Decreasing Hepatitis C Virus Infection in Thailand in the Past Decade: Evidence from the 2014 National Survey

Abstract

Hepatitis C virus (HCV) infection affects ≥ 180 million individuals worldwide especially those living in developing countries. Recent advances in direct-acting therapeutics promise effective treatments for chronic HCV carriers, but only if the affected individuals are identified. Good treatment coverage therefore requires accurate epidemiological data on HCV infection. In 2014, we determined the current prevalence of HCV in Thailand to assess whether over the past decade the significant number of chronic carriers had changed. In total, 5964 serum samples from Thai residents between 6 months and 71 years of age were obtained from 7 provinces representing all 4 geographical regions of Thailand and screened for the anti-HCV antibody. Positive samples were further analyzed using RT-PCR, sequencing, and phylogenetic analysis to identify the prevailing HCV genotypes. We found that 56 (0.94%) samples tested positive for anti-HCV antibody (mean age = 36.6±17.6 years), while HCV RNA of the core and NS5B subgenomic regions was detected in 23 (41%) and 19 (34%) of the samples, respectively. The seropositive rates appeared to increase with age and peaked in individuals 41–50 years old. These results suggested that approximately 759,000 individuals are currently anti-HCV-positive and that 357,000 individuals have viremic HCV infection. These numbers represent a significant decline in the prevalence of HCV infection. Interestingly, the frequency of genotype 6 variants increased from 8.9% to 34.8%, while the prevalence of genotype 1b declined from 27% to 13%. These most recent comprehensive estimates of HCV burden in Thailand are valuable towards evidence-based treatment coverage for specific population groups, appropriate allocation of resources, and improvement in the national public health policy.

Estimating the Impact of Expanding Treatment Coverage and Allocation Strategies for Chronic Hepatitis C in a Direct Antiviral Agent Era

“…Susceptible populations were persons with unsafe injection practices, inadequate sterilization of medical equipment in health care settings, and unscreened blood products. The risk of HCV transmission has decreased because of nationwide HCV screening of blood transfusions since 1992 and the discovery of interferon as a treatment for HCV [ 13 , 29 ]. A public health campaign and improvement in the public health care system has decreased the prevalence of HCV in intravenous drug users who shared needles [ 13 ].…”

Systematic review: epidemiology and response to direct‐acting antiviral therapy in genotype 6 chronic hepatitis C virus infection

“…However, sample size of the studies is relatively small, in which additional epidemiology studies would have offered more accurate conclusions . Other endemic countries for GT6 are Vietnam, Thailand and Myanmar, although the most prevalent genotypes in Thailand, Myanmar and Vietnam are 3a, 3b and 1a, respectively . Interestingly, a recent study from Thailand reported the decline in prevalence of HCV by half in the past decades but opposed to other genotypes, GT6 turned out to have an increasing trend (9%‐34%) .…”

“…Other endemic countries for GT6 are Vietnam, Thailand and Myanmar, although the most prevalent genotypes in Thailand, Myanmar and Vietnam are 3a, 3b and 1a, respectively . Interestingly, a recent study from Thailand reported the decline in prevalence of HCV by half in the past decades but opposed to other genotypes, GT6 turned out to have an increasing trend (9%‐34%) . However, caution should be exercised regarding the increasing trend of HCV GT6 in Thailand since it earlier could have partly been due to selection bias and misclassification of GT6 as genotype 1b with as earlier genotypic assay .…”

“…These observations suggest a pattern of transmission in one of a high risk population across borders, and to different regions. In a similar study from Thailand that recruited immigrant workers from neighbouring countries (Myanmar and Cambodia), the subtypes identified were those that were frequently found in Thailand (6f) and these were mingled with subtypes that were not commonly found in the natives (subtype 6m was common in Myanmar and subtype 6r originated in Cambodia) . Of interest, in India, despite being in proximity to Southeast Asia, HCV GT6 was found to be uncommon in most epidemiological reports .…”

Differences in clinical features of HIV/HCV co-infected individuals compared with HCV mono-infected individuals in Southern Thailand

“…The prevalence of HCV infection and its particular genotype varies between different countries and regions. In Thailand, recent surveys in 7 of Thailand's 76 provinces found approximately 759,000 anti-HCV + individuals and 357,000 who had viremic HCV infection (3,4), with genotype 3a predominant (36.4%). For genotypic distribution in Thailand, genotype 3 was predominant in southern Thailand, while, genotype 6 was more common in the North than the other regions (5).…”