Schistosomiasis (also known as Bilharzia, snail fever, or Katayama fever) is caused by flatworm parasites that live in the blood vessels of the bladder and intestines. Schistosomiasis - also known as bilharzia, snail fever, or Katayama fever - is caused by flatworm parasites that live in the blood vessels of the bladder and intestines. Health Matters
A Tornado warning means A tornado has been  spotted/touched down in your alert area. You should take  cover if a tornado warning is issued for your area;  go into a cellar, or the lowest, most inner part of your house  where there are no windows (a downstairs or basement bathroom is  ideal).
The difference between a tornado watch and a tornado warning means the difference between taking action or taking precautions. A watch means that conditions are favorable for a tornado to occur. A warning means that a tornado has been seen or picked up by radar. A warning requires you to take shelter and brace for a potential tornado.