Detection of Opisthorchis viverrini Infection among the ASEAN Population in Thailand Using a Verbal Screening Test and Fecal Concentrator Kit

Background: Opisthorchis viverrini is a serious health problem in Southeast Asia. The infection is associated with cholangiocarcinoma. Therefore, this study was aimed to detect O. viverrini infections among the ASEAN population in Thailand. Methods: A cross-sectional study was conducted among 249 individuals from ASEAN populations in Thailand including Thai, Laotian, Cambodian, and Myanmar. Participants were screened using the O. viverrini verbal screening test (OvVST). Fecal samples were processed by the mini-parasep sf parasite fecal concentrator. Results: The infection rate of O. viverrini was 27.21%. The majority of infections was detected in females, in the age group 31-40 yr old, in the primary school education level, and in the occupation of labor. By country, O. viverrini infection was detected more often in the Lao PDR (30.77%). In screening for O. viverrini infection, OvVST had a high sensitivity (93.48%), specificity (86.70%), NPV (98.32%), and accuracy (87.95%). The PPV was 61.43% for OvVTS. The observed agreement was substantial for OvVST (k-value = 0.64). Conclusion: O. viverrini infections are still detected in ASEAN countries therefore large scale active surveillance is required. OvVST had a high sensitivity, specificity, and accuracy for screening the risk groups for O. viverrini

Prevalence of intestinal parasitic infections and genetic differentiation of Strongyloides stercoralis among migrant workers from Myanmar, Lao PDR and Cambodia in northeastern Thailand.

Intestinal parasitic infections (IPIs) remain a public-health problem worldwide, including in countries of the Lower Mekong subregion. Increases in human migration from neighboring countries might cause reemerging parasitic infections, leading to spread of parasites in the landscape. Here, we conducted a cross-sectional study to identify the prevalence of IPIs in migrant workers from Myanmar, Lao PDR, and Cambodia who were dwelling in Nakhon Ratchasima Province, northeastern Thailand. The identification of Strongyloides species and genetic differentiation of worms from migrant workers with different countries of origin was also assessed. Fresh stool samples were collected from 338 migrant workers and examined for evidence of IPIs using agar plate culture (APC) and the formalin-ethyl acetate concentration technique (FECT). Among those nine samples positive for nematodes by APC, the Strongyloides or hookworm species present was confirmed using the polymerase chain reaction (PCR) followed by DNA sequencing. This revealed eight cases of Strongyloides stercoralis infection and one of Necator americanus. Fifty-one out of 338 individuals (15.09%) were positive for IPIs using FECT and APC. Eggs of Opisthorchis-like flukes were the most common parasite (11.83% of samples), followed by S. stercoralis (2.37%), Entamoeba coli (1.50%), hookworm (0.89%), Taenia sp. (0.60%) and Hymenolepis nana (0.30%). The genetic differentiation of S. stercoralis recovered from migrant workers with different countries of origin was analyzed. Specimens of S. stercoralis isolated from workers from Lao PDR, Cambodia and Myanmar were genetically similar to those sequenced from Thailand. However, there were population-genetic differences between S. stercoralis from these Southeast Asian countries and other regions of the world. This study demonstrated that IPIs were prevalent in migrant workers in the northeastern region of Thailand. Our findings provided molecular confirmation of the presence of S. stercoralis and explored the genetic differentiation of S. stercoralis from those infected migrant workers. An effective anti-parasitic drug should be provided for migrant workers and its administration enforced