Source, Getty Images
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- Written by, Kate Bowie
- Title, BBC World Service, Global Health Unit
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Reading time: 3 min
It enters our body through our skin and circulates in our blood. It lays its eggs in our liver, lungs and genitals. And it may go undetected for years.
Scientists have warned that the parasites that cause schistosomiasis, which has not been taken seriously until now, may get out of control.
Every year, 250 million people worldwide are treated for this disease.
The vast majority of them are in Africa, where snails that carry this parasite live.
However, the disease is also transmitted outside the continent: Schistosomiasis transmission has been detected in 78 countries, including China, Venezuela and Indonesia.
In Türkiye, until now, this parasite had only been detected in people returning from abroad.
But this situation may change.
The World Health Organization (WHO) announced that the parasite that causes schistosomiasis has evolved and adapted to survive in new regions.
The organization made this statement on World Neglected Tropical Diseases Day.
This day is used to draw attention to diseases caused by viruses, bacteria, parasites and fungi, which are thought to be not given enough importance even though they affect one billion people.
What is schistosomiasis?
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This disease is seen in humans and animals that enter water containing parasite larvae released from the bodies of snails.
These larvae secrete enzymes that will allow them to digest the skin and get under it, and after entering the body, they begin to live in the blood vessels.
While these eggs laid by females are sometimes excreted from the body with feces and urine, sometimes they cannot be excreted.
Thereupon, the immune system begins to attack these eggs, and in the meantime, the tissue around the eggs is damaged.
This can lead to organ failure.
Eggs can sometimes accumulate in the sexual organs. This disease is called urinary schistosomiasis, and in addition to pain, it can also lead to cancer and even death in severe cases.
Schistosomiasis can be cured with parasite medications. WHO recommends that at-risk groups such as children, agricultural workers and fishermen use this medicine regularly for several years.
But Prof. from the Liverpool Wellcome Clinical Research Program in Malawi. Janelisa Musaya says it’s possible that evolving parasites may be immune to existing treatments.
tip of the iceberg
So what causes new persistent epidemics?
Researchers found that the human and animal versions of this parasite formed a new hybrid.
Since these hybrids can affect both humans and animals, their transmission is more difficult to control.
Prof. In his new research, Musaya says that 7% of the parasites tested in samples taken from humans and animals were hybrids, and that this rate may be “the tip of the iceberg” because the tests were conducted in a small number of regions.
Musaya adds that hybrid parasites could eliminate two types of human parasites and animal parasites in the future.
Doctors have not yet figured out how to cure patients who harbor this hybrid strain.
That’s why Musaya says, “We are sending a wake-up call to politicians. They must do something before this problem grows rapidly.”
Cases in genital organs may not show up in tests
The new research also reveals that although these hybrids affect people’s genitals, they are difficult to detect.
The reason for this is that the eggs of hybrids do not look like typical parasite eggs under the microscope.
Healthcare professionals may also confuse the symptoms of this parasite with the symptoms of sexually transmitted diseases.
If left untreated, urinary schistosomiasis can lead to genital sores and infertility, and increases the risk of HIV transmission.
Epidemics in southern Europe
Scientists are of the opinion that the ability of hybrids to spread around the world has increased.
With climate change and increased travel, hybrid parasites are becoming more difficult to control.
In recent years, epidemics caused by hybrids have been observed in the south of Europe.
Dr., who is the head of WHO’s schistosomiasis control program. Amadou Garba Djirmay says this has “become a global concern.”
Thanks to comprehensive parasite control programs, schistosomiasis cases decreased by 60% from 2006 to 2024.
But aid to fight neglected tropical diseases has fallen by 41% between 2018 and 2023, according to the WHO.