hog cholera, acute, highly infectious viral disease of swine, also called swine fever. It is perhaps the most serious disease of swine in North America. It is characterized by dullness and listlessness, loss of appetite, rise in temperature to between 105°F; (41°C;) and 107°F; (42°C;), diarrhea, and often death. Purple hemorrhagic areas will appear on the abdomen and many pigs display nervous signs, such as circling, incoordination, muscle tremors, and convulsions. Mortality is very high and recovered animals are permanently stunted. The disease is transmitted readily by direct or indirect contact. The virus may enter a herd through contaminated feed, water, equipment, or by contact with an infected animal or person. At one time, feeding pigs raw garbage containing pork scraps from infected pigs was a common cause of infection. For this reason the United States and many other countries now prohibit the feeding of uncooked garbage to pigs. A national hog cholera eradication program has been established in the United States to eliminate all possible sources of virus introduction. A vaccine is available in areas where the disease is still present.

cholera or Asiatic cholera, acute infectious disease caused by strains of the bacterium Vibrio cholerae that have been infected by bacteriophages. The bacteria, which are found in fecal-contaminated food and water and in raw or undercooked seafood, produce a toxin that affects the intestines causing diarrhea, vomiting, and severe fluid and electrolyte loss. This overwhelming dehydration is the outstanding characteristic of the disease and is the main cause of death. Cholera has a short incubation period (two or three days) and runs a quick course. In untreated cases the death rate is high, averaging 50%, and as high as 90% in epidemics, but with effective treatment the death rate is less than 1%. The intravenous and oral replacement of body fluids and essential electrolytes and the restoration of kidney function are more important in therapy than the administration of antibacterial drugs. In regions of Asia, Africa, and South America where public sanitation is poor the disease is still endemic or epidemic; vaccination is recommended for people living in those areas. A theory of evolutionary biologists holds that the cystic fibrosis gene, a common but lethal recessive gene carried by approximately one in twenty Caucasians, affords those carriers partial protection against cholera.

or swine fever

Often fatal viral disease of swine in Europe, North America, and Africa, transmitted by vehicles used to carry pigs, people dealing with them, and uncooked garbage in feed. Fever progresses to symptoms that include appetite loss; affected eyes and digestive tract; respiratory difficulty; rash; and inflamed mouth and throat. The pig moves reluctantly and staggers; later it cannot rise; coma follows. Antiserum is rarely effective. Survivors become chronically ill and can spread the virus. Illness must be reported, infected animals slaughtered, and quarantine instituted. A vaccine can control it. The African strain causes death sooner and has no effective prevention or treatment.

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Acute bacterial infection with Vibrio cholerae, causing massive diarrhea with severe depletion of body fluids and salts. (See bacterial disease.) Cholera often occurs in epidemics, spreading in contaminated water or food. The bacteria secrete a toxin that causes the diarrhea, which along with vomiting leads to dehydration, with severe muscle cramps and intense thirst. Stupor and coma may precede death by shock. With fluid and salt replacement, the disease passes in two to seven days, sooner if antibiotics are taken the first day. Prevention requires good sanitation, especially clean drinking water.

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