Can trichomonas be caught non-sexually?
Q One of my patients, who has been married for 20 years, had Trichomonas vaginalis on a cervical smear. She and her husband both deny extramarital relationships. Could she have acquired it in any other way?
A A cervical smear does not have high specificity for
T. vaginalis. The result should be confirmed using a specific test.
If this confirms the diagnosis she should be treated. However, if microscopy is negative it could be a false negative since the test is only about 65 per cent sensitive. The GUM doctor will discuss with the woman whether to treat her.
If wet mount microscopy confirms the infection, how did she get it? T. vaginalis is almost exclusively sexually transmitted. The organism has been shown to survive on toilet seats for an hour and on bath towels for up to 24 hours. But this does not demonstrate transmission from these surfaces; it would be most unlikely.
She probably hasn't got trichomoniasis but if she does, she almost certainly acquired it sexually.
If trichomonas has been asymptomatic for 20 years, could it have been missed on previous smears? Yes, easily. Exactly how long it could persist is unclear – it's hard to do a natural history study ethically. In Australia
T. vaginalis is relatively common in women in their 30s and 40s, compared with chlamydia. The assumption is that this represents infection persisting for years.
So the infection could have been acquired years before. I think it's important to give people a way out – that there is an alternative to their partner having been unfaithful.
Stephen Baguley is consultant in genito-urinary medicine at Woolmanhill Hospital, Aberdeen