Is Bacterial Vaginosis (BV) considered a Sexually Transmitted Disease (STD)?

Is Bacterial Vaginosis (BV) a Sexually Transmitted Disease?

Bacterial vaginosis is NOT classified as a sexually transmitted disease, despite its strong association with sexual activity. 1, 2

The Definitive Classification

The CDC explicitly states that BV "is not considered exclusively an STD" even though it is clearly associated with sexual activity. 1 This classification is based on several key observations that distinguish BV from true STDs:

• Partner treatment does not prevent recurrence: Multiple trials demonstrate that treating male sexual partners fails to reduce BV recurrence in women, which is fundamentally inconsistent with sexually transmitted infections. 1, 2, 3
• BV occurs in sexually inactive populations: Women who have never been sexually active can develop BV, though this is rare, contradicting the requirement for sexual transmission. 1, 4
• Virginal adolescents develop BV: Studies show no significant difference in BV prevalence between sexually active and virginal adolescent girls (13% overall prevalence with similar rates in both groups), providing strong evidence against exclusive sexual transmission. 4

Why BV Appears STD-Like: The "Sexually Enhanced Disease" Model

BV is better conceptualized as a sexually enhanced disease rather than a sexually transmitted infection. 5 The sexual associations exist but operate through different mechanisms:

Sexual Activity Risk Factors

• Multiple sexual partners significantly increase BV risk 1, 3, 6
• New sexual partners elevate risk 3
• Frequency of intercourse is a critical factor, not just partner number 5
• Earlier age at first intercourse correlates with higher BV rates 6

Mechanisms of Sexual Enhancement (Not Transmission)

• Alkalinization of vaginal pH: Unprotected intercourse introduces semen, which disrupts the acidic vaginal environment (normal pH 3.8-4.2 to >4.5), allowing anaerobic bacterial overgrowth. 2, 5
• Mechanical transfer: Both protected and unprotected intercourse can mechanically transfer perineal enteric bacteria into the vagina, similar to mechanisms in urinary tract infections. 5, 7
• Non-coital sexual behaviors: BV is associated with digital-genital contact, oral sex, and female-to-female sexual contact, indicating that penetrative intercourse is not required. 5

The True Pathophysiology: Vaginal Dysbiosis

BV represents an ecological disruption rather than infection with a single sexually transmitted pathogen:

• Loss of protective lactobacilli: The fundamental cause is replacement of H₂O₂-producing Lactobacillus species with anaerobic bacteria including Gardnerella vaginalis, Bacteroides species, Mobiluncus species, Prevotella bivia, Prevotella disiens, Porphyromonas species, Peptostreptococcus species, and Mycoplasma hominis. 1, 2, 7
• Polymicrobial syndrome: BV is not caused by a single transmissible pathogen but by overgrowth of multiple organisms that are often part of normal vaginal flora. 2, 7

Critical Clinical Implications

Do NOT Treat Male Partners (Standard Recommendation)

• The CDC explicitly recommends against treating male sexual partners because it does not affect women's response to therapy or prevent relapse. 1, 3
• Six older randomized trials support this recommendation. 8

Exception: Recurrent BV Cases

• Newer 2025 evidence suggests that for women with recurrent BV specifically, treating male partners with metronidazole 400 mg orally twice daily for 7 days plus 2% clindamycin cream applied to penile skin twice daily for 7 days may be considered. 8
• This represents evolving evidence that challenges older guidelines, but remains limited to recurrent cases only. 8

Common Pitfalls to Avoid

• Do not use BV diagnosis as evidence of sexual abuse in children: BV can occur in virginal adolescents and is not proof of sexual activity. 4
• Do not assume all cases are symptomatic: Up to 50% of women meeting clinical criteria for BV are completely asymptomatic. 1, 2, 3
• Do not routinely treat partners: Standard practice remains no partner treatment except in carefully selected recurrent cases. 1, 3
• Recognize BV increases STI susceptibility: Women with BV have 1.8-fold increased risk for gonorrhea and 1.9-fold increased risk for chlamydia infection, making it a risk factor for true STDs. 6

When BV Matters Most: High-Risk Scenarios

Despite not being an STD, BV requires aggressive management in specific clinical contexts:

• Before surgical abortion or hysterectomy: Screen and treat even asymptomatic BV to prevent post-abortion pelvic inflammatory disease, vaginal cuff cellulitis, and endometritis. 2, 3
• During pregnancy: Test and treat all symptomatic pregnant women due to associations with premature rupture of membranes, preterm labor, preterm birth, and postpartum endometritis. 2, 3, 7
• Before IUD placement or hysterosalpingography: Consider screening before these invasive procedures. 2, 3