When talking about chickenpox, the image that immediately comes into mind are multiple red spots all over the body, and itchy blisters that eventually break, form crusts, and turn into dry brown scabs.
This is the typical course of the disease.
A person with chickenpox will also experience flu-like symptoms, such as fever, headache and tiredness.
The symptoms are usually mild and self-limiting, but can be more serious in adults and infants.
Most of us regard chickenpox, which is caused by the varicella-zoster virus (VZV), as a harmless childhood infection which only occurs once in a lifetime. This is not entirely true.
Chickenpox can sometimes cause serious complications, such as secondary infection of the lesions (due to excessive scratching), scarring, pneumonia, and exacerbation of asthma. It can also cause partial or complete blindness.
While this viral disease affects children ages six to 10 most frequently, it is not limited only to children.
As an adult, you can contract chickenpox if you have not had it in the past, or, in rare cases, you may get it for a second time, albeit in a slightly different form.
Getting chickenpox in adulthood
The majority of us get chickenpox when we were children. The infection usually doesn't strike twice, as our body builds a life-long immunity against the virus after we had it the first time.
Chickenpox tends to be more serious when it occurs in adulthood.
There are more blisters, and the resulting scars can be more severe.
Though rare, adult chickenpox can be complicated by serious conditions, such as pneumonia, or can even be fatal.
In fact, compared to children aged one to four years, adults have a 25 times greater risk of dying from chickenpox.
On the other hand, adults are more mentally prepared and can cope better with the itchiness compared with children.
The virus strikes back
Although the body builds immunity towards VZV after the first encounter, it doesn't mean that the virus is eliminated from your body.
The virus stays in your body long after you recovered from the disease during your childhood.
It remains dormant (inactive) in the nerve cells near the spinal cord.
VZV can become active again many years later in adulthood. When the virus re-emerges, usually triggered by stress or a weakened immune system, it travels along the nerves to the surface of the skin.
This time, it causes the development of a painful skin rash, known as shingles (also known as herpes zoster).
As many as 20% of adults who have had chickenpox will develop shingles at a later point in their lives. Those who are more likely to get shingles are usually above 50 years old, as the risk of getting shingles increases as one gets older.
People with certain medical conditions that keep the immune system from functioning properly (eg cancer, HIV) or receiving medications that suppress the immune system are also at greater risk for a second eruption of the chickenpox virus.
VZV infections can still be transmitted to vulnerable individuals (ie not exposed to chickenpox, not been vaccinated) through contact with the blisters of an infected person.
On the other hand, you won't get shingles from someone with chickenpox.
Chickenpox during pregnancy
For women who have not had chickenpox in the past, contracting chickenpox during pregnancy amplifies the risk for health complications.
If pregnant women acquire chickenpox in the third trimester, they are at a greater risk of developing varicella pneumonia, a potentially life-threatening infection of the lungs by VZV.
Chickenpox during early pregnancy can also be transmitted from mother to infant, increasing the risk of birth defects in the child.
When a pregnant woman is infected with chickenpox during her early pregnancy (the first two trimesters), her baby may be born with birth defects known as "congenital varicella syndrome", in which multiple distinctive anomalies are present, eg low birth weight, abnormalities of the limbs, skin (eg thickened and overgrown scar tissue), and the nervous system (eg eye and brain abnormalities).
Severe maternal chickenpox may also confer a risk of miscarriage.
If maternal chickenpox is acquired during the last three weeks of pregnancy (at least five days before delivery), the infant is likely to develop neonatal chickenpox.
Neonatal chickenpox acquired during this period is usually mild and runs an uncomplicated course, as adequate antibodies from the mother's body are transferred to the foetus, and therefore the risk for complications in the foetus is lower.
If maternal chickenpox happens five days before to two days after delivery, it can lead to severe chickenpox in the newborn, as the baby is not immunologically protected, ie no time for transfers of varicella-associated antibody from mother to baby.
This type of neonatal chickenpox is fatal in one out of five newborns.
Preventing the spread
Regardless of the form of the disease, chickenpox or shingles, the disease-causing virus is infectious, and can be passed on from adults to children, or vice versa.
As long as your body doesn't have the defence built against the virus, you are at risk.
The best way to prevent chickenpox is through vaccination. A vaccinated child will be protected from catching the disease from the people around him, sparing him the unnecessary discomfort and suffering.
Chickenpox vaccination also helps to reduce the complications in adult chickenpox.
Although it does not necessarily prevent the infection, it lessens the severity of the symptoms and risks of complications.
Furthermore, when adults are protected against VZV infection, they significantly reduce, if not totally eliminate, the risk of passing the disease to unprotected children and adults.
In Malaysia, a combination vaccine containing varicella vaccine together with the mandatory measles-mumps-rubella (MMR) vaccines for childhood immunisation is currently available.
While chickenpox vaccination is optional (not mandatory), the four-component combination vaccine is able to provide children protection against four illnesses, all conveniently and safely in one shot.