Category: H

An abnormal pregnancy, also called a molar pregnancy, which probably re sults from the fertilization of a so called empty egg, an egg without chromosomes. In this condition, the fertilized egg degenerates and the placenta grows into a mass of tissue resembling a cluster of grapes. When a woman has a hydatidiform mole, the uterus…

A disease caused by bacteria in the Ehrlichia genus that is carried and transmitted to humans by ticks, probably the dog tick or Lone Star tick. For many people, exposure to the bacteria does not cause symptoms. Other people who are infected may have mild symptoms including fever, severe headaches, malaise, muscle pains, chills, and…

An infection in humans that is transmitted by the black-legged tick and the western black-legged tick (Ixodes pacificus) in the United States. Human granulocytic ehrlichiosis (HGE) is an illness that resembles Rocky Mountain spotted fever. Unlike Rocky Mountain spotted fever, which is caused by bacteria of the Rickettsia genus, HGE is caused by bacteria of…

A condition that occurs when one or two species of nematodes, or round- worms, enter the human body. Hookworm infestation is a common cause of iron deficiency anemia among people who live in regions with a warm, humid climate, such as the tropics. The infestation generally occurs when a person’s bare skin makes direct contact…

Kits that can be purchased without a prescription to help diagnose pregnancy. Home tests are similar to the pregnancy tests performed by doctors, but the results may not be as accurate. Several different types of home pregnancy testing kits are available; they all involve the detection of a hormone called HCG (human chorionic gonadotropin) in…

Substances that help the body identify tissue as its own or as foreign. Histocompatibility antigens also help determine whether tissue or organ transplants will be accepted or rejected. Histocompatibility means “tissue compatibility.” If a tissue donor and recipient are histocompatible, as is the case with identical twins, a transplanted organ or tissue will be accepted…

A popular name for the medical term hypertension.  

Painful inflammation and ulceration of the outer surface (cornea) of the eye because of infection with the herpes virus. Most herpes infections of the eye are caused by type 1 herpes simplex virus, the type of herpes virus that causes fever blisters and cold sores. Prompt treatment with antiviral drugs (eye drops or pills) can…

An itchy rash that develops in the second or third trimester of pregnancy and usually disappears by 3 months after childbirth. The rash consists of fluid-filled blisters that can occur anywhere on the skin. Herpes gestationis is linked with premature birth. It often recurs in subsequent pregnancies, with menstruation, or while taking oral contraceptives. The…

A member of the herpes group of viruses that is carried by rhesus and other Asiatic macaque monkeys. Herpes B virus is also referred to as Herpesvirus simiae and can cause serious disease, including encephalitis. It is transmitted to humans from infected monkeys. Transmission via person-to-person contact has been documented in only one case.