Detection of Zika Virus Infection in Thailand, 2012-2014.
Bottom Line: Zika virus (ZIKV) is an emerging mosquito-borne pathogen with reported cases in Africa, Asia, and large outbreaks in the Pacific.However, there have been several cases reported in travelers returning from Thailand.These endemic cases, combined with previous reports in travelers, provide evidence that ZIKV is widespread throughout Thailand.
Affiliation: Department of Disease Control, Bureau of Epidemiology, Ministry of Public Health, Nonthaburi, Thailand; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand; Department of Medicine, University of Toronto, Toronto, Ontario, Canada.Show MeSH
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Mentions: Three samples taken from Ratchaburi province, Thailand, were positive for ZIKV infection based on serologic studies whereas ZIKV RNA was detected in the other four samples. The 77 base pair RT-PCR amplicon, used for ZIKV diagnosis from a sample from Sisaket province, was sequenced and found to have high nucleotide identity (between 90% and 100%) to the prM/E region of ZIKV sequences reported in GenBank. Subsequently, three serum samples collected in Phetchabun province that were positive or equivocal for ZIKV by PCR were sent for virus isolation by intrathoracic inoculation of Toxorhynchites splendens mosquitoes followed by inoculation of mosquito-derived C6/36 cells. Typing ELISA using the universal flavivirus (4G2 monoclonal) antibody and DENV serotypes 1, 2, 3, and 4 specific monoclonal antibodies was also completed on the supernatants from the C6/36 cells.18,19 One supernatant sample positive for 4G2 antibody, but negative for DENV antibodies, underwent next-generation sequencing (Illumina MiSeq Platform, Illumina, Hayward, CA). De novo assembly produced a 10,685 nucleotide (nt) consensus sequence (depth of coverage greater than 10,000). Maximum likelihood (ML) phylogenetic analysis of a 789-bp partial sequence of ZIKV nonstructural protein 5 (ZIKV NS5) (GenBank accession no. KM851039) indicated that the isolate belonged to the ZIKV Asian lineage, which includes strains from the Canadian traveler to Thailand (2013)11 and strains from Cambodia (2010),15 Micronesia (2007),2 and French Polynesia (2013)20 (Figure 1). Pairwise genetic distance calculation illustrated that the isolate was most closely related to the French Polynesia 2013 strain (p-distance = 0.009) with approximately 99% nucleotide identity (782/789).
Affiliation: Department of Disease Control, Bureau of Epidemiology, Ministry of Public Health, Nonthaburi, Thailand; Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand; Department of Medicine, University of Toronto, Toronto, Ontario, Canada.