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Trichomonas Vaginalis

Trichomonas Vaginalis – Causes, Diagnosis and its Treatment



Trichomonas vaginalis is a protozoan parasite that causes an infection known as trichomoniasis. Trichomoniasis is transmitted through sexual intercourse and is one of the most common sexually transmitted infections (STIs).


The infection is caused by the protozoan parasite trichomonas vaginalis and is easily transmitted through sexual contact. The infection is found in the vagina and the urethra in women, while in men, it is found in the urethra. In a very small number of cases, the infection occurs in women with no history of sexual intercourse.

The disease largely affects women but men may be affected through sexual contact. It is predominantly transmitted through unprotected vaginal sex.

Clinical presentation

Symptoms usually show within a month of infection. However, a majority of infected men and women do not show any symptoms at all.

The symptoms are similar to other sexually transmitted infections. In women, the symptoms include abnormal vaginal discharge, which may be frothy, thick, thin, yellow-green in color, or blood stained. There may be more discharge than normal, with an unpleasant smell. There may also be inflammation or soreness around the vagina and sometimes, itching around the vagina and even around the inner thigh area. Symptoms also include dysuria (pain while passing urine) and dyspareunia (pain during sexual intercourse). There may also be bleeding after intercourse in some cases and lower abdominal pain.

In men, a majority of patients experience no symptoms. In symptomatic patients, it is largely the urethra that is affected. In some cases, the foreskin, prostate gland (which produces semen) and the tip of the penis may also be affected. The symptoms may include irritation inside the penis, mild discharge and a burning sensation after urination or ejaculation. There may be soreness or swelling around the foreskin and the tip of the penis.


The symptoms for this infection are quite similar to those of other STIs which makes it difficult to diagnose it correctly. Diagnosis would usually involve examination of the genital area. In men, the practitioner would examine the penis for any signs of inflammation or discharge. In women, signs of abnormal vaginal discharge are looked out for.

After a physical examination, typically a swab from the vagina or penis is taken and sent for laboratory testing. During the pelvic exam, a sample may be collected by inserting a speculum into the vagina and using an applicator. The sample is observed under a microscope to detect presence of the parasite. A urine sample may also be taken in men. It is possible that medication may be started before confirmation to reduce the chances of the infection spreading.

If trichomoniasis is confirmed, it is important to notify sexual partners of the patient so that they also may be tested and treated, if required.

Treatment for Trichomonas Vaginalis

Trichomoniasis is easily treated with antibiotics. An antibiotic called metrodinazole is usually prescribed for the infection. It is taken orally, generally for a period up to seven days and if taken correctly, is quite effective in treating the infection. Possible side effects include nausea and vomiting. It is possible to take a large single dose instead of the longer treatment but the risk of side effects may be higher in such cases.

Alcohol should be avoided while taking metrodinazole as the combination can lead to uncomfortable side effects including abdominal pain.

Pregnant or breastfeeding women may be prescribed clotrimazole which is used topically. The medicine is inserted inside the vagina for a certain number of days. However, this has a lower cure rate than a dosage of metrodinazole.

Usually no follow-up tests are required but if symptoms persist or recur, further testing may be required to determine if the symptoms are caused by a different STI.

Even if male partners do not show any symptoms, it is important that they get tested and treated so as to avoid reinfection.


If left untreated, trichomoniasis in pregnant women may lead to premature rupture of protective membranes and premature labor. There is evidence to suggest that babies born to infected mothers have relatively lower weights at birth. Also since the infection causes inflammation of genital areas, it makes a woman more susceptible to contracting HIV infection or passing it on.


Having the infection once does not mean that one would be immune from it in the future. In fact, if the patient’s sexual partner is left untreated, the infection may recur.

Safe sex and good hygiene practices may help prevent the infection. Using a condom during vaginal sexual intercourse, and a condom or other barriers during oral sex may help prevent STIs generally, including trichomoniasis. While these may reduce the risk of contracting and spreading the infection, it is not entirely failsafe and a person may contract the infection even after having used barriers.

For sexually active individuals, it may be a good idea to get regular sexual health check-ups so as to ensure early detection and treatment.