Wasting Syndrome
The involuntary loss of more than 10 percent of body weight, plus more than 30 days of either diarrhea or weakness and fever. Wasting refers to the loss of muscle mass, although part of the weight loss may also be due to loss of fat. HIV-associated wasting syndrome is considered an AIDS-defining condition.

Western Blot
A laboratory technique used to detect a specific protein. A Western blot test to detect HIV proteins in the blood is used to confirm a positive HIV antibody test (ELISA).
See Also:   Enzyme-Linked Immunosorbent Assay

White Blood Cells
Also known as leukocytes. These cells make up the immune system and include lymphocytes, monocytes, neutrophils, eosinophils, macrophages, and mast cells. White blood cells are made by bone marrow and help the body fight infection and other diseases.

Wild-Type Virus
A term to describe virus strains (including strains of HIV) that have not acquired any genetic mutations that create special characteristics, such as resistance to particular drugs.

Window Period
The time period between a person's infection with HIV and the appearance of detectable anti-HIV antibodies. Because antibodies to HIV take some time to form, an HIV antibody test will not be positive immediately after a person is infected. The time delay typically ranges from 14 to 21 days, but varies for different people. Nearly everyone infected with HIV will have detectable antibodies by 3 months after infection.
See Also:   Enzyme-Linked Immunosorbent Assay
                   Antibody

WIHS
See: Women's Interagency HIV Study

Women's Interagency HIV Study (WIHS)
A multicenter study established in 1993 to research the impact of HIV infection in women. The study’s ultimate goal is to gain a better understanding of and provide adequate support for women who are currently HIV infected or who are at risk for HIV infection. The study is jointly supported by the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC).