Age- Chicken pox is the disease of childhood. But it can occur at any age and adult chicken pox which is more common in some tropical areas for reasons not understood is much more serious.
Source of infection -The source of infection is a chicken pox or herpes zoster patient. Infectivity is maximum during the initial stages of the disease when the virus is present abundantly in the upper respiratory tract. Infectivity diminishes with the progress of the disease and the scabs are practically non- infectious.
Route of entry-The portal of entry of the virus is the upper respiratory tract.
Incubation Period- 7-23 days, average 2 weeks.
Onset-Acute.
Clinical Features- There are malaise, headache, weakness, fever and prodromal rash. In children the prodromal illness is mild and so the disease is usually noticed only when the skin lesions appear. In adults, however, prodromal fever and malaise with respiratory symptoms lasting 2-3 days are common features. True rash usually appears on the first day of the disease and is vesicular in nature. The rash is centripetal in distribution, affecting mainly the trunk along with face & scalp and sparing the distal parts of the limbs. Moreover, the rash is very superficial and does not involve the deeper layers of the skin. With each fresh crops of rash temperature rises. The vesicles are unilocular and not umbilicated. Fever subsides as soon as new lesions cease to appear. Eventually the pustules crust and heal without scarring. The illness tends to be more severe in older children and can be debilitating in adults. One of the most characteristic features of the rash is pleomorphism and so all stages of the rash that is papules, vesicles and crusts may be seen simultaneously at one time in the same area.
Complications-
Secondary bacterial infection usually due to staphylococci or streptococci may occur.
Varicella pneumonia- It is an important complication that usually 1-6 days after skin eruption. Varicella pneumonia is found mainly in adults where it usually becomes fatal. Besides these, CNS ( Central nervous system) involvement occurs in rare cases. The immunocompromised are susceptible to disseminated infection with multi-organ involvement.
Prognosis- Chicken pox requires no treatment in healthy children and infection results in life-long immunity. But the disease may be fatal in the immunodeficient or the immunosuppressed. If the primary infection occurs during pregnancy, the virus may cross the placenta with subsequent infection of the foetus. Primary infection of the mother near term may lead to neonatal varicella.
Treatment- Rhus.t ( Rhus toxicodendron) 30 is very effective to cope with skin lesions & should be used six times daily for one week or till the lesions heal & then should be stopped. Dulc (Dulcamara) & Merc.s ( Mercurius –Hydrargyrum ) be also used especially for high temperature.