Dysentery, amebic - definition of Dysentery, amebic in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia.

Dysentery

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 (tenesmus), 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."

It should be noted that some doctors use the word "dysentery" to refer only to the first two major types of dysentery discussed below, while others use the term in a broader sense. For example, some doctors speak of schistosomiasis, a disease caused by a parasitic worm, as bilharzial dysentery, while others refer to acute diarrhea caused by viruses as viral dysentery.

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 & symptoms

Causes

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

Symptoms

In addition to the characteristic bloody and/or watery diarrhea and abdominal cramps of dysentery, the various types have somewhat different symptom profiles:

Diagnosis

Patient history and physical examination

The physical examination in the primary care doctor's office will not usually allow the doctor to determine the specific parasite or other disease agent that is causing the bloody diarrhea and other symptoms of dysentery, although the presence or absence of fever may help to narrow the diagnostic possibilities. The patient's age and history are usually better sources of information. The doctor may ask about such matters as the household water supply and food preparation habits, recent contact with or employment in a nursing home or day care center, recent visits to tropical countries, and similar questions. The doctor will also need to know when the patient first noticed the symptoms.

The doctor will also evaluate the patient for signs of dehydration resulting from the loss of fluid through the intestines. Fatigue, drowsiness, dryness of the mucous membranes lining the mouth, low blood pressure, loss of normal skin tone, and rapid heartbeat (above 100 beats per minute) may indicate that the patient is dehydrated.

Laboratory tests

The most common laboratory test to determine the cause of dysentery is a stool sample. The patient should be asked to avoid using over-the-counter antacids or antidiarrheal medications until the sample has been collected, as these preparations can interfere with the test results. The organisms that cause cryptosporidiosis, bacillary dysentery, amebic dysentery, and giardiasis can be seen under the microscope, as can the eggs produced by parasitic worms. In some cases repeated stool samples, a sample of mucus from the intestinal lining obtained through a proctoscope, or a tissue sample from the patient's colon may be necessary to confirm the diagnosis. Antigen testing of a stool sample can be used to diagnose a rotavirus infection as well as parasitic worm infestations.

The doctor will also usually order a blood test to evaluate the electrolyte levels in the patient's blood in order to assess the need for rehydration.

Imaging studies

Imaging studies (usually CT scans, x rays, or ultrasound) may be performed in patients with amebic dysentery to determine whether the lungs or liver have been affected. They may also be used to diagnose schistosomiasis, as the eggs produced by the worms will show up on ultrasound or MRI studies of the liver, intestinal wall, or bladder.

Treatment

Medications are the primary form of treatment for dysentery:

Newer drugs that have been developed to treat dysentery include tinidazole (Tindamax, Fasigyn), an antiprotozoal drug approved by the Food and Drug Administration (FDA) in 2004 to treat giardiasis and amebiasis in adults and children over the age of three years. This drug should not be given to women in the first three months of pregnancy. In addition, adults taking tinidazole should not drink alcoholic beverages while using it, or for three days after the end of treatment. The other new drug is nitazoxanide (Alinia), another antiprotozoal medication that has the advantage of lacking the bitter taste of metronidazole and tinidazole.

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. Infalyte and Pedialyte are oral rehydration fluids formulated for the special replacement needs of infants and young children.

Surgery

Surgery is rarely necessary in treating dysentery, but may be required in cases of fulminant colitis, particularly if the patient's colon has perforated. Patients with liver abscesses resulting from amebic dysentery may also require emergency surgery if the abscess ruptures. In some cases exploratory surgery may be needed to determine whether severe abdominal pain is caused by schistosomiasis, amebic dysentery, or appendicitis.

Alternative treatments

There are a number of alternative treatments for dysentery, most of which are derived from plants used by healers for centuries. Because dysentery was known to ancient civilizations as well as modern societies, such alternative systems as traditional Chinese medicine (TCM) and Ayurvedic medicine developed treatments for it.

Ayurvedic medicine

Ayurvedic medicine recommends fruits and herbs, specifically cumin seed, bael fruit (Aegle marmelos, also known as Bengal quince), and arjuna (Terminalia arjuna) bark for the treatment of dysentery. Ayurvedic practitioners may also give the patient dietary supplements known as Isabbael, Lashunadi Bati, and Bhuwaneshar Ras. To rehydrate the body, adult patients may be given a combination of slippery elm water and barley to drink, at least a pint per day.

Traditional chinese medicine

To treat dysentery, traditional Chinese doctors use astringent drugs, which are intended to constrict or tighten mucous membranes and other body tissues to slow down fluid loss. Myrobalan fruit (Terminalia chebula), nut galls (swellings produced on the leaves and stems of oak trees by the secretions of certain insects), and opium extracted from the opium poppy (Papaver somniferum) are the natural materials most commonly used. Paregoric, a water-based solution of morphine that is still used in the West to treat diarrhea, is derived from the opium poppy.

Other plant-based remedies

Researchers in Mexico reported in early 2005 that the roots of Geranium mexicanum, a plant that produces a sap traditionally used to treat coughs or diarrhea, contains compounds that are active against both Giardia lamblia and Entamoeba histolytica. Plant biologists in Africa are studying the effectiveness of African mistletoe (Tapinanthus dodoneifolius), a traditional remedy for dysentery among the Hausa and Fulani tribes of Nigeria.

Dietary supplements

A study published in the American Journal of Clinical Nutrition in early 2005 reported that supplemental zinc (twice the recommended daily dietary allowance) boosts the body's immune response during acute shigellosis.

Homeopathy

There are at least ten different homeopathic remedies used to treat diarrhea. Contemporary homeopaths, however, distinguish between diarrhea that can be safely treated at home with such homeopathic remedies as Podophyllum, Veratrum album, Bryonia, and Arsenicum, and diarrhea that indicates dysentery and should be referred to a physician. Signs of dehydration (loss of normal skin texture, dry mouth, sunken eyes), severe abdominal pain, blood in the stool, and unrelieved vomiting are all indications that mainstream medical care is required.

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.

Prevention

The disease agents that cause dysentery do not confer immunity against reinfection at a later date. As of 2005 there are no vaccines for bacillary dysentery or amebic dysentery; however, a vaccine against schistosomiasis is under investigation. An oral vaccine against rotavirus infections was developed for small children but was withdrawn in 2004 because it was associated with an increased risk of small-bowel disorders. Newer vaccines against rotaviruses and caliciviruses are being developed as of 2005.

Public health measures

Public health measures to control the spread of dysentery include the following:

Key terms

Anthelminthic (also spelled anthelmintic) — A type of drug or herbal preparation given to destroy parasitic worms or expel them from the body.

Bacillus — A rod-shaped bacterium. One common type of dysentery is known as bacillary dysentery because it is caused by a bacillus.

Enterotoxin — A type of harmful protein released by bacteria and other disease agents that affects the tissues lining the intestines.

Fulminant — Occurring or flaring up suddenly and with great severity. A potentially fatal complication of amebic dysentery is an inflammation of the colon known as fulminant colitis.

Probiotics — Food supplements containing live bacteria or other microbes intended to improve or restore the normal balance of microorganisms in the digestive tract.

Proctoscope — An instrument consisting of a thin tube with a light source, used to examine the inside of the rectum.

Protozoan (plural, protozoa) — A member of the simplest form of animal life, a one-celled organism. Amebic dysentery is caused by a protozoan.

Reiter's syndrome — A group of symptoms that includes arthritis, inflammation of the urethra, and conjunctivitis, and develops as a late complication of infection with Shigella flexneri. The syndrome was first described by a German doctor named Hans Reiter in 1918.

Tenesmus — Straining to urinate or defecate without being able to do so. Tenesmus is a characteristic feature of bacillary dysentery.

Trophozoite — The active feeding stage of a protozoal parasite, as distinct from its encysted stage.

Personal precautions

Individuals can lower their risk of contracting dysentery by the following measures:

Resources

Books

Cummings, Stephen, MD, and Dana Ullman, MPH. Everybody's Guide to Homeopathic Medicines, revised and expanded. New York: Jeremy P. Tarcher, 1991.

"Enterobacteriaceae Infections." Section 13, Chapter 161 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

"Intestinal Protozoa." Section 13, Chapter 161 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

Pelletier, Kenneth R., MD. The Best Alternative Medicine. New York: Simon & Schuster, 2002.

Reid, Daniel P. Chinese Herbal Medicine. Boston: Shambhala, 1993.

Periodicals

Calzada, F., J. A. Cervantes-Martinez, and L. Yepez-Mulia. "In vitro Antiprotozoal Activity from the Roots of Geranium mexicanum and Its Constituents on Entamoeba histolytica and Giardia lamblia." Journal of Ethnopharmacology 98 (April 8, 2005): 191-193.

Chijide, Valda M., MD, and Keith F. Woeltje, MD. "Balantidiasis." eMedicine, 12 March 2002. http://www.emedicine.com/med/topic203.htm.

Deeni, Y. Y., and N. M. Sadiq. "Antimicrobial Properties and Phytochemical Constituents of the Leaves of African Mistletoe (Tapinanthus dodoneifolius (DC) Danser) (Loranthaceae): An Ethnomedicinal Plant of Hausalan, Northern Nigeria." Journal of Ethnopharmacology 83 (December 2002): 235-240.

Eisen, Damon, MD. "Cryptosporidiosis." eMedicine, 18 November 2004. http://www.emedicine.com/med/topic484.htm.

Goodgame, Richard W., MD. "Gastroenteritis, Viral." eMedicine, 14 June 2004. http://www.emedicine.com/MED/topic856.htm.

Hlavsa, M. C., J. C. Watson, and M. J. Beach. "Cryptosporidiosis Surveillance—United States 1999–2002." Morbidity and Mortality Weekly Report, Surveillance Summaries 54 (January 28, 2005): 1-8.

Hlavsa, M. C., J. C. Watson, and M. J. Beach. "Giardiasis Surveillance—United States, 1998–2002." Morbidity and Mortality Weekly Report, Surveillance Summaries 54 (January 28, 2005): 9-16.

Hu, F., R. Lu, B. Huang, and M. Liang. "Free Radical Scavenging Activity of Extracts Prepared from Fresh Leaves of Selected Chinese Medicinal Plants." Fitoterapia 75 (January 2004): 14-23.

Kroser, Joyann A., MD. "Shigellosis." eMedicine, 17 May 2002. http://www.emedicine.com/med/topic2112.htm.

Nachimuthu, Senthil, MD, and Paul Piccione, MD. "Food Poisoning." eMedicine, 10 January 2005. http://www.emedicine.com/med/topic807.htm.

Pennardt, Andre, MD. "Giardiasis." eMedicine, 25 June 2004. http://www.emedicine.com/emerg/topic215.htm.

Rahman, M. J., P. Sarker, S. K. Roy, et al. "Effects of Zinc Supplementation as Adjunct Therapy on the Systemic Immune Responses in Shigellosis." American Journal of Clinical Nutrition 81 (February 2005): 495-502.

Scoggins, Thomas, MD, and Igor Boyarsky, DO. "Reiter Syndrome." eMedicine, 7 December 2004. http://www.emedicine.com/EMERG/topic498.htm.

Swords, Robert, MD, and J. Robert Cantey, MD. "Amebiasis." eMedicine, 22 February 2002. http://www.emedicine.com/med/topic116.htm.

White, C. A. Jr. "Nitazoxanide: A New Broad-Spectrum Antiparasitic Agent." Expert Review of Anti-Infective Therapy 2 (February 2004): 43-49.

Wingate, D., S. F. Phillips, S. J. Lewis, et al. "Guidelines for Adults on Self-Medication for the Treatment of Acute Diarrhea." Alimentary Pharmacology and Therapeutics 15 (June 2001): 773-782.

Organizations

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. http://www.cdc.gov

Infectious Diseases Society of America (IDSA). 66 Canal Center Plaza, Suite 600, Alexandria, VA 22314. (703) 299-0200. Fax: (703) 299-0204. http://www.idsociety.org.

World Health Organization (WHO). http://www.who.int/en/.

Other

Centers for Disease Control and Prevention. Disease Information. "Shigellosis." http://www.cdc.gov/ncidod/dbmd/diseaseinfo/shigellosis_t.htm

Centers for Disease Control and Prevention, Division of Parasitic Diseases. Fact Sheet. "Amebiasis." http://www.cdc.gov/ncidod/dpd/parasites/amebiasis/factsht_amebiasis.htm

Centers for Disease Control and Prevention, National Center for Infectious Diseases, Travelers' Health. "New Medication Approved for Treatment of Giardiasis and Amebiasis." http://www.cdc.gov/travel/other/tinidazole_approval_2004.htm

World Health Organization. "Shigella." http://www.who.int/topics/shigella/en/.

dysentery /dys·en·tery/ (dis´en-ter?e) any of a number of disorders marked by inflammation of the intestine, especially of the colon, with abdominal pain, tenesmus, and frequent stools containing blood and mucus.dysenter´ic

amebic dysentery dysentery due to ulceration of the bowel caused by severe amebiasis.

bacillary dysentery dysentery caused by Shigella.

viral dysentery dysentery caused by a virus, occurring in epidemics and marked by acute watery diarrhea.

dys·en·ter·y (d

n-t

)

An inflammatory disorder of the lower intestinal tract, usually caused by a bacterial, parasitic, or protozoan infection and resulting in pain, fever, and severe diarrhea, often accompanied by the passage of blood and mucus.

dysen·teric adj.

dysentery,

n intestinal inflammation, particularly in the colon caused by bacteria, chemical irritants, parasites, or protozoa. Symptoms include abdominal pain; tenesmus; and bloody, frequent stools.

Dysentery.

dysentery

(dis´

nter´ē),
n an inflammation of the intestine, especially of the colon, that may be caused by chemical irritants, bacteria, protozoa, or parasites. It is characterized by frequent and bloody stools and severe abdominal pain.