How long can a person with chlamydia be asymptomatic and still be contagious?

From the Guidelines

A person with chlamydia can remain asymptomatic and contagious for months or even years if left untreated. Many infected individuals (up to 70% of women and 50% of men) never develop symptoms, yet they can still transmit the infection to sexual partners throughout this entire period. The bacteria Chlamydia trachomatis can live in the body without causing noticeable symptoms while still being shed during sexual contact. This is why regular STI screening is crucial, especially for sexually active individuals with new or multiple partners.

Key Considerations

• The Centers for Disease Control and Prevention (CDC) recommends that persons treated for chlamydia should be instructed to abstain from sexual intercourse for 7 days after single-dose therapy or until completion of a 7-day regimen 1.
• Treatment with antibiotics such as azithromycin (1g single dose) or doxycycline (100mg twice daily for 7 days) effectively clears the infection and stops contagiousness, typically within 7 days of starting treatment.
• Anyone diagnosed with chlamydia should abstain from sexual activity until they and their partner(s) complete treatment to prevent reinfection.
• The asymptomatic nature of chlamydia contributes significantly to its spread and highlights the importance of routine testing rather than waiting for symptoms to appear.

Prevention and Screening

• The US Preventive Services Task Force recommends screening for chlamydial infection in pregnant women at the first prenatal visit and during the third trimester if they remain at increased risk or acquire a new risk factor 1.
• The optimal interval for screening for nonpregnant women is unknown, but the CDC recommends at least annual screening for women at increased risk.
• The evidence is insufficient to determine the balance of benefits and harms related to screening men for chlamydial infection, but primary care clinicians can institute screening in men as part of a comprehensive approach to prevention.

From the Research

Asymptomatic Chlamydia Infection

• A person with chlamydia can be asymptomatic and still be contagious, as a substantial proportion of initial infections in both men and women are asymptomatic 2.
• The duration of asymptomatic contagion is not explicitly stated in the provided studies, but it is known that chlamydia can persist in the body for a long time, even after treatment 3.
• Spontaneous resolution of chlamydia can occur in some individuals, with one study finding that 18% of participants experienced spontaneous resolution of the infection 4.

Contagion Period

• The contagion period for chlamydia is not directly stated in the provided studies, but it is known that the infection can be transmitted through sexual contact, even if the infected person is asymptomatic 2.
• The use of nucleic acid amplification-based diagnostic tests on first-void urine makes it possible to initiate community-based screening programs aimed at identifying asymptomatically infected men and women 2.
• Directly observed single-dose therapy with azithromycin is now available, which can help reduce the transmission of chlamydia 2.

Treatment and Persistence

• The efficacy of single-dose azithromycin therapy in the treatment of cervical Chlamydia trachomatis infections is comparable to that of a standard seven-day course of treatment with doxycycline 5.
• However, some studies suggest that azithromycin may be less effective against chlamydial gastrointestinal infection than against genital infections 3.
• The natural history of untreated Chlamydia trachomatis infection is not fully understood, but it is known that spontaneous resolution of the infection can occur, and that some individuals may experience persistent infection or develop complications 4.