Chickenpox natural history
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Natural History
In a typical scenario, a young child is covered in pox and out of school for a week. The first half of the week the child feels miserable from intense itching; the second half from boredom. Since the introduction of the chickenpox vaccine, classic chickenpox is much less common. Chickenpox is extremely contagious, and can be spread by direct contact, droplet transmission, and airborne transmission. Even those with mild illness after the vaccine may be contagious. When someone becomes infected, the pox usually appear 10 to 21 days later. People become contagious 1 to 2 days before breaking out with pox. They remain contagious while uncrusted blisters are present. Once you catch chickenpox, the virus usually remains in your body for your lifetime, kept in check by the immune system.
Complications
The pox are worse in children who have other skin problems, such as eczema or a recent sunburn. Complications are more common in those who are immunocompromised from an illness or medicines like chemotherapy. Some of the worst cases of chickenpox have been seen in children who have taken steroids during the incubation period, before they have any symptoms.
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.
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.
Prognosis
Chickenpox is rarely fatal (usually from varicella pneumonia), with pregnant women and those with a suppressed immune systems being more at risk. Pregnant women not known to be immune and who come into contact with chickenpox may need urgent treatment as the virus can cause serious problems for the baby. This is less of an issue after 20 weeks.
Later in life, viruses remaining dormant in the nerves can reactivate causing localised eruptions of shingles. This occurs particularly in people with compromised immune systems, such as the elderly, and perhaps even those suffering sunburn. Unlike chickenpox which normally fully settles, shingles may result in persisting post-herpetic neuralgia pain.
Chickenpox infection is milder in young children, and symptomatic treatment, with a sodium bicarbonate baths or antihistamine medication may ease itching.[1] 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. [2]
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.[3]Necrotizing fasciitis[4] 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.
References
- ↑ Somekh E, Dalal I, Shohat T, Ginsberg GM, Romano O (2002). "The burden of uncomplicated cases of chickenpox in Israel". J. Infect. 45 (1): 54–7. PMID 12217733.
- ↑ US Centers for Disease Control and Prevention. "Varicella Treatment Questions & Answers". CDC Guidelines. CDC. Retrieved 2007-08-23.
- ↑ "Definition of Chickenpox". MedicineNet.com. Retrieved 2006-08-18.
- ↑ "Is Necrotizing Fasciitis a complication of Chickenpox or of Cutaneous Vasculitis?". atmedstu.com. Retrieved 2008-01-18.