According to a study published this week by scientists at the University of London, children who soak up more rays from the sun may actually be less likely to spread the virus associated with chickenpox.
The results of the study were published in the scientific journal Virology and indicated that the UV rays in sunlight may serve to ℠deactivate´ the viruses on the surface of the skin, thus making it more difficult for the virus to spread to new hosts.
Researchers compared various geographic regions and found that those with higher levels of sunlight also had a lower incidence of the virus, which predominantly affects children between the ages of 4 and 10.
Scientists have insisted, however, that the role of sunlight in curbing the spread of the virus is still largely speculative, as other factors such as relative temperature and humidity could also play a currently unknown role in the virus´ epidemiology.
The varicelli-zoster virus which causes chickenpox is an airborne disease which can easily spread through coughing or sneezing, particularly during the first 2-3 days of infection. The most common source of infection, however, is from contact with the red blisters and spots that are most commonly associated with the illness. An infected individual is already contagious one to two days before the rash appears and will typically remain infectious until all of the red blisters have formed a crust.
Researchers have long been aware that UV light has a repressive effect on a variety of different viruses types, and the University of London´s Dr. Phil Rice suspects that this is the key to understanding the lower rate of chickenpox infections in tropical countries. Dr. Rice also points out that his theory is further corroborated by the increased incidence of the virus during summer months when people spend less time outside and tend to wear more clothing.
Rice´s research team collected and examined data from some 25-years worth of chicken pox studies conducted all around the world. After plotting the data in various graphs and looking for patterns, the scientists say that their attention was drawn a very obvious correlation between the prevalence of the varicelli-zoster virus and levels of UV exposure.
The connection between sunlight and infection levels had been essentially sitting right under researchers noses for years, said Rice.
“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.”
Still, Professor Judy Breuer of nearby University College London remains cautious, noting that while UV may indeed play a significant role, it is likely that there are a number of other factors which figure into the disparate infection rates seen in tropical regions compared to their northern neighbors.
“Lots of things aside from UV could affect it ,” Breuer told BBC News, such as “heat, humidity and social factors such as overcrowding. It´s quite possible that UV is having an effect, but we don´t have any firm evidence showing the extent this is happening.”
Regardless of the extent of the role played by sunlight in the virus´ epidemiology, Rice´s team has provided researchers in the field with a focal point for years to come.
On the Net: