Behavior: Battling an Elusive Invader

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On rare occasions, herpes in the trigeminal ganglia will journey to the brain, where it causes a generally fatal form of encephalitis. Or, in about 500,000 cases a year (including recurrences), it may follow the trigeminal nerve to the eye, provoking an infection that can seriously damage vision if left untreated. Similarly, Type 2 located in the sacral ganglia will sometimes travel to the spinal cord, producing a mild form of meningitis.

Genital herpes has also been associated with cancer of the cervix, though the evidence is inconclusive. Obscuring the issue is cervical cancer's linkage with such other factors as an early loss of virginity and a high number of sexual partners. Recently, researchers have found pieces of viral DNA in cervical tumor cells. Says Microbiologist Fred Rapp of Pennsylvania's Hershey Medical Center, "This suggests that the link is more than just statistical."

How the latent virus awakens from its slumber remains the central enigma of herpes. Dr. Abner Notkins and others of the National Institutes of Health (NIH) believe that a chemical change may cause nerve cells where the virus lurks to become "permissive" to viral replication and hence to an attack. Whatever the internal mechanism, recurrences can be triggered by sunlight, sex, menstruation and stress.

When genital herpes recurs in the final weeks of pregnancy, strict medical precautions are necessary. Herpes is lethal to up to 60% of infected newborns. For surviving babies, there is a 50% risk of blindness or brain damage. Because neonatal herpes is generally acquired during passage through an infected birth canal, a caesarean is necessary if the mother has an active infection. Los Angeles Obstetrician Lynn Yonekura, a specialist in high-risk births, recommends biweekly tests for the presence of the virus during the final trimester of pregnancy. If the tests are all negative, Yonekura believes that a vaginal delivery is safe.

The only proven treatment for genital herpes and the only one approved by the FDA is acyclovir, a creamy salve marketed by Burroughs Wellcome Co. under the trade name Zovirax. Acyclovir, which retails for about $20 a tube, works by interfering with viral replication. Applied during the initial episode of herpes, acyclovir will alleviate symptoms and speed up healing. Unfortunately, it is less effective in treating subsequent episodes and will not reduce the frequency of outbreaks. However, according to Virologist Lawrence Corey of the University of Washington, early tests of an oral acyclovir "suggest it is quite a bit more effective" than the cream. An intravenous form appears to be the best solution for acute cases of herpes.

At the University of Michigan, Dr. Charles Shipman is studying a group of compounds imposingly called acetylpyridine thiosemicarbazones, which, he says, "have a potency hundreds of times greater than that of drugs currently used." The drugs, which Shipman hopes to bring to market by 1987, do not prevent recurrences, but, he says, "they stop the lesions in their tracks."