Chickenpox natural history

Complications
There are quite a few complications associated with the chickenpox disease. Two of the most common complications are:


 * Bacterial infections of the skin and soft tissues in children
 * Pneumonia in adults

Some of the severe complications associated with chickenpox include:


 * Toxic shock syndrome
 * Necrotizing fasciitis
 * Septicemia
 * Osteomyelitis
 * Bacterial pneumonia
 * Septic arthritis]

Other complications include:


 * Cerebellar ataxia
 * Encephalitis
 * Viral pneumonia
 * Hemorrhagic conditions.

Prognosis
Chickenpox infection is milder in young children, and symptomatic treatment, with a sodium bicarbonate baths or antihistamine medication may ease itching. Paracetamol (acetaminophen) is widely used to reduce fever. Aspirin, or products containing aspirin, must not be given to children with chickenpox (or any fever-causing illness), as this risks causing the serious and potentially fatal Reye's Syndrome.

In adults, the disease can be more severe, though the incidence is much less common. Infection in adults is associated with greater morbidity and mortality due to pneumonia, hepatitis and encephalitis. In particular, up to 10% of pregnant women with chickenpox develop pneumonia, the severity of which increases with onset later in gestation. In England and Wales, 75% of deaths due to chickenpox are in adults. Inflammation of the brain, or encephalitis, can occur in immunocompromised individuals, although the risk is higher with herpes zoster. Necrotizing fasciitis is also a rare complication.

Secondary bacterial infection of skin lesions, manifesting as impetigo, cellulitis, and erysipelas, is the most common complication in healthy children. Disseminated primary varicella infection, usually seen in the immunocompromised or adult populations, may have high morbidity. Ninety percent of cases of varicella pneumonia occur in the adult population. Rarer complications of disseminated chickenpox also include myocarditis, hepatitis, and glomerulonephritis.

Hemorrhagic complications are more common in the immunocompromised or immunosuppressed populations, although healthy children and adults have been affected. Five major clinical syndromes have been described: febrile purpura, malignant chickenpox with purpura, postinfectious purpura, purpura fulminans, and anaphylactoid purpura. These syndromes have variable courses, with febrile purpura being the most benign of the syndromes and having an uncomplicated outcome. In contrast, malignant chickenpox with purpura is a grave clinical condition that has a mortality rate of greater than 70%. The etiology of these hemorrhagic chickenpox syndromes is not known.