Chickenpox is a contagious disease that presents with fever and rash, commonly found in children. It is caused by infection with the varicella-zoster virus. Generally, the highest incidence is found in the age group 5-9 years, followed by 0-4 years, 10-14 years, 15-24 years, and 25-34 years, respectively. It can occasionally be found in people aged 35 years and older. This disease occurs almost equally in both females and males, usually in those who have never had the disease or have never been vaccinated against it.

Chickenpox is a disease that spreads easily, especially in schools, daycare centers, or residential communities. It can be found throughout the year but has the highest incidence from January to April.

What causes chickenpox?

Chickenpox is caused by a virus called “Varicella zoster virus” (VZV) or Human herpesvirus type 3 (HHV-3). This virus causes chickenpox in individuals who are infected for the first time. Afterward, the virus hides in nerve ganglia. When a person ages or has a weakened immune system, the hidden virus can reactivate and cause shingles.

Transmission of chickenpox

It is transmitted by inhaling respiratory droplets from an infected person or by direct contact with the fluid from the blisters of an infected person during the contagious period. The contagious period is from 1-2 days before the rash appears until all the blisters have crusted over. Therefore, caution is needed when close to infected individuals.

Incubation period of chickenpox

Approximately 10-21 days, with an average of about 14-17 days after exposure to the virus or contact with an infected person.

Symptoms of chickenpox

Starts with low-grade fever, muscle aches, and rash beginning on the trunk and face, spreading to the arms and legs. The rash is more prominent on the trunk than on the limbs. Blisters may also appear in the mouth and mucous membranes. Initially, the rash is red and usually itchy, then quickly turns into blisters and crusts over. The crusts eventually fall off within 5-20 days.

Diagnosis of chickenpox

Generally, doctors can diagnose this disease by physical examination based on the characteristic symptoms. Additional tests are not usually necessary except in cases with complications or when a definitive diagnosis is required. In such cases, doctors may perform serological tests to detect antibodies against the chickenpox virus or test fluid from the blisters.

Possible complications

Complications are rare, especially in otherwise healthy children.

However, in adults, complications may be more common. The most frequent is secondary bacterial infection leading to pus formation and possible scarring.
Severe but rare complications include pneumonia and encephalitis.
In pregnant women, if chickenpox occurs during the first 3 months of pregnancy, it may cause congenital varicella syndrome in the fetus, resulting in scarring, limb deformities, small eyes, cataracts, microcephaly, intellectual disability, and other abnormalities.
Additionally, if infection occurs 5 days before or 2 days after delivery, the newborn may develop severe chickenpox.
After recovery from chickenpox, the virus remains dormant in nerve ganglia and can cause shingles when the immune system weakens due to aging, illness, or immunosuppression.

Treatment of chickenpox

Most symptoms are mild and resolve on their own.
Antiviral treatment may shorten the duration of illness if given within 24 hours after rash onset. Not all patients require antiviral drugs; doctors usually prescribe them for those at risk of severe complications.
If fever is high, cooling measures and antipyretics such as paracetamol may be used. Aspirin should be avoided as it may increase the risk of Reye’s syndrome, a serious brain and liver disorder.
Doctors may consider antihistamines or calamine lotion to relieve itching.
Patients should avoid scratching to prevent secondary bacterial infection. It is recommended to keep nails short.

Prevention of disease spread

Individuals with chickenpox should isolate themselves from others by staying home from school or work until all blisters have crusted over. They should avoid close contact with others, especially pregnant women, infants, and immunocompromised individuals.

Chickenpox vaccine

The vaccine is a live attenuated vaccine administered subcutaneously. Adults and children over 12 years old require two doses spaced at least 4-8 weeks apart. Because it is a live vaccine, it is contraindicated in immunocompromised individuals such as those on immunosuppressive drugs, untreated AIDS patients, and pregnant women.

In children without contraindications, the vaccine can be given starting at 12-15 months of age, with a booster dose at 4-6 years old, or two doses spaced at least 3 months apart. The two-dose regimen provides better immunity than a single dose.

After two doses, 99% of vaccine recipients develop immunity. Some vaccinated individuals may still get chickenpox, but symptoms are usually milder, such as no fever or fewer rashes compared to unvaccinated individuals.

Currently, there is a combined vaccine available that protects against measles, mumps, rubella, and chickenpox (MMRV), making vaccination more convenient and less painful.

Chickenpox (Varicella)