Recurrence in ocular herpes simplex infection.

c.ontinuing recurrence of disease is one of the most troublesome characteristics of herpes simplex keratitis. If ocular herpes were a one-time infection, the likelihood of deep involvement, with its scarring, decreased vision, and even blindness, would be much smaller. With each recurrence, the chance of encountering these complications increases. Recent advances in research have led to a better understanding of the state in which the herpes simplex virus (HSV) exists in carriers between manifestations of recurrent disease. The most tenable theory to date is that the virus enters a stage of "latent" infection, during which time it is present within host cells in subviral form or in amounts too small to be detected by conventional means. Periodically, the latent virus undergoes reactivation. Infectious virus can then be found in the tear film with or without clinically recognizable disease. One explanation for this phenomenon is that neuron cell bodies act as the reservoir for latent herpes. Their axons then function as conduits transporting virus to and from peripheral tissues. The foregoing assumptions have been termed the neuronal hypothesis. A great deal of evidence in support of this hypothesis has been amassed through the years. In 1929, Goodpasture proposed the nervous system, particularly the sensory ganglia, as the site of the latent virus. It was not until 1971, however, that the presence of latent HSV infection was clearly dem-