infections
Cholera
Introduction
Cholera is a serious infection of the intestine that is caused by the Overview of Gram-Negative Bacteria and that causes severe diarrhea, which can be fatal without treatment. People are infected when they consume contaminated food, often shellfish, or water. Cholera is rare except in areas where sanitation is inadequate. People have watery diarrhea and vomit, usually with no fever. Identifying the bacteria in a stool sample confirms the diagnosis. Replacing lost fluids and giving antibiotics treat the infection effectively. (See also Overview of Bacteria .) Several species ofVibriobacteria cause diarrhea (see table). The most serious illness, cholera, is caused byVibrio cholerae. Cholera may occur in large outbreaks. Vibrio choleraeinfection is acquired by consuming water, shellfish, or other foods contaminated by the stool of infected people. Once infected, people excrete the bacteria in stool. Thus, the infection can spread rapidly, particularly in areas where human waste is untreated. Once common throughout the world, cholera is now most common in parts of Asia, the Middle East, Africa, and South and Central America. Small outbreaks have occurred in Europe, Japan, and Australia. In the United States, cholera can occur along the coast of the Gulf of Mexico. Large outbreaks of cholera continue to occur wherever there is poverty and people lack access to clean drinking water and sanitary disposal of human waste. A severe cholera epidemic occurred in Haiti after the earthquake in 2010 and lasted until 2017. During this outbreak, over 820,000 people became ill, and nearly 10,000 died. An outbreak in Yemen started in 2016 and has not yet ended. This outbreak has had even greater devastating effects. Over 2.5 million people in Yemen have become ill, and almost 4,000 have died. It is thought to be the largest, fastest-spreading cholera outbreak in modern history. In endemic areas (areas where there is an ongoing, relatively constant rate of infection), outbreaks usually occur when war or civil unrest disrupts public sanitation services. Infection is most common during warm months and among children. In newly affected areas, outbreaks may occur during any season and affect all ages equally. For infection to develop, many bacteria must be consumed. Then, there may be too many for stomach acid to kill, and some bacteria can reach the small intestine, where they grow and produce a toxin. The toxin causes the small intestine to secrete enormous amounts of salt and water. The body loses this fluid as watery diarrhea. It is the loss of water and salt that causes death. The bacteria remain in the small intestine and do not invade tissues. Because stomach acid kills the bacteria, people who produce less stomach acid are more likely to get cholera. Such people include Young children Older people People taking drugs that reduce stomach acid, including proton pump inhibitors (such asomeprazole) and histamine-2 (H2) blockers (such asfamotidine) People living in endemic areas gradually acquire some Acquired Immunity . Without treatment, more than one half of people with severe cholera die. 