What causes chickenpox? Learn the five causes early

We all know that chickenpox is not acne. The so-called chickenpox belongs to herpes zoster, an acute infectious disease caused by the initial infection. Red papules and rashes will appear all over the body. If not treated early, there will be more and more rashes all over the body, and the situation will become more and more serious.

reason:

1. Source of infection Symptomatic patients are the only source of infection. Generally believed. The disease is most contagious during the brief prodromal period and early stages of the rash. Starting from 10 to 21 days after exposure to the pathogen, that is, before the herpes appears, the chickenpox patient has already excreted the virus through nasopharyngeal secretions and is contagious. This is why chickenpox is easy to spread.

2. Transmission route VZV virus mainly exists in the patient's lesions, skin tissue,

3. Susceptible populations Humans are generally susceptible to VZV, but compared with adults, children under 14 years old and infants are highly susceptible. The majority of the patients are children and infants under 14 years old, and less than 2% of the patients are over 20 years old. If a pregnant woman contracts chickenpox within 6 days before delivery, the fetus may be infected. Neonates develop the disease within 10 to 14 days after birth. Some infants receive partial immunity through the placenta before 6 months of age. Therefore, the susceptible people in the epidemiological sense mainly refer to children and pregnant women who have not been infected with VZV. Chickenpox patients have a certain immunity after the disease, but some patients may relapse 10 years later, and the relapse is often manifested as shingles.

4. Epidemic characteristics: The occurrence of varicella has a clear seasonal peak. The peak season is late winter and early spring, with the peak in March, but sporadic cases can also occur in early summer and late autumn. VZV infection often spreads in a cycle of 3 to 4 years (the emergence of a new group of susceptible people is the condition for another epidemic).

5. Chickenpox is spread all over the world. According to the results of the varicella epidemiological survey in my country, people in all regions are widely infected, with an average antibody positivity rate of 60% to 70%, the lowest being about 14% to 24% in children aged 1 to 6 years old, and the antibody positivity rate rises rapidly with age. In recent years, the incidence of chickenpox has been on the rise, both among children and adults. But the vast majority of cases are children. Varicella can cause epidemics in childcare institutions, primary schools, or other places where children gather together. Mycobacterium susceptibility is also one of the important diseases causing nosocomial infections in children's hospitals or pediatric clinics. A total of 197,939 cases of varicella were reported nationwide from 2005 to 2006. People under the age of 14 accounted for 82.62% of the total number of reported cases; a total of 940 varicella incidents were reported, of which 97.87% occurred in schools, with rural primary schools being an important place for varicella incidents to occur.

Pathogenesis and pathology:

1. The varicella virus invades the epithelial cells of the upper respiratory tract and replicates, then enters the bloodstream. After replicating inside the white blood cells, it enters the bloodstream in large quantities to form viremia. The virus spreads to various organs and tissues throughout the body, causing systemic lesions. Skin lesions are mainly characterized by edema and degeneration of the spinous cell layer, with nuclear division into multinucleated giant cells and the formation of eosinophilic inclusion bodies in the nuclei. The cells liquefy to form unilocular thin-walled varicella. Early herpes fluid specimens observed under an electron microscope can be seen to contain a large number of viruses. Later, due to increased leukocyte infiltration and mixing of tissue cell debris, the appearance of the herpes fluid may gradually become turbid, or it may take on a pustular appearance due to degeneration of the blister wall. The viral content in late-stage herpes fluid decreases.

2. The dermal tissue around and beneath the herpes becomes congested, forming a linear red halo surrounding the base of the herpes. Occasionally, eosinophilic infiltration may be seen at the base of the herpes. Because the lesions are superficial, they generally do not leave scars after healing. Herpes may also form on the mucous membranes of the eyes, nose, mouth, and pharynx, and may easily break open and form ulcers, but they heal easily. Autopsy confirmed. Allergic inflammation in varicella patients can occur in a variety of tissues, including the lungs, liver, spleen, adrenal glands, gastrointestinal tract, myocardium, pancreas, vascular endothelial segment, and brain. The lung tissue of patients with varicella pneumonia shows extensive inflammatory changes, with scattered focal necrotic areas; alveoli may bleed, and the alveoli and bronchioles contain fibrinous exudates, red blood cells, and multinucleated humular cells with inclusion bodies; there is mononuclear cell infiltration in the lung interstitium and around the bronchioles. In patients with varicella pneumonia, degeneration and necrosis of brain tissue nerve cells, punctate hemorrhage, demyelinating changes around interstitial blood vessels, and lymphocytic infiltration around visceral blood vessels can be seen.