Cholera (cont.)

Cholera is an acute infectious disease caused by a bacterium, Vibrio cholerae (V. cholerae), which results in a painless, watery diarrhea in humans. Some affected individuals have copious amounts of diarrhea and develop dehydration so severe it can lead to death. Most people who get the disease ingest the organisms through food or water sources contaminated with V. cholerae. Although symptoms may be mild, approximately 5%-10% of previously healthy people will develop a copious diarrhea within about one to five days after ingesting the bacteria. Severe disease requires prompt medical care. Hydration (usually by IV for the very ill) of the patient is the key to surviving the severe form of the disease.

The term cholera has a long history (see history section below) and has been assigned to several other diseases. For example, fowl or chicken cholera is a disease that can rapidly kill chickens and other avian species rapidly with a major symptom of diarrhea. However, the disease-causing agent in fowl is Pasteurella multocida, a gram-negative bacterium. Similarly, pig cholera (also termed hog or swine cholera) can cause rapid death (in about 15 days) in pigs with symptoms of fever, skin lesions, and seizures. This disease is caused by a pestivirus termed CSFV (classical swine fever virus). Neither one of these animal diseases are related to human cholera, but the terminology can be confusing.

The symptoms and signs of cholera are a watery diarrhea that often contains flecks of whitish material (mucus and some epithelial cells) that are about the size of pieces of rice. The diarrhea is termed "rice-water stool" (See figure 1) and smells "fishy." The volume of diarrhea can be enormous; high levels of diarrheal fluid such as 250 cc per kg or about 10 to 18 liters over 24 hours for a 70 kg adult can occur. People may go on to develop one or more of the following symptoms and signs:

• Vomiting
• Rapid heart rate
• Loss of skin elasticity (washer woman hands sign; see figure 2)
• Dry mucous membranes
• Low blood pressure
• Thirst
• Muscle cramps
• Restlessness or irritability (especially in children)

Those infected require immediate hydration to prevent these symptoms from continuing because these signs and symptoms indicate that the person is becoming or is dehydrated and may go on to develop severe cholera. People with severe cholera (about 5%-10% of previously healthy people; higher if a population is compromised by poor nutrition or has a high percentage of very young or elderly people) can develop severe dehydration, leading to acute renal failure, severe electrolyte imbalances (especially potassium and sodium), and coma. If untreated, this severe dehydration can rapidly lead to shock and death. Severe dehydration can often occur four to eight hours after the first liquid stool, ending with death in about 18 hours to a few days in undertreated or untreated people. In epidemic outbreaks in underdeveloped countries where little or no treatment is available, the mortality (death) rate can be as high as 50%-60%.

Source: MedicineNet.com
http://www.medicinenet.com/cholera/article.htm