HERPES ZOSTER

The possibility that the incidence of herpes zoster-related disease may be increasing is focusing attention on the value of prevention using the herpes zoster vaccine (Zostavax), according to Marc Labetoulle MD.
Dr Labetoulle, professor of ophthalmology, Hôpital Bicêtre, University of Paris-Sud, Paris, France, provided an update on the epidemiology, prevention and treatment of herpes zoster ophthalmicus (HZO) at the 5th EuCornea Congress in London.
HZO accounts for 10 to 20 per cent of all herpes zoster infections. However, studies of various adult populations investigating the prevalence of circulating antibodies against the varicella zoster virus (VZV), and of DNA evidence of VZV in neurological tissue, indicate that almost all adults over the age of 50 are at risk for virus reactivation and of developing zoster, said Dr Labetoulle. 
He explained that varicella-specific cell-mediated immunity is an important mechanism in preventing reactivation of latent virus. Contact with a person having active varicella zoster disease (chickenpox) will boost the immune system in a person with latent virus. 
However, as a result of widespread use of the chickenpox vaccine, opportunities for such restimulation are now decreased. Consequently, experts are expecting that the classical epidemiology of herpes zoster may change, forecasting that the incidence of zoster will begin to rise about 15 years after the beginning of systematic use of the chickenpox vaccine.
“We should soon see this in the United States if this prediction comes true. However, we need to consider that herpes zoster is a debilitating disease with a huge negative effect on quality of life. 
"Therefore, it seems that the more efficient is vaccination against chickenpox, the more we will need the herpes zoster vaccine,” said Dr Labetoulle, adding that results from the Shingles Prevention study showed the vaccine reduced both the incidence of zoster and of post-herpetic neuralgia. 
In Europe and the US, the herpes zoster vaccine is licensed for use in adults aged 50 years and older. However, recommendations about who should receive the vaccine vary. 
The US Centers for Disease Control recommends vaccination in people 60 years and older, based on the Shingles Prevention study. In France, the recommendation is for persons 65-74 years old. During the first year following its inclusion in the vaccination calendar, people from 75-79 years of age may be vaccinated in the context of a catch-up. In the UK, the vaccine is recommended for persons of 70-79 years old. 
Although the vaccine is contraindicated in persons who are immunocompromised, Dr Labetoulle noted some new information indicates that exclusion should be reconsidered.
Recommended antiviral regimens for treatment of zoster ophthalmicus (with or without keratitis) vary depending on the patient’s immune status and age, according to Dr Labetoulle. 
Immune competent patients may be treated with oral acyclovir 800mg five times daily, valacyclovir 1.0g three times daily, famciclovir 750mg once daily, 500mg twice daily, or 250mg three times daily. 
“Valacyclovir and famciclovir offer the convenience of less frequent dosing compared to acyclovir, and there is also some evidence that they are more effective for relieving pain and inflammatory complications of HZO,” Dr Labetoulle said.
Treatment should be started within three days of disease onset. The available evidence suggests that for immune competent adults, there is no benefit for treating longer than seven days.
“However, there is evidence that VZV DNA persists for up to 24 days after development of the rash. Therefore, longer treatment might be considered in certain fragile populations, including the very old, patients who are immunosuppressed, and in children who tend to have more severe complications from HZO and inflammatory recurrence once antiviral treatment is tapered,” Dr Labetoulle said.
Intravenous acyclovir is recommended for treatment of HZ/HZO in patients who are immunocompromised. Oral brivudin (bromovinyl-deoxyuridine) is approved for the treatment of herpes zoster in Italy and Germany, and there is some evidence that it is effective in immunocompromised patients, he added.

Marc Labetoulle: marc.labetoulle@bct.ap-hop-paris.fr