Seroprevalence of antibodies to Chlamydia pneumoniae in elderly people: a two-decade longitudinal and cohort difference study.

A gerontological population of 178 men and 249 women was investigated regarding the prevalence of antibodies specific to Chlamydia pneumoniae. A longitudinal substudy was carried out on 22 men and 44 women, age range 70-90 y. Antibodies specific to C. pneumoniae were common. Men had higher prevalences and higher antibody levels than women. More than half of the individuals in the longitudinal study had significant IgG and/or IgA titre changes (> or = 4-fold) between the ages of 70 and 90 y, suggesting that C. pneumoniae infections are common in the elderly population. This is of importance for the treatment of respiratory infections in elderly people.