CHICKENPOX

Varicella

Chicken pox {varicella} is a highly contagious acute viral disease caused by the virus from herpes virus family {varicella zoster virus}. The disease has a characteristic skin rash that forms small, itchy blisters with transparent content, which eventually scab over, usually starts on the chest, back, and face then spreads to the rest of the body.

Pathogenesis:

  1. Inoculation of virus and it’s replication in epithelial cells of upper respiratory tract.
  2. With lymph it enters to the blood and viremia develops.
  3. Damage of the skin epithelium and mucosa epithelium.
  4. Damage of the nervous system – (intravertebral ganglia, brain and cerebellum cortex, subcortical region).
  5. Generalization of the infection (damage of liver, kidneys, lungs) in immunosupressed persons.

Exposure to Varicella initiates the production of host immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) antibodies; the IgG antibodies persist for life and confer immunity.

 

After primary infection, Varicella spreads from mucosal and epidermal lesions to local sensory nerves, then remains latent in the dorsal ganglion cells of the sensory nerves. Reactivation results in the clinically distinct syndrome of herpes zoster (i.e. shingles).

Clinical presentation. 

·        The incubation period ranges from 10 to 21 days (most cases 14-17days).

·        The contagious period extends from 1 to 2 days before the rashes erupt until all of the lesions have crusted (5 days after the last rashes have appeared).

·        The prodrome consists of 1 to 2 days of fever, headache, malaise, and anorexia.

·        The rashes, often pruritic, begin as a maculae and progresses rapidly through the stages of papule, vesicle , and crusted lesion. The spots first appear on the face or trunk, obvious on the scalp and, at the height of the illness, are more numerous centrally than distally. In severe cases may be present on palms and soles (as spots and papules) . The lesions erupt in crops for 3 to 4 days (sometimes to 7 days) and it is characteristic of the rashes that lesions in different stages of development may be found on one area (false polymorphism) . The vesicle is a 2 to 3 mm oval filled with   clear fluid surrounded by an erythematous base. The fluid clouds and a crust forms appear within 1 day. Lesions occurring on the mucous membranes do not crust but form a shallow ulcer. Posterior cervical lymph nodes usually are enlarged.

 

The congenital varicella syndrome may develop, in babies whose mothers have clinical varicella before 29 weeks gestation. Maternal varicella 4 days or less before delivery may result in severe disseminated or total chickenpox in the newborn.

Severity

Mild :

  • vesicles rashes are not numerous on the skin,  body t° 37,5-38 °С
  • Smooth, without complications

Moderate :

  • Considerable presence of the vesicles rashes on a skin, single on mucus membranes of the oral cavity, body t°  38-39 °С
  • Complicated by encephalitis, neuritis, poly radiculo neuritis

Severe :

  • numerous rashes, hardening on the stage of vesicles on a skin and mucus membranes, bodt° is up to 40 °С and higher
  • Complicated by secondary bacterial infection aslymphadenitispyodermia (staphylo-and streptodermia), erysipelasphlegmon, abscess, sepsis.

Generalized {visceral} :

  • neurotoxicosis with a convulsive syndrome and meningo encephalitic reactions, hyperthermiamultiple rashes as vesicles quite often with the hemorrhagic impregnation, damage of the internal organs.

Effaced {rudimentary} :

  • rashes on the skin does not achieve the stage of vesicles (only macula-papules), body t° is normal.

 

Complications:

  • Secondary bacterial – infection of lesions (with staphylococci as pustulosis (photo) or b-hemolytic group A streptococci as erysipelas, phlegmona (photo) are the most common complications; also may be otitis, pneumonia.
  • Viral:  Primary varicella pneumonia affects immunocompromised patients and up to  35% of  normal  adults; croup; Encephalitis follows varicella in  fewer than 1:1000 cases (involvement of the  cerebellum, or cerebrum, less  common – Guillain-Barre syndrome, transverse  myelitis, optic neuritis, and facial  nerve  palsy.
  • Rare complications: idiopathic thrombocytopenic purpura, nephritis, myocarditis, arthritis.

 

Diagnosis

The diagnosis of chickenpox is primarily based on the signs and symptoms, with typical early symptoms followed by a characteristic rash and confirmation of the diagnosis can be established by examination of the fluid within the vesicles of the rash, or by testing blood for evidence of an acute immunologic response. 

Vesicle scrapings contain multinucleated giant cells, and vesicle fluid contains virus in the first days of illness. It could be detected by the:

  • immune fluorescent method
  • Serological reactions: CBR, Immune-enzyme reaction, to find antibodies against viruses with fourfold increasing of antibodies title in 10-14 days may be used.
  • CSF investigation (signs of serous meningitis) – in case of meningoencephalitis.
  • Prenatal diagnosis of fetal varicella infection can be performed using ultrasound {to investigate any defects in the fetus development}, though a delay of 5 weeks following primary maternal infection is advised. A PCR (DNA) test of the mother’s amniotic fluid can also be performed, though the risk of spontaneous abortion due to the amniocentesis procedure is higher than the risk of the baby’s developing fetal varicella syndrome.

 

Treatment

In most cases only symptomatic (Basic therapy) up to disappear of clinical signs

  • antiseptic fluids for skin lesions to prevent secondary bacterial infection (1% brilliant green, 1-2% KMnO4);
  • Gurgling with oral antiseptic fluids after the food intake
  • antihistamines for itching;
  • Acetaminophen for fever control.

Etiological therapy by Acyclovir (IV 10 mg/kg 3 t.d. for 7 days or up to 48 hours the last elements appear) – for immunocompromised children:

  • Patients with oncohematologic diseases
  • Patients after bone marrow or inner organs transplantation
  • Patients who achieve corticosteroids
  • Patients with the primary immune deficit
  • Patients with HIV-infection
  • Inborn Chicken pox
  • Chicken pox complicated by the damage of CNS, hepatitis, thrombocytopenia, pneumonia
  • And Severe forms of Chicken pox (Acyclovir orally 80 mg/kg/day 4 t.d. for children elder than 2 years and teenagers.

Also for severe cases in neonates – varicella-Zoster immune globulin (0.2 ml/kg).

In case of encephalitis

  • acyclovir,
  • parenteral detoxication,
  • dexamethasone 0.15 mg/kg 4 t.d. (every 6 hours) for 4 days,
  • dehydration with mannitol 1-1.5 g/kg,
  • symptomatic treatment.

Prevention:

  1. To isolate ill person until the 5 day after the last vesicles has appeared.
  2. To isolate contact persons from 9 till 21 day after exposure.
  3. VZ immune globulin in immunocompromised children (not later than 72 hours after exposure).