Chlamydia Trachomatis in Older Los Angeles County Residents, 1991–1998: Implications and Recommendations for the Detection of Sexually Transmitted Infections in Older Age Groups


Address correspondence to Lisa V. Smith, DrPH, MS, Department of Epidemiology, UCLA School of Public Health, Los Angeles, California 90095. E-mail:


OBJECTIVES: This study examined the incidence and implications of reported chlamydia cases in Los Angeles County residents aged 50 and older.

DESIGN: Observational study of passive surveillance data submitted to the Los Angeles County Sexually Transmitted Disease Program.

SETTINGS: Private and public health facilities in Los Angeles County.

PARTICIPANTS: Los Angeles County residents aged 50 and older.

MEASUREMENTS: Chlamydia cases were identified from the Los Angeles County Sexually Transmitted Disease Program passive surveillance system reports received from 1991 to 1998.

RESULTS: Between 1991 and 1998, 1,421 cases of chlamydia were reported in persons aged 50 and older in Los Angeles County, accounting for 1% of total chlamydia cases. The average annual incidence rate for this period was 9.3 per 100,000, and appeared relatively stable. The mean age ± standard deviation was 59.0 ± 9.2 years, with a range of 50 to 96 years. Rates for older women were 1.1 to 3.0 times higher than in older men, similar to rate ratios for 20- to 35-year-olds. Rates among older African Americans appear to be substantially higher than any other older racial/ethnic group.

CONCLUSIONS: Our data show that there are no age barriers for sexually transmitted infections. Although this population is highly unlikely to experience adverse reproductive outcomes, transmission to younger sex partners and contribution to the overall chlamydia epidemic are serious concerns. Surveillance and prevention strategies aimed at older persons will be needed as this population continues to grow.