Chickenpox virus - zoster (VZ)

Chickenpox virus - zoster (VZ) can cause a highly contagious lung disease in children - chicken pox, manifested in the development of vesicle rashes on the skin and mucous membranes. In adults (and extremely rarely in children), the same virus causes shingles (zoster), characterized by an inflammatory reaction in the posterior roots of the spinal cord and in the ganglia; it is accompanied by the precipitation of vesicles on the skin in a site innervated by the affected sensory nerve. Chicken pox is seen as a reaction to the primary contact of the virus with the human body, while the zoster is the response of the partially immune host to the reactivation of the virus present in the latent form in sensitive ganglia.

This virus is identical to the herpes simplex virus by its morphological, biological and even antigenic properties, but it does not multiply in the body of laboratory animals. It has an effect on human cells: the stopping of fission in metaphase, the shrinking of chromosomes, the breaking of chromosomes and the formation of micronuclei are often seen.

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Pathogenesis and symptoms of chicken pox

The virus VZ is transmitted by airborne droplets, the source of infection is a sick person. Primary reproduction of the virus occurs in the epithelium of the mucosa of the upper respiratory tract. Then the virus enters the lymphogenous way into the blood, with it - into the skin. Epithelial cells swell, ballooning degeneration (dystrophy) of spikey layer cells is observed, accumulation of tissue fluid leads to the formation of vesicles. In the nuclei of the affected cells, especially in the early stages, eosinophilic body-inclusions are found. In herpes zoster, in addition, there is an inflammatory response in the posterior roots of the spinal cord and sensitive ganglia. The incubation period with varicella is 14-21 days, with shingles not known. Chickenpox begins with malaise, fever, rash on the face, then on the trunk and limbs. First, an itchy speck appears, which quickly turns into a vial filled with a serous-turbid liquid. Then the vesicle bursts, in its place a crust is formed, subsequently tearing away and leaving no scar. The rashes of new vesicles last 3-4 days, the contents of them include a huge amount of the virus. Mortality and complications (encephalitis, pneumonia) are quite rare, often observed in newborns. In the first three months of pregnancy, the transferred chicken pox in women can lead to congenital malformations of the fetus.

In herpes zoster after a malaise and rising temperature, there are severe pains in the mucous membrane or skin area innervated by one or more groups of sensitive ganglia. A few days later bubbles appear in this zone. Most often it is observed on the body (along the intercostal nerve), on the skin of the head or neck.

Laboratory diagnostics of chicken pox

It is conducted in the same way as the diagnosis of herpes simplex, but the following points should be considered. Herpes simplex virus causes the development of lesions in the rabbit's cornea, the brain of mice and the chorion-allantoic membrane of the chick embryo, while the VZ virus almost does not infect these tissues. In most cell cultures, the herpes simplex virus grows rapidly, forms plaques in 18-24 h. The VZ virus grows mainly in fibroblast cells within 3-5 days. These viruses differ in the morphology (mainly in size) of virions in the vesicular fluid by electron microscopy, as well as in the presence of antigen in the vesicular fluid, which is detected by immunodiffusion in a gel with specific precipitating sera (against herpes, VZ and vaccinia viruses).

Treatment of chicken pox

A good therapeutic effect is gammaglobulin, obtained from the serum of patients with shingles in the recovery stage . This drug can also be used to prevent varicella in contact children with immunodeficiency conditions.