What causes vaginitis?

Vaginitis is the medical term for inflammation or infection of the vagina, or birth canal. It typically occurs when there is an infection or a decrease in the acidity, and therefore an increase in pH level, of the vagina. In premenopausal women, the normal pH level of the vagina is approximately 4.0 on the 0.0 to 14.0 pH scale, which goes from acidic at the low end to alkaline at the high one. The vagina's acidity normally limits the development of infectious bacteria, fungi and parasites.

Vaginitis may also result from reduced levels of estrogen occurring after menopause.

Is there more than one type of vaginitis?

There are several types of vaginitis. The three most common types are bacterial vaginosis, yeast infection and trichomoniasis. Bacterial vaginosis is caused by an overgrowth of one of several bacteria that are usually present in the vagina. Yeast infections are caused by an overabundance of candida, a microscopic fungus that normally inhabits the vagina. Trichomoniasis is caused by a parasite in the vagina, typically Trichomonas vaginalis.

How common is vaginitis?

Almost 75 percent of all adult women will have a yeast infection at some point in their lives, according to the U.S. Centers for Disease Control and Prevention (CDC), and approximately 5 percent of patients will develop a condition called recurrent vulvovaginal candidiasis. Recurrent vulvovaginal candidiasis is classified as more than three symptomatic vaginal yeast infections over the course of one year. Bacterial vaginosis is even more common than yeast infections, although it is not as well understood. Trichomoniasis affects approximately 5 to 10 percent of women in the United States.