Other infections and cancer

A pair of Schistosoma haematobium blood worms

Parasites and cancer

The International Agency for Research on Cancer (IARC) has categorised three parasites as ‘carcinogenic to humans’, which means there is sufficient evidence to show that they can cause cancer in people.

These parasites include two small liver worms (Clonorchis sinensis and Opisthorchis viverrini) and a blood worm (Schistosoma haematobium). All three of these parasites are extremely rare in the UK.

The liver worms Clonorchis sinensis and Opisthorchis viverrini are mainly linked to bile duct cancer (a type of liver cancer) and are common in Asian countries, such as China, Thailand, Korea, Vietnam, Laos and Cambodia. Both these parasites are spread through contaminated food, particularly through undercooked fish.

The blood worm Schistosoma haematobium is mainly linked to bladder cancer and is common in Sub-Saharan Africa and the Middle East. This parasite lives in stagnant or slow-flowing water in these regions, so it is best not to swim in waters like this to avoid infection.

Human T-Lymphotropic Virus 1 (HTLV-1)

Human T-Lymphotropic virus type 1 (HTLV-1) can cause a type of Non-Hodgkin Lymphoma called ‘Adult T-Cell Leukaemia/Lymphoma’. But infection with this virus is very rare in the UK, and most people who carry the HTLV-1 virus will never develop the disease.

The virus is spread through contact with blood and other bodily fluids, so people can get infected by sharing contaminated needles or razors, or through sex. It’s also possible to get infected through blood transfusions, but in the UK, all donated blood is screened for this virus and any contaminated donations are destroyed. There’s less research into preventing the spread of this infection, but it’s best to keep sexual contact safer, and to avoid sharing needles or razors.

The virus can also be spread from mother to child, mainly through breastfeeding, but in the UK less than 5 in 10,000 pregnant women are infected. If you’re pregnant and know you have HTLV-1, speak to your doctor.

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