Seminal studies by Spruance and colleagues in the 1970s demonstrated that peak replication of HSV occurs rapidly after reactivation of the latent molecule. The opportunity to prevent viral replication and the subsequent clinical recurrence using an antiviral agent is therefore limited to a narrow window. Lesion development occurs early and evolves rapidly in the course of the recurrence and the natural healing process starts within the first 24 hours after onset of the episode. It is logical to see that antiviral therapy should be initiated as soon as possible in order to have the maximal opportunity to impact on viral replication and exert a beneficial effect.

Many patients with HSV infection experience a prodrome and are alerted to the onset of a recurrence by symptoms such as tingling, itching or burning. Patient initiation of treatment with oral antiviral agents ensures that the drug is administered at the earliest opportunity, when it is likely to be most effective in managing the recurrence. Greater exposure to the drug in this short window of opportunity is likely to be the most efficient way to treat the impending recurrence. Data also show that antivirals have no effect on the course of the outbreak if they are given later than 12 hours after the start of the episode, and this has led to a change in the way that antivirals are used in recent years, with therapy tending towards shorter courses and even single doses. In the 1980s, aciclovir was given for 7 days; since then, and with the improvements in our understanding of the natural history of these infections, the length of treatment has steadily declined until it has reached only a single day with famciclovir for genital herpes recurrences, and indeed a single dose of famciclovir is effective for treating herpes labialis. We have now reached the point where as physicians we are seriously contemplating a future where patients may be able to take a single tablet to manage their genital herpes recurrences

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