Chicken pox is also known as Varicella or third disease. It is a common and highly infectious disease, affecting mainly children (age 2 to 8 years), but no age group is exempted. The varicella virus is one of the human herpes viruses and is an extremely infectious exanthema.

The characteristic crops of small vesicles have a central distribution (face, scalp, trunk). The virus remains latent after initial infection and reactivate later in life as herpes zoster (shingles).

Epidemiology

It is one of the most easily transmitted viruses, probably by airborne spread, usually via a person with chicken pox (occasionally with herpes zoster).

Varicella is contagious only while the patient has symptoms and vesicles remain; drying of the vesicles indicates that infectivity has stopped. The scabs are not infectious.

The incubation period is 10-21 days (usually 2 weeks). Laboratory diagnosis is by serology or immunofluorescence of vesicular fluid.

In infants or children, specific anti-varicella IgG may be needed to prevent or ameliorate the disease on exposure.

Symptoms of Chicken Pox

In children, the onset has no prodrome but in adults, there is an influenza-like prodrome (muscle aches, fever, headaches) for 2-3 days.

In children, the maculopapular rash appears almost simultaneously as the fever, starting in the scalp and descending to the body and the extremities. The typical vesicles form without 24 hours. The rash is itchy.

Diagnosis

Varicella is readily diagnosed on clinical grounds, although the virus may be detected from the fluid within the vesicles.

Complications

• Bacterial infection of the cutaneous lesions are the commonest
• Viral pneumonia is uncommon in adults and rare in children
• Rare complications include thrombocytopenia, acute cerebellitis, meningoencephalitis and purpura fulminans
• Death is rare except in the immunocompromised and neonates with congenital varicella

Varicella encephalitis is a complication occurring in approximately 1 case per 1000. Symptoms include headache, vomiting, neck stiffness and ataxia. This complication tends to present between the fifth and eighth day of the illness.

Management

No specific therapy is required and management is symptomatic. Many people worry about scarring, but the lesions invariably heal, leaving normal skin, unless they become infected.

Medications

• Antihistamines – for itch
• Antibiotics – for secondary bacterial skin infection
• Antiviral agents – to be started within the first 3 days of the eruption for severe cases.
• Zoster immune globulin (ZIG) – for children with malignancy disease, neonates and others with compromised immune systems and who are varicella contacts.

School exclusion

It is recommended until full recovery, usually for 7 days. A few remaining scabs are not an indication to continue exclusion. Except for immunocompromised children, contacts should not be excluded from school.

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Rubella is also known as German measles or Second disease. The virus can be detected in blood for up to a week before, and in the nasopharynx from 10 days before and until 2 weeks after the onset of rash.

It is a mild disease and can go unnoticed by the patient. Approximately one-third of infections are asymptomatic (subclinical). Incubation period is 14-21 days. Rubella occurs most commonly in children aged 5-10 years. It is much less contagious than measles.Its importance does not lie with management of the patient but its possibility of transmission to a mother in early pregnancy and who is non-immune.

Congenital rubella in the foetus may occur with tragic results. It is still the most important cause of blindness and deafness in the newborn.

Clinical features

A widespread rash, sometimes itchy, may be the only evidence of infection. There is often a reddened throat but is seldom sore. There can sometimes be discharge seen as well as rash on the palate. Fever is usually mild, rarely above 38 degrees celsius, and rarely for more than 1 day. Prominent lymph nodes swelling are seen. Other features are headache, myalgia (bodyache) and conjunctivitis. In adolescent girls and women, polyarthritis (small joints) or arthralgia (joint ache) lasting one to several weeks are common and appear on the third day.

The rash is a discrete pale pink maculopapular rash, starting from the face and neck, spreads to the trunk and extremities. It is of variable extent and may be absent in subclinical infection. The rash is exaggerated on skin exposed to the sun and is of a brief duration, usually fades on the third day. There is no staining or desquamation.

The patient is infectious for up to 10 days from the onset of rash.

Congenital rubella

Infection of the mother in the first trimester can lead to abortion, stillbirth or fetal malformation.

Management

Management is symptomatic, especially since rubella is a mild disease. Patients should rest quietly until they feel well and take paracetamol for fever and aching joints.

Related Info Measles And Rubella

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Measles is also known as the First Disease, caused by the highly contagious Measles virus (an RNA paramyxovirus).

The clinical presentation can be considered in three stages:

• Prodromal stage: The prodrome (before appearance of the rash) lasts for 4-5 days with fever, malaise, loss of appetite, diarrhoea and upper respiratory tract symptoms of runny nose, cough and red eyes. The pathognomonic sign is the Koplik spots in the oral mucosa which appear during the prodrome.
• Exanthema stage: The rash is a typically blotchy, bright red maculopapular eruption, appearing first on the face and neck, and then gradually spreading to the body and extremities. This will last for 4-5 days. The rash is often confluent in the upper part of the body, but discrete in the legs. The rash blanches under pressure and the fever is even higher when the rash appears. The fever usually subsides within 5 days of the onset of the rash.
• Convalescent stage: The rash fades, leaving a temporary brownish “staining”. The patient’s cough may persist for days.

Complications

Respiratory:
During the course of measles, all patients show evidence of viral respiratory tract involvement. Middle ear infection is the most frequent bacterial complication in children. Bacterial laryngitis, tracheo-bronchitis and pneumonia are also well-recognized complications. Giant cell pneumonia is an uncommon, progressive fatal complication observed in children with immune deficiency.

Central nervous system:
Febrile convulsion is a common complication. In about 1 in 1000 cases, post-infective encephalitis appears on the fourth to seventh day after the appearance of the rash. The symptoms vary according to the degree and site of neural tissue involved. There is invariably disturbance of consciousness, ranging from agitation, drowsiness and stupor to coma, in association with one or more of the following:

• speech and visual disturbance
• convulsions
• pyramidal signs
• cerebellar signs
• involuntary movements
• cranial nerve palsies

Death occurs in about 10% of cases and neurological and psychological sequelae are present about 30-40% of the survivors.

Late complications:
Two rare complications are bronchiectasis and subacute sclerosing panencephalitis. The latter can occur months or years after the measles infection, especially it occurred before the age of 2 years. The onset is insidious with gradual deterioration of intellect, accompanied by motor disturbance, myoclonic jerks and visual loss.

Treatment

There is no specific treatment except for symptomatic relieve. The patient should rest quietly, avoid bright lights and stay in bed until the fever subsides.

School exclusion

Children should be kept away from school until they have recovered or for at least 5 days from the onset of the rash.

Prevention

All children should be immunized against measles. Children having cytotoxic agents for malignant disease, or with immunodeficiency should not be given vaccine.

Related Info Measles And Rubella

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