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.
So make sure and get one that is a good fit for your mouth size and the right tube size if it is for kids. Here we give you our advice from years of experience on what types work best (we buy new ones almost every trip to test them out). First let's just look at the basics. Your snorkel is how you breathe with your face stuffed in the water. It has a mouthpiece that is soft and comfortable and that seals out any water. It attaches to the side of your face mask strap, and will allow you to breathe in a variety of head positions common to snorkeling.