Chicken pox is a disease entity caused by Varicella zoster virus. It is a highly contagious illness. In case of a case occurring in the family, there are high chances of other members getting infected.

The epidemiology of Varicella infection has changed over the past 2 decades. Previously what was considered a childhood illness, is now affecting adults who have not been previously exposed.

It is a droplet infection. Virus enters the body of affected person through droplets   if someone harbouring the virus coughs or sneezes in the vicinity. 

After entry, it causes fever, body ache, cold, i.e. flu like symptoms. As the virus multiplies and spreads in the body, these flu like symptoms are followed by vesicular eruptions on the body.

These eruptions soon enlarge in size, become pustular, then dry up and shed.  These skin lesions are troublesome as they cause intense itching.

Secondary bacterial infection can develop over these lesions because of itching, causing boils at times. The virus may be cleared totally or it may become latent in the root ganglia of nerves.

This latent virus can be reactivated later causing herpes zoster. Herpes zoster causes vesicular eruptions   in distribution of a nerve or nerve root.

The affection and inflammation of the nerve causes intense burning pain. Some persons suffer from pain for months after due to the inflamed nerve (post herpetic neuralgia).

In case of eye involvement ( herpes opthalmicus), severe pain occurs in affected eye. One may develop herpes zoster without  having chicken pox before,  due to the virus being present in the body but not due to a concentration producing the disease.

Complications occur due to spread of virus in other organs. Commonly pneumonia and infections of the brain or spinal cord occur.

In a healthy individual, chicken pox will subside in a week or so. But in a person with low immunity as in AIDS patients or diabetics, the disease can be more severe with greater potential for complications.

Normally this infection  occurs  once in a life time in a person because the body develops antibodies against it. But a immune depressed individual is prone to develop recurrent attacks of herpes zoster.

Diagnosis is made by typical clinical features and serological tests. Treatment is mainly palliative to provide relief in itching. Antiviral drugs are useful when started early within 48 to 72 hours of infection.

Potential of the disease to infect others develops with the onset of the infection but it is highly contagious in the stage when the eruptions dry up and shedding of scabs begins.  Ideally a patient of chicken pox should be isolated.

The patient should be advised not to remove the scabs manually as it can cause permanent scarring. Keeping the mouth covered while coughing or sneezing is a small measure but very useful   to prevent transmission of all droplet infections including chicken pox.

Vaccination for chicken pox is recommended for all children up to 12 years. Adults who test negative for antibodies to chicken pox can also take vaccination for prevention, which will be 2 doses of the vaccine.

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