Chickenpox, a extremely contagious infection, is usually a benign illness of childhood characterized by an exanthematous vesicular rash. Children between the ages of 5 and 9 are most commonly affected and account for 50 percent of all cases.

Clinically, chickenpox presents as a rash, low-grade fever, and malaise.

The skin lesions, the hallmark of the infection, include maculopapules, vesicles, and scabs in various stages of development. These lesions, which evolve from maculopapules to vesicles over hours to days, appear on the trunk and face and rapidly spread to involve other areas of the body. Most are small and have an erythematous base with a diameter of 5 to 10 mm. Successive crops of rash appear over a 2 to 4 day period. Lesions also can be found on the mucosa of the pharynx and or the vagina. Their severity varies from one individual to another. Some individuals have very few lesions, while others have as many as 2000. Younger children tend to have fewer vesicles than older individuals.

The most common infectious complication of chickenpox is secondary bacterial superinfection of the skin.

The most common extracutaneous site of involvement in children is the nervous system. Pneumonia is the most serious complication following chickenpox, developing more commonly in adults.

Other complications of chickenpox include myocarditis, corneal lesions, nephritis, arthritis, bleeding diatheses, acute glomerulonephritis, and hepatitis.

Chickenpox, is more severe in the immunocompromised than in the normal individual.