Chlamydophila pneumoniae infection among young children with respiratory diseases in Thailand.

A total of 136 children aged 5 years and under with respiratory tract diseases were examined for Chlamydophila pneumoniae infection. By means of the micro-immunofluorescence test, an acute infection was suggested in 37 (27.2%) of them. Infection was found in 23 (43.4%) of 53 children with bronchitis, seven (70.0%) of 10 with pharyngitis, and two (22.2%) of nine with pneumonia. C. pneumoniae DNA was detected in seven of 55 children by means of nasopharyngeal swabs, and serological evidence was present in all of seven. Five of them were suggested the acute infection and four of the five showed IgG titers increasing four times and over. By age distribution, five of the seven DNA-positive children were 1 year old, and the remaining two were 2 and 4 years old, respectively. The clinical findings of the seven DNA-positive children were characterized as indicative of bronchitis (n = 4), pharyngitis (n = 2), and pneumonia (n = 1). In Thailand, C. pneumoniae infection occurs frequently among children aged 5 years and under, and may cause pharyngitis, bronchitis, and sometimes pneumonia. However, it is suggested that C. pneumoniae infection is not a major cause of severe pneumonia among children in that age group.