Large-scale outbreak of Chikungunya virus infection in Thailand, 2018-2019

• Published in: PloS one 2021-03, Vol.16 (3), p.e0247314-e0247314
• Main Authors: Khongwichit, Sarawut, Chansaenroj, Jira, Thongmee, Thanunrat, Benjamanukul, Saovanee, Wanlapakorn, Nasamon, Chirathaworn, Chintana, Poovorawan, Yong
• Format: Article
• Language: English
• Subjects: Antibodies; Antigens; Biology and life sciences; Biosensors; Chikungunya fever; Chikungunya virus; Computer and Information Sciences; Distribution; Editing; Epidemics; Epidemiology; Fever; Fluorescence; Genetic aspects; Genomes; Genotype & phenotype; Hybridization; Immunoassay; Immunoglobulin M; Infections; Infectious diseases; Laboratories; Medicine; Medicine and Health Sciences; Microbiology; Mutation; Pain; Patients; Pediatrics; People and Places; Polymerase chain reaction; Public health; Real time; Research and Analysis Methods; Reverse transcription; Risk factors; Vector-borne diseases; Virology; Viruses; Xenichthys xanti
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0247314

Between 2018 and 2019, the incidence of chikungunya was approximately 15,000 cases across 60 provinces in Thailand. Here, the clinical presentations in chikungunya, emergent pattern, and genomic diversity of the chikungunya virus (CHIKV) causing this massive outbreak were demonstrated. A total of 1,806 sera samples from suspected cases of chikungunya were collected from 13 provinces in Thailand, and samples were tested for the presence of CHIKV RNA, IgG, and IgM using real-time PCR, enzyme-linked immunoassay (ELISA), commercial immunoassay (rapid test). The phylogenetic tree of CHIKV whole-genome and CHIKV E1 were constructed using the maximum-likelihood method. CHIKV infection was confirmed in 547 (42.2%) male and 748 (57.8%) female patients by positive real-time PCR results and/or CHIKV IgM antibody titers. Unsurprisingly, CHIKV RNA was detected in >80% of confirmed cases between 1 and 5 days after symptom onset, whereas anti-CHIKV IgM was detectable in >90% of cases after day 6. Older age was clearly one of the risk factors for the development of arthralgia in infected patients. Although phylogenetic analysis revealed that the present CHIKV Thailand strain of 2018-2020 belongs to the East, Central, and Southern African (ECSA) genotype similar to the CHIKV strains that caused outbreaks during 2008-2009 and 2013, all present CHIKV Thailand strains were clustered within the recent CHIKV strain that caused an outbreak in South Asia. Interestingly, all present CHIKV Thailand strains possess two mutations, E1-K211E, and E2-V264A, in the background of E1-226A. These mutations are reported to be associated with virus-adapted Aedes aegypti. Taken together, it was likely that the present CHIKV outbreak in Thailand occurred as a result of the importation of the CHIKV strain from South Asia. Understanding with viral genetic diversity is essential for epidemiological study and may contribute to better disease management and preventive measures.