Who is at risk of contracting Legionnaires disease?
A. The risk of infection is based on two key factors: the number of legionellae reaching the body and the resistance of the individual. Young and healthy people can get Legionnaires disease, but persons who are immunocompromised either because of illness (e.g., cancer) or medical treatment (e.g., chemotherapy) are at a much higher risk because they can be infected by relatively low legionellae counts. HIV-infected patients, for example, have a 40-fold increased risk; organ transplant recipients have a 200-fold increased risk. Smokers, persons over 65 years of age, and heavy drinkers have a moderately higher risk. Children have contracted Legionnaires’ disease. Most cases have occurred in immunosuppressed children, but a number of immunocompetent children, particularly newborns, have acquired the disease, most often after surgeries, or through the use of legionellae-contaminated ventilators.
