A ray of hope for prevention and treatment of chickenpox
Though commonly found all year round in Hong Kong, chickenpox tends to be more active in the winter months, and a recent discovery could explain why.
Dr Phil Rice, a virologist and researcher at St George's, University of London, has found that the acute infectious disease is much less common in places with high ultraviolet ray levels, compared to those with low levels. During winter and spring, UV rays are at their lowest, which could explain the peaks in chickenpox cases.
Rice, whose study has been published in Virology Journal, believes UV rays can inactivate the virus, Varicella zoster, on the skin before it spreads to another person.
Since the Hong Kong Department of Health added chickenpox to its notification system in February 1999, the number of cases annually has fluctuated. The record is 17,940 notifications in 2007; last year saw a four-year high of 12,378 cases. However, the pattern of peaks and troughs within the year has remained largely the same.
Rice believes his discovery could lead to fresh ways of preventing and treating chickenpox and its relative, shingles.
Chickenpox mainly affects children under age 12, and though highly infectious, is generally mild and self-limiting. It spreads through droplets or air, or contact with the discharge from a patient's blisters.
It usually takes one to two days before rashes appear, first on the body, then the face, arms and legs. These itchy spots start out flat and then become fluid-filled blisters which dry up in three to four days to form scabs. Recovery typically takes two to four weeks.
Those with weakened immunity, pregnant women and newborn babies are more likely to suffer from severe complications such as pneumonia and encephalitis. Infection in early pregnancy may lead to abnormalities of the foetus.
There is no cure but symptoms can be eased with medication. Wear clean cotton gloves while sleeping and avoid contact with others.
Most people develop immunity to chickenpox after infection, but the virus may remain silent in the body and appear years later as shingles.
To prevent infection maintain good hygiene. Vaccination is effective - about 90 per cent of people vaccinated gain immunity.
For more information, go to the Centre for Health Protection website at www.chp.gov.hk