Longitudinal Assessment of Infecting Serovars of Chlamydia trachomatis in Seattle Public Health Clinics: 1988–1996

BACKGROUND: There have been few longitudinal studies of fluctuations in the prevalence of Chlamydia trachomatis serovars in a given community; such studies could improve our understanding of the epidemiology and transmission of C trachomatis. STUDY DESIGN: This was a longitudinal study of 7110 female patients (62%) and 4344 male patients (38%) presenting with first-time infections to health department clinics between 1988 and 1996. GOAL: The goal was to ascertain trends in the proportion of infecting serovars over the 9-year study period and determine independent relationships between serovar and age, gender, race, and year of infection. RESULTS: Serovar E was the most prevalent (32%), followed by F (18%) and D (13%). Being female, African American, and infected with serovar B was associated with young age (P < 0.001, P < 0.001, and P = 0.09, respectively). Class C serovars were found in older patients (P < 0.001). Over the 9-year period, the percentage of infections with serovar types F and G increased (P = 0.007, P = 0.009), those with I and K decreased (P < 0.001, P = 0.008), and those with B, D, D-, E, H, Ia, and J remained stable. The age of those with positive Chlamydia cultures decreased (P < 0.001). CONCLUSION: In this population, while the major serovars appeared stable over 9 years, significant changes in the distribution of minor serovars, especially G, were observed over time.