AMOEBIC DYSENTERY

I. Definition

Amoebic dysentery (amoebiasis) is an infection of the intestine (gut) caused by an amoeba.

II. Etiologic Agent

Entamoeba Histolytica

III. Mode of Transmission

1. The disease can be passed from one person to another through fecal-oral transmission.

2. The disease can be transmitted through direct contact, through sexual contact by orogenital, oroanal, and proctogenital sexual activity.

3. Through indirect contact, the disease can infect humans by ingestion of food especially uncooked leafy vegetables or foods contaminated with fecal materials containing E. histolytica cysts.

IV. Disease Process

Entamoeba histolytica can exist in two forms in contaminated food and drink:

as free amoebae (known as 'trophozoites') as infective cysts, which are a group of

amoebae surrounded by a protective wall, that have been passed (excreted) in the carrier's faeces (human or animal).

If you swallow contaminated food that contains the free amoebae (trophozoites), hardly anything is likely to happen because they usually die in the stomach on account of its acidity.

On the other hand, cysts are particularly resistant to the acidic contents of the stomach, and food contaminated with cysts represents a genuine risk of infection.

When the cysts reach the intestine of another person, the individual amoebae are released from the cysts and are able to cause infection.

V. Incubation Period

The incubation period in severe infection is three days. In subacute and chronic form it lasts for

several months. In average cases the incubation period varies from three to four weeks

VI. Clinical Manifestations

Weight loss Anaemia Indigestion Intermittent diarrhoea with foul-smelling

stool that may be preceeded by constipation Dehydration Blood and mucus in the stool Gas and Abdominal Bloating Abdominal cramps and tenderness Fever Fatigue Chills

Complications:

1. Amebic colitis 2. Amebic liver abscess 3. Brain abscess

VII. Medical Management

1. Metronidazole (Flagyl) 800mg TID X 5 days2. Tetracyline 250 mg every 6 hours3. Ampicillin, quinolones sulfadiazine4. Streptomycin SO4, Chloramphenicol5. Lost fluid and electrolytes should be

replaced

VIII. Nursing Management

1. Observe isolation and enteric precaution2. Provide health education and instruct patient

to :o Boil water for drinking or use purified

watero Avoid washing food from open drum

or pailo Cover leftover foodo Wash hands after defacation and

before eatingo Avoid ground vegetables (lettuce,

carrots, and the like)

Reporter # 8:

AISA ALYANNA B. HABIB

Intestinal amebiasisIntestinal amebiasis can be subdivided into several categories:

ASYMPTOMATIC INFECTION. Most persons with amebiasis have no noticeable symptoms. Even though these individuals may not feel ill, they are still capable of infecting others by person-to-person contact or by contaminating food or water with cysts that others may ingest, for example, by preparing food with unwashed hands.

CHRONIC NON-DYSENTERIC INFECTION. Individuals may experience symptoms over a long period of time during a chronic amebiasis infection and experience recurrent episodes of diarrhea that last from one to four weeks and recur over a period of years. These patients may also suffer from abdominal cramps, fatigue, and weight loss.

AMEBIC DYSENTERY. In severe cases of intestinal amebiasis, the organism invades the lining of the intestine, producing sores (ulcers), bloody diarrhea, severe abdominal cramps, vomiting, chills, and fevers as high as 104-105°F (40-40.6°C). In addition, a case of acute amebic dysentery may cause complications, including inflammation of the appendix (appendicitis), a tear in the intestinal wall (perforation), or a sudden, severe inflammation of the colon (fulminating colitis).

Key termsAmeboma — A mass of tissue that can develop on the wall of the colon in response to amebic infection.

Antibody — A specific protein produced by the immune system in response to a specific foreign protein or particle called an antigen.

Appendicitis — Condition characterized by the rapid inflammation of the appendix, a part of the intestine.

Asymptomatic — Persons who carry a disease and are usually capable of transmitting the disease but who do not exhibit symptoms of the disease are said to be asymptomatic.

Dysentery — Intestinal infection marked by diarrhea containing blood and mucus.

Fulminating colitis — A potentially fatal complication of amebic dysentery marked by sudden and severe inflammation of the intestinal lining, severe bleeding or hemorrhaging, and massive shedding of dead tissue.

Inflammatory bowel disease (IBD) — Disease in which the lining of the intestine becomes inflamed.

Lumen — The inner cavity or canal of a tube-shaped organ, such as the bowel.

Protozoan — A single-celled, usually microscopic organism that is eukaryotic and, therefore, different from bacteria (prokaryotic).

AMEBOMA. An ameboma is a mass of tissue in the bowel that is formed by the amebiasis organism. It can result from either chronic intestinal infection or acute amebic dysentery. Amebomas may produce symptoms that mimic cancer or other intestinal diseases.

PERIANAL ULCERS. Intestinal amebiasis may produce skin infections in the area around the patient's anus (perianal). These ulcerated areas have a "punched-out" appearance and are painful to the touch.

Extraintestinal amebiasisExtraintestinal amebiasis accounts for approximately 10% of all reported amebiasis cases and includes all forms of the disease that affect other organs.

The most common form of extraintestinal amebiasis is amebic abscess of the liver. In the United States, amebic liver abscesses occur most frequently in young Hispanic adults. An amebic liver abscess can result from direct infection of the liver by E. histolytica or as a complication of intestinal amebiasis. Patients with an amebic abscess of the liver complain of pain in the chest or abdomen, fever, nausea, and tenderness on the right side directly above the liver.

Other forms of extraintestinal amebiasis, though rare, include infections of the lungs, chest cavity, brain, or genitals. These are extremely serious and have a relatively high mortality rate.

DiagnosisDiagnosis of amebiasis is complicated, partly because the disease can affect several areas of the body and can range from exhibiting few, if any, symptoms to being severe, or even life-threatening. In most cases, a physician will consider a diagnosis of amebiasis when a patient has a combination of symptoms, in particular, diarrhea and a possible history of recent exposure to amebiasis through travel, contact with infected persons, or anal intercourse.

It is vital to distinguish between amebiasis and another disease, inflammatory bowel disease (IBD) that produces similar symptoms because, if diagnosed incorrectly, drugs that are given to treat IBD can encourage the growth and spread of the amebiasis organism. Because of the serious consequences of misdiagnosis, potential cases of IBD must be confirmed with multiple stool samples and blood tests, and a procedure involving a visual inspection of the intestinal wall using a thin lighted, tubular instrument (sigmoidoscopy) to rule out amebiasis.

A diagnosis of amebiasis may be confirmed by one or more tests, depending on the location of the disease.

Stool examinationThis test involves microscopically examining a stool sample for the presence of cysts and/or trophozoites of E. histolytica and not one of the many other intestinal amebas that are often found but that do not cause disease. A series of three stool tests is approximately 90% accurate in confirming a diagnosis of amebic dysentery. Unfortunately, however, the stool test is not useful in diagnosing amebomas or extraintestinal infections.

SigmoidoscopySigmoidoscopy is a useful diagnostic procedure in which a thin, flexible, lighted instrument, called a sigmoidoscope, is used to visually examine the lower part of the large intestine for amebic ulcers and take tissue or fluid samples from the intestinal lining.

Blood testsAlthough tests designed to detect a specific protein produced in response to amebiasis infection (antibody)

are capable of detecting only about 10% of cases of mild amebiasis, these tests are extremely useful in confirming 95% of dysentery diagnoses and 98% of liver abscess diagnoses. Blood serum will usually test positive for antibody within a week of symptom onset. Blood testing, however, cannot always distinguish between a current or past infection since the antibodies may be detectable in the blood for as long as 10 years following initial infection.

Imaging studiesA number of sophisticated imaging techniques, such as computed tomography scans (CT), magnetic resonance imaging (MRI), and ultrasound, can be used to determine whether a liver abscess is present. Once located, a physician may then use a fine needle to withdraw a sample of tissue to determine whether the abscess is indeed caused by an amebic infection.

TreatmentAsymptomatic or mild cases of amebiasis may require no treatment. However, because of the potential for disease spread, amebiasis is generally treated with a medication to kill the disease-causing amebas. More severe cases of amebic dysentery are additionally treated by replacing lost fluid and blood. Patients with an amebic liver abscess will also require hospitalization and bed rest. For those cases of extraintestinal amebiasis, treatment can be complicated because different drugs may be required to eliminate the parasite, based on the location of the infection within the body. Drugs used to treat amebiasis, called amebicides, are divided into two categories:

Luminal amebicidesThese drugs get their name because they act on organisms within the inner cavity (lumen) of the bowel. They include diloxanide furoate, iodoquinol, metronidazole, and paromomycin.

Tissue amebicidesTissue amebicides are used to treat infections in the liver and other body tissues and include emetine, dehydroemetine, metronidazole, and chloroquine. Because these drugs have potentially serious side effects, patients given emetine or dehydroemetine require bed rest and heart monitoring. Chloroquine has

been found to be the most useful drug for treating amebic liver abscess. Patients taking metronidazole must avoid alcohol because the drug-alcohol combination causes nausea, vomiting, and headache.

Most patients are given a combination of luminal and tissue amebicides over a treatment period of seven to ten days. Follow-up care includes periodic stool examinations beginning two to four weeks after the end of medication treatment to check the effectiveness of drug therapy.

PrognosisThe prognosis depends on the location of the infection and the patient's general health prior to infection. The prognosis is generally good, although the mortality rate is higher for patients with ameboma, perforation of the bowel, and liver infection. Patients who develop fulminant colitis have the most serious prognosis, with over 50% mortality.

PreventionThere are no immunization procedures or medications that can be taken prior to potential exposure to prevent amebiasis. Moreover, people who have had the disease can become reinfected. Prevention requires effective personal and community hygiene.

Specific safeguards include the following:

Purification of drinking water. Water can be purified by filtering, boiling, or treatment with iodine.

Proper food handling. Measures include protecting food from contamination by flies, cooking food properly, washing one's hands after using the bathroom and before cooking or eating, and avoiding foods that cannot be cooked or peeled when traveling in countries with high rates of amebiasis.

Careful disposal of human feces. Monitoring the contacts of amebiasis patients.

The stools of family members and sexual partners of infected persons should be tested for the presence of cysts or trophozoites.