More formally known as varicella, it is an acute, contagious disease predominantly of children – although it may occur at any age – characterised by fever and an eruption on the skin. The name, chickenpox, is said to be derived from the resemblance of the eruption to boiled chick-peas.
It is due to the varicella zoster virus and is very contagious from child to child. Although an attack confers life-long immunity, the virus may lie dormant and manifest itself in adult life as HERPES ZOSTER or shingles.
There is an incubation period of 14–21 days after infection, and then the child becomes feverish and may have vomiting and muscle pain. Almost at the same time, an eruption consisting of red pimples which quickly change into vesicles (blisters) filled with clear fluid appears on the back and chest, sometimes about the forehead, and less frequently on the limbs. These vesicles appear over several days and during the second day may show a change of their content to a more opaque yellow fluid. Within a day or two they burst, or shrivel up and become covered with brownish crusts. The small crusts have all dried up and fallen off in little more than a week and recovery is almost always complete, although there are rare complications, the most serious being ENCEPHALITIS.
The fever can be reduced with paracetamol and the itching soothed with CALAMINE lotion. If the child has an immune disorder, is suffering from a major complication such as encephalitis or pneumonia, an antiviral drug, ACICLOVIR is given A vaccine is available in many parts of the world but is not used in the UK; the argument against its use being that it may delay chickenpox until adult life when the disease tends to be much more severe.