Warts Do Not Always Indicate Recent Infection : Only 20% of new human papillomavirus infections actually produce lesions during the first few months.


HOUSTON — Diagnosis of human papillomavirus infection in a genital wart should not trigger a rush to judgment regarding recent sexual transgression or child abuse, Peter J. Lynch, M.D., said at a conference on vulvovaginal diseases.

Only 20% of new human papillomavirus (HPV) infections produce lesions within the first few months. The average incubation period lasts 2 months to 2 years, after which the virus can remain latent for years or even a lifetime in the unsuspecting human host, said Dr. Lynch, a dermatologist in Sacramento.

He attributed 95% of adult infections to sexual transmission but said genital warts in children often result from infections transmitted by parents. Transmission not only can happen during vaginal delivery in a woman who is asymptomatic, but infections can also remain latent for years before a wart is detected, he said at the meeting, sponsored by Baylor College of Medicine.

Theoretically, a parent infected with a finger or hand wart can transmit the virus innocuously when bathing a child. If a genital wart is the only evidence of child abuse, he advised practitioners not to assume the child was assaulted.

“Vertical transmission occurs and, thus, not all childhood genital HPV infections are child abuse,” he said. “Latency occurs, so that the appearance of active disease does not tell you anything about when the original infection was acquired.”

HPV is widespread in the general population, but it is difficult to diagnose, and its prevalence has been hard to establish, according to Dr. Lynch. It grows only in epithelial cells, and researchers have been unable to grow the virus in culture.

Clinicians are unable to diagnose latent virus in the absence of discernable lesions, Dr. Lynch said, warning that acetic acid soaks have turned out to be misleading and should not be used. Conventional biopsy also can be misleading, he said; sometimes pathologists will misidentify clear cells as koilocytes.

The best test for identifying HPV type uses polymerase chain reaction, which is expensive and generally reserved for research, said Dr. Lynch. Though simple inexpensive test kits have become available, he predicted questions about their accuracy would prevent wide use until they are resolved.

Meanwhile, research in women with sexually transmitted diseases has shown 60% to be infected with HPV. In more typical populations of sexually active women, he estimated prevalence at 20%. Because cervical infections are more common than vulvar infections, he reckoned that 5%-10% of women have active or latent HPV infections of the vulva.

Sexual partners do not need to be examined after a woman is diagnosed with HPV. “The acquisition may not have been sexual; it may have occurred years ago and be latent,” he said.

“How would you examine the partner anyway?” he asked, describing one test used in men as “neither accurate nor specific.” Nonetheless, he added, men diagnosed with HPV should notify female sexual partners because of the risk of cervical and vulvar infection.

When anogenital warts are diagnosed in children, they are often best left alone; nearly 100% will resolve spontaneously within 2 years. If such warts are treated, he recommended home care with imiquimod (Aldara) or podofilox (Condylox) to minimize psychological and physical trauma.

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