Trichomonas Infection

What is trichomonas?

Trichomonas is a protozoan, which is a tiny germ, similar to bacteria. It can infect the genital area. That is, the vagina and urethra in women, and the urethra and sometimes the prostate gland in men. The infection does not usually go further into the body and so does not tend to be as serious as other sexually transmitted infections. The exact number of cases in the UK is not known, but it is uncommon.

What are the symptoms of a trichomonas infection?

Women

• A vaginal discharge is common. This is usually greeny-yellow, and may be 'frothy'. The discharge usually has an unpleasant or fishy smell.
• Your vagina and vulva may be itchy and uncomfortable. The irritation may extend into the groin. Sex may be painful.
• It may be sore when you pass urine.
• No symptoms occur in up to half of infected women.

• Discharge from the penis is common.
• It may be sore when you pass urine.
• You may pass urine frequently (due to irritation inside the penis).
• No symptoms occur in up to half of infected men.

Trichomonas infection is usually passed on by having sex. As no symptoms may occur in both men and women who are infected, you can pass on the infection without realising it.

What are the possible complications with trichomonas infection?

• Pregnancy. If you have untreated trichomonas infection during pregnancy, you have an increased risk of having an early labour and a baby with a low birth weight.
• In men, trichomonas infection can rarely cause prostatitis (an unpleasant infection of the prostate).
• HIV. If you have untreated trichomonas infection, you have an increased risk of developing HIV infection if you have sex with someone who is infected with HIV.

It is important to get the correct diagnosis as the same symptoms can be caused by a number of different infections.

• A doctor or nurse may take a swab (sample of the discharge) from the vagina or penis. This is sent to the laboratory to be tested.
• Trichomonas is sometimes seen by chance when a smear test is done in women.
• A sample of urine from men may also show the infection.

An antibiotic called metronidazole is the common treatment. More than 9 in 10 infections clear with a short course of metronidazole tablets. Treatment is usually straightforward. Read the leaflet that comes with the tablets for a full list of possible side-effects and cautions. However, main points to note about metronidazole include:

• The usual dose is 400 mg twice a day for 5-7 days. A single dose of 2 grams is an alternative, although this may be less effective and may cause more side-effects.
• Some people feel sick, and may vomit when they take metronidazole. This is less likely to occur if you take the tablets straight after food.
• A metallic taste is also a common side-effect.
• Do not drink any alcohol while taking metronidazole, and for at least 48 hours after stopping treatment. The interaction with alcohol can cause vomiting and other problems.
• Breastfeeding: metronidazole can get into breast milk, but is not thought to affect breastfed babies. However, to play safe, the standard 7-day course with the lower dose is preferred so as a baby does not get a large dose. If it is essential to use the large 2-gram single dose then it should be taken after the last breastfeed of the evening, at the start of the overnight breastfeeding break, to limit exposure to the baby.

Tinidazole is an alternative antibiotic that is sometimes used.

If you do not take treatment, in some cases the infection clears away by itself. However, this may take several weeks, and there is no way of predicting if it will clear or not. Therefore, treatment is usually advised in all cases.

Yes. Even if they do not have symptoms. You and your partner should be treated at the same time. You should not have sex until you have finished treatment, and symptoms have gone.

Some other points about trichomonas infection

• After you are treated, you may get the infection back if your sexual partner was not treated, or if you have sex with a new partner who has the infection.
• Other sexually transmitted infections are more common in people with trichomonas infection. You (and your partner) may be advised to be tested for other infections.

Further help and information

If you suspect that you have trichomonas, or any other a sexually transmitted disease, then see you GP or contact your local Genitourinary Medicine (GUM) clinic. You can go to the local GUM clinic without a referral from your GP. You can ring the local hospital or health authority and ask where the nearest clinic is. It may also be listed in the phone book under 'Genitourinary Medicine'.

Web resources
www.ssha.info - Society of Sexual Health Advisers. Information on sexually transmitted infections and related issues. Includes contact details of all the GUM clinics in the UK and Ireland.

© EMIS and PIP 2005   Updated: January 2006   PRODIGY Validated

The authors and editors of this article are employed to create accurate and up to date content reflecting reliable research evidence, guidance and best clinical practice. They are free from any commercial conflicts of interest.

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