by Datuk Dr Zulkifli Ismail
Chicken pox, or Varicella, is a common and contagious disease of childhood, occurring most frequently among children aged 6 to 10. It is caused by the varicella-zoster virus.
Once the virus enters the body, it starts replicating in the respiratory region, which is its route of entry, and the regional lymph nodes within two to three days. The virus then enters the bloodstream and further replicates in the liver, spleen and other organs.
Symptoms start 10 to 21 days after exposure to the virus, beginning with fever, headache, sore throat, loss of appetite and tiredness. Then, multiple pimple-like red bumps pop up all over the body, causing mild to intense itching.
These bumps develop into blisters, which burst and dry after a few days. They then turn into brown scabs.
Children often have milder symptoms and fewer blisters than adults. The most common complications in children are secondary infection of the lesions, scarring and encephalitis (inflammation of the brain).
Most of us develop a lifetime immunity against chicken pox after the first infection. However, the virus stays in our nerve cells near the spinal cord long after the illness, remaining dormant. It may reactivate later in life, and move along the nerves to the surface of the skin, causing shingles/herpes zoster. Shingles is a rash of painful blisters that can last for two to three weeks.
About 10-20% of people who have had chickenpox develop shingles, usually those above the age of 50 years. Shingles is generally not dangerous, but it can be very painful and often cause lingering nerve pain for months after the rash is gone.
Adults and those above the age of 12 years generally suffer a more severe form of chickenpox. Adults are 20 times more likely to die from chickenpox than children, and almost 10 times more likely to be hospitalised for the disease. Adults are at a higher risk of developing bacterial pneumonia or encephalitis. The resultant scarring in adults and teenagers can be more severe too.
The best way to prevent chicken pox in your child is through varicella vaccination. Vaccinating also reduces the costs related to the disease. Parents need not miss work to care for their child who is suffering from chicken pox and the child need not miss school.
In Malaysia, the varicella vaccine has been available since 1997. It contains weakened live varicella-zoster virus. The vaccine is given through injection. For children between 12 months and 12 years of age, one dose of the chicken pox vaccine is required. For those above the age of 12, two doses are required, with an interval of at least 28 days in between the two shots.
The vaccine is reported to be more than 95% effective in preventing moderate to severe forms of the infection. In rare cases, vaccinated people still get chickenpox, but they experience a milder form of the illness, with fewer blisters and symptoms.
Data on the duration of immunity induced by the vaccination is still unavailable. Studies are underway to determine if a booster dose is required in the future. Current evidence shows that a booster dose may be indicated.
Side-effects caused by the chicken pox vaccine are rare and mild. Possible reactions toward the vaccine include redness, soreness, tiredness, fever, nausea and swelling of the area where the shot was given.
In 7-8% of people who have been vaccinated, a rash of several small bumps may develop at the area where the shot was given.
The chicken pox vaccine is not recommended for people with impaired immune systems, those allergic to gelatin or the antibiotic neomycin, and pregnant women. Patients who are taking steroids or aspirin should not be given the vaccine until after stopping the medicines. These will include some asthmatics and children recovering from Kawasaki disease.
In the US, the tetravalent MMR-VZV vaccine is available. It protects against four illnesses – measles, mumps, rubella and chicken pox. This vaccine may be made available in Malaysia in the future.
How It Spreads
The varicella virus is highly contagious and it spreads easily through direct contact with the infected person, through a sneeze or cough, or by touching the fluid from a chicken pox blister. It can also spread indirectly, through contact with contaminated surfaces.
People can also catch chickenpox from someone with shingles. It is contagious two days before the rash appears, up to the time when all the blisters have dried up.
Many children get infected through direct contact with their infected sibling. The US Centers for Disease Control and Prevention (CDC) reports that there is a 90% risk of developing chicken pox among people living within the same household as the infected person.
To prevent chickenpox from spreading, keep your infected child away from his siblings and get him to wash his hands frequently.
Acyclovir, an antiviral agent, is only effective when given during the early stages of the infection.
Home Treatment Tips
* Let your child have cool/lukewarm baths.
* Calamine lotion will help relieve the itchy rash.
* A prescribed antihistamine may relieve severe itching.
* Ensure your child gets adequate fluids and nutrients.
* Give foods that are cold, soft, and bland. Avoid acidic or salty foods.
* Give paracetomol, or acetaminophen, if your child is having fever.
* Trim your child’s fingernails. Let him wear gloves when he sleeps to prevent him from scratching. Scratching predisposes to secondary bacterial infection and causes scarring.
* Never use aspirin to reduce pain or fever in children with chickenpox.
Contracting chicken pox during pregnancy heightens the risk of health complications. Chickenpox infection during early pregnancy leads to birth defects, low birth rate, or limb abnormalities in the foetus.
Chicken pox within one week before and after delivery can lead to severe chicken pox in the newborn baby who is not immunologically protected. If you are pregnant and have never had chicken pox, get your husband and children vaccinated to reduce the risk of them passing it on to you.
If the mother gets infected within 10 days after delivery, her newborn baby may suffer a life-threatening infection. An immune mother can protect her baby from infection within baby’s first few months of life, as her immunity can pass to the baby through the placenta and breast milk. Hence the importance of breastfeeding!
Parents are encouraged to vaccinate their children against chicken pox to spare them the risks of complications and discomforts caused by the disease. Talk to your doctor if you have any questions regarding chickenpox or the varicella vaccine.
More info on CHICKEN POX here.