title: Letter: Widal tests for water workers.
mesh_terms: D000372:Agglutination Tests; D006801:Humans; D006920:Hygiene; D012478:Salmonella Food Poisoning / Q000517:prevention & control; D012480:Salmonella Infections / Q000276:immunology / Q000517:prevention & control*; D012698:Serologic Tests; D014435:Typhoid Fever / Q000175:diagnosis; D014876:Water Pollution / Q000517:prevention & control*