Schistosomiasis, also known as bilharzia (bill-HAR-zi-a), is a disease caused by parasitic worms. Infection with Schistosoma mansoni, S. haematobium, and S. japonicum causes illness in humans.Although schistosomiasis is not found in the United States, more than 200 million people are infected worldwide.chistosomiasis, also known as bilharzia (bill-HAR-zi-a), is a disease caused by parasitic worms. Infection with Schistosoma mansoni, S. haematobium, and S. japonicum causes illness in humans.
Part 2: How do Dry Snorkels Work? Dry snorkels have a mechanism at the top of the tube that closes when you submerge under water. It also has a covering at the top to prevent surface water from splashing into the top of tube. The dry snorkel has a valve/hinge mechanism at the top. When you submerge underwater, accidentally or purposely, the hinge reacts via a float mechanism and closes onto the top of the tube and seals it which prevents water from filling the tube.
Re: How exactly do snorkels work when you are under the... Or more to the point: Snorkels don't work under water. They work on the surface by allowing the wearer to have his/her face in the water so that one can look at what is going on and the top of the snorkel is several inches above the surface allowing the user to breath through the tube.