An "unknown" sexually transmitted infection that is more common than gonorrhoea has surged among women from ethnically diverse backgrounds.
Trichomonas vaginalis (TV) is disproportionately common among minority and deprived groups and often has no symptoms, research from Preventx has found.
If untreated, TV can increase the likelihood of acquiring HIV and can cause complications in pregnant women.
A new study has found TV is more common among ethnically diverse communities than gonorrhoea is among the UK's heterosexual population.
The research was presented by Preventx at the British Association for Sexual Health and HIV annual conference.
It shows that 5.2% of women from black, black British, Caribbean or African backgrounds who were experiencing vaginal discharge, an established symptom of TV, tested positive for the infection.
This compared to 3.4% in white women and 3.5% across all women.
TV also disproportionately affects asymptomatic women from black, black British, Caribbean or African backgrounds, with a positivity rate more than twice that of asymptomatic white British women (2.0% versus 0.8%).
For the first time, the researchers also looked at the relationship between TV positivity rates and levels of deprivation.
The most-deprived communities had higher levels of positivity than other communities, with 5.9% of symptomatic women in the most deprived quintile testing positive for TV.
This was significantly higher than the 1.4% positivity rate seen in the least deprived areas.
TV causes the condition trichomoniasis and women with trichomoniasis can experience painful urination, vulval itching and discomfort, vaginal discharge and offensive odour.
If left untreated, it can increase the likelihood of acquiring HIV after exposure and can cause complications in pregnant women, including low birth weight and early birth.
Once diagnosed, TV can be easily treated with antibiotics and follow-up testing is recommended to confirm the infection has gone. Testing and treating sexual partners is also vital to prevent reinfection.
"Trichomoniasis is a relatively unknown STI among the general population, but it can cause significant pain and discomfort. I know from the patients in my care that it can also cause a lot of emotional distress for the person infected too," said Dr John White, medical director at Preventx and consultant physician in sexual health.
"Women, in particular, can remain infected for years - and their distressing symptoms are often misdiagnosed or dismissed. If untreated, TV can also increase the chance of acquiring HIV in at-risk communities, as well as cause complications in pregnancy.
"Our new data shows worryingly high positivity rates, with certain communities more affected than others. As TV can easily be diagnosed with remote NAAT tests, it is vital that more high-quality TV testing is carried out across the UK, helping us to understand more about the distribution of this infection.
"This will allow us to address the consequences of undiagnosed TV and reduce transmission."
High-quality testing is not carried out in the UK as standard, but the infection is far more common than gonorrhoea globally, which is routinely tested for.
As part of the study, the team reviewed data from 8,676 women from six English local authority areas who had completed remote STI tests.