Dysentery

(Survival manual/6. Medical/b) Disease/Dysentery

The Free Dictionary, by Farlex
<http://medical-dictionary.thefreedictionary.com/dysentery&gt;

Definition
Dysentery is a general term for a group of gastrointestinal disorders characterized by inflammation of the intestines, particularly the colon. Characteristic features include abdominal pain and cramps, straining at stool, and frequent passage of watery diarrhea or stools containing blood and mucus. The English word dysentery comes from two Greek words meaning “ill” or “bad” and “intestine.”

Dysentery is one of the most dangerous types of diarrhea and is more deadly than other forms of acute diarrhea. The disease is caused by a bacteria. Mortality is high among infants and the elderly.

The primary symptom is bloody diarrhea.
Other symptoms may include abdominal cramps, fever and or severe pain during defecation.
Most cases last up to seven days but can be persistent for fourteen days or more. The disease may cause blood poisoning, rectal prolapse and may affect the kidneys and blood clotting system.

The disease is spread by poor sanitation, especially unwashed hands. Unlike Cholera, dysentery is not spread through contaminated food or water. Epidemics of dysentery occur during hot, humid and rainy seasons, especially in crowded areas with inadequate sanitation and poor hygiene and limited water supplies.

Dysentery was rampant in the United States during the Civil War. Disease, not battle wounds, were the biggest killer during the War. In the Union Army three of five died of disease and in the Confederate Army two of three. Half of these were due to intestinal disorders, including typhoid fever, diarrhea and dysentery. The remainder died from pneumonia and tuberculosis. The military camps introduced contagious diseases to the soldiers, many for the first time, causing outbreaks of common contagious diseases including measles, chickenpox, mumps and whooping-cough. Poor camp conditions contributed to the spread of disease such as dysentery.

* Prevention, diagnosis and treatment of these diseases are or will be, available in posts located in category: Survival Manual/6. Medical/b) Disease

Description
Dysentery is a common, but potentially serious disorder of the digestive tract that occurs throughout the world. It can be caused by a number of infectious agents ranging from viruses and bacteria to protozoa and parasitic worms; it may also result from chemical irritation of the intestines. Dysentery is one of the oldest known gastrointestinal disorders, having been described as early as the Peloponnesian War in the fifth century B.C. Epidemics of dysentery were frequent occurrences aboard sailing vessels as well as in army camps, walled cities, and other places in the ancient world where large groups of human beings lived together in close quarters with poor sanitation. As late as the eighteenth and nineteenth centuries, sailors and soldiers were more likely to die from the “bloody flux” than from injuries received in battle. It was not until 1897 that a bacillus (rod-shaped bacterium) was identified as the cause of one major type of dysentery.

Dysentery in the modern world is most likely to affect people in the less developed countries and travelers who visit these areas. According to the Centers for Disease Control and Prevention (CDC), most cases of dysentery in the United States occur in immigrants from the developing countries and in persons who live in inner-city housing with poor sanitation. Other groups of people at increased risk of dysentery are military personnel stationed in developing countries, frequent travelers, children in day care centers, people in nursing homes, and men who have sex with other men.

Causes
The most common types of dysentery and their causal agents are as follows:

•  Bacillary dysentery. Bacillary dysentery, which is also known as shigellosis, is caused by four species of the genus Shigella: S. dysenteriae, the most virulent species and the one most likely to cause epidemics; S. sonnei, the mildest species and the most common form of Shigella found in the United States; S. boydii; and S. flexneri.
S. flexneri is the species that causes Reiter’s syndrome, a type of arthritis that develops as a late complication of shigellosis. About 15,000 cases of shigellosis are reported to the CDC each year for the United States; however, the CDC maintains that the true number of annual cases may be as high as 450,000, since the disease is vastly underreported. About 85 percent of cases in the United States are caused by S. sonnei. The Shigella organisms cause the diarrhea and pain associated with dysentery by invading the tissues that line the colon and secreting an enterotoxin, or harmful protein that attacks the intestinal lining.
•  Amebic dysentery. Amebic dysentery, which is also called intestinal amebiasis and amebic colitis, is caused by a protozoon, Entamoeba histolytica. E. histolytica, whose scientific name means “tissue-dissolving,” is second only to the organism that causes malaria as a protozoal cause of death. E. histolytica usually enters the body during the cyst stage of its life cycle. The cysts may be found in food or water contaminated by human feces. Once in the digestive tract, the cysts break down, releasing an active form of the organism called a trophozoite. The trophozoites invade the tissues lining the intestine, where they are usually excreted in the patient’s feces. They sometimes penetrate the lining itself, however, and enter the bloodstream. If that happens, the trophozoites may be carried to the liver, lung, or other organs. Involvement of the liver or other organs is sometimes called metastatic amebiasis.
•  Balantidiasis, giardiasis, and <cryptosporidiosis. These three intestinal infections are all caused by protozoa, Balantidium coli, Giardia lamblia, and Cryptosporidium parvum respectively. Although most people infected with these protozoa do not become severely ill, the disease agents may cause dysentery in children or immunocompromised individuals. There are about 3,500 cases of cryptosporidiosis reported to the CDC each year in the United States, and about 22,000 cases of giardiasis.
•  Viral dysentery. Viral dysentery, which is sometimes called traveler’s diarrhea or viral gastroenteritis, is caused by several families of viruses, including rotaviruses, caliciviruses, astroviruses, noroviruses, and adenoviruses.
There are about 3.5 million cases of viral dysentery in infants in the United States each year, and about 23 million cases each year in adults. The CDC estimates that viruses are responsible for 9.2 million cases of dysentery related to food poisoning in the United States each year. Whereas most cases of viral dysentery in infants are caused by rotaviruses, caliciviruses are the most common disease agents in adults. Noroviruses were responsible for about half of the outbreaks of dysentery on cruise ships reported to the CDC in 2002.
•  Dysentery caused by parasitic worms. Both whipworm (trichuriasis) and flatworm or fluke (schistosomiasis) infestations may produce the violent diarrhea and abdominal cramps associated with dysentery.
Schistosomiasis is the second most widespread tropical disease after malaria. Although the disease is rare in the United States, travelers to countries where it is endemic may contract it. The World Health Organization (WHO) estimates that about 200 million people around the world carry the parasite in their bodies, with 20 million having severe disease.

Symptoms
In addition to the characteristic bloody and/or watery diarrhea and abdominal cramps of dysentery, the various types have somewhat different symptom profiles:
•  Bacillary dysentery. The symptoms of shigellosis may range from the classical bloody diarrhea and tenesmus characteristic of dysentery to the passage of non bloody diarrhea that resembles the loose stools caused by other intestinal disorders. The high fever associated with shigellosis begins within one to three days after exposure to the organism. The patient may also have pain in the rectum as well as abdominal cramping. The acute symptoms last for three to seven days, occasionally for as long as a month. Bacillary dysentery may lead to two potentially fatal complications outside the digestive tract: bacteremia (bacteria in the bloodstream), which is most likely to occur in malnourished children; and hemolytic uremic syndrome, a type of kidney failure that has a mortality rate above 50 percent.
•  Amebic dysentery. Amebic dysentery often has a slow and gradual onset; most patients with amebiasis visit the doctor after several weeks of diarrhea and bloody stools. Fever is unusual with amebiasis unless the patient has developed a liver abscess as a complication of the infection. The most serious complication of amebic dysentery, however, is fulminant or necrotizing colitis, which is a severe inflammation of the colon characterized by dehydration, severe abdominal pain, and the risk of perforation (rupture) of the colon.
•  Dysentery caused by other protozoa. Dysentery associated with giardiasis begins about 1-3 weeks after infection with the organism. It is characterized by bloating and foul-smelling flatus, nausea and vomiting, headaches, and low-grade fever. These acute symptoms usually last for three or four days. The symptoms of cryptosporidiosis are mild in most patients but are typically severe in patients with AIDS. Diarrhea usually starts between seven and 10 days after exposure to the organism and may be copious. The patient may have pain in the upper right abdomen, nausea, and vomiting, but fever is unusual.
•  Viral dysentery. Viral dysentery has a relatively rapid onset; symptoms may begin within hours of infection. The patient may be  severely dehydrated from the diarrhea but usually has only a low-grade fever.  The diarrhea itself may be preceded by one to three days of nausea and vomiting. The patient’s abdomen may be slightly tender but is not usually severely painful.
•  Dysentery caused by parasitic worms. Patients with intestinal schistosomiasis typically have a gradual onset of symptoms. In addition to bloody diarrhea and abdominal pain, these patients usually have fatigue. An examination of the patient’s colon will usually reveal areas of ulcerated tissue, which is the source of the bloody diarrhea.

Treatment
Medications are the primary form of treatment for  dysentery:

  • Bacillary dysentery. Dysentery caused by Shigella is usually treated with such antibiotics as trimethoprim-sulfamethoxazole (Bactrim, Septra), nalidixic acid (NegGram), or ciprofloxacin (Cipro, Ciloxan). Because the various species of Shigella are becoming resistant to these drugs, however, the doctor may prescribe one of the newer drugs described below. Patients with bacillary dysentery should not be given antidiarrheal medications, including loperamide (Imodium), paregoric, and diphenolate (Lomotil), because they may make the illness worse.
  • Amebic dysentery. The most common drugs given for amebiasis are diloxanide furoate (Diloxide), iodoquinol (Diquinol, Yodoxin), and metronidazole (Flagyl). Metronidazole should not be given to pregnant women but paromomycin (Humatin) may be used instead. Patients with very severe symptoms may be given emetine dihydrochloride or dehydroemetine, but these drugs should be stopped once the patient’s symptoms are controlled.
  • Dysentery caused by other protozoa. Balantidiasis, giardiasis, and cryptosporidiosis are treated with the same drugs as amebic dysentery; patients with giardiasis resistant to treatment may be given albendazole (Zentel) or furazolidone (Furoxone).
  • Viral dysentery. The primary concern in treating viral dysentery, particularly in small children, is to prevent dehydration. Antinausea and antidiarrhea medications should not be given to small children. Probiotics, including Lactobacillus casei and Saccharomyces boulardii, have been shown to reduce the duration and severity of viral diarrhea in small children by 30-70 percent.
  • Dysentery caused by parasitic worms. Whipworm infestations are usually treated with anthelminthic medications, most commonly mebendazole (Vermox). Schistosomiasis may be treated with praziquantel (Biltricide), metrifonate (Trichlorfon), or oxamniquine, depending on the species causing the infestation.

* Fluid replacement is given if the patient has shown signs of dehydration. The most common treatment is an oral rehydration fluid containing a precise amount of salt and a smaller amount of sugar to replace electrolytes as well as water lost through the intestines.

Prognosis
Most adults in developed countries recover completely from an episode of dysentery. Children are at greater risk of becoming dehydrated, however; bacillary dysentery in particular can lead to a child’s death from dehydration in as little as 12-24 hours.

  • Bacillary dysentery. Most patients recover completely from shigellosis, although their bowel habits may not become completely normal for several months. About 3 percent of people infected by S. flexneri will develop Reiter’s syndrome, which may lead to a chronic form of arthritis that is difficult to treat. Elderly patients or those with weakened immune systems sometimes develop secondary bacterial infections after an episode of shigellosis.
  • Amebic dysentery. Most people in North America who become infected with E. histolytica do not become severely ill. Patients who develop a severe case of amebic dysentery, however, are at increased risk for such complications as fulminant colitis or liver abscess.
    About 0.5 percent of patients with amebic dysentery develop fulminant colitis, but almost half of these patients die. Between 2 and 7 percent of cases of amebic liver abscess result in rupture of the abscess with a high mortality rate. Men are 7-12 times more likely to develop a liver abscess than women. Any patient diagnosed with amebic dysentery should have stool samples examined for relapse 1, 3, and 6 months after treatment with medications whether or not they have developed complications.
  • Dysentery caused by other protozoa. Cryptosporidiosis may lead to respiratory infections or pancreatitis in patients with AIDS. The risk of these complications, however, is reduced in AIDS patients who are receiving highly active antiretroviral therapy (HAART).
  • Viral dysentery. Most people in North America recover completely without complications unless they become severely dehydrated. Viral dysentery in children in developing countries, however, is a major cause of mortality.
  • Dysentery caused by parasitic worms. Untreated whipworm infections can lead to loss of appetite, chronic diarrhea, and retarded growth in children. Untreated schistosomiasis can develop into a chronic intestinal disorder in which fibrous tissue, small growths, or strictures (abnormal narrowing) may form inside the intestine. Patients treated for schistosomiasis should have stool samples checked for the presence of worm eggs 3 and 6 months after the end of treatment.

Preventing dysentery
Dysentery is spread because of poor hygiene. To minimize the risk of catching the disease:
•  wash your hands with soap and water after using the toilet and regularly throughout the day, particularly after coming into contact with an infected person,
•  wash your hands before handling, eating or cooking food,  handling babies and feeding children or elderly people,
•  keep contact with an infected person to a minimum,
•  do not share towels and face cloths, and
•  wash the laundry of an infected person on the hottest setting possible.

Travel advice
Good hygiene and proper sanitation are an enormous challenge for people living in poor conditions in developing countries, where there is little or no access to fresh water and disinfectant.
If you are travelling in an area/ to a country that has a high risk of contamination by the amoeba that causes dysentery, the following advice can help prevent infection:
•  Do not drink the local water unless it has been boiled for at least 10 minutes. Safe alternatives are bottled water or carbonated (fizzy) drinks from sealed cans or bottles. Another way to make water safe is by filtering it through an ‘absolute 1 micron’ filter and dissolving iodine tablets in the filtered water. Absolute 1 micron filters can be found in camping/outdoor supply stores.
•  Do not drink from public water fountains or clean your teeth with tap water, and do not have ice in your drinks as it may be made from the local water.
•  Do not eat fresh fruit or vegetables that cannot be peeled before eating.
•  Do not eat or drink milk, cheese or dairy products that may not have been pasteurized.
•  Do not eat or drink anything sold by street vendors (except drinks from properly sealed cans or bottles).

See also the post: Survival Manual/6. Medical/b) Disease/Traveler’s diarrhea

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