VARICELLAVARICELLAVARICELLAVARICELLAVARICELLAVARICELLAVARICELLAVARICELLA

(Chicken pox)(Chicken pox)

Infectious and Tropical Pediatric Division, Department of Child Health,

Medical Faculty, University of Sumatera Utara

Definition : Varicella is a common contagious disease caused by primary infection with varicella-zoster virus (VZV). It is characterized by a short or absent prodromal period and by a pruritic rash consisting of crops of papules, vesicles, pustules, and crusting

Etiology : Varicella zoster virus (VZV) �Herpesvirus group

Epidemiology : worldwide distribution, usually endemic in large cities. The mostly age distribution is 5-9 year old. Transmission by direct contact, droplet. The patient can transmit the disease 1 day before the rash appeared until crusted was dried. In mild cases, crusted was dried. In mild cases, crusted was completed until 5 days, and in severe cases until 10 days.

Epidemiology of primary Epidemiology of primary varicellavaricella

• 90% of cases occur at <10 years of age; maximum incidence ages 1-6

• Older children more likely to have prodromal symptoms[Whitney RJ (1990) Antiviral agents and viral diseases of man. Raven Press, NY]

• Higher risk of herpes zoster in healthy children infected with VZV during infancy [Kakourou T et al.(1998) JAAD 39, 207-10; Baba K et al.

(1986) J Pediatr 372-7.]

• Highly contagious, with >90% household transmission rate [Ross AH (1962) NEJM 267, 369-76.]

• 10-35% transmission rate with secondary contacts like school [Ross AH (1962) NEJM 267, 369-76.]

Pathogenesis :

Primary Primary varicellavaricella

• Days 2-4: initial viral replication in regional lymph nodes

• Days 4-6: primary viremia• Days 4-6: primary viremia

• Subsequent second round of viral replication in liver, spleen, other organs

• Secondary viremia seeds capillaries and then epidermis by day 14-16

Herpes zosterHerpes zoster

• VZV spreads from skin/mucosa into sensory nerve endings

• Virus travels to dorsal root ganglion and becomes latentbecomes latent

• Reactivation occurs with decreased cell-mediated immunity

• Initial replication occurs in affected DRG after reactivation

• Ganglionitis ensues, with inflammation and neuronal necrosis

• Pain ensues with travel of the virus • Pain ensues with travel of the virus down the sensory nerve

Clinical manifestations :

Incubation period 14-16

days (10-21 days). The

disease begins with

low-grade fever, low-grade fever,

malaise, and the

appearance of rash. In

children the exanthem

and symptoms usually

occur simultaneously.

Rash : The typical vesicle of chickenpox is superficially located in the skin. The lesion appear in crops that appear in crops that generally involve the trunk, scalp, face, and extremities. The distribution typically central especially on trunk and face.

The rash is more profuse on the proximal parts of the extremities than on the distal parts. A distinctive manifestation of the eruption is the presence of lesions in all stages in any one general anatomical area; macules, papules, vesicles, pustules, and crusts are usually located in proximity to each other. In summary, the rash characterized by (1) a summary, the rash characterized by (1) a rapid evolution of macule to papule to vesicle to pustule to crust, (2) a central distribution of lesions that appear in crops, and (3) the presence of lesions in all stages in any one anatomical area.

Fever : The height of the fever usually paralels the severity of the rash. When the eruption is sparse, the temperature is usually normal or slightly elevated.

Other symptoms : headache, malaise, and anorexia usually accompany the fever. The most distressing symptom is pruritus, The most distressing symptom is pruritus, which is present during the vesicular stage of the disease.

Unusual manifestations :

Hemorrhagic, progressive, and disseminated varicella � in immunompromised host and a potencially fatal outcome. Our department had been reporting 3 cases with varicella hemorrhagic, two in immunocompromised child and the other in normal child. child and the other in normal child.

Congenital varicella syndrome is extremely rare. Manifestations of this syndrome include a hypoplastic extremity, zosteriform skin scarring, microphthalmia, cataracts, choreoretinitis, and abnormalities of the CNS.

Severe or fatal

varicella in 5 to 10

day-old infants may

occur when their occur when their

mothers have

varicella 5 days or

less before delivery.

Diagnosis :

1. Confirmatory clinical factors, (1) development of a pruritic papulovesicular eruption concentrated on the face and trunk associated with fever and mild constitutional associated with fever and mild constitutional symptoms;

(2) the rapid progression of macules to papules, vesicles, pustules, and crusts; (3) the appearance of these lesions in crops, with a predominant central distribution including the scalp; (4) the presence of shallow white ulcers on the mucous membranes of the mouth; and (5) the membranes of the mouth; and (5) the eventual crusting of the skin lesions.

2. Detection of the causative agent from vesicular fluid

3. Serological tests : ELISA, FAMA, RIA, LA

Differential diagnosis :

1. Impetigo

2. Insect bites, papular urticaria, and urticaria

3. Scabies

4. Dermatitis herpetiformis

5. Rickettsialpox5. Rickettsialpox

6. Eczema herpeticum and other forms of HSV infection

7. Steven-Johnson syndrome

8. Smallpox

Chickenpox versus smallpoxChickenpox versus smallpox

CHICKENPOX

• 14-21 day incubation

• Mild to no preceding illness

• Lesions most numerous

SMALLPOX

• 7-17 day incubation

• Fevers, severe systemic symptoms precede rash by 2-3 days• Lesions most numerous

on trunk

• Palms and soles spared

• Lesions at varying stages of development

• Scabs form 4-7 days after rash appears

• Vesicles do collapse on puncture

by 2-3 days

• Lesions most numerous on face, arms, legs

• Palms and soles involved

• Lesions at same stage of development

• Scabs form 10-14 days after rash appears

• Vesicles do not collapse on puncture

Complications : are not common

1. Secondary bacterial infection

2. Encephalitis

3. Varicella pneumonia

4. Reye’s syndrome

5. Disseminated varicella5. Disseminated varicella

Prognosis : usually a benign disease, clears spontaneously without sequaelae.

Complications and mortality in Complications and mortality in varicellavaricella

• In healthy children aged 1-14, mortality rate estimated at 2/100,000 [Mehta PN (2004) eMedicine online]

• Bacterial superinfection is most common complication; Staph exotoxin can result in bullous varicella [Melish ME (J Pediatr (1973) 83, 1019-21]

• CNS is most common extracutaneous site; symptoms include Reye’s syndrome, acute cerebellar ataxia, encephalitis, myelitis [McKendall and

Kiawans (1978) Handbook of clinical neurology. Elsevier Press]

• Rare complications: myocarditis, appendicitis, glomerulonephritis, hepatitis, pancreatitis, vasculitis, arthritis, keratitis, iritis, optic neuritis Whitney RJ (1990) Antiviral agents and viral diseases of man. Raven

Press, NY]

Immunity : an attack of chickenpox usually confers lasting immunity.

Treatment : self limited disease

1. Symptomatic � acetaminophen for high fever; oral antihistamines and local applications of of calamine lotion may help applications of of calamine lotion may help control the itching. Fingernails should be kept short and clean in an attempt to minimize secondary skin infections. For same reason, daily bathing also recommended during chickenpox.

2. Treatment of complications :

(1) bacterial infections

(2) encephalitis

3. Specific antiviral : 20 mg/kg of acyclovir four times daily for 5 days (max 800 mg)

Preventive measures : Preventive measures :

1. Zoster immunoglobulin (ZIG) 5 ml/IM within 72 hours of a household exposure to children with underlying leukemia.

2. Live attenuated varicella vaccine.