Also known as chickenpox. Varicella is caused by the varicella zoster virus, a type of herpes virus. It is an acute contagious infectious disease—especially of children. The infection spreads from person to person by direct contact or through the air from an infected person’s coughing or sneezing. The disease is marked by a low-grade fever and a blister-like rash on the body. The rash causes itching. A person with chickenpox is contagious 1-2 days before the rash appears and until all blisters have formed scabs.

Viral Fitness:

As HIV obtains certain genetic mutations, its ability to replicate can be diminished compared to that of wild-type strain.

Virologic Failure:

Based on U.S. Department of Health and Human Services guidelines, this is defined as detectable HIV virus in the blood after 24 weeks from initiating therapy or changing therapy. HIV RNA level greater 500 copies/ml at 12 to 16 weeks is a good predictor of failure.


The study of viruses and viral disease.


Also known as AZT or ZDV. An antiretroviral drug in the class of nucleoside reverse transcriptase inhibitors. It was the first drug approved in the U.S. for treatment of HIV/AIDS. It was approved in 1987.

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