Pre–eruptive Stage There is sudden onset with mild or moderate fever, pain in the back, shivering and malaise. This stage is very brief, and lasting for about 24 hours. In adults, the prodromal illness is usually more severe and may last for about two to three days before the rash comes out.
Eruptive Stage In children, the rash is often the first sign. It appears on the day the fever starts. The distinctive features of the rash are:
- Centripetal Distribution
The rash is symmetrical. It first appears on the trunk where it is abundant, and then on the face, arms and legs, where it is less abundant. Mucosal surfaces (e.g. buccal, pharyngeal) are generally involved. Axilla may be affected, but palms and soles are not usually affected. The density of the eruption diminishes centrifugally.
- Rapid Evolution
The rash advances quickly through the stages of macule, papule, vesicle and scab. In fact, the first to attract attention are often the vesicles filled with clear fluid and looking like “Dewdrops” on the skin. They are superficial in site, with easily ruptured walls and surrounded by an area of inflammation. Usually, they are not umbilicated. The vesicles may form crusts without going through the pustular stage. Many lesions may abort. Scabbing begins four days to a week days after the rash appears.
A characteristic feature of the rash in Chicken Pox is its pleomorphism, that is, all stages of the rash (papules, vesicles and crusts) may be seen simultaneously at one time, in the same area. This is due to the rash appearing in successive crops for four to five days in the same area.
The fever does not run high but gets exacerbated with each fresh crop of eruption.
Complications In most cases, Chicken Pox is a mild, self–limiting disease. The mortality is less than 1% in uncomplicated cases. However, Varicella may be accompanied by severe complications, particularly in immuno–suppressed patients, and may also occur in normal children and adults. These include hemorrhages (varicella hemorrhagica), pneumonia, encephalitis, acute cerebellar ataxia and Reye’s Syndrome (acute encephalopathy associated with fatty degeneration of the viscera, especially the liver). Maternal Varicella during pregnancy may cause fetal wastage and birth defects such as cutaneous scars, atrophied limbs, microcephaly, and low birth weight. Intrauterine infection occurring near term may cause Typical Varicella in the newborn with varying degrees of severity depending on the transfer of maternal–specific lG antibodies.