High Liver Fluke Infection Rates Reported Among New University Students in Northeastern Thailand Raise Public Health Concerns

Thailand – Health screening programs conducted among newly enrolled university students in Thailand's northeastern province of Maha Sarakham have revealed a notable prevalence of liver fluke (Opisthorchis viverrini) infection, highlighting the continued public health challenge posed by foodborne parasitic diseases in the region.

According to reports from local health authorities, Mahasarakham University screened 12,733 first-year students for the 2026 academic year and identified 4,233 positive cases, representing approximately 33% of those tested. Meanwhile, Rajabhat Maha Sarakham University screened 1,922 new students, with 380 students (19%) testing positive.

The findings have prompted provincial authorities to strengthen food safety inspections and expand public awareness campaigns encouraging restaurants to use properly cooked fermented fish products, locally promoted under the campaign "Cooked Pla Ra Restaurants."

A Persistent Foodborne Parasite

The liver fluke responsible for most infections in the Mekong region is Opisthorchis viverrini, a flatworm parasite that resides in the bile ducts of humans and other mammals.

Medical studies indicate that adult liver flukes can survive inside the human body for more than 20 years, with some reports suggesting survival for up to 25–30 years if left untreated.

How Infection Occurs

The parasite has a complex life cycle involving freshwater snails and freshwater cyprinid fish before infecting humans.

People become infected primarily by consuming raw or undercooked freshwater fish, including traditional dishes such as:

• Raw fish salad (Koi Pla)
• Raw fermented fish (Pla Ra)
• Uncooked fermented fish products

After ingestion, parasite larvae migrate through the digestive system into the bile ducts, where they mature into adult worms.

Link to Cholangiocarcinoma

Liver fluke infection is recognized as one of the leading risk factors for cholangiocarcinoma (bile duct cancer), one of the most aggressive forms of liver-related cancer.

Researchers have identified several mechanisms through which chronic infection contributes to cancer development:

• Continuous mechanical injury to the bile duct lining
• Chronic inflammation that produces reactive oxygen and nitrogen species capable of damaging DNA
• Parasite-secreted proteins, including Ov-grn-1, which stimulate abnormal cell proliferation

The combination of persistent inflammation, DNA damage, and excessive cell growth significantly increases the long-term risk of bile duct cancer.

Symptoms Often Go Unnoticed

Most infected individuals experience no symptoms during the early stages, allowing infections to persist for many years.

When symptoms develop, they may include:

• Abdominal discomfort, particularly in the upper right abdomen
• Bloating and indigestion
• Fatigue
• Enlarged liver

Advanced disease can lead to bile duct obstruction, jaundice, gallbladder inflammation, and eventually cholangiocarcinoma.

Prevention Remains the Best Protection

Health experts emphasize that liver fluke infection is largely preventable through proper food preparation and sanitation.

Recommended preventive measures include:

• Eating only thoroughly cooked freshwater fish and fermented fish products
• Avoiding raw or undercooked traditional fish dishes
• Using sanitary toilet facilities to prevent parasite eggs from contaminating water sources
• Seeking medical evaluation if at risk; infection can be diagnosed through stool examinations or other laboratory tests

When infection is confirmed, physicians commonly prescribe Praziquantel, an antiparasitic medication that effectively eliminates liver flukes. However, experts note that while treatment removes the parasite, it cannot reverse DNA damage or chronic tissue injury that may already have occurred, underscoring the importance of prevention.

A Continuing Public Health Challenge

Liver fluke infection remains a significant public health concern in parts of Southeast Asia, particularly in areas where eating raw or undercooked freshwater fish remains part of local food culture.

Public health authorities continue to promote food safety education, early screening, and behavioral change to reduce infection rates and lower the long-term burden of bile duct cancer in affected communities.

 

Source : Thai Health Promotion Foundation