What Causes Chickenpox?

Varicella (chickenpox) is an acute infectious disease caused by the initial infection with varicella-zoster virus. It mainly occurs in infants and preschool children. Adults have more severe symptoms than children. It is characterized by fever and skin and mucous membranes appearing in batches of red maculopapular rash, herpes, and rash. The rash is distributed concentrically, mainly in the chest, abdomen, and back, with few limbs. Frequent in winter and spring, it is highly infectious. Chicken pox is the only source of infection. It is infectious from 1 to 2 days before the onset of the rash to the dry and crusting period. It can be transmitted by contact or inhalation by droplets. The rate can reach more than 95%. The disease is a self-limiting disease and generally does not leave scars. If it is infected with bacteria, it will leave scars. After the illness, lifelong immunity can be obtained. Sometimes the virus remains in the ganglia in a static state. After many years, the infection recurs and herpes zoster appears.

Basic Information

English name: varicella
Visiting department: Infectious Diseases
Multiple groups: Infants, preschool children

Common causes: Caused by primary infection with varicella-zoster virus
Common symptoms: Fever with maculopapular rash or herpes, or rash without fever
Contagious: Have
way for spreading: Respiratory tract droplets, direct contact

Causes of chickenpox

The disease is caused by varicella-zoster virus (VZV) infection. Varicella-zoster virus belongs to the herpesvirus family, and is a double-stranded DNA virus with only one serotype. There are at least eight types of viral glycoproteins, which determine the pathogenicity and immunogenicity of the virus. The virus has weak viability in the external environment, is not heat-resistant and acid, and can be inactivated by disinfectants such as ether. Humans are the sole host of the virus, and patients are the only source of infection. The period of infection usually ranges from 1 to 2 days before the appearance of the rash until the herpes is completely scabbed. Patients with immunodeficiency may be contagious throughout the course of the disease. Varicella can also occur in children in contact with people with shingles because they have the same cause.

Chickenpox is highly contagious and is transmitted mainly through respiratory droplets or direct contact. After the virus infected the human body, the local lymph nodes in the nasopharynx proliferated and replicated for 4 to 6 days, and then invaded the blood and spread throughout the body, causing pathological changes in various organs. The disease is mainly in the spinous cell layer of the skin. Cells swell and degenerate to form cystic cells. There are eosinophilic inclusions in the nucleus. Herpes are formed after cell lysis and infiltration of interstitial fluid. The blister fluid contains a large number of infectious virus particles. Blisters are also common on the surface of the oropharynx, respiratory tract, gastrointestinal tract, eye conjunctiva, and vaginal mucosa.

People of any age can be infected with chickenpox-zoster virus. Infants and preschool and school-age children are more likely to develop the disease, and infants under 6 months are less common. The spread of chickenpox in susceptible populations depends mainly on factors such as climate, population density and medical and health conditions.

Clinical manifestations of chickenpox

The incubation period of the disease is 12 to 21 days, with an average of 14 days. Onset is more acute. Older children and adults may have precursor symptoms such as fever, headache, general burnout, nausea, vomiting, and abdominal pain before the rash appears. In children, the rash and systemic symptoms appear simultaneously.

A rash occurs within 24 hours of onset. The rash first develops in the scalp and the compressed part of the trunk and is distributed concentrically. The beginning is a small pink spotted rash, which immediately turns into a round, tense blister with rice grains to the size of a pea. Mucosa is also often invaded, and is found in the mouth, pharynx, eye conjunctiva, vulva, and anus.

Endothelial rashes appeared in batches during the rash period of 1 to 6 days, and the skin lesions evolved from tiny red maculopapular rash herpes crusting exfoliation, leaving no scar after exfoliation. Painful itch in the blister stage is obvious, if the secondary infection due to scratching can leave a slight dent. Weak people can develop high fever, and about 4% of adults can develop disseminated chickenpox and chickenpox pneumonia.

The clinical manifestations of chickenpox include: bullous varicella, hemorrhagic varicella, neonatal varicella, and adult varicella. In addition, if infected with chickenpox during pregnancy, it can cause fetal malformation, premature birth or stillbirth.

Chickenpox check

If necessary, the following laboratory tests can be selected:

Electron microscopy

Taking fresh herpes fluid for electron microscopy, herpes virus particles can be seen, which can be quickly distinguished from variola virus.

2. Virus isolation

Within 3 days of onset, herpes fluid was inoculated into human embryonic amniotic tissue, and the positive rate of virus isolation was high.

3. Serology

Complement binding test is commonly used. Patients with chickenpox appear complement-binding antibodies in the serum 1 to 4 days after the visit, peaking in 2 to 6 weeks, gradually decreasing after 6 to 12 months, and the titer of the antibody in the double serum is 4 times higher high. Can also be detected by indirect fluorescent antibody method

4.PCR method

Detection of viral DNA in nasopharyngeal secretions by PCR is a sensitive and rapid early diagnostic method.

5. Blood image

The total number of white blood cells is normal or slightly reduced, and lymphocytes are increased.

6. Herpes scrape or biopsy

Fresh herpes substrates were scraped and Wyeth or Giemsa staining was used to examine multinucleated giant cells, and acidic staining was used to examine intranuclear inclusions.

Chickenpox diagnosis

It is not difficult to make a diagnosis based on medical history and rash characteristics, and laboratory tests can be used to confirm the diagnosis if necessary.

1. A history of close contact with patients with chicken pox or shingles 2 to 3 weeks before the illness.

2. Fever and rash (macropollis, herpes) occur at the same time, or rash occurs without fever. The rash is distributed concentrically and is more common on the trunk, head, and waist. The rash appeared in batches, maculopapular rash herpes rash scab, different forms of rash existed at the same time, and no scar remained after the palate was detached.

3. The white blood cell count is normal or slightly lower, and the lymphocytes are relatively increased.

Chickenpox Treatment

Children should be isolated early until all rashes have crusted, usually no less than two weeks after the illness. Children who have come in contact with chickenpox patients should be observed for 3 weeks in isolation. There is no effective treatment for this disease. It is mainly symptomatic treatment and prevention of secondary skin infections, keeping it clean and avoiding scratching. Intensify care, change clothes and cut nails frequently to prevent secondary infection from scratching the blister. Actively isolate patients to prevent infection.

Local treatment is mainly for itching and prevention of infection. External calamine lotion can be applied externally. Those with herpes rupture or secondary infection can use topical 1% methyl violet or antibiotic ointment. Antibiotics are available when the symptoms of secondary infection are severe. Avoid using corticosteroids to prevent the spread and aggravation of chickenpox.

For patients with disseminated chickenpox with low immune capacity, neonatal chickenpox or chickenpox pneumonia, encephalitis and other severe cases, antiviral drugs should be treated as soon as possible. Acyclovir is currently the first choice antiviral drug for the treatment of chickenpox-zoster. , But must be applied within 24 hours after the onset of better results. Or add alpha-interferon to inhibit virus replication, prevent virus spread, promote healing of skin lesions, accelerate disease recovery, and reduce mortality.

Varicella Home Care

1. Pay attention to disinfection and cleaning

The clothes, bedding, towels, dressings, toys, tableware, etc. that come in contact with the varicella herpes solution should be washed, dried, ironed, boiled, burned and disinfected according to the situation, and should not be shared with healthy people. At the same time, change your clothes and keep your skin clean.

2.Timed window opening

Air circulation can also kill viruses in the air, but care must be taken to prevent patients from getting cold when ventilating the room. Keep the room as bright as possible and open the glass windows.

3. Fever

If you have a fever, it is best to use ice pillows, towels, and drink plenty of water to reduce fever. To allow sick children to rest and eat a nutritious and digestible diet, drink plenty of boiling water and fruit juice.

4. Pay attention to changes in your condition

Pay attention to changes in the condition, such as persistent high fever, cough, or vomiting, headache, irritability, or drowsiness after the rash is found. You should go to the hospital in time for convulsions.

5. Avoid scratching herpes by hand

In particular, do not scratch the acne on the face to avoid purulent infection due to herpes being scratched. If the lesion is deeply damaged, it may leave scars. To prevent this, cut your child's nails short and keep hands clean.

Chickenpox prevention

Control the source of infection, isolate the child until the rash has crusted, and quarantine the exposed susceptible child for 3 weeks. For immunocompromised patients, immunosuppressants and pregnant women, if they have a history of exposure, they can use gamma globulin, or shingles immunoglobulin, intramuscularly. Live attenuated chickenpox vaccine is the first human herpes virus vaccine approved for clinical application in many countries. Follow-up observation after vaccination has found that chickenpox vaccine has a better protection rate for vaccinated persons.