Control approaches for Opisthorchis viverrini and co-infections in Lao PDR

Abstract

Background: In Lao People’s Democratic Republic (Lao PDR) helminth infections are highly prevalent. All groups of helminths, including nematodes, trematode and cestodes can be found throughout the country. Besides high rates and intensity of infections, most individuals are infected with several different species of intestinal parasitic infections. As in many other countries, a main underlying factor for high worm infestations is the scarce economic resources which lead to a lack of appropriate sanitary facilities, and hygiene related education and adequate behaviour. Therefore, the parasite infection is common among the rural population. However in Laos, there is an additional, particular risk factor responsible for the populations, high worm-load; namely the consumption of raw or insufficiently cooked foodstuff such as raw meat, fish and vegetables. This habit is deeply culturally rooted, and widespread in the Lao population. In this PhD thesis, we tested and determined the appropriate control approaches for Opisthorchis viverrini (O. viverrini) and other important helminth infections such as Strongyloides stercoralis (S. stercoralis) and Schistosoma mekongi (S. mekongi). The tested approaches compose of latrine promotion programme, eco-health intervention study and novel urine test for S. mekongi diagnosis in Khong District, Champasack Province, Lao PDR. Goal and specific objectives: The present PhD study aimed to develop the appropriate control approaches for O. viverrini infection and co-infections in Lao PDR. Four specific objectives were pursued: i). To assess S. stercoralis infection and the risk of infection among the populations on three islands in Khong district, Champasack province, Southern Laos; ii). To define O. viverrini, S. mekongi and STH infections in humans in the ecological environment of Khong district, Champasack province where their potential animal reservoir, and intermediate hosts are living in close connectivity; iii).To compare the diagnostic tools for detection of S. mekongi infection in Lao People’s Democratic Republic and neighbouring country Cambodia; and iv). To assess the impact of improved sanitation and its use on the transmission of intestinal helminth infections in highly endemic areas, three islands in Khong district, Champasack province, Southern Laos. Methodology: Both cross-sectional and cohort studies were used in this PhD thesis’s research. All data of this PhD thesis were obtained from community-based studies. First study of this PhD research was latrine intervention which was called as latrine study, conducted in March 2011 to January 2013 on three islands, i.e. Donlong, Donthan and Donlieng island located in the Mekong River in Khong district, Champasack province, southern Laos. Given an experimental pre-test and post-test with one control group was used to assess the effects of latrine in the study villages on preventing of helminth infections particularly O. viverrini and S. mekongi. Household-based promoting latrine construction was conducted. Two stool…