Trichomoniasis: symptoms, transmission, and treatment

What is trichomoniasis?

Trichomoniasis is a sexually transmitted infection (STI) caused by a parasite, Trichomonas vaginalis.

It is one of the most common STIs worldwide: the WHO estimates that there were 156 million new cases in 2020 among people aged 15–49.

It often goes unnoticed, but when symptoms do occur, they mainly include heavy and foul-smelling discharge, itching, and burning.

It is easily cured with antiparasitic treatment, which must also be taken by your partner.

What are the symptoms of trichomoniasis?

Most infections cause no symptoms (WHO): according to the Federal Office of Public Health, half of infected women have no signs (FOPH).

This is why it is easily transmitted without people realising it.

Trichomoniasis: symptoms in women

When present, the most common symptoms are:

• heavy vaginal discharge, sometimes yellow-green or frothy: this is the main sign, occurring in more than half of women with symptoms;

• an unpleasant odour, often described as strong or sweetish;

• itching and redness of the vulva and vagina;

• stinging or burning when urinating;

• pain during sex.

Trichomoniasis: symptoms in men

In men, the infection is silent even more often.

Some experience discharge from the urethra (around 10%), irritation of the penis, or burning when urinating. A partner without symptoms can therefore easily be a carrier.

How long does it take for symptoms to appear?

Symptoms generally appear within a few days to a few weeks after infection, but they may also never appear at all.

If you have no symptoms, it therefore does not mean that you are not infected.

How do you catch trichomoniasis?

Trichomoniasis is mainly transmitted during sex without a condom with an infected person, even if they have no symptoms.

Vaginal sex is the primary route. A pregnant woman can also pass it to her baby during childbirth, but this is rare.

Can you catch trichomoniasis without having sex?

It is possible, but extremely rare. The FOPH mentions indirect transmission through shared damp fabrics or items, such as a towel or flannel, or via unchlorinated swimming pool water (FOPH).

In the vast majority of cases, infection comes from sexual intercourse. If you are diagnosed with trichomoniasis, it says nothing about anyone's fidelity: the infection can remain silent for a long time.

Do condoms protect against trichomoniasis?

They significantly reduce the risk, without eliminating it completely.

Trichomoniasis, thrush or bacterial vaginosis: how to tell the difference?

All three infections cause unusual discharge and can look similar.

Here are the typical indicators:

These indicators help to provide a clue, but they are not enough: infections can coexist, and trichomoniasis is often symptomless. Only a test can confirm the diagnosis.

How is trichomoniasis tested for?

Diagnosis is based on a vaginal swab (or a urine sample in men), analysed under a microscope or by a molecular test, which is considered the gold standard.

You can request it from your GP, your gynaecologist, or at a sexual health clinic. As with any STI, the WHO recommends also screening for other infections, including HIV and syphilis.

How is trichomoniasis treated?

Trichomoniasis is cured with prescription oral antiparasitic medication, such as metronidazole or tinidazole.

There are no over-the-counter treatments or effective natural remedies.

For women, 2021 US guidelines recommend a 7-day course rather than a single dose, which fails more often. Your doctor will select the appropriate regimen. Finish the full course of treatment, even if symptoms disappear earlier.

Does your partner need to be treated?

Yes, always, even if they have no symptoms. Otherwise, they will reinfect you.

Avoid having sex until both of you have completed the treatment and symptoms have cleared.

In Switzerland, the FOPH website lovelife.ch provides advice on how to inform your partners.

Do you need to be retested after treatment?

Reinfections are common. US guidelines advise women to get retested around 3 months after treatment.

Is trichomoniasis serious?

Trichomoniasis is generally not dangerous and responds well to treatment. However, if left untreated, it can have consequences:

• An increased risk of HIV: the infection increases the risk of acquiring HIV by 1.5 times.

• During pregnancy: it is associated with a risk of preterm delivery, premature rupture of membranes, and low birth weight.

• Persistent symptoms and transmission to your partners.

Trichomoniasis and pregnancy: what should you do?

If you are pregnant and notice unusual discharge, speak to your doctor or midwife promptly. Metronidazole can be prescribed during pregnancy, but only your doctor can decide on the appropriate treatment.

How can you protect yourself against trichomoniasis?

• Use a condom with every new partner.

• Get screened for STIs when you have a new partner or if you develop symptoms.

• Do not share damp towels or flannels.

• If you are receiving treatment, wait until both you and your partner have completed it before having sex again.