Schistosomiasis

Schistosomiasis or Bilharziasis, widespread disease caused by the infestation of the human body by (flukes) commonly called blood flukes, of the genus Schistosoma. Blood flukes spend most of their life cycle in two hosts; the adult stage is spent in a mammal, usually humans, and the immature stages are spent in certain snails. Eggs discharged from the host hatch into larval forms in fresh water; from the water, the larvae, miracidia, invade the snail that acts as an intermediate host. The larval form of the parasite undergoes partial maturation in the snail, then escapes back into the water, as mature larvae called cercariae. At this stage they penetrate the skin of the host from the water and then migrate through the blood vessels to specific capillaries as maturation completes. There they remain and lay eggs.

Rickets

Rickets, nutritional disorder characterized by skeletal deformities. Rickets is caused by a decreased concentration of the mineral hydroxyapatite in bones and cartilage due to low levels of calcium and phosphorus in the blood. Vitamin D is essential for the maintenance of normal calcium and phosphorus levels. Classic rickets, a deficiency disease of children characterized by improper development or hardening of bones, is due to lack of sufficient vitamin D in the diet, or to insufficient ultraviolet radiation from direct sunlight, a lack that prevents conversion of the element 7-dehydrocholesterol in the skin to vitamin D. The type of skeletal deformities depends largely on the child's age when the vitamin-D deficiency occurs. A child who has not yet learned to walk develops vertebral curvatures; a walking child develops leg curvatures.

Riboflavin

Riboflavin, also called vitamin B2 or vitamin G, a substance essential for the breakdown and utilization of carbohydrates, fats, and proteins in the body, and in the production of energy. Riboflavin plays a vital role in the health of the skin and is needed for production of certain hormones by the adrenal glands, the pair of hormone-secreting organs that sit on top of each kidney. Because it is a water-soluble vitamin—that is, it is not stored in the body, but is excreted in sweat or urine—riboflavin needs to be constantly replaced in the body.

Rich sources of riboflavin include milk, cheese and yogurt, lean meat, liver, green leafy vegetables, eggs, and enriched breads and cereals. Because cheese and milk are such good dietary sources of the vitamin, lactose-intolerant people, including many of the elderly, are vulnerable to deficiency problems. Individuals who exercise often, especially women, are also at risk for riboflavin deficiency. A lack of riboflavin in the diet may result in inflammation, scaling, and blistering of the skin—symptoms characteristic of such conditions as dermatitis and eczema. Other problems can include general fatigue, burning eyes, cracks and sores in mouth and on the lips, and digestive problems.

Tracheotomy

Tracheotomy, surgical operation in which an incision, or opening, is cut through the front of the neck and into the trachea, or windpipe. The oldest mention of the operation in medical literature is found in the writings of the Greek physician Galen (2nd century ad).

A tracheotomy creates an alternate passage to the lungs for air that cannot flow from the nose and mouth through the trachea because of an obstruction. Obstructions may occur when a foreign body lodges in the larynx, or voice box, above the trachea; as a result of swelling or spasm of the larynx or vocal cords; or from infection and swelling of the epiglottis, the thin flap of cartilage covering that keeps food and liquid out of the trachea.

The purpose of a tracheostomy is to keep the airway from closing prematurely and to enable the physician to take further measures, if necessary, to ensure that the patient has a patent airway. When a tracheotomy is performed on a patient suffering from severe bronchial or lung congestion, a catheter, or small-diameter, flexible tube, is inserted through the stationary tube and used with a suction device to clean out the bronchial tubes and lungs while the patient is encouraged to cough vigorously.

Syringe

Syringe, device used to eject or collect fluids. A syringe consists of a hollow barrel made of glass, plastic, or metal with a close-fitting plunger or a rubber bulb on one end. The other end of the barrel has a nozzle which may be designed to accept a needle or other attachment. The barrel fills by suction when the plunger is pulled out, or when the bulb is compressed and subsequently allowed to inflate. Pushing in the plunger or squeezing the bulb forces the fluid out through the needle or nozzle.

Syringes come in many sizes and serve many purposes. The small syringe used in medicine to give hypodermic injections (forceful introduction of medication or fluid beneath the skin) has a plunger and a fine hollow needle. Its barrel is calibrated, featuring a set of equally spaced marks that measure the volume of its contents. The larger medical syringes used to cleanse wounds or body cavities, or to extract unwanted fluids from the body, have wider, flexible nozzles on one end and rubber bulbs on the other end.

Sharing unsterilized syringes can cause serious health problems. Human immunodeficiency virus (HIV), which may lead to acquired immunodeficiency syndrome (AIDS), has been spread by infected substance abusers who share the same syringe to inject intravenous drugs. The viruses that cause hepatitis A and hepatitis B, both of which inflame the liver, are also commonly transmitted through the use of shared needles and syringes.