Although previously considered a mere nuisance infection, untreated bacterial vaginosis may cause complications, such as increased susceptibility to sexually transmitted infections including HIV and pregnancy complications.

It has been shown that HIV-infected women with bacterial vaginosis (BV) are more likely to transmit HIV to their sexual partners than those without BV. Diagnostic criteria for BV have also been associated with a female genital tract factor that induces expression of HIV.

There is evidence of an association between BV and increased rates of sexually transmitted infections such as HIV/AIDS. BV is associated with up to a six-fold increase in HIV shedding. There is also a correlation between the absence of vaginal lactobacilli and infection by Neisseria gonorrhea and Chlamydia trachomatis. BV is a risk factor for viral shedding and herpes simplex virus type 2 infection. BV may increase the risk of infection with or reactivation of human papillomavirus (HPV).

In addition, bacterial vaginosis an intercurrent disease in pregnancy may increase the risk of pregnancy complications, most notably premature birth or miscarriage.

Pregnant women with BV have a higher risk of chorioamnionitis, miscarriage, preterm birth, premature rupture of membranes, and postpartum endometritis. BV is associated with gynecological and obstetric complications. Data suggest an association between BV, tubal factor infertility, and pelvic inflammatory disease. Women with BV who are treated with in vitro fertilization have a lower implantation rate and higher rates of early pregnancy loss.

Healthy vaginal microbiota consists of species which neither cause symptoms or infections, nor negatively affect pregnancy. It is dominated mainly by Lactobacillus species. BV is defined by the disequilibrium in the vaginal microbiota, with decline in the number of lactobacilli. While the infection involves a number of bacteria, it is believed that most infections start with Gardnerella vaginalis creating a biofilm, which allows other opportunistic bacteria to thrive.

One of the main risks for developing BV is douching, which alters the vaginal flora and predisposes women to developing BV. Douching is strongly discouraged by the U.S. Department of Health and Human Services and various medical authorities, for this and other reasons.

BV is a risk factor for pelvic inflammatory disease, HIV, sexually transmitted infections (STIs), and reproductive and obstetric disorders or negative outcomes. It is possible for sexually inactive persons to develop bacterial vaginosis.

Bacterial vaginosis may sometimes affect women after menopause. Also, subclinical iron deficiency may correlate with bacterial vaginosis in early pregnancy. A longitudinal study published in February 2006, in the "American Journal of Obstetrics and Gynecology", showed a link between psychosocial stress and bacterial vaginosis persisted even when other risk factors were taken into account. Exposure to the spermicide nonoxynol-9 does not affect the risk of developing bacterial vaginosis.

Having a female partner increases the risk of BV by 60%. The bacteria associated with BV have been isolated from male genitalia. BV microbiota has been found in the penis, coronal sulcus, and male urethra, in the male partners of infected females. Partners who have not been circumcised may act as a ‘reservoir’ increasing the likelihood of acquiring an infection after sexual intercourse. Another mode of transmission of the BV-associated microbiota is to a female sexual partner via skin-to-skin transfer. BV may be transmitted via the perineal enteric bacteria from the microbiota of the female and male genitalia.

Vaginitis is the disruption of the healthy vaginal microbiota. The vaginal microbiota consists of those organisms which generally do not cause symptoms, infections, and results in good pregnancy outcomes, and is dominated mainly by Lactobacillus species. The disruption of the normal microbiota can cause a vaginal yeast infection. Vaginal yeast infection can affect women of all ages and is very common. The yeast "Candida albicans" is the most common cause of vaginitis. Specific forms of vaginal inflammation include the following types:

Infectious vaginitis accounts for 90% of all cases in reproductive age women:

- Candidiasis: vaginitis caused by proliferation of "Candida albicans", "Candida tropicalis", "Candida krusei"

- Bacterial vaginosis: vaginitis caused by increased growth of "Gardnerella" (a bacterium).

- Aerobic vaginitis

Other less common infections are caused by gonorrhea, chlamydia, "Mycoplasma", herpes, "Campylobacter", improper hygiene, and some parasites, notably "Trichomonas vaginalis". Women who have diabetes develop infectious vaginitis more often than women who do not.

Vaginal infections often have multiple causes (varies between countries between 20 and 40% of vaginal infections), which present challenging cases for treatment. Indeed, when only one cause is treated, the other pathogens can become resistant to treatment and induce relapses and recurrences. Therefore, the key factor is to get a precise diagnosis and treat with broad spectrum anti-infective agents (often also inducing adverse effects).

Further, either a change in pH balance or introduction of foreign bacteria in the vagina can lead to infectious vaginitis. Physical factors that have been claimed to contribute to the development of infections include the following: constantly wet vulva due to tight clothing, chemicals coming in contact with the vagina via scented tampons, antibiotics, birth control pills, or a diet favoring refined sugar and yeast.

Research has shown a link between trichomoniasis and two serious sequelae. Data suggest that:

- Trichomoniasis is associated with increased risk of transmission and infection of HIV.

- Trichomoniasis may cause a woman to deliver a low-birth-weight or premature infant.

- The role of trichomonas infection in causing cervical cancer is unclear, although trichomonas infection may be associated with co-infection with high-risk strains of HPV.

- "T. vaginalis" infection in males has been found to cause asymptomatic urethritis and prostatitis. In the prostate, it may create chronic inflammation that may eventually lead to prostate cancer.

Hormonal vaginitis includes atrophic vaginitis usually found in postmenopausal or postpartum women. Sometimes it can occur in young girls before puberty. In these situations the estrogen support of the vagina is poor.

There were about 58 million cases of trichomoniasis in 2013. It is more common in women (2.7%) than males (1.4%). It is the most common non-viral STI in the U.S., with an estimated 3.7 million prevalent cases and 1.1 million new cases per year. It is estimated that 3% of the general U.S. population is infected, and 7.5-32% of moderate-to-high risk (including incarcerated) populations.

A vaginal yeast infection results from overgrowth of candida albicans, or yeast, in the vagina. This is a relatively common infection, with over 75% of women having experienced at least one yeast infection at some point in their life. Risk factors for yeast infections include recent antibiotic use, diabetes, immunosuppression, increased estrogen levels, and use of certain contraceptive devices including intrauterine devices, diaphragms, or sponges. It is not a sexually transmitted infection. Candida vaginal infections are common; an estimated 75% of women will have at least one yeast infection in their lifetime. Vaginal discharge is not always present in yeast infections, but when occurring it is typically odorless, thick, white, and clumpy. Vaginal itching is the most common symptom of candida vulvovaginitis. Women may also experience burning, soreness, irritation, pain during urination, or pain during sex. The diagnosis of Candida vulvovaginitis is made by looking at a sample taken from the vagina under the microscope that shows hyphae (yeast), or from a culture. It is important to note that the symptoms described above may be present in other vaginal infections, so microscopic diagnosis or culture is needed to confirm the diagnosis. Treatment is with intra-vaginal or oral anti-fungal medications.

About 5 to 10% of women are affected by aerobic vaginitis. Reports in pregnant women point to a prevalence of 8.3–10.8%.

When considering symptomatic women, the prevalence of AV can be as high as 23%.

Bacterial vaginosis (BV) is an infection caused by a change in the vaginal flora, which refers to the community of organisms that live in the vagina. It is the most common cause of pathological vaginal discharge in women of childbearing age and accounts for 40–50% of cases. In BV, the vagina experiences a decrease in a bacterium called lactobacilli, and a relative increase in a multitude of anaerobic bacteria with the most predominant being "Gardnerella vaginalis". This imbalance results in the characteristic vaginal discharge experienced by patients with BV. The discharge in BV has a characteristic strong fishy odor, which is caused by the relative increase in anaerobic bacteria.[1] The discharge is typically thin and grey, or occasionally green. It sometimes is accompanied by burning with urination. Itching is rare. The exact reasons for the disruption of vaginal flora leading to BV are not fully known. However, factors associated with BV include antibiotic use, unprotected sex, douching, and using an intrauterine device (IUD). The role of sex in BV is unknown, and BV is not considered an STI. The diagnosis of BV is made by a health care provider based on the appearance of the discharge, discharge pH > 4.5, presence of clue cells under the microscope, and a characteristic fishy odor when the discharge is placed on a slide and combined with potassium hydroxide ("whiff test"). The gold standard for diagnosis is a gram stain showing a relative lack of lactobacilli and a polymicrobial array of gram negative rods, gram variable rods, and cocci. BV may be treated with oral or intravaginal antibiotics, or oral or intravaginal lactobacillus.

Sexually transmitted disease that affect the vagina include:

- Herpes genitalis. The herpes simplex virus (HSV) can infect the vulva, vagina, and cervix, and this may result in small, painful, recurring blisters and ulcers. It is also common for there to be an absence of any noticeable symptoms.

- Gonorrhea

- Chlamydia

- Trichomoniasis

- Human papillomavirus (HPV), which may cause genital warts.

HIV/AIDS can be contracted through the vagina during vaginal intercourse, but it is not associated with any local vaginal or vulval disease.

Because of STIs, health authorities and other health outlets recommend safe sex practices when engaging in sexual activity.

"Candida" yeasts are generally present in healthy humans, frequently part of the human body's normal oral and intestinal flora, and particularly on the skin; however, their growth is normally limited by the human immune system and by competition of other microorganisms, such as bacteria occupying the same locations in the human body.

"Candida" requires moisture for growth, notably on the skin. For example, wearing wet swimwear for long periods of time is believed to be a risk factor. In extreme cases, superficial infections of the skin or mucous membranes may enter into the bloodstream and cause systemic "Candida" infections.

Factors that increase the risk of candidiasis include HIV/AIDS, mononucleosis, cancer treatments, steroids, stress, antibiotic usage, diabetes, and nutrient deficiency. Hormone replacement therapy and infertility treatments may also be predisposing factors. Treatment with antibiotics can lead to eliminating the yeast's natural competitors for resources in the oral and intestinal flora; thereby increasing the severity of the condition. A weakened or undeveloped immune system or metabolic illnesses are significant predisposing factors of candidiasis. Almost 15% of people with weakened immune systems develop a systemic illness caused by "Candida" species. Diets high in simple carbohydrates have been found to affect rates of oral candidiases.

"C. albicans" was isolated from the vaginas of 19% of apparently healthy women, i.e., those who experienced few or no symptoms of infection. External use of detergents or douches or internal disturbances (hormonal or physiological) can perturb the normal vaginal flora, consisting of lactic acid bacteria, such as lactobacilli, and result in an overgrowth of "Candida" cells, causing symptoms of infection, such as local inflammation. Pregnancy and the use of oral contraceptives have been reported as risk factors. Diabetes mellitus and the use of antibiotics are also linked to increased rates of yeast infections.

In penile candidiasis, the causes include sexual intercourse with an infected individual, low immunity, antibiotics, and diabetes. Male genital yeast infections are less common, but a yeast infection on the penis caused from direct contact via sexual intercourse with an infected partner is not uncommon.

Most vaginal discharges occur due to normal bodily functions, such as menstruation or sexual arousal (vaginal lubrication). Abnormal discharges, however, can indicate disease. Normal vaginal discharges include blood or menses (from the uterus), the most common, and clear fluid either as a result of sexual arousal or secretions from the cervix. Other non-infective causes include dermatitis. Non-sexually transmitted discharges occur from bacterial vaginosis, aerobic vaginitis and thrush or candidiasis. The final group of discharges include the sexually transmitted diseases gonorrhea, chlamydia, and trichomoniasis. The discharge from thrush is slightly pungent and white, that from trichomoniasis more foul and greenish, and that from foreign bodies resembling the discharge of gonorrhea, greyish or yellow and purulent (pus-like).

Aerobic vaginitis has been associated with several gynecological and obstetrical complications, including:

- Premature rupture of membranes

- Preterm labour

- Ascending chorioamnionitis.

- Increased risk to acquire sexually transmitted infections (including HIV)

- Abnormal Pap test results

Among individuals being treated in intensive care units, the mortality rate is about 30-50% when systemic candidiasis develops.

Vulvitis, inflammation of the vulva, can have a variety of etiologies in children and adolescents, including allergic dermatitis, contact dermatitis, lichen sclerosus, and infections with bacteria, fungi, and parasites. Dermatitis in infants is commonly caused by a soiled diaper being left on for an extended period of time. Increasing the frequency of diaper changes and topical application of emollients are sufficient to resolve most cases. Dermatitis of the vulva in older children is usually caused by exposure to an irritant (e.g. scented products that come into contact with the vulva, laundry detergent, soaps, etc.) and is treated with preventing exposure and encouraging sitz baths with baking soda as the vulvar skin heals. Other treatment options for vulvar dermatitis include oral hydroxyzine hydrochloride or topical hydrocortisone.

Lichen sclerosus is another common cause of vulvitis in children, and it often affects an hourglass or figure eight-shaped area of skin around the anus and vulva. Symptoms of a mild case include skin fissures, loss of skin pigment (hypopigmentation), skin atrophy, a parchment-like texture to the skin, dysuria, itching, discomfort, and excoriation. In more severe cases, the vulva may become discolored, developing dark purple bruising (ecchymosis), bleeding, scarring, attenuation of the labia minora, and fissures and bleeding affecting the posterior fourchette. Its cause is unknown, but likely genetic or autoimmune, and it is unconnected to malignancy in children. If the skin changes are not obvious on visual inspection, a biopsy of the skin may be performed to acquire an exact diagnosis. Treatment for vulvar lichen sclerosus may consist of topical hydrocortisone in mild cases, or stronger topical steroids (e.g. clobetasol propionate). Preliminary studies show that 75% of cases do not resolve with puberty.

Organisms responsible for vulvitis in children include pinworms ("Enterobius vermicularis"), "Candida" yeast, and group A hemolytic "Streptococcus". Though pinworms mainly affect the perianal area, they can cause itching and irritation to the vulva as well. Pinworms are treated with albendazole. Vulvar "Candida" infections are uncommon in children, and generally occur in infants after antibiotic therapy, and in children with diabetes or immunodeficiency. "Candida" infections cause a red raised vulvar rash with satellite lesions and clear borders, and are diagnosed by microscopically examining a sample treated with potassium hydroxide for hyphae. They are treated with topical butoconazole, clotrimazole, or miconazole. "Streptococcus" infections are characterized by a dark red discoloration of the vulva and introitus, and cause pain, itching, bleeding, and dysuria. They are treated with antibiotics.

In young sexually active women, sexual activity is the cause of 75–90% of bladder infections, with the risk of infection related to the frequency of sex. The term "honeymoon cystitis" has been applied to this phenomenon of frequent UTIs during early marriage. In post-menopausal women, sexual activity does not affect the risk of developing a UTI. Spermicide use, independent of sexual frequency, increases the risk of UTIs. Diaphragm use is also associated. Condom use without spermicide or use of birth control pills does not increase the risk of uncomplicated urinary tract infection.

Women are more prone to UTIs than men because, in females, the urethra is much shorter and closer to the anus. As a woman's estrogen levels decrease with menopause, her risk of urinary tract infections increases due to the loss of protective vaginal flora. Additionally, vaginal atrophy that can sometimes occur after menopause is associated with recurrent urinary tract infections.

Chronic prostatitis in the forms of chronic prostatitis/chronic pelvic pain syndrome and chronic bacterial prostatitis (not acute bacterial prostatitis or asymptomatic inflammatory prostatitis) may cause recurrent urinary tract infections in males. Risk of infections increases as males age. While bacteria is commonly present in the urine of older males this does not appear to affect the risk of urinary tract infections.

Leukorrhea is also caused by trichomonads, a group of parasitic protozoan, specifically "Trichomonas vaginalis". Common symptoms of this disease are burning sensation, itching and discharge of frothy substance, thick, white or yellow mucous.

Urinary catheterization increases the risk for urinary tract infections. The risk of bacteriuria (bacteria in the urine) is between three and six percent per day and prophylactic antibiotics are not effective in decreasing symptomatic infections. The risk of an associated infection can be decreased by catheterizing only when necessary, using aseptic technique for insertion, and maintaining unobstructed closed drainage of the catheter.

Male scuba divers utilizing condom catheters and female divers utilizing external catching devices for their dry suits are also susceptible to urinary tract infections.

Vulvitis is inflammation of the vulva, the external female mammalian genitalia that include the labia majora, labia minora, clitoris, and introitus (the entrance to the vagina). It may co-occur with vaginitis, inflammation of the vagina, and may have infectious or non-infectious causes.

It is not a major issue but is to be resolved as soon as possible. It can be a natural defense mechanism that the vagina uses to maintain its chemical balance, as well as to preserve the flexibility of the vaginal tissue. The term "physiologic leukorrhea" is used to refer to leukorrhea due to estrogen stimulation.

Leukorrhea may occur normally during pregnancy. This is caused by increased bloodflow to the vagina due to increased estrogen. Female infants may have leukorrhea for a short time after birth due to their in-uterine exposure to estrogen.

An ameboma, also known as an amebic granuloma, is a rare complication of "Entamoeba histolytica" infection, where in response to the infecting amoeba there is formation of annular colonic granulation, which results in a large local lesion of the bowel.

Many postmenopausal women (who are not using topical estrogen) have at least some degree of vaginal atrophy; however, many women do not actively ask that medical attention be paid to this, possibly because it is naturally caused, or because of the taboo that still exists surrounding aging and sexuality.

The cause of vaginal atrophy is usually the normal decrease in estrogen as a result of menopause. Other causes of decreased estrogen levels are decreased ovarian functioning due to radiation therapy or chemotherapy, immune disorder, removal of the ovaries, entering the post-partum period, and lactation. Various medications can also cause or contribute to vaginal atrophy, including tamoxifen (Nolvadex), danazol (Danocrine), medroxyprogesterone acetate (Depo-Provera), leuprolide (Lupron), and nafarelin acetate (Synarel). Vaginal atrophy can also be idiopathic.

The ameboma may manifest as a right lower quadrant abdominal mass, which may be mistaken for carcinoma, tuberculosis, Crohn's disease, actinomycosis, or lymphoma.

Due to the difficulty of exploring host and amebic factors involved in the pathogenesis of amebic liver abscess in humans, most studies have been conducted with animal models (e.g., mice, gerbils, and hamsters). Histopathological findings revealed that the chronic phase of amebic liver abscess in humans corresponds to lytic or liquefactive necrosis, whereas in rodent models there is granulomatous inflammation. However, the use of animal models has provided important information on molecules and mechanisms of the host/parasite interaction in amebic liver abscess.

Genital symptoms include dryness, itching, burning, soreness, pressure, white discharge, malodorous discharge due to infection, painful sexual intercourse, bleeding after intercourse. In addition, sores and cracks may occur spontaneously. Atrophic vaginitis is one possible cause of postmenopausal bleeding (PMB).

Urinary symptoms include painful urination, blood in the urine, increased frequency of urination, incontinence, and increased likelihood and occurrence of infections.