Definition of Chicken pox :

Definition : Chicken pox is an acute, highly infectious disease caused by varicella zoster virus.

Epidemiology of chicken pox :

• Occurrence : Worldwide
• Agent :  Varicella zoster
• Reservoir/host  : Man
• Environment : More common in winter and spring
• Mode of transmission : Droplet infection / Direct Contact/Air brone
• Incubation period : 2 to 3 weeks (14-17 days).
• Immunity : One attack gives durable immunity, second attacks are rare.

Symptoms of chicken pox :

A. The first symptoms of chicken pox include :

1. Headache
2. Fever
3. Sore throat
4. Backache
5. Feeling generally unwell.

Once the chicken pox rash appears, it goes through three phases :

1. Raised pink or red bumps (papules) which break out over several days.
2. Fluid-filled blisters (vesicles) forming from the raised bumps over about one day before breaking and leaking
3. Crusts and scabs, which cover the broken blisters and take several more days to heal.

Clinical features of chicken pox :

Clinical spectrum of chicken pox may vary from a mild illness and only a few scattered lessons to febrile illness and widespread rash. The clinical course of chicken pox may be divided into two stages :

Pre – eruptive stage:

1. Mild to moderate fever
2. Pain in the back
3. Shivering
4. Malaise

Eruptive stage :

In children the rash is often the first sign.

Distribution : 

• Rashes are symmetrical.
• First appears in trunk abundant).
• They come to face, arms, and where it is less abundant.
• Mucosal surface usually affected
• Axilla may be affected.
• Palms and soles are not usually affected.
• Centripetal

2) Rapid evolution : Stages – Macule Papule, Vesicle, Scab

• Vesicles are filled and fluid be and looking like dew drops on the skin.
• Vesicles may form crust without going through pustular stage.

3) Pieomorphism : All the stages of the rash (papule, vesicle, crust) may be seen simultaneously at one time in the same area.

4) Fever : Fever does not run high but shows exacerbations and each fresh crop of eruption.

Treatment of chicken pox :

1. Rest
2. Pain relief such as paracetamol to relieve fever.
3. Itching can be treated with lotions such as calamine available.
4. Tepid baths with ½ cup of sodium bicarbonate or solutions such as Pinetarsol added can also be helpful in relieving itching.
5. To prevent infection of the sores, trim children’s fingernails short and wash hands frequently with antibacterial soap.
6. Antibiotic therapy such as Flocloxacillin 500mg 6-hourly should be prescribed if secondary bacterial infection progresses.

Complications of chicken pox :

1. Haemorrhage (Varicella haemorrhagica)
2. Pneumonia
3. Encephalitis
4. Acute cerebral ataxia
5. Reye’s syndrome (acute encephalopathy associated & fatter degeneration of viscera especially liver).
6. Congenital defects and malformation (foetal wastage, cutaneous scar, atrophied limbs, microcephaly, low birth weight, cataract, microphthalmia chorioretinitis, deafness and cerebro – cortical atrophy).
7. Oncogeneity
8. Skin infection
9. Septicemia
10. Septic arthritis.

Prevention  of chickenpox :

1. Varicella Zoster Immunoglobulin (VZIG) : Varicella-Zoster Immunoglobulin (VZIG) given within 72 hours of exposure for prevention of chickenpox in exposed susceptible individuals particularly in immuno-suppressed persons. These include –

• Susceptible persons receiving im unosuppressive therapy.
• Persons with congenital cellular immunodeficiency.
• Persons with acquired immunodeficiency including HIV/AIDS.
• Susceptible and exposed persons, in particular pregnant women.
• Newborn.
• Premature infants of low birth weight.

2) Vaccine : A live attenuated varicella virus vaccine is safe and currently recommended for children between 12-18 months of age who have not had chickenpox. The high-risk groups are

• Health-care workers
• Household contact of immuno-suppressed individuals.
• Persons who live or work in environments where transmission can occur e.g. college students, teachers, non-pregnant woman of childbearing age etc.

Control of chickenpox :

The usual control measures are – 

1. Notifications
2. Isolation of cases for about 6 days after onset of rash.
3. Disinfection of articles soiled by nose and throat discharges.
4. Ay Antiviral therapy acyclovir, valacylovir, famiciclovir and foscarnet.

Some important about chicken pox :

1) . Incubation period : About 15 days (range 7-21 days) 

 2) Distribution of rash :

• Centripetal
• Seldom affected.
• Axilla affected.
• Rash mostly on flexor surfaces.

3) Characteristics of rash : 

• Superficial.
• Unilocular, dew-drop like appearance.
• Rash pleomorphic.
• An area of inflammation is seen around the vesicles.

4) Evolution of rash :

• Evolution of rash very rapid.
• Scabs begin to from 4-7 days after the rash appears.

6) fever :

• Temperature rise with each fresh crop of rash.