Integrated Epidemiology and Disease Prevention of Schistosoma mekongi and Opisthorchis viverrini in the Mekong Region

Parasitic helminth infections such as schistosomiasis and opisthorchiasis continue to pose significant public health threats in the Mekong region. While Schistosoma japonicum has been the focus of much research in South-East Asia, Schistosoma mekongi—a zoonotic species endemic to Thailand, Lao People’s Democratic Republic (Lao PDR), Cambodia, and Myanmar—remains neglected. Similarly, Opisthorchis viverrini, a liver fluke endemic to the same region, causes opisthorchiasis, a major risk factor for cholangiocarcinoma (bile duct cancer), yet remains under-addressed in integrated control strategies.

S. mekongi is transmitted by snails of the genus Neotricula and is known to infect humans, dogs, and pigs. Community-level prevalence in Cambodia and Lao PDR ranges from 0.6% to 33%, although recent data—especially on zoonotic reservoirs—remain limited. O. viverrini infections, on the other hand, are strongly associated with consumption of raw or undercooked freshwater fish and are endemic in northeast Thailand and Lao PDR, where they affect millions of people.

The Mekong basin is recognized as one of the regions most vulnerable to climate change. Predicted increases in temperature (0.4°C to 3.3°C by 2060) and altered rainfall patterns (up to ±17%) are expected to influence the distribution and intensity of helminth transmission, including both S. mekongi and O. viverrini which are reliant on molluscan hosts. As climate conditions shift transmission zones, understanding the zoonotic and environmental drivers of infection is critical.

This project seeks to develop an integrated, multi-helminth control and elimination program in the Mekong region. The broader initiative will incorporate mass drug administration (MDA), health education, community-led water, sanitation and hygiene (CL-WASH), precision diagnostics, environmental monitoring, and targeted treatment strategies. Within this program, the PhD project will focus on both S. mekongi and O. viverrini, with emphasis on zoonotic transmission, diagnostics development, baseline epidemiological mapping, and post-intervention assessment—including the emerging threat of drug resistance in opisthorchiasis.

• Aim 1: Identify and characterize animal reservoirs of S. mekongi and O. viverrini in Cambodia and Lao PDR.
• Aim 2: Develop and validate novel diagnostic tools for S. mekongi and O. viverrini for use in both human and animal populations.
• Aim 3: Conduct baseline prevalence surveys of S. mekongi and O. viverrini in humans and animals in selected endemic sites using newly developed diagnostics.
• Aim 4: Evaluate the impact of an integrated intervention (MDA and health education) on the prevalence and transmission of S. mekongi and O. viverrini at 12–18 months post-intervention.
• Aim 5: Investigate the presence and genetic markers of potential drug resistance in Opisthorchis viverrini, particularly in areas with long-standing praziquantel use.

This project will contribute significantly to our understanding of multi-helminth epidemiology in the Mekong region and provide scalable tools and strategies for integrated parasite control in a changing climate.