-PCR), followed by direct sequencing and phylogenetic analysis.ResultsOne hundred and seventy-nine patients were diagnosed with CHIK fever by molecular analysis and/or anti-CHIKV IgM antibody detection. Patients diagnosed with CHIK fever were significantly older than controls (mean age 38.8±19 vs. 28.7±18 years, p