Researchers shed light on parasite problem

Scientists have predicted that the rate of foodborne trematode infections will remain stable up to 2030.

Foodborne trematodiases, including clonorchiasis, fascioliasis, fasciolopsiasis, opisthorchiasis, and paragonimiasis, are a neglected public health problem, particularly in the WHO South East Asia and Western Pacific regions.

Infections from the parasites typically occur through ingestion of contaminated fish, crustaceans, or plants carrying the larvae of trematodes. It is estimated that about 100 species of foodborne trematodes can infect humans, including liver flukes, lung flukes, and intestinal flukes. Infection can result in severe liver and lung disease.

Using the Global Burden of Disease 2021 database, the crude and the age-standardized prevalence rate (ASPR) and age-standardized prevalence disability-adjusted life years rate (ASDR) of foodborne trematodiases at the global, regional, and national level from 1990 to 2021 were described in the journal Infectious Diseases of Poverty. Scientists also looked at disability-adjusted life years (DALYs) and projected trends to 2030.

In 2021, almost 44.5 million cases were estimated across 17 countries. The Western Pacific region had the highest ASPR and ASDR. The disease burden was greater among males, peaking in the 50 to 59 age group.

From 1990 to 2021, Lao PDR, Thailand, and the Philippines showed substantial declines in foodborne trematodiases, while Kazakhstan had the largest average annual percentage change in DALYs.

In 2021, the global DALYs for foodborne trematodiases were 998,028 and the ASDR were 11.78, representing a reduction of 2.40 from 1990 to 2021. 

A public health threat
The Western Pacific region consistently had the highest number of cases from 1990 to 2021. South-East Asia experienced the greatest decrease. However, prevalence of foodborne trematodes has increased in the Americas, the Eastern Mediterranean region, and the European region. In some African nations, the chronic symptoms caused by trematodiases were not considered a priority or monitored, resulting in a lack of data.

In 2021, the countries with the most infections were China, Thailand, Republic of Korea, and Vietnam, which accounted for 85 percent of the global foodborne trematodiases cases.

The largest increase in the ASDR from 1990 to 2021 was in Iran, followed by Ukraine, Spain, and Japan.

The prevalence of foodborne trematodiases is influenced by human behaviors in endemic regions. It is also impacted by ecological and environmental factors, including poverty, pollution, and population dynamics.

Scientists said trematodiases remain a public health threat but the ASDR is projected to remain stable with a slight decline in the coming years.

From a control perspective, the issue is inadequately covered or entirely unaddressed in most countries. Reinfection was common due to the difficulty in changing deeply rooted cultural food habits. The complex life cycle of foodborne trematodes, involving snails, fish, plants, and animals makes interrupting the transmission process challenging. Health education programs that targeted primary students were more effective at promoting and maintaining changed behavior. 

Low-income countries also face underestimated disease burdens, highlighting the need for improved surveillance and control programs.

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Source: https://www.foodsafetynews.com/2025/01/researchers-shed-light-on-parasite-problem/