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varicella(vâr'əsĕl`ə), infectious disease usually occurring in childhood. It is believed to be caused by the same herpesvirus that produces shingles. Chicken pox is highly communicable and is characterized by an easily recognizable rash consisting of blisterlike lesions that appear two to three weeks after infection. Usually there are also low fever and headache. When the lesions have crusted over, the disease is believed to be no longer communicable; however, most patients simultaneously exhibit lesions at different stages of eruption. Chicken pox is usually a mild disease requiring little treatment other than medication to relieve the troublesome itching, but care must be taken that the rash does not become secondarily infected by bacteria. Pneumonia and encephalitis are rare complications. A vaccine for chicken pox was approved for use in the United States in 1995. The drug acyclovir may be used to treat the disease, particularly in older patients.
an acute infectious disease accompanied by fever and a characteristic vesicular rash on the skin. Children up to ten years of age are chiefly affected. After infection with chicken pox, immunity is maintained for life. The causative agent of chicken pox is a filterable virus, which is transmitted from an infected person to a healthy one mainly by means of air droplets (fine sprays of saliva during coughing, speaking, or sneezing). The increasing circulation of the virus in the blood (viremia) causes its penetration into various sections of the skin, where, at first, small red spots are formed, slightly raised above skin level, which subsequently turn into blisters.
The incubation period (the time from infection until the appearance of the first symptoms of the disease) is from 11 to 21 days. After the rise in temperature (which lasts 5-7 days) to 39-39.5° C, the rash appears on various parts of the body, in the pharynx, and on the mucosa of the nasopharynx. The blisters formed are filled with a transparent fluid and are surrounded by a thin red rim. Later, the blisters burst, and their contents dry and form crusts. Repeated skin eruptions and multiformity of rashes is characteristic. In addition to spots and blisters, crusts may form. The rash is distributed over the face, the scalp, the torso, and sometimes the extremities, including the palms and soles. Complications with chicken pox are extremely rare (mainly in debilitated children); they may develop with the introduction of purulent infection from scratching the rash (impetigo, abscesses, and so forth).
The patient may transmit the infection beginning with the last days of the incubation period (one to two days before the appearance of the rash) until five days from the last eruption of spots. Therefore a primary prophylactic measure is to forbid, during all this time, any contact by the patient with healthy, previously uninfected children, since the infectiousness of chicken pox is very great. Previously uninfected children who have been in contact with an infected one are subjected to quarantine (at home) or separation for a period of 21 days; if the day of contact is definitely established, children are isolated from 11 days until 21 days after contact. Inasmuch as there is sufficient evidence of the identity of the chicken-pox virus with that of herpes zoster, it is necessary to protect previously uninfected children from contact with herpes zoster patients.
Treatment includes bed rest during the first days of the illness and strict maintenance of cleanliness in order to avoid introduction of purulent infection from scratching the rash. Elements of the rash are also smeared with a dark red solution of potassium permanganate or a solution of brilliant green.
REFERENCENosov, S. D. Uchebnik detskikh infektsionnykh boleznei, 2nd ed. Moscow, 1961.
K. V. BUNIN [4-1769-1J