Clinical and molecular characterization of chikungunya virus in South Thailand

In 2008, an outbreak of chikungunya virus (CHIKV) occurred in Narathiwat province, south Thailand. To determine the clinical significance, molecular epidemiology and evolutionary origin of the CHIKV causing this outbreak, 47 patients who had been admitted to Narathiwatratchanakharin provincial hospital due to acute febrile illness were enrolled in this study. Sera were tested for IgM antibodies, and RT-PCR was performed for CHIKV and dengue virus. We diagnosed 10 patients with CHIKV infection and 5 with dengue virus infection. Joint pain is a significant symptom of chikungunya fever. Five strains of CHIKV were isolated. Their genome sequences were different from those isolated from the previous outbreaks in Thailand (1988, 1995-1996) but similar to the sequences isolated from the 2008 Singapore outbreak. We speculated that the outbreak was caused by a group of viruses different from the previous outbreaks. RT-PCR, serology to detect IgM antibodies or paired sera for IgG for CHIKV should be performed in all patients with presumed hemorrhagic fever to promptly detect outbreaks of CHIKV. This precaution would help control global epidemics of this virus.