Interepidemic Detection of Chikungunya Virus Infection and Transmission in Northeastern Thailand

Abstract

Chikungunya fever is a viral mosquito-borne, acute febrile illness associated with rash, joint pain, and occasionally prolonged polyarthritis. Chikungunya outbreaks have been reported worldwide including many provinces of Thailand. Although chikungunya virus (CHIKV) occurs in Thailand, details on its epidemiology are lacking compared with dengue, a common mosquito-borne disease in the country. Therefore, study on CHIKV and its epidemiology in both humans and mosquitoes is required to better understand its importance clinically and dynamics in community settings. So a prospective examination of virus circulation in human and mosquito populations in northeastern Thailand using serological and molecular methods, including the genetic characterization of the virus, was undertaken. The study was conducted among febrile patients in eight district hospitals in northeastern Thailand from June 2016 to October 2017. Using real-time PCR on the conserved region of nonstructural protein 1 gene, CHIKV was detected in eight (4.9%) of 161 plasma samples. Only one strain yielded a sequence of sufficient size allowing for phylogenetic analysis. In addition, anti-CHIKV IgM and IgG were detected in six (3.7%) and 17 (10.6%) patient plasma samples. The single sequenced sample belonged to the East/Central/South Africa (ECSA) genotype and was phylogenetically similar to the Indian Ocean sublineage. Adult Aedes mosquitoes were collected indoors and within a 100-m radius from the index case house and four neighboring houses. CHIKV was detected in two of 70 (2.9%) female Aedes aegypti mosquito pools. This study clearly demonstrated the presence and local transmission of the ECSA genotype of CHIKV in the northeastern region of Thailand.

Complex relationships between Aedes vectors, socio-economics and dengue transmission—Lessons learned from a case-control study in northeastern Thailand

“…Chikungunya fever incidence was extremely low during the 2016–2017 period, with a total of 18 and 10 cases, in 2017 and 2016 respectively but increased to around 3600 cases in 2018, although the epidemic was centered in southern Thailand [ 40 , 77 , 78 ]. In addition, CHIKV was detected among eight patients out of 161 tested in the period 2016–2017 in our study participants [ 79 ]. Regarding Zika infection, a recent study demonstrated the circulation of the virus, at low incidence, in Thailand for years [ 80 ].…”

Characterization and Involvement of Exosomes Originating from Chikungunya Virus-Infected Epithelial Cells in the Transmission of Infectious Viral Elements

“…The equal amount of total proteins (estimated by BCA method) either from 0.1% Triton-X-100-treated or untreated samples derived CHIKV-infected or -uninfected Vero cells were coated in MaxiSorp™ flat-bottom 96-well plates (Nunc™, Thermo Fisher Scientific, Waltham, MA, USA) for overnight at 4 °C. Bovine serum albumins (BSA, Sigma-Aldrich, St. Louis, MO, USA) were used in the sample blocking step before being incubated with a high titer of CHIKV-positive human immunoglobulin G (IgG) plasma from our previous study [ 70 ] for 1 h. The secondary antibody, an HRP-conjugated mouse monoclonal anti-human IgG (HP-6017, dilution = 1:10,000; Merck KGaA, Darmstadt, Germany) was applied to the reaction and incubated for 1 h. According to the manufacturer’s instructions, SureBlue™ TMB 1-Component Microwell Peroxidase Substrate (SeraCare, Milford, MA, USA) was added to the well followed by the TMB Stop Solution (KPL; SeraCare, Milford, MA, USA). Using an absorbance microplate reader (Tecan™, Männedorf, Switzerland), optical density at 450 nm was measured and then analyzed with Magellan™ software (Tecan™, Männedorf, Switzerland) from triplicated samples in three independent experiments.…”

Low Transmission of Chikungunya Virus by Aedes aegypti from Vientiane Capital, Lao PDR

“…In Lao PDR, arboviruses represent major public health problems with the circulation or co-circulation of CHIKV, ZIKV, and the four DENV serotypes in Vientiane capital and at the country level [ 20 , 21 , 22 , 23 , 26 , 39 ]. Intriguingly, despite the evidence of the active circulation of CHIKV for decades in Southeast Asia [ 15 , 16 , 17 , 18 ], including in countries bordering Lao PDR, the first CHIKV outbreak was only documented in 2012–2013 in the southern Lao province of Champasak [ 23 , 27 , 28 ]. The virus at the origin of this epidemic was imported from Cambodia/Thailand and belonged to the ECSA-IOL lineage (23).…”

“…Since the first CHIKV isolation in Uganda in 1952 [ 10 , 11 ], the virus has been detected in many sub-Saharan African countries, in Asia, and more recently in the Americas, South Pacific, and Europe [ 8 , 12 , 13 , 14 , 15 ]. In Asia, CHIKV was first reported in 1958 in Thailand, but retrospective studies of human sera suggest that the virus has circulated in the region prior the discovery of the virus [ 15 , 16 ]. Since then, in addition to the former Asian lineage, two additional lineages have emerged and spread in this part of the world since 2006: ECSA and ECSA-IOL [ 15 , 16 , 17 , 18 , 19 ].…”

“…In Asia, CHIKV was first reported in 1958 in Thailand, but retrospective studies of human sera suggest that the virus has circulated in the region prior the discovery of the virus [ 15 , 16 ]. Since then, in addition to the former Asian lineage, two additional lineages have emerged and spread in this part of the world since 2006: ECSA and ECSA-IOL [ 15 , 16 , 17 , 18 , 19 ].…”