Chickenpox lecture (Varicella)

2021-03-23 12:00 AM

Young children can get chickenpox after contact with an adult with Herpes Zoster, but adults rarely get Herpes Zoster after contact with a child with chickenpox.


Chickenpox is an acute infectious disease that spreads through the respiratory tract. The main clinical symptoms of the disease are fever, rash and blisters on the mucous skin, the rash grows in waves 3-4 days apart.

Research history

Chickenpox has been described by authors since ancient times (CS Plimus) and is considered a mild form of smallpox. Vogel (1765) named the disease Varicella. Heberden (1767) first described chickenpox as a disease with a separate clinical picture. Steiner (1875) demonstrated chickenpox as an infectious disease. Aragao (1911) and E.Paschen (1917) demonstrated that the pathogen is a virus.



The chickenpox virus is a large-sized virus called Varicella-Zoster virus (Varicella-Zoster virus), whose nucleus is DNA. The size is about 150-200mm, the outside of the virus body is less stable. Virus culture in chicken embryos and tissue environment.

Varicella-Zoster virus causes two types of disease, chickenpox and Herpes Zoster (shingles), described by Kindratitf in 1925.


As a chickenpox patient, the patient is likely to be contagious from the end of the incubation period until the rash is crusted.

Young children can get chickenpox after contact with an adult with Herpes Zoster, but adults rarely get Herpes Zoster after contact with a child with chickenpox.


Chickenpox is spread through the respiratory tract due to the virus in the patient's saliva and throat fluid released into the surrounding environment. When a patient coughs, sneezes infects other children who are not yet sick. The main entrance is the respiratory tract mucosa, also the gastrointestinal tract, eye conjunctiva but is rare.

The body perceives immune properties

Chickenpox can be caught at all ages. The most susceptible age group is children from 6 months to 7 years old. Adults are less likely to get sick because they have immunity, only about 10% of adults over 20 years old get chickenpox.

Patients after the disease have a stable immunity for life, but also about 1% of reinfection. The disease is common in the cold season.

Mechanism of pathogenesis and pathology

Mechanism of pathogenesis

From the entrance is the lining of the respiratory tract, the virus enters the bloodstream and travels to other organs. The rash appears on the skin and mucous membranes because the chickenpox virus is localized and develops there. Some authors suggest that the chickenpox virus may persist in dormant nerve cells after it has recovered.

Injury from pathological surgery

Major damage to the skin and mucous membranes, oedema, and water degeneration of epithelial cells form blisters with a compartment in the skin. The blisters contain chickenpox virus, degenerative leukaemia and giant cell fluid. Cases with complications of encephalitis are often fatal, the pathological image of which is post-secondary viral encephalitis.


Divide the clinical form


Typical conventional form.

An unusual form of chickenpox.

Symptoms study according to each disease

Chickenpox is typically typical

Incubation period: From 14-17 days (10-21 days with no clinical symptoms).

Onset: About 1 day may have no fever or mild fever, aching muscles and joints, young children often refuse to play, fussy. There are cases of high fever 39-400, laboured convulsions, accompanied by pharyngitis, inflammation of the upper respiratory tract secretion.

Full-blown period (rash period): Chickenpox rash appears quickly from the first days of the disease. The rash develops when the systemic condition is almost normal or is mild in children, accompanied by a high fever and severe systemic intoxication in adults. Chickenpox board has the following characteristics:

At first, the rash is red, a few hours later it becomes a clear, very shallow blister-like placed on the skin, after 24 to 48 hours it turns yellow, the chickenpox becomes a spherical floating 2mm on the skin, About 5mm in diameter, around the nodule with reddened skin 1mm wide, some burns slightly concave in the centre.

Chickenpox is scattered throughout the entire body, tends to be thicker on the abdomen, chest, front of the skin, feet, hands are thinner on the soles of the feet, hands are almost absent. But the chickenpox at the hairline is always present.

Chickenpox burns have only one compartment, so when poked in them, they will be immediately flattened.

The rash grows in waves (every 3-4 days), so on one area of ​​the skin, there are enough rashes of different ages.

In the oral mucosa, there are also bulges, such as on the palate tongue, when the bulges rupture forming shallow, round or oval sores, causing the patient to drool, swallowing pain, and less likely a rash grows on the membrane. synaptic or in the vulva.

Patients often itchy often when the rash grows, the ruptured papules are easily superinfected, the peripheral lymph nodes may swell.

After 4-6 days, the chickenpox nodules dry on their own, crusting dark brown, scabbing off after a week, leaving no permanent scarring, unless there are ulcers and superinfection.

Laboratory tests: The number of peripheral blood leukocytes may decrease, the leukocytes decrease at first, then increase during the recovery period. Lymphocytes also increased; blood speed increased.

Light form

The patient does not have a fever, a sparse rash does not progress to blistering nodules, or the rash grows only locally in an area of ​​infrared irradiated skin, around the waist.

Chickenpox is abnormal

Contaminated chickenpox nodules cause pus, bacteria superinfection is usually streptococcal.

Chickenpox nodules are bloody, in children with a blood disease, malnourished children, and worsening chickenpox nodules can be necrotic, forming deep sores, gray fluid.

Haemorrhagic varicella (Varicella Haemorrhagica): Burns containing blood and bleeding, often accompanied by hematuria, gastrointestinal bleeding, nosebleeds.

Varicella Ganraenosa (Varicella Ganraenosa). The burn can be necrotic, causing deep ulcers, the base of the ulcer is fluid, the edge of the ulcer is crumpled.

Haemorrhagic chickenpox and gangrene often progress severe, prolonged or have complications of sepsis, high mortality rate.


Inflammation of the oral mucosa, otitis media of the middle and outer ear, laryngitis, pseudo-Croup syndrome ... ..

Nephritis in severe cases, a rash that grows late on the 3rd and 4th day of the disease can cause blood to urinate.

Inflammation of osteoarthritis: Common in severe forms, arthritic joints and effusion, rarely purulent.

Pneumonia is common in adults with chickenpox

Combination disease: Chickenpox can be combined with another infectious disease appearing as diphtheria, whooping cough, measles. These diseases often overwhelm the clinical form of chickenpox.

Encephalitis: The cause can be chickenpox virus, or an allergy or another virus. This is post-secondary viral encephalitis common in boys with chickenpox. Onset from day 3 to day 8 of the disease. Maybe slower on day 21 of illness. The mortality rate is about 5%.

Other complications: Myocarditis, inflammation of the lymph nodes, neuritis, some severe infections can lead to sepsis.

Implementing the quadrants


The disease starts suddenly.

Mild systemic symptoms.

The rash grows on the first day of the disease, only the blister will not be infected if there is no pustule.

The rash grows out of order, grows in waves 3-4 days apart, the rash always occurs at the hairline.

There are many different age rashes in the same area of ​​skin.

When the rash does not leave permanent scars.


Peripheral blood leukocytes decreased; Lymphocytes increased. Virus isolation, serological testing, screening for chickenpox virus with electron microscopy, immunofluorescence ... However, these tests are rarely used in clinical practice.


The disease is common in young children who have not been sick, with many infected children in the same group, chickenpox usually occurs in the winter, cold and dry weather.

Differential diagnosis

Mild and specific smallpox does not have pustules or pustules, respectively, of the same age. When the pox grows, the body temperature decreases, the test for peripheral blood leukocytes increases.

Systemic pox vaccination (after smallpox vaccine). The rash appears at the vaccination site, appears at the same time 8-10 days after the vaccination, has many years of age as a papule, without pustules. After three days begins to dry, leaving scars.

Some skin diseases that cause burns such as impetigo, atopic dermatitis, and systemic shingles (Herpes Zoster Generalisatus)


The principles of treatment

Isolate to prevent spread.

There is no cure, only symptomatic treatment.

Well, handling burns, ulcers to prevent superinfection.

Quarantine time: Until the rash disappears, the rash is gone.

Treat specific symptoms

When there is a high fever: Take antipyretic drugs Paracetamol, anticonvulsants Gacdenal, seduxen, Canxibromua 3% ...

Anti-itch with antihistamines such as Dimedrol 1% ...

When superinfection: Use appropriate antibiotics

Vitamins of group B, C ...

The care of chickenpox patients is very important:

The patient is in a ventilated room, avoiding drafts

Prevent and detect complications.

Oral hygiene, with normal saline, 1% boric acid solution ... Clean ear, nose and throat.

Skin hygiene: Keep the skin dry, clean, and prevent the child from scratching and causing the burn. Dab 1/4000 blue methylene blue solution on the sores, and wear soft, clean clothing.

Eat liquid, warm, nutritious.


Patients are isolated and treated at home. Only serious cases with complications go to the hospital.

Disinfect the patient's chamber every day.

Quarantine time: 5 days after the last eruption.

Children of kindergarten and preschool age who have not had chickenpox, if exposed to a chickenpox patient, must be kept at home for 11 to 21 days from the time of exposure.

Chickenpox does not have a preventive vaccine, can prevent children with weak resistance against chickenpox by intramuscular injection of 3ml Gamma Globulin.