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Chlamydia pneumoniae infection in children with lower respiratory tract infections
1Department of Pediatrics and Child Health, Kurume University School of Medicine, Japan.
Insights
Chlamydia pneumoniae (C. pneumoniae) infection is common in Japanese children, with antibody prevalence increasing after age 6. Mild, cold-like symptoms are typical, similar to adults.
Area of Science:
- Pediatric Infectious Diseases
- Microbiology
- Immunology
Background:
- Chlamydia pneumoniae (C. pneumoniae) infection is a significant cause of respiratory illness.
- Data on C. pneumoniae antibody incidence and clinical features in Japanese children were previously lacking.
- Understanding pediatric C. pneumoniae epidemiology is crucial for public health.
Purpose of the Study:
- To investigate the incidence of C. pneumoniae antibodies in healthy Japanese children.
- To describe the clinical manifestations of C. pneumoniae infection in pediatric patients.
- To compare C. pneumoniae seroprevalence between healthy children and those with respiratory infections.
Main Methods:
- Sera from 580 healthy children (including cord blood) were tested for C. pneumoniae antibodies using microimmunofluorescence (MIF).
- Throat swabs from 130 children with lower respiratory tract infections were analyzed for C. pneumoniae via culture and PCR.
- IgM and IgG serum titers were determined for patients with confirmed infections.
Main Results:
- C. pneumoniae antibody positivity was 50% in newborns, decreased to 0% at age 1, and rose significantly after age 6, reaching 55% by age 7.
- Recent infection (high IgG titer) was found in 2.2% of healthy children, with some asymptomatic cases.
- C. pneumoniae infection was confirmed in 7.7% of pediatric patients with respiratory illness, presenting with mild, cold-like symptoms.
Conclusions:
- Primary-school-aged children in Japan exhibit C. pneumoniae antibody prevalence similar to adults.
- C. pneumoniae infections in children often present with mild clinical symptoms, mimicking the common cold.
- The study highlights the widespread occurrence and generally mild nature of C. pneumoniae infections in pediatric populations.
Abstract:
The incidence of antibody and the clinical features of Chlamydia pneumoniae (C.pneumoniae) infection have not been studied in children in Japan. We investigated the incidence of C.pneumoniae antibody in sera from 580 healthy children (including 30 umbilical cord blood samples) during the 2-year period between June 1992 and June 1994. The antibody titer was determined by a microimmunofluorescence (MIF) test by using the elementary body of C.pneumoniae TW-183 as the antigen. Umbilical cord blood samples were positive for the antibody in 50% of newborns tested at birth. The incidence of positivity decreased to 0% in 1-year-old children. It was still low in children up to 5 years of age and then increased rapidly in children 6 years of age or older. The positivity reached increased rapidly in children 6 years of age or older. The positivity reached 55% in 7-year-old children and remained at this level in children older than 7 years of age. High antibody titer (IgG > or = 512), indicating recent infection, was observed in 13 (2.2%) of the 580 children, two of whom showed no symptoms. We detected the pathogen in throat swabs by culture and capillary polymerase chain reaction (PCR), and determined IgM and IgG serum titers to C.pneumoniae in 130 children with lower respiratory tract infection (91 with pneumonia and 39 with bronchitis) between December 1993 and December 1994. The infection due to C.pneumoniae was confirmed in 10 (7.7%). Of these, 7 were boys and 3 were girls, ranging in age from 9 months to 12 years. The clinical manifestations of the infection were mild symptoms like in common cold; post-nasal discharge, hoarseness and prolonged cough were relatively characteristic. There was no significant difference in the incidence of serum positivity between the healthy children group and the patients group. The present study suggests that primary-schoolers show antibodies for C.pneumoniae with nearly the same frequency as adults. Mild clinical symptoms are very common in C.pneumoniae infections in children as in adults.