Dictionary

Y-linked A gene on the Y chromosome that is passed from father to son. See also holandric inheritance.

Yersinia A family of bacteria that includes Yersinia pestis, which causes the bubonic, pneumonic, and septicemic plagues; Y. entercolitica, which causes intestinal infections, including mesenteric lymphadenitis, a condition that mimics appendicitis; and Y. pseudotuberculosis, which usually adversely affects only animals but can cause illness in immunocompromised patients. Both Y. entercolitica and Y. pseudotuberculosis have also…

yellow jacket stings Stings from yellow jackets that can trigger allergic reactions of varying severity. Avoidance and prompt treatment of allergic reactions (including diphenhydramine, brand name: Benadryl; and epinephrine, brand name: Epi-Pen) are essential. In selected cases, allergy injection therapy is highly effective for prevention.

yellow fever vaccination A live attenuated (weakened) viral vaccine for yellow fever. Yellow fever vaccination is recommended for people traveling to or living in the tropical areas in the Americas and Africa where yellow fever occurs. Because yellow fever vaccination is a live vaccine, it should not be given to infants or people with immune-system…

yellow fever An acute, systemic viral illness transmitted to humans through the bite of infected mosquitos that may cause a flu-like illness or a more severe illness with high fever, bleeding into the skin, and death of cells (necrosis) in the kidney and liver. The liver damage (hepatitis) causes yellowing of the skin from severe…

yeast vulvitis A yeast infection of the vulva. Yeast vulvitis commonly occurs with yeast vaginitis. Common symptoms include itching, burning, soreness, pain during intercourse and urination, and vaginal discharge. Treatment involves use of topical or oral antifungal medications. See also Candida albicans; yeast; yeast infection; yeast vaginitis.

yeast vaginitis Infection of the vagina by Candida albicans, which characteristically causes itching, burning, soreness, pain during intercourse and urination, and vaginal discharge. Yeast vaginitis occurs when new yeast are introduced into the vagina or when the quantity of yeast in the vagina increases relative to the quantity of bacteria. Yeast vaginitis can be exacerbated…

yeast rash A slightly raised pink-to-red rash that is caused by proliferation of yeast, usually in a moist area such as the groin. Yeast rash is most common in infants, but it can also occur on the skin of older children and adults. Treatment involves keeping the affected area clean and dry and applying topical…

yeast infection Overgrowth of yeast that affects the skin (yeast rash), mouth (thrush), digestive tract, esophagus, vagina (vaginitis), or other parts of the body. Yeast infections occur most frequently in moist areas of the body. Although Candida albicans and other Candida yeasts are the most frequent offenders, other yeast groups are known to cause illness,…

yeast diaper rash Infection in the diaper area of a baby that is caused by a yeast called Candida. Certain conditions, such as antibiotic use or excessive moisture, can upset the balance of microbes and allow an overgrowth of Candida. The infected skin is usually fiery red with areas that may have a raised red…

yeast A group of single-celled fungi that reproduce by budding. Most yeast is harmless, and yeast is commonly present without ill effect on normal human skin and mucous membranes, including the gastrointestinal (GI) tract. In the GI tract, the amount of yeast is usually controlled by helpful bacteria, although this balance can be upset by…

yaws A chronic infectious disease that occurs commonly in the warm, humid regions of the tropics. Yaws is characterized by bumps on the skin of the face, hands, feet, and genital area. Almost all cases of yaws are in children under 15 years of age. The organism that causes yaws is a type of spirochete…