Serologic evidence of a sporadic outbreak in Illinois of infection by Chlamydia (psittacosis-LGV agent) in patients with primary myocardial disease and respiratory disease

Northern Illinois experienced an outbreak of chlamydial infection in 1963, 1964, and 1965, as reflected by an increase in the number of patients showing antibody to this group of agents during the period. Among these individuals, a disproportionately large number with PMD showed serologic activity against Chlamydia. This suggests that there was something distinctive about the response of the PMD patients in the face of this outbreak. The clinical manifestations of heart disease in PMD patients were similar regardless of their serologic status, i.e., whether or not they had antibody of Chlamydia. Specific serum reactivity to Chlamydia was verified by: (1) use of multiple chlamydial antigens, (2) application of both complement-fixation and RIP test systems, and (3) absence of reactivity to uninfected egg tissue or to egg tissue infected with Newcastle disease virus. Reactivity to Chlamydia persisted in our PMD population for periods of months to more than five years. While the evidence cited in this paper linking chlamydial agent to the PMD is inferential and no direct evidence of chlamydial infection was found in the tissue of 12 hearts examined, epidemiologic considerations strongly suggest an etiologic relationship.