Also known as varicella. 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 chickpeas.
Causes The disease occurs in epidemics aﬀecting especially children under the age of ten years. It is due to the varicella zoster virus, and the condition is an extremely infectious one 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.
Symptoms There is an incubation period of 14–21 days after infection, and then the child becomes feverish or has a slight shivering, or may feel more severely ill with vomiting and pains in the back and legs. Almost at the same time, an eruption consisting of red pimples which quickly change into vesicles 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 contents to turbid, purulent ﬂuid. Within a day or two they burst, or, at all events, 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.
Treatment 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 pneumonia, or is very unwell, an antiviral drug (aciclovir) can be used. It is likely to be eﬀective only at an early stage. A vaccine is available in many parts of the world but is not used in the UK; the argument against its use is that it may delay chickenpox until adult life when the disease tends to be much more severe.