Is Bacterial Vaginosis a Sexually Transmitted Disease?
Bacterial vaginosis is NOT classified as a sexually transmitted disease (STD), despite its strong association with sexual activity. 1, 2
The Classification Paradox
BV occupies a unique position in gynecologic infections—it is best understood as a sexually-enhanced disease rather than a sexually transmitted infection. 3 Here's why this distinction matters:
Evidence Against STD Classification
Women who have never been sexually active are rarely affected by BV, but the condition can occur in adolescent girls without sexual experience, contradicting that sexual transmission is necessary for disease acquisition 1, 4, 3
Treatment of male sex partners has consistently failed to prevent BV recurrence in women, which is a critical finding that distinguishes BV from true STDs 1, 2, 4
The pathophysiology involves disruption of normal vaginal flora (replacement of H₂O₂-producing Lactobacillus species with anaerobic bacteria) rather than acquisition of a specific sexually transmitted pathogen 1, 2
Evidence Supporting Sexual Association
Despite not being an STD, BV shows clear sexual associations:
Multiple sexual partners strongly correlate with BV acquisition, with increasing lifetime partners showing a dose-response relationship 4, 5
The prevalence is 29.2% among reproductive-age women in the U.S., with higher rates among those with multiple partners 5
Non-coital sexual behaviors also increase risk, including digital-genital contact and oral sex, suggesting mechanical transfer of bacteria rather than transmission of a specific pathogen 3
The Mechanism: Why Sexual Activity Matters
Sexual activity enhances BV through two distinct non-transmissible mechanisms: 3
Alkalinization of the vaginal environment during unprotected intercourse disrupts the acidic pH that supports Lactobacillus dominance 3
Mechanical transfer of perineal enteric bacteria occurs with both protected and unprotected intercourse, introducing organisms that can disrupt normal flora 3
Clinical Implications
Key Practice Points
BV is common among women-who-have-sex-with-women, further supporting that it's not a classic male-to-female STD 3
Condom use is only slightly protective, unlike with true STDs where barrier protection is highly effective 3
Up to 84% of women with BV are asymptomatic, so absence of symptoms doesn't exclude the diagnosis 5
Important Caveat
While BV itself is not an STD, it significantly increases susceptibility to acquiring true STDs including HIV, making its diagnosis and treatment clinically important beyond symptom relief 2, 6, 5
The CDC's position remains clear: BV is associated with sexual activity but is not considered exclusively an STD, and this classification has remained consistent from 1993 through current guidelines 1, 2