Alternative name: varicella

What’s it?

Chickenpox is a highly contagious infectious disease caused by a virus called varicella-zoster. This virus can cause several types of infections: primary (well-established chickenpox), latent (without clinical manifestation), and reactivation.

This virus remains in our body for the whole life as though it were sleeping; its reactivation determines a disease located in the area corresponding to one or more sensory nerves and then is called herpes-zoster.

How is it acquired?

In the pre-vaccine era, 90% of susceptible people developed the primary disease, chickenpox. In the contact within the household, the disease contamination occurs in over 80% of susceptible individuals; in less intimate contact (e.g. school), contagion decreases to 30% of infants.

The passage of the disease from person to person in the same house usually makes the picture more severe. The transmission period begins 24 to 48 hours before the appearance of skin lesions, and it extends until all vesicles have developed crusts, usually taking 7 to 9 days. The time between contact and onset of the disease (incubation) is of 14 to 16 days, ranging between 10 and 21 days. Transmission occurs through the air, from one respiratory airway to another or by direct contact with the vesicular lesions whose fluid is rife with virus.

What does one experience?

Once lodged in the body, the virus starts to reproduce itself, invades the blood and generates signs of infection: fever at 38 to 38.5°C, discomfort, appetite loss, headache. The symptoms are more or less intense depending on the amount of contaminating viruses and the individual’s defense ability.

Skin and mucosa lesions:

The virus present in the respiratory tree is taken to the skin and mucosae by the bloodstream. A local inflammatory response begins; small reddish papules with intense itching appear and evolve rapidly into small vesicles with crystalline fluid, which eventually becomes dark. The vesicles retreat at the center, and formation of a dark crust starts. All of this takes place in approximately 2-3 days. The lesions appear in independent “spells”, which results in lesions of different developmental stages in the same individual, this finding being one of the most important for supporting the diagnosis. The number of lesions ranges greatly (10 to 1500 in normal individuals); on average, we can speak of around 300 lesions.

Diagnosis and treatment

The diagnosis is primarily clinical. Treatment is directed at minimizing the symptoms. It’s a benign illness, and its cure is achieved through the response by the patient’s organism itself. Currently, the most serious complications take place by contamination with bacteria. Pregnant women, newborns, and individuals with low defenses are cases that entail special attention.

Herpes-zoster x chickenpox – trivia

Shingles (zoster) can’t develop by contact with chickenpox, but chickenpox can develop in contact with shingles. How?

As shingles is the reactivation of the virus that’s been already present in the body, who has zoster has already cured chickenpox (with or without symptoms), and the ones that haven’t had chickenpox may be contaminated with it due to the virus present in the shingles rash.


The vaccine against chickenpox is recommended after the first year of life in a single dose.

Susceptible teenagers need 2 doses.