The parasitic worm that causes schistosomiasis hatches in water and grows up in a freshwater snail, as shown here.
Once mature, the worms swim back into the water, where they can infect people through skin contact. Initially, an infected person might have a rash, itchy skin or flu-like symptoms, but the real damage is done over time to internal organs.
The image above shows a slice through the tentacle of an infected snail. The swirls of orange, blue, and green on the periphery of the image are snail muscle. The darker centre of the image reveals a mother worm in which hundreds of daughter worms are developing. The daughters will leave the mother, migrate, and colonize other parts of the snail, and ultimately give rise to thousands even millions of individuals that can infect humans once they are released into fresh water.
This massive multiplication inside the snail maximizes the transmission of this major human parasite.
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.