Better diagnostic, Tx options needed for trich. (Some Metronidazole Resistance).

WASHINGTON -- Diagnosis and treatment of trichomoniasis can be tricky, Dr. Anne Rompalo said at an update on sexually transmitted diseases sponsored by OB.GYN. NEWS and Boston University.

"We think we know a lot about trichomonas, but we really don't," said Dr. Rompalo of Johns Hopkins University, Baltimore. Approximately 170 million new cases of trichomoniasis are believed to occur worldwide each year, with about 8 million in North America. Its incidence is second only to chlamydia among nonviral STDs, with as many as one in four sexually active individuals becoming infected with trichomonas at some point in their lives.

Congenital trichomonas has not been documented, and the parasite is not believed to be transmitted by fomites. However, there has been at least one credible case report of a virgin becoming infected via a hot tub. "I never say never," Dr. Rompalo remarked.

Unlike chlamydia, which tends to infect adolescents and younger women, trichomonas appears to be more evenly distributed among sexually active women of all ages. It is often seen with gonococcal infections and bacterial vaginosis, yet it is not clear whether the presence of trichomonas itself is a marker for high-risk sexual behavior, she said.

Indeed, while Trichomonas vaginalis is the only species that attacks the genitourinary tract, there are two others that can infect humans: T. tenax, found in the mouth, and Pentatrichomonas hominis, found in the intestine. It may be that some positive trichomonas cultures found in urine samples may actually be another non-STD species, something to consider when such a result is found in an unlikely STD candidate, she remarked.

In women, the disease often--although not always--presents with a diffuse, malodorous, yellow-green discharge with vulvar irritation. Symptoms include itching, burning, and a frothy discharge that worsens after menses. But some women are asymptomatic.

Although approximately two-thirds of male sexual partners of infected women will develop urethral colonization, men rapidly clear the organism. However, some men present with nongonococcal urethritis.