Problem pathogens: paediatric legionellosis--implications for improved diagnosis.

Legionnaires' disease is an established and frequent cause of pneumonia in adults but is thought to be a rare cause in children. We reviewed the medical literature for cases of Legionnaires' disease in children and analysed the epidemiology, clinical characteristics, and treatment. 76 cases of legionella infection in children were identified. In 56%, diagnosis was made with culture methodology. 46% were community-acquired infections. 51.5% were under 2 years of age. 78% of the patients had an underlying condition such as malignancy. Fever, cough, and tachypnoea were the most common symptoms. The overall mortality rate was 33% and was higher in immunosuppressed children and in children younger than the age of 1 year. Patients who were treated empirically with anti-legionella therapy had a notably lower mortality rate compared with patients on inappropriate therapy (23%vs 70%). In 88% of hospital-acquired cases, an environmental link to potable water colonised with legionella was identified. We found no clinical features unique to Legionnaires' disease in children that would allow differentiation from pneumonia due to other respiratory pathogens. Awareness of legionella as a potential cause of paediatric pneumonia is particularly important because infection can be severe and life threatening and antimicrobial therapy often used for empirical therapy in children is not effective against legionella. In any case of pneumonia unresponsive to antibiotics, Legionnaires' disease should be considered and specific diagnostic tests to verify this diagnosis should be done. As legionella diagnostic tests become more widely applied, we predict that legionellosis may appear as an emerging infectious disease in children.