Clonorchiasis and opisthorchiasis are snail-transmitted trematode infections. The disease is endemic in many parts of Asia. Local case reports have been predominantly in Chinese with a history of travel to endemic countries. Thus far, 20 cases of liver fluke infestation have been reported in this country. This report presents another two cases of clonorchiasis and a case of opisthorchiasis. We also briefly review pertinent aspects of the disease.
Food-borne parasitic zoonoses have emerged as a major public health problem in many countries and are posing a medical challenge. They are not only important from the economic point of view but also because of their severe sequelae. In Malaysia, these parasitoses are a tip of an iceberg problem. The article documents all the food-borne parasitic zoonoses reported in Malaysia. An epidemiological assessment of the diseases with research needs is highlighted.
Opisthorchiasis is endemic in parts of Southeast Asia, including the northern and northeastern regions of Thailand. In these regions, the transmission by fish intermediate hosts has received little attention. We investigated the intensity of Opisthorchis viverrini metacercariae (OV MC) in wild cyprinid fishes from five districts within the Nakhon Phanom Province, Northeast Thailand. Fishes were procured from local markets in five districts throughout three different seasons (hot, rainy and cold) between February 2018 and January 2019. The samples were identified, counted and weighed before metacercariae detection was performed via the artificial digestion method. A total of 2,149 freshwater fishes, representing 20 species were collected. The fish most commonly contaminated with OV MC were Anematichthys repasson and Hampala dispar. The intensity of OV MC in Nakhon Phanom was 0.23 OV MC/fish and varied among districts, ranging from 0.07 to 0.52. A low intensity of OV MC/fish (defined as <=1 cyst) was found in all three different seasons in the Nakhon Phanom Province; hot season (0.55), cold season (0.22) and the rainy season (0.13). The intensity of OV MC/fish was moderate (defined as >1 cyst) in the Renu Nakhon district (2.5) in the hot season. By fish species, H. dispar yielded the highest, with a moderate intensity of 2.1. In natural freshwater cyprinid fish in Nakhon Phanom, OV MC infection is endemic with intensity rates varying according to district, season and fish species.
Opisthorchiasis caused by Opisthorchis viverrini infection is a major public health concern in Thailand. Despite many decades of national campaigns in place to reduce and control opisthorchiasis in Thailand, the infections remain to exist particularly in the northern and northeastern parts of the country. This study aimed to evaluate the current prevalence of O. viverrini infection in rural communities in northeast Thailand. A cross-sectional survey was conducted between February and October 2018 in three districts (Na Kae, That Phanom and Wang Yang) in Nakhon Phanom Province, Thailand. Demographic data were collected using a standardised questionnaire. Stool samples were collected and processed using the Kato-Katz technique to determine the presence of O. viverrini and other intestinal parasites. In total, 564 individuals were enrolled. The overall intestinal helminth infections were 15.2% (95% CI: 12.4-18.5). Species distribution included a majority of O. viverrini mono-infections (12.9%), followed by Strongyloides stercoralis (1.4%) and Taenia spp. (0.4%). The prevalence of O. viverrini was significantly higher in Wang Yang district (P = 0.022), in males (P = 0.004) and those previously positive with helminth infections (P<0.001) and received treatment of anti-helminths (P<0.001), than in their counterparts. Multivariate regression analysis revealed that being male (adjusted odds ratio [aOR] 1.77, P = 0.035) and those who previously tested positive for helminth infections (aOR 8.69, P<0.001) were significantly associated with a higher odd of O. viverrini infections, but lower in those who had previous stool examination (aOR 0.22, P = 0.001). This study demonstrated that the updated prevalence of O. viverrini infection is still high in rural communities in northeast Thailand. The data of this study will be useful to guide and improve strategies for future O. viverrini and other helminths prevention and control in this region.
Epidemiological studies have been conducted to determine the association between fish and disease. The fish were obtained from rivers, streams, ponds and lakes but few from aquaculture farms. While no defined studies have been carried out in Malaysia, baseline data show that fish obtained from aquaculture farms (mixed farming) contributed to cases of opisthorchiasis and clonorchiasis.