BV is considered a sexually associated infection, not specifically an STI. This is because it can be spread through sexual contact, but women can also get this infection unrelated to sexual activity. It is simply an imbalance in the bacteria in the vagina.
Bacterial vaginosis is the most common cause of vaginal symptoms among women, but it is not clear what role sexual activity plays in the development of BV.
The prevalence in the United States is estimated to be 21.2 million (29.2%) among women ages 14–49, based on a nationally representative sample of women who participated in NHANES 2001–2004. The following are other findings from this study.
- Most women found to have BV (84%) reported no symptoms.
- Women who have not had vaginal, oral, or anal sex can still be affected by BV (18.8%), as can pregnant women (25%), and women who have ever been pregnant (31.7%).
- Prevalence of BV increases based on lifetime number of sexual partners.
- Non white women have higher rates (African-American 51%, Mexican Americans 32%) than white women (23%).
How is bacterial vaginosis spread?
Researchers do not know the cause of BV or how some women get it. We do know that the infection typically occurs in sexually active women. BV is linked to an imbalance of “good” and “harmful” bacteria that are normally found in a woman’s vagina.
Having a new sex partner or multiple sex partners, as well as douching, can upset the balance of bacteria in the vagina. This places a woman at increased risk for getting BV.
We also do not know how sex contributes to BV. There is no research to show that treating a sex partner affects whether or not a woman gets BV. Having BV can increase your chances of getting other STDs.
BV rarely affects women who have never had sex. You cannot get BV from toilet seats, bedding, or swimming pools.
Frequent symptoms of BV
Bacterial vaginosis (BV) is caused by an imbalance of the naturally occurring bacteria in the vagina and, most specifically, a decline of a type of “good” bacteria known as lactobacilli. When this happens, other “bad” bacteria can predominate and cause infection.
Of the 21 million women in the United States who develop BV each year, as many as 84 percent will have no symptoms, according to a report from the Centers for Disease Control and Prevention.
Of those that do, the most common include:
- A grayish white or yellow discharge that usually coats the walls of the vagina
- A “fishy” smell that can get often worse after intercourse
- A burning sensation when urinating
- Vaginal itchiness, redness, and swelling (usually mild)
- Vaginal bleeding after intercourse
Even after a woman has been successfully treated for BV, as many as 50 percent will experience a recurrence of symptoms within a year.
On rare occasions, BV may cause dysuria (painful or difficult urination) or dyspareunia (painful intercourse). These are most often caused by a secondary infection of the urinary tract and vagina.
Diagnosing and treating BV is important as it can greatly reduce the risk of complications. The three most common concerns are the increased risk of sexually transmitted infections (including HIV), pelvic inflammatory disease (PID), and pregnancy loss or preterm birth.
Sexually Transmitted Infections
Bacterial vaginosis is characterized by the inflammation of vaginal tissues. When this occurs, the tissues and underlying blood vessels will start to swell and expand to allow larger immune cells closer to the site of infection.
While this process is vital to healing, it also has a downside: It makes these tissues more permeable and vulnerable to sexually transmitted infections. This is especially true when BV symptoms are severe.
According to a 2018 study from the St. Louis School of Medicine, symptomatic BV increases the risk of gonorrhea, chlamydia, and trichomoniasis by 270 percent.
The same appears to be true with genital herpes and syphilis; the relationship between BV and the human papillomavirus (HPV) is somewhat less clear.
By contrast, women with subclinical BV (in which there are no observable symptoms) were not seen to be at an increased risk.
By contrast, the relationship between BV and HIV is not only clear but insidious. HIV is a disease associated with the rapid depletion of immune cells called CD4 T-cells. When BV occurs, white blood cells will flood the vaginal tissue in order to surround and contain the bacterial infection.
However, if HIV is present, those same white blood cells will “capture” the viruses and carry them back to the CD4 T-cells to be neutralized. But, instead of being killed, HIV will turn the table on the CD4 T-cells and infects them instead.
In the end, having a BV infection helps facilitate HIV by providing it more targets for infection.
And, it’s not just women who are at risk. If a woman has HIV, the development of BV can lead to a phenomenon known as viral shedding in which a genital infection will inherently increase the concentration of HIV in semen or vaginal secretions. If this occurs, a woman will be more likely to pass the virus to a sexual partner (in some cases, even if she is on HIV therapy).
Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) is caused when a bacterial infection in the vagina passes through the cervix and enables the spread of infection to the uterus and fallopian tubes. While there has been some debate as to the relationship between BV and PID, 2013 evidence suggests that PID is most likely to affect women under 25 who either have severe or recurrent bouts of BV.
PID is characterized pelvic and abdominal pain, often long-term. Severe complications include:
- The development of scar tissue both outside and inside of the fallopian tubes which can lead to tubal blockage
- Ectopic pregnancy (a pregnancy that develops outside of the womb)
Should BV be treated in pregnant women?
According to the Centers for Disease Control and Prevention (CDC), pregnant women with BV should be treated because of the possible risks of BV to the fetus.
Risks of BV during pregnancy include delivering an infant preterm (before 37 weeks of pregnancy) and delivering an infant with a low birth weight (generally, 5.5 pounds or less).
The CDC recommends that pregnant women be tested—and treated if necessary—if they have symptoms of BV.
In addition, the CDC recommends that all pregnant women who have ever had a preterm delivery or delivered an infant with a low birth weight be considered for BV examination regardless of whether they have symptoms.
Some research shows that treating BV in pregnant women does not reduce the risk of preterm birth. Further study is needed to better understand these outcomes.
Can bacterial vaginosis be cured?
BV will sometimes go away without treatment. But if you have symptoms of BV you should be checked and treated. It is important that you take all of the medicine prescribed to you, even if your symptoms go away. A health care provider can treat BV with antibiotics, but BV may return even after treatment. Treatment may also reduce the risk for some STDs.
Male sex partners of women diagnosed with BV generally do not need to be treated. BV may be transferred between female sex partners.
If you don’t have any symptoms and aren’t pregnant, you may not need treatment. Your BV may go away on its own.
When you do have symptoms, your doctor can prescribe antibiotics to get rid of your infection. This could be a tablet you take by mouth or a cream or gel you apply to your vagina.
You’ll need to take most treatments for 5 to 7 days. And you should finish all of your medicine, even if your symptoms go away. If you stop early, your infection could come back.
Since BV could be spread through sex, avoid all sexual contact until you’re better. If your partner is another woman, she may want to see her doctor so she can be treated, too.
If you use an IUD and BV keeps coming back (recurrent BV), you may want to talk to your doctor about a different type of birth control instead.
Even after BV is treated and goes away, it’s common for it to return. If that happens, you’ll probably need to take antibiotics again for a longer time.
To lower your chances of getting BV, use only water – not even soap — when you wash your genital area. Don’t douche. When you go to the bathroom, wipe from front to back, from your vagina toward your anus.
As with all STIs, the most effective protection is to abstain from sexual activity or be monogamous with one long-term partner who has tested negative for BV.
Using latex condoms or dental dams can help reduce the risk of contracting or spreading the infection. Also avoid douching, as this can remove good bacteria and make BV worse.
Limit the number of sex partners you have. Get tested for STIs, and have your partners get tested, too.