vaginitis An inflammation or infection of the vagina. Vaginitis occurs when the normal environment of the vulva and vagina is disturbed, usually by common bacteria. Although the vagina resists disease as well as the rest of the body, vaginal imbalance and lowered resistance to infection can be caused by poor diet; lack of sleep, exercise or cleanliness; and stress. Causes of vaginitis include trichomona virus, candida, bacterial vaginosis, and several other possibilities. The presence of vaginal pathogens may predispose women to increased frequency of herpes outbreaks or recurrences of
vaginosis See bacterial vaginosis.
valaciclovir A medication used in the treatment of herpes zoster (shingles) and herpes simplex (genital herpes). It inhibits the replication of viral DNA that is necessary for viruses to reproduce themselves. Valaciclovir is actually a prodrug, meaning that it is not active itself against the virus. Rather, in the body it is converted to acyclovir, which is active against the viruses. It has been shown to be more effective at lower doses than acyclovir. Valaciclovir, therefore, is active against the same viruses as acyclovir but has a longer duration of action. (Trade name is Valtrex.)
valganciclovir A prodrug form of ganciclovir, which is taken orally. Through absorption in the body, the drug converts rapidly into ganciclovir. It has been approved for the treatment of cytomegalovirus (CMV) in HIV patients. It does not cure people of cMV but does slow or stop the progression of the disease, which otherwise would lead to blindness in many people. If people are taking AzT and ddI, their dosages of those drugs must be changed, as valganciclovir alter their metabolism. Side effects are similar to those of ganciclovir, so people who have had allergies to one drug should not take the other. common side effects include diarrhea, nausea, headache, and sometimes neutropenia. currently the drug is taken twice a day, an improvement over the intravenous administration ganciclovir, formerly used to treat cMV. (Trade name is Valcyte.)
valley fever See coccidioidomycosis.
variable In research studies, an element or condition that changes or may change in a measurable way in relation to other elements, providing a means to value and compare results. An independent variable is controlled by the investigator directly to allow examination of its effects; a dependent variable is one which is influenced by the independent variable. See drug trial.
varicella-zoster virus (VZV) Also known as human herpesvirus-3 (HHV-3). VZV is a virus related to the herpes simplex viruses. It is responsible for two different illnesses in humans: chicken pox (varicella) and shingles (herpes zoster). Upon initial infection the virus causes chicken pox, a rash of pustules that begins typically on the body, moving outward to the arms, legs, and face. These pustules then crust over and typically disappear. It is highly contagious at this point and can be spread through the air by sneezing and coughing. After the illness ends, the virus does not leave the body. It lies dormant in the ganglia, the "nerve roots," of the spinal cord. When the VZV is reactivated, it causes pain and a rash in the area supplied by the affected sensory nerves. This is commonly called shingles. The virus typically reactivates in later years or when people have immune disorders. Shingles can be contagious to children or adults who have not had chicken pox if they have contact with the broken blisters caused in shingles. Someone who has had shingles is most unlikely to contract it again; it recurs in only 4 percent of adults. People with compromised immune systems may, however, have recurring cases, though in a different location from the first outbreak.
vas deferens The tube that transfers sperm from the testicles to the seminal vesicles.
vasectomy The surgical severing of the vas defer-ens, usually as a means to prevent conception. Vasectomy leaves the man's genital system basically unchanged. His sexual hormones remain operative, and there is no noticeable difference in his ejaculate because sperm makes up only a small part of the semen. A vasectomy does not offer protection from HIV transmission during a sexual encounter. The semen of an HIV-positive man can transmit HIV regardless of whether or not a man has had a vasectomy.
VD See sexually transmitted disease.
VDRL See venereal disease research laboratories TEST.
vector A carrier or means of transport. A disease vector is a carrier that moves a disease-causing agent from one organism to another. An example of a disease vector is a mosquito. A viral vector is an engineered virus used to introduce genes into an organism; it can also be a live virus used in a vaccine to insert an antigen into an organism and generate an immune response.
vector vaccine A vaccine using a non-disease-causing virus or bacterium to transport HIV or other foreign genes into the body. The genomes of these "vector" viruses, including hiv dna, integrate into the host cell's genetic machinery.
Venereal Disease Research Laboratories (VDRL) test A laboratory test, named after the Venereal Disease Research Laboratory of the U.S. public health service, where it was developed, for the presence of antibodies in the blood to Treponema pallidum, the microorganism that causes syphilis. It is the only test for syphilis that uses spinal fluid in deriving its results.
Was this article helpful?