Schistosoma haematobium is a flatworm that infects humans and is found in Africa and parts of the Middle East. Research has shown that it can increase the risk of developing cervical cancer. (Image credit: DE AGOSTINI PICTURE LIBRARY via Getty Images)
A parasite that affects millions of people in Africa may silently cause cervical cancer, and surprisingly, standard treatment for the infection may increase the risk, according to new research.
Schistosoma haematobium, a freshwater flatworm that burrows through the skin, is already known to increase the risk of bladder cancer. But new research presented April 12 at ESCMID Global 2025, the annual conference on clinical microbiology and infectious diseases, has shown how the worm can activate cancer-related genes in the cervix both during active infection and after treatment.
The study involved a small group of women, so its results need to be confirmed in larger trials.
“More research is needed to find out if this association really exists and how much it increases the risk of cervical cancer,” said Dr. Joshua Cohen, medical director of the gynecologic cancer program at the City of Hope Orange County, who was not part of the study.
However, “given that parasitic infections are most common in countries with limited access to clean water and sanitation, it is important to focus efforts on reducing parasitic infections among all people living in these regions,” Cohen added in an email to Live Science.
An undetected factor in cervical cancer?
S. haematobium infects approximately 110 million people worldwide. However, previous studies in African countries suggest that only 1.7% to 3% of cervical cancer cases in these regions can be attributed to this infection. The main causative agent of cervical cancer is the human papillomavirus (HPV); almost all cervical cancer cases are associated with chronic infections with highly oncogenic strains of the virus.
HPV causes cancer by producing viral proteins that disrupt the life cycle of cervical cells and by infiltrating the DNA of the infected host. But S. haematobium uses a different mechanism, Dr. Jennifer Downs, an assistant professor of medicine at Weill Cornell Medicine who was involved in the new study, told Live Science in an email.
The flatworm, native to Africa and parts of the Middle East, causes a disease known as schistosomiasis, which can cause itchy skin, fever, chills, cough and muscle pain. To understand how the worm might affect the cervix, the researchers analyzed tissue samples from 39 women in Tanzania — 20 with active infections and 19 without them.
All infected participants received standard treatment with a drug called praziquantel. Tissue samples were collected before treatment and again after 4 to 12 months.
The team analyzed gene activity in the tissues, identifying several genes that responded differently in infected women compared to uninfected women; they also identified genes that changed their activity after antiparasitic treatment. Four of the altered genes are known to play an important role in the process of carcinogenesis, as their overactivity can lead to abnormal cell growth and tumors.
After treatment, genes involved in inflammation and tissue repair, as well as genes responsible for the breakdown of protective barriers in the cervix, were activated to a greater extent. These changes were associated with increased blood vessel formation and decreased cell death, as well as activation of some processes associated with cancer.
Changes in genes that help maintain the cervical barrier are “particularly concerning,” said lead study author Dr. Anna Mertelsmann, a researcher at the University Hospital Zurich and Weill Cornell Medicine who specializes in infectious diseases and
Sourse: www.livescience.com
