Varicella

Varicella (chickenpox) Virus

Definition/History:

* Chickenpox also known as varicella is a very contagious infection caused by the varicella zoster virus.

* Varicella was not reliably distinguished from smallpox until the end of the 19th century. Herpes zoster (shingles) has been recognized since ancient times and was described in the early medical literature.

* Clinical observations of the relationship between varicella and herpes zoster were made in 1888 by Von Bokay, when susceptible children acquired varicella after contact with herpes zoster.

The etiology:

* Chickenpox is usually acquired by the inhalation of airborne respiratory droplets from a varicella-zoster virua infected host. High viral titers are found in the characteristic vesicles of chickenpox; thus, viral transmission may also occur through direct contact with these vesicles.

Mode of transmission:

* Chickenpox is easily transmissible from person to person. About 90% of non-immune household contacts of someone infected with chickenpox will contract the disease.

* Transmission of chickenpox occurs via infected respiratory tract secretions, respiratory droplets, and fluid from the blisters. A person is infectious from one to two days before the rash appears to the time the blisters crust over and no longer contain fluid.

Symptoms:

Chickenpox infection usually lasts about five to 10 days. The rash is the telltale indication of chickenpox. Other signs and symptoms, which may appear one to two days before the rash, include:

* Fever

* Loss of appetite

* Headache

* Tiredness and a general feeling of being unwell (malaise)

Once the chickenpox rash appears, it goes through three phases:

* Raised pink or red bumps (papules), which break out over several days

* Fluid-filled blisters (vesicles), forming from the raised bumps over about one day before breaking and leaking

* Crusts and scabs, which cover the broken blisters and take several more...