UV rays may prevent spread of chickenpox

Ultraviolet rays may help prevent the spread of chickenpox, new research has found.

The research, conducted at St George’s, University of London, found that chickenpox is much less common in places with high UV light levels, as compared to those with low levels.

Although the findings suggest that people in milder climates are at higher risk of catching the disease, the discovery could also lead to new ways of preventing chickenpox and its more severe relative, shingles.

The highly infectious varicella zoster virus responsible for chickenpox and shingles is usually transmitted when people come into direct contact with the virus, present in the fluid-filled blisters and spots of the typical chickenpox rash.

It has long been known that UV light can inactivate viruses. However, virologist Dr Phil Rice thinks that UV rays could inactivate the varicella-zoster virus on the skin before it transmits to another person.

This would explain why there is less transmission of the virus in the tropics, where chickenpox is much less frequent than in temperate countries.

It also explains why chickenpox peaks in temperate zones – where it is seasonal – in winter and spring, when UV rays are lowest.

Previously, it was thought that geographical differences in the incidence of chickenpox were related to heat, humidity, population density, or infection with other viruses that protect against it.

Dr Rice analysed data from 25 studies on varicella-zoster virus prevalence patterns in temperate and tropical areas across the world, and plotted the data against a range of climatic factors.

The study, published in Virology Journal, found that UV rays were the only factor to match the patterns of infection in each country studied.

Dr Rice said: "No one had considered UV as a factor before, but when I looked at the epidemiological studies they showed a good correlation between global latitude and the presence of the virus."

This article was published on Mon 19 December 2011