Once inside a host, the incubation period may be up to two weeks. Prodromal symptoms are flu-like, including fever, chills, and dry cough. Advanced stages of the disease cause problems with the gastrointestinal tract and the nervous system and lead to diarrhea and nausea. Other advanced symptoms of pneumonia may also present. However, the disease is generally not a threat to most healthy individuals, and tends to lead to severe symptoms more often in immunocompromised hosts and the elderly. Consequently, the water systems of hospitals and nursing homes should be periodically monitored. The Texas Department of State Health Services provides recommendations for hospitals to detect and prevent the spread of hospital-acquired disease due to Legionella infection.Report of the Texas Legionnaires' Disease Task Force, Texas Department of State Health Services According to Infection Control and Hospital Epidemiology, hospital-acquired Legionella pneumonia has a fatality rate of 28%, and the source is the water distribution system.
