Health

Fluke infection can cause cancer – VnExpress


Liver flukes cause bladder cancer, schistosomiasis causes biliary tract cancer when they are parasitic in the body.

MSc Nguyen Thanh Trung (Department of Oncology, Tam Anh General Hospital in Hanoi) said that cancer can be caused by environmental and physiological conditions. Viral, bacterial and parasitic infections have the potential to cause cancer in humans. It is estimated that around 1.2 million cases of infectious malignancies occur worldwide each year, most commonly in developing countries.

According to the American Cancer Society, certain parasites such as Schistosoma haematobium (schistosomiasis) and Opisthorchis viverrini (liver fluke) are strongly associated with bladder cancer and cholangiocarcinoma.

Liver fluke infection causes biliary tract cancer

Liver flukes are common in East and Southeast Asian countries and are rare in other parts of the world. The liver fluke larvae in the duodenum and jejunum migrate through the vater duct (large papilla) in the bile duct. They will parasitize, develop into adult flukes here and can live up to 30 years.

Doctor Trung said, liver fluke causes inflammation of the cells in the biliary tract, releasing reactive oxygen radicals and active nitrogen radicals. They have the ability to damage DNA, proteins and cell membranes, alter enzyme activity and gene expression, and can cause cancer.

According to Dr. Trung, patients can be infected with parasites by eating raw foods such as raw, pickled, undercooked fish, raw vegetables, drinking unboiled water… People with chronic liver fluke infections often No specific symptoms, can be confused with other diseases. Some people may experience pain in the right flank (common in women), diarrhea, loss of appetite, indigestion…

“Hepatic fluke infection can cause hepatomegaly, hepatitis, liver abscess… but the most serious complication is an increased possibility of cholangiocarcinoma. O.viverrini is a carcinogen secreted by liver flukes. “, said Doctor Trung.

The habit of eating raw foods can cause helminth infections. Image: Shutterstock

schistosomiasis causes bladder cancer

According to the International Agency for Research on Cancer (IARC), people infected with schistosomiasis are five times more likely to develop bladder cancer than the uninfected group. There are 5 species of schistosomiasis that infect humans, but the most common are S. haematobiumand and S. mansoni.

The mechanism of bladder cancer of schistosomes is the fibrosis process caused by fluke eggs that can induce proliferation and hyperplasia. These are precancerous changes that can be resolved. Infection and increased excretion of nitrosamines from schistosomiasis precursors in the urine are also bladder carcinogens. Urine stagnation facilitates the growth of bladder cell carcinomas.

3D image of schistosomiasis.  Photo: Shutterstock

3D image of schistosomiasis. Image: Shutterstock

Dr Trung added that schistosomiasis larvae can enter the human body through the skin when swimming or wading in dirty water. Once in the body, they move through the bloodstream to the liver to develop into adult flukes and lay eggs in the bloodstream. Infection with schistosomiasis almost does not show obvious symptoms, if present, it is usually a rash, itchy skin papules at the site of entry of larvae; acute fever 2-4 weeks after laying eggs, cough, nausea, abdominal pain, myalgia, urticaria. Chronic conditions can cause intestinal mucosal ulcers, bleeding, diarrhea, focal fibrosis, fistulas, splenomegaly, bladder wall ulcers… leading to many dangerous complications. Bladder cell carcinoma is the most serious complication caused by this fluke.

Vietnam is located in a tropical climate, with many river and stream systems, so fish, snails and crabs thrive. These are favorable conditions for parasites such as liver flukes and schistosomiasis to exist.

According to Dr Trung, Avoiding parasitic infections is a proactive way to prevent cancer. Everyone should eat cooked, drink boiling; avoid using water or bathing in contaminated areas; do not discharge manure directly into the environment, avoid using domestic wastewater to irrigate vegetables. Note deworming, worms periodically (every 6 months); wash hands with antibacterial soap before eating and after using the toilet; periodic health checkup. Early diagnosis, prompt treatment and prevention of parasitic infections greatly reduce the risk of cancer.

Nguyen Phuong

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