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Infections with Legionella pneumophila in children
Insights
Legionella pneumophila is not a common cause of acute respiratory illness in young children. However, over half of the children studied showed evidence of frequent exposure to this bacterium.
Area of Science:
- Pediatric infectious diseases
- Microbiology
- Immunology
Background:
- Legionella pneumophila causes Legionnaires' disease in adults.
- The role of L. pneumophila in childhood respiratory illness is not well understood.
Purpose of the Study:
- To investigate the role of Legionella pneumophila in acute lower respiratory tract disease in children under four years of age.
- To determine the prevalence of L. pneumophila infections in this pediatric population.
Main Methods:
- Prospective study of 52 children with acute lower respiratory tract illness.
- Collected viral, mycoplasmal, and bacterial cultures.
- Obtained acute, convalescent, and annual serum samples for serologic testing (indirect immunofluorescence antibody titers) over 3-5 years.
Main Results:
- No acute episodes were serologically confirmed as L. pneumophila infections.
- 52% of children demonstrated significant rises in indirect immunofluorescent antibody titers to L. pneumophila, primarily serogroup 2.
- Most titer rises occurred after the acute illness phase, suggesting frequent exposure rather than acute infection.
Conclusions:
- L. pneumophila is unlikely to be a common cause of acute respiratory disease in early childhood in the studied region.
- Children in the study area are frequently exposed to L. pneumophila.
- Observed serologic responses may be due to cross-reactivity with other microorganisms.
Abstract:
To learn the role of Legionella pneumophila, the agent of Legionnaires' disease, in childhood illness, a prospective study was conducted among 52 children younger than four years of age with acute disease of the lower respiratory tract. Viral, mycoplasmal, and bacterial cultures and acute- and convalescent-phase sera were obtained during 64 episodes of acute illness; additional sera were drawn annually for three to five years. On the basis of serologic evidence, none of the acute episodes appeared to be due to L. pneumophila serogroup 1 or 2. However, examination of annual serum specimens showed that 27 (52%) of the children had rises in titer of indirect immunofluorescent antibody (a fourfold or greater rise to a reciprocal titer of greater than or equal to 128). Most rises in titer were in response to the serogroup 2 antigen. These results suggest that L. pneumophila is not a common cause of acute respiratory disease in early childhood in the study area but that children are frequently exposed to the organism. Alternatively, the serologic responses might be to unrelated cross-reacting microorganisms.