Prevention of reactivated herpes simplex infection by human leukocyte interferon after operation on the trigeminal root.

Microneurosurgical procedures on the trigeminal-nerve root are often followed by reactivation of herpes simplex virus infection, manifested by herpes labialis or oropharyngeal herpesvirus shedding or both. In a double-blind study of the ability of human leukocyte interferon to prevent this reactivation, patients with a history of herpes labialis were given 7 x 10(4) U of interferon per kilogram of body weight per day or placebo for five days beginning on the day before operation. In 18 patients treated with placebo, herpes labialis developed in 10, and virus shedding in the oropharynx in 15. In 19 patients treated with interferon, lesions developed in five, and shedding in eight. The frequency of reactivation as measured by lesions or positive throat cultures or both was significantly reduced by interferon (P less than 0.05). Of 127 daily throat-wash cultures in the placebo group, 42 per cent were positive for herpesvirus, but of 134 in the interferon group, only 9 per cent were positive (P less than 0.001). We conclude that interferon at a well-tolerated dosage reduces reactivation of latent herpes simplex virus infection after a potent operative stimulus.