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).
Tornado watch. An example of a tornado watch for parts of Kansas and Nebraska, issued by the Storm Prediction Center on May 5, 2007. A tornado watch (SAME code: TOA) is issued when weather conditions are favorable for the development of severe thunderstorms called a Supercell that are capable of producing tornadoes. A tornado watch therefore implies that it is also a severe thunderstorm watch.