TYPHOID

also called typhoid fever acute infectious disease of humans caused by the bacterium Salmonella typhi. The bacterium usually enters the body through the mouth by the ingestion of contaminated food or water, penetrates the intestinal wall, and multiplies in lymphoid tissue there; it first enters into the bloodstream within 24 to 72 hours, causing septicemia (blood poisoning) and systemic infection. After an average 1014 day incubation period, the early symptoms of typhoid appear: headache, lassitude, generalized aching, fever, and restlessness that may interfere with sleep. There may be loss of appetite, nosebleeds, cough, and diarrhea or constipation. Persistent fever develops and gradually rises, usually in a stepwise fashion, reaching a peak of 103 or 104 F (39.4 or 40 C) after 710 days and continuing with only slight morning remissions for another 1014 days. During the first few days of the disease the patient may remain ambulatory. During about the second week of fever, when typhoid bacilli are present in great numbers in the bloodstream, a rash of small, rose-coloured spots appears on the trunk, lasts four or five days, and then fades away. The lymph follicles (Peyer's patches) along the intestinal wall in which the typhoid bacilli have multiplied become inflamed and necrotic and may slough off, leaving ulcers in the walls of the bowel. The dead fragments of bowel tissue may erode blood vessels, causing a hemorrhage into the bowel, or they may perforate the bowel wall, allowing the bowel's contents to enter the peritoneal cavity (peritonitis). Other complications can include acute inflammation of the gall bladder, heart failure, pneumonia, osteomyelitis, encephalitis, and meningitis. With a continued high fever the symptoms usually increase in intensity, and mental confusion and delirium may appear. By the end of the third week the patient is prostrated and emaciated, his abdominal symptoms are marked, and mental disturbance is prominent. In favourable cases, during about the beginning of the fourth week, the fever begins to decline, the symptoms begin to abate, and the temperature gradually returns to normal. If untreated, typhoid proves fatal in up to 25 percent of all cases. Most major epidemics of typhoid have been caused by the pollution of public water supplies. Food and milk may be contaminated, however, by a carrier of the disease who is employed in handling and processing them; by flies; or by the use of polluted water for cleaning purposes. Shellfish, particularly oysters, grown in polluted water and fresh vegetables grown on soil fertilized or contaminated by untreated sewage are dangerous. The prevention of typhoid fever depends mainly on proper sewage treatment, filtration and chlorination of water, and the exclusion of carriers from employment in food industries and restaurants. In the early part of the 20th century, prophylactic vaccination using killed typhoid organisms was introduced, mainly in military forces and institutions, and contributed to a lowering of the incidence of the disease. The treatment of typhoid formerly was entirely symptomatic and supportive. After 1948 treatment with antibiotics, particularly with chloramphenicol, proved to be effective. Chloramphenicol begins to lower the patient's fever within three or four days after beginning therapy, and there is progressive improvement thereafter. The drug treatment is continued for several weeks in order to prevent relapses. Ampicillin, often in combination with other drugs, is an effective alternate treatment. About 30 percent of typhoid cases become transient carriers of the disease, excreting the causative bacteria in the stool or urine for weeks or months. About 5 percent remain long-term carriers, harbouring the microorganisms and shedding them for years. In these carriers, who show no apparent ill effects, the bacilli are found mainly in the gallbladder and biliary passages. The bacteria may be excreted continuously or intermittently. One of the most famous instances of carrier-borne disease in medical history was the early 20th-century case of Typhoid Mary (q.v.).