Sulfa Drugs

Sulfa Drugs, common name applied to a group of chemotherapeutic agents that are effective against a number of infectious diseases. In 1935 the German chemist, Gerhard Johannes Paul Domagk discovered that an azo dye, Prontosil, cured streptococcal infections in mice. The active principle in Prontosil was found to be paraaminobenzenesulfonamide, commonly known as sulfanilamide. Clinical trials with sulfanilamide proved effective in arresting various bacterial diseases. Among the derivatives of sulfanilamide that have proved effective against such conditions as puerperal fever, scarlet fever, erysipelas, meningitis, pneumonia, and bacteremia are sulfapyridine, sulfathiazole, sulfadiazine, sulfaguanidine, sulfamerazine, and sulfasuxidine. All the sulfa drugs are somewhat toxic, producing blood abnormalities and kidney damage when indiscriminately used. Since the discovery of penicillin, which is as effective as the sulfa drugs although far less toxic, the use of sulfa drugs has somewhat declined. Because bacteria often develop resistance to a particular kind of treatment, however, sulfa drugs are used when bacterial tolerance for penicillin has developed. See Antibiotic.

Infection

Infection, injurious contamination of the body or part of the body by pathogenic agents, such as fungi (see Fungus Infections), bacteria, protozoa, rickettsiae, or viruses, or by the toxins that these agents may produce. An infection may be local and confined to one area or generalized and spread throughout the body. Once the infectious agent enters the host and begins to proliferate, the defense mechanisms of the body react to the infection, producing the characteristic symptoms of pain, swelling, reddening at the site of infection, functional disorders, rise in body temperature and pulse rates, and an increase in the number of white cells (see Immune System).

Infectious agents may enter the body of the host by several routes. The most common route is through the respiratory passages, urinary tract, and gastrointestinal tract, but other common entry routes are through the skin, especially injured skin, the mucosal surfaces of other body openings, and the conjunctiva of the eyes. Pregnant mothers may also transmit infections to their fetuses. The degree of infection is related to the dose and virulence of the infecting agent, as well as to the resistance or immunity of the host against that organism. Resistance to infection is lowered by many diseases of the immune system, leukemia, and cancer, as well as by conditions such as severe burns or malnutrition. In healthy people, the body's own so-called natural flora of bacteria form a line of defense against mild infections, which may thus be taken care of without further treatment. Antibiotics such as sulfa drugs and other pharmaceuticals are used against more severe infections, and vaccines serve as preventive measures against a wide range of infectious diseases (see Immunization).

Among the many infectious diseases are the common cold, chicken pox, cholera, diphtheria, German measles, influenza, malaria, mumps, rabies, tuberculosis, and sexually transmitted infections. See also Disease.

Addison’s Disease

Addison’s Disease, chronic endocrine disorder resulting from underactive adrenal glands that do not produce enough corticosteroid hormones. The disease was first described by the British physician Thomas Addison in 1855. Adrenal glands may be adversely affected by a severe infection, such as tuberculosis, massive bleeding of the adrenals, or surgery affecting the glands, such as removal of a tumor, but in most cases the origin of the disease is unknown. The resulting lack of hormone secretion causes such symptoms as weakness and fatigue, weight loss, low blood pressure, gastrointestinal distress, low blood sugar, depression and irritability, and increased skin pigmentation.

Viruses That Cause Human Disease

Viruses are responsible for many common human diseases, such as colds, flu, diarrhea, chicken pox, measles, and mumps. Some viral diseases—such as rabies, hemorrhagic fevers, encephalitis, polio, yellow fever, and acquired immunodeficiency syndrome (AIDS)—can result in death. German measles and cytomegalovirus can cause serious abnormalities or death in unborn infants.

Mononucleosis, Infectious

Mononucleosis, Infectious, also glandular fever, an acute disease of humans, caused by the Epstein-Barr virus. Its mode of transmission is not known, but may be facilitated by saliva exchange, as in kissing. The disease, which attacks chiefly adolescents and young adults, usually runs its course in two to four weeks, although cases may be as brief as a week or last six to eight weeks. After recovery, weakness may continue for several months. Mononucleosis is characterized by fever, sore throat, fatigue, malaise, and loss of appetite, often associated with nausea. Patients generally have swelling of the lymph nodes in the neck and elsewhere and often have an enlarged spleen.

Examination of the blood usually shows an increase in the white blood cells, due to the appearance in the blood of many atypical lymphocytes. The blood serum in infectious mononucleosis often contains an antibody known as heterophile antibody that agglutinates, or clumps, the red blood cells of sheep. Serological tests based on this property of the patient's serum may serve to confirm the diagnosis of the disease. In addition, tests for liver function frequently show mild abnormalities. No therapeutic agent has proved effective in the treatment of mononucleosis.

See also List of human diseases caused by viruses