What are the risk factors for chlamydia?

Risk Factors for Chlamydia Infection

Young age (under 25 years) is the most important risk factor for chlamydia infection, with women under 25 having more than 5 times increased likelihood of infection compared to women over 30 years. 1

Demographic Risk Factors

• Age-related risk:

  • Women ≤25 years are at highest risk 2, 1
  • Adolescents and young adults are particularly vulnerable 2

• Race/ethnicity:

  • Higher prevalence rates among African-American and Hispanic populations 2, 1

• Marital status:

  • Being unmarried increases risk 2, 1

Behavioral Risk Factors

• Sexual partner history:

  • Having new or multiple sexual partners 2, 1
  • Having two or more partners in the past 2-12 months 3, 4
  • Having a partner with concurrent partners 1
  • Having a partner with chlamydia infection 1, 3

• Previous STI history:

  • Prior history of chlamydia or other sexually transmitted infections 2, 1
  • Diagnosis of chlamydia within the past 12 months 3

• Contraceptive and protection practices:

  • Inconsistent condom use 2, 1
  • Early age of first intercourse 5

• Other behavioral factors:

  • Commercial sex work 1
  • Drug use 1

Anatomical Risk Factors

• Cervical ectopy (particularly in young women) 2, 5

High-Risk Settings

• Adolescent clinics 1
• Correctional facilities 1
• STD clinics 1
• Women undergoing termination of pregnancy 3

Clinical Considerations

Screening Implications

The identified risk factors should guide targeted screening efforts, particularly focusing on:

• All sexually active women ≤25 years (annual screening) 1
• Women >25 years with risk factors 1
• Pregnant women with risk factors at first prenatal visit and third trimester 1
• Sexual partners of individuals diagnosed with chlamydia 3

Pitfalls to Avoid

1. Missing asymptomatic infections: 70-90% of women and a large percentage of men with chlamydia are asymptomatic 2, making risk-based screening crucial.

2. Overlooking reinfection risk: Individuals previously infected should be rescreened at 6-12 months due to high reinfection rates 2.

3. Neglecting partner notification: All sexual partners should be notified, tested, and treated to prevent reinfection 3.

4. Focusing only on women: While women bear the greatest burden of complications, men can also be infected and serve as vectors for transmission.

5. Ignoring local prevalence data: Clinicians should consider the characteristics of their communities when determining screening strategies, as prevalence varies widely 2.

The evidence clearly shows that young age is the strongest risk factor for chlamydia infection, with sexual behavior patterns (multiple partners, inconsistent condom use) and demographic factors (race/ethnicity, marital status) further modifying risk. Early identification through risk-based screening is essential to prevent serious complications including PID, infertility, and chronic pelvic pain.