What Causes a Vaginal Infection?
Bacterial vaginosis (BV) is the most common cause of vaginitis. Bacterial vaginosis is caused by a change or imbalance in the types of the bacteria normally found in the vagina and causes an overgrowth of organisms such as Gardnerella vaginalis.
- Risk factors include pregnancy, intrauterine device (IUD) use, and frequent douching. It is associated with sexual activity, and possibly a new sexual partner or multiple sexual partners. Women who have never had sexual intercourse are rarely affected.
- You do not get bacterial vaginosis from toilet seats, bedding, or swimming pools.
- In the United States, as many as 25% of pregnant women have bacterial vaginosis. This varies by race and ethnicity from 6% in Asians and 9% in whites to 16% in Hispanics and 23% in African Americans.
Vaginal yeast infections are caused by a fungus, mainly by Candida albicans. This is also called candidiasis, genital candidiasis, or vulvovaginal candidiasis (VVC). Yeast infection can spread to other parts of the body including skin, mucous membranes, heart valves, esophagus, and other areas. In rare circumstances, it can cause life-threatening systemic infections mostly in people with weakened immune defenses (such as women who are pregnant and people who are HIV positive, have diabetes, or are taking steroids).
A majority of adult women have had at least one genital yeast infection in their lifetime. Vaginal yeast infection is not considered a sexually transmitted disease, but some men will develop symptoms such as itching and penile rash following sexual contact with an infected partner.
Yeast infections are caused by an overgrowth of normally growing fungi in the vagina that creates unpleasant symptoms. The yeast are normally kept under control by naturally occurring bacteria in the body. If the natural balance of microorganisms is disrupted, the yeast grow out of control. It is not clear how fungal infections originate, but they are not thought to be sexually transmitted. Infections tend to happen when an imbalance occurs, possibly caused by any of these events:
- Use of antibiotics: Antibiotics destroy protective bacteria in the vagina. These bacteria normally stop the candidal organisms from overgrowing. Yeast infection may occur after taking a course of antibiotics for another condition such as strep throat.
- Diabetes or pregnancy: Both diabetes and pregnancy make the vagina better suited for fungal growth. These conditions lower the glycogen store in certain vaginal cells. They may also raise the sugar content (and the pH) of the vagina and increase the risk of yeast infection.
- Birth control pills: Changes in the vaginal environment occur with increased hormonal levels from estrogen-containing birth control pills. This change creates an environment for the fungus to grow and cause symptoms.
- Hormonal changes such as ovulation, menopause, or pregnancy
- Steroid use
- Wearing underwear that is tight or non-cotton: This can increase temperature, moisture, and local irritation.
- Weakened immune system: HIV/AIDS, for example
- Use of douches, perfumed feminine hygiene sprays
- Scratches in the vagina (during insertion of a tampon or other objects)
Trichomoniasis is a sexually transmitted disease (also called trich, pronounced "trick") caused by the parasite Trichomonas vaginalis. Trichomoniasis is primarily an infection of the urinary and genital tract. For women, the vagina is the most common site of infection. For men, the urethra is most commonly affected.
Other causes of vaginal inflammation may be allergies to spermicides, vaginal hygiene products, and detergents and fabric softeners. Another type of sexually transmitted disease may be present. Older women may experience atrophic vaginitis (a thinning of the vaginal walls with menopause). Foreign objects such as a forgotten tampon or another foreign object may cause vaginal irritation.