May 14, 2009
Chicken pox hits adults harder
This is because a key immune response, which involves searching for viruses and destroying them, weakens with age. POON CHIAN HUI reports
Senior Minister Goh Chok Tong was hospitalised in the Singapore General Hospital on May 4 for chicken pox, commonly seen as a childhood disease.
However, when adults get chicken pox, it is usually more severe than in children.
This is because a key immune response, cell-mediated immunity, which involves searching for viruses and destroying them, weakens with age, said Dr Wong Wei Mon, a senior physician at Raffles Medical.
Given a less efficient immune response, the virus may then go on to infect vital organs.
'In adults, the two most common serious complications are pneumonia and encephalitis, which are the inflammation of the lungs and brain respectively,' said Dr Chin Khong Ling, a family physician at Healthway Medical Sengkang Clinic.
When immune systems are weakened, such complications may be potentially fatal. An elderly patient may develop pneumonia, which can cause death, said Dr Leslie Tay, a general practitioner at Karri Family Clinic.
About 10 per cent of adults develop complications from chicken pox, added Dr Chin.
Older teens are as susceptible as adults. The American Academy of Pediatrics estimated that sufferers aged 14 years and above are 10 times more likely to be hospitalised compared to those under that age, but death from chicken pox is very rare.
Caused by the varicella-zoster virus, chicken pox spreads by air or by direct contact. An infected person is contagious one to two days before the skin rash starts.
Symptoms - fever and red spots on the face and body - may not show until 10 to 21 days after exposure to the virus, the Health Promotion Board's website said.
The red spots later become blisters that are usually itchy, and bacterial skin infection is a common complication. The blisters take about a week to dry up.
People who have had the disease will become immune to it. Meanwhile, adults who have yet to get chickenpox may want to get vaccinated, said Dr Chin.
'The vaccine offers up to 90 per cent protection,' she said. It is administered in two doses, six weeks apart, and is expected to give lifelong immunity.
Newborn babies are particularly vulnerable. The virus can be passed to the child during pregnancy or delivery.
Pregnant women cannot receive the vaccine. Women should get vaccinated at least three months before getting pregnant, said Dr Chin.