Case Study of Amoebiasis

METROPOLITAN MEDICAL CENTERCOLLEGE OF ARTS SCIENCE AND TECHNOLOGY#1357 G. Masangkay Corner Mayhaligue Streets, Sta. Cruz, Manila

INTRODUCTION:

Amoebiasis protozoal infection of human beings initially involves the colon, but may

spread to soft tissues, most commonly to the liver or lungs, by contiguity or hematogenous or

lymphatic dissemination.

Amoebiasis is the third leading parasitic cause of death worldwide, surpassed only by

malaria and schistosomiasis. On a global basis, amoebiasis affects approximately 50 million

persons each year, resulting in nearly 100,000 deaths.

METROPOLITAN MEDICAL CENTERCOLLEGE OF ARTS SCIENCE AND TECHNOLOGY#1357 G. Masangkay Corner Mayhaligue Streets, Sta. Cruz, Manila

Amoebiasis is due to invasion of the intestinal wall by the protozoan parasite Entemoeba

histolytica. Amoebic colitis results from ulcerating mucosal lesions caused by the release of

parasite-derived hyaluronidases and proteases. It refers to infection of man by Entamoeba

hystolytica initially involving the colon but which may spread to other soft tissues organs by

contiguity or by hematogenous or lymphatic dissemination most commonly to the liver and

lungs.

It is a worldwide parasitic disease. It creates many medical and surgical problems.

About15 to 20 per cent of Indians are affected by the parasite. It can be acute and chronic and

can have intestinal and extra-intestinal manifestations. The causative organism is protozoa that

remains in the large intestine and can be transmitted to other organs like liver, lungs, brain,

spleen and skin. It is transmitted through contaminated food, water and infected human feces.

Amoebiasis can occur at any age. There is no gender or racial difference in the

occurrence of the disease. It is a household infection and the human being is responsible for

spreading the disease. Most of the infected people remain asymptomatic (without symptoms) and

are called as healthy carriers. If one person in a family gets infected with the parasite, other

family members are at the great risk of infection. The human carrier can discharge up to 1.5x107

cysts per day.

Pathogenic amoeba, which produce condition of a great clinical variation:

1. Acute Amoebic Dysentery

stools contain blood and mucus, which may give rise to amoebic hepatitis or liver

abscess.

2. Chronic Amoebic Dysentery

with recurrent attack of diarrhea or relatively mild dysentery.

3. Amoebic Colitis

characterized by periods of constipation and diarrhea and episodes of abdominal

discomfort frequently stimulating appendicitis.

METROPOLITAN MEDICAL CENTER COLLEGE OF ARTS SCIENCE AND TECHNOLOGY #1357 G. Masangkay Corner Mayhaligue Streets, Sta. Cruz, Manila

History of Discovery:

Human infections of the parasite are not a recent phenomenon. The earliest record of

symptoms of the disease—bloody, mucose diarrhea—was from the Sanskrit document Brigu-

samhita, written at around 1000BC. Assyrian and Babylonian texts also have references to the

diseases, with descriptions of blood in the feces, thus suggesting that amoebiasis occurred in the

Tigris-Euphrates basin before the sixth century BC. Later records were able to distinguish

bacterial infections with those of amoebic origin: epidemics of dysentery by itself are more likely

to result from bacterial infections, while dysentery that is associated with disease of the liver is

more likely to cause by amoeba. Thus, around the second century AD; there was clearer

understanding of the association between liver abscesses and amoebas.

Around the 16th century, amoebiasis became more widespread in the developed world,

mostly due to the growth of European colonies and increased world trade. There had been many

clear descriptions of the hepatic and intestinal forms of amoebiasis, considered as the cause of a

“bloody flux” spreading through Europe, Asia, Persia, and Greece. The first accurate description

of both forms of the disease came from the book Researches into the Causes, Nature and

Treatment of the More Prevalent Diseases of India and of Warm Climates Generally by James

Annersley, written in the 19th century. Considering their small size, protozoans were difficult to

identify before the invention of the microscope in the 17th century. Friedrich Losch discovered

the causal agent, Entamoeba histolytica, in Russia in 1873. His early observations came from the

case of a young farmer who had from been suffering chronic dysentery. In his diagnosis, Losch

found large numbers of amoeba in his feces and associated the amoebas to be the cause of the

dysentery.


Etiologic Agent: Enatamoeba Histolytica

Prevalent in unsanitary areas

Common in warm climate

Acquired by swallowing

Cysts survives a few days outside of the body

Cyst passes to the large intestine and hatch into trophozoites. It passes into the mesenteric veins, to

the portal vein, to the liver, thereby forming amoebic liver abscess.

Entamoeba Histolytica has two developmental stages:

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1. Trophozoites/vegetative form

Trophozoites are facultative parasites that may invade the tissues or may be found in the

parasitized tissues and liquid colonic contents.

2. Cyst

Cyst is passed out with formed or semi-formed stools and are resistant to environmental

conditions.

This is considered as the infective stage in the cycle of E. histolytica

Source: Human Excreta

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

Period of Communicability:

The microorganism is communicable for the entire duration of the illness.


Modes 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.

Food or drinks maybe contaminated by cyst through pollution of water supplies, exposure to

flies, use of night soil for fertilizing vegetables, and through unhygienic practices of food

handlers.

Clinical Manifestations:

a. Acute amoebic dysentery

Slight attack of diarrhea, altered with periods of constipation and often accompanied by tenesmus.

Diarrhea, watery and foul smelling stool often containing blood-streaked mucus

Colic and gaseous distension of the lower abdomen

Nausea, flatulence, abdomnal distension and tenderness in the right iliac region over the colon

b. Chronic amoebic dysentery

Attack dysentery that lasts for several days, usually succeeded by constipation

Tenesmus accompanied by the desire to defacate

Anorexia, weight loss, and weakness

Liver may be enlarged

The stool at first is semifluid but soon becomes watery, bloody, and mucoid

Vague abdominal distress, flatulence, constipation or irregularity of bowel

Mild toxemia, constant fatigue and lassitude


Abdomen loses its elasticity when picked up between fingers

On sigmoidoscopy, scattered ulceration with yellowish and erythematous border

The gangrenous type (fatal cases) is characterized by the appearance of large sloughs of intestinal

tissues in the stool accompanied by hemorrhage.

c. Extraintestinal forms

Hepatic

Pain at the upper right quadrant with tenderness of the liver

Abscess may break through the lungs, patient coughs anchovy-sauce sputum

Jaundice

Intermittent fever

Loss of weight or anorexia

Clinical Features:

1. Onset is gradual

2. Diarrhea increases and stool

becomes bloody and mucoid

3. In untreated cases:


ANATOMY AND PHYSIOLOGY:

Amebiasis is an intestinal illness that is typically transmitted when someone eats or drinks

something that is contaminated with a microscopic parasite called Entamoeba histolytica (E.

histolytica). The parasite is an amoeba, a single-celled organism. That is how the illness got its

name — amebiasis.

In many cases, the parasite lives in a person’s large intestine without causing any

symptoms. But sometimes, it invades the lining of the large intestine, causing bloody diarrhea,

stomach pains, cramping, nausea, loss of appetite, or fever. In rare cases, it can spread into other

organs such as the liver, lungs, and brain.

I. Structure. The GI System consists of the oral structures, esophagus, stomach, small intestine, large

intestine and associated structures.

A. Oral Structures include the lips, teeth,

gingivae and oral mucosa, tongue, hard

palate, soft palate, pharynx and salivary

glands.

B. The esophagus is a muscular tube

extending from the pharynx to the stomach.

Esophageal openings include:

1. The upper esophageal sphincter at the

cricopharyngeal muscle.

2. The lower esophageal sphincter (LES), or cardiac sphincter, which normally remains closed

and opens only to pass food into the stomach.


C. The Stomach is a muscular pouch situated in the upper abdomen under the liver and diaphragm.

Te stomach consists of three anatomic areas: the fundus, body (i.e., corpus), and antrum (i.e.,

pylorus)

D. Sphincters. The LES allows food to enter the stomach and prevents reflux into the esophagus. The

pyloric sphincter regulates flow of stomach contents (chyme) into the duodenum.

E. The small intestine, a coiled tube, extends from the pyloric sphincter to the ileocecal valve at the

large intestine. Sections of the small intestine include the duodenum, jejunum and ileum

F. The large intestine is a shorter, wider tube beginning at the ileocecal valve and ending at

the anus. The large intestine consists of three sections:

1. The cecum is a blind pouch that extends from the ileocecal valve to the vermiform

appendix.

2. The colon, which is the main portion of the large intestine, is divided into four

anatomic sections: ascending, transverse, descending and sigmoid.

3. The rectum extends from the sigmoid colon to the anus.

G. The ileocecal valve prevents the return of feces from the cecum into the small intestine

and lies at the upper border of the cecum.

H. H. The appendix, which collects lymphoid tissues, arises from the cecum

The GI tract is composed of five layers:

1. An inner mucosal layer lubricates and protects the inner surface of the alimentary canal.

2. A submucosal layer is responsible for secreting digestive enzymes.

3. A layer of circular smooth muscle fibers is responsible for movement of the GI tract.

4. A layer of longitudinal smooth muscle fibers also facilitates movement of the GI tract.

5. The peritoneum, an outer serosal layer, covers the entire abdomen and is composed of the

parietal and visceral layers.


II. Function. The GI system performs two major body functions: digestion and elimination.

A. Digestion of food and fluid, with absorption of nutrients into the bloodstream, occurs in the

upper GI tract, stomach and small intestines.

1. Digestion begins in the mouth with chewing and the action of ptyalin, an enzyme contained

in saliva that breaks down starch.

2. Swallowed food passes through the esophagus to the stomach, where digestion continues

by several processes.

a. Secretion of gastric juice, containing hydrochloric acid and the enzymes pepsin

and lipase ( and renin in infants)

b. Mixing and churning through peristaltic action

3. From the pylorus, the mixed stomach contents (i.e. chyme) pass into the duodenum

through the pyloric valve.

4. In the small intestine, food digestion is completed, and most nutrient absorption occurs.

Digestion results from the action of numerous pancreatic and intestinal enzymes (e.g.,

trypsin, lipase, amylase, lactase, maltase, sucrose and bile).

B. Elimination of waste products through defecation occurs in the large intestines and rectum. In

the large intestine, the cecum and ascending colon absorb water and electrolytes from the now

completely digested material. The rectum stores feces for elimination.


PATHOPHYSIOLOGY:

When cyst is swallowed, it passes through the stomach unharmed and shows no activity

while in an acidic environment. When it reaches the alkaline medium of the intestine, the

metacyst begins to move within the cyst wall, which rapidly weakens and tears. The

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quadrinucleate amoeba emerges and divides into amebulas that are swept down into the cecum.

This is the first opportunity of the organism to colonize, and its success depends on one or more

metacystic trophozoites making contact with the mucosa.

Mature cyst in the large intestines leaves the host in great numbers (the host remains

asymptomatic). The cyst can remain viable and infective in moist and cool environment for at

least 12 days and in water for 30 days. The cysts are resistant to levels of chlorine normally used

for water purification. Purification, desiccation and temperatures below 5 and above 40 degrees

rapidly kill them.


The metacystic trophozoites of their progenies reach the cecum and those that are

exposed to the oral mucosa penetrate or invade the epithelium by lytic digestion.

The trophozoites burrow deeper with tendency to spread laterally or continue the lysis of

cells until they reach the sub-mucosa forming flash-shape ulcers. There may be several points of

penetration.


From the primary site of invasion, secondary lesions maybe produced at the lower level

of the large intestine.

Progenies of the initial colonies are squeezed out to the lower portion of the bowel and

thus, have the opportunity to invade and produce additional ulcers. Eventually, the whole colon

may be involved.

E. histolytica has been demonstrated in practically every soft organ of the body.

Trophozoites which reach the muscularis mucosa frequently erode the lymphatics or

walls of the mesenteric venules in the floor of the ulcers, and are carried to the intrahepatic portal

vein.

If thrombi occur in the small branches of the portal veins, the trophozoites in thrombi

cause lytic necrosis on the wall of the vessels and digest a pathway into the lobules.

The colonies increase in size and develop into abscess.

A typical liver abscess develops and consists of:

Central zone necrosis

Median zone of stoma only

An outer zone of normal tissue newly invaded by amoeba. Most amoebic abscess of the

liver are in the right lobe.

Next to the liver, the organ that is the frequent site of extra-intestinal amoebiasis is the

lungs. This commonly develops as an extension of the hepatic abscess.


Laboratory Diagnosis:

1. Stool exam (cyst, white and yellow pus

with plenty of amoeba)

2. Blood exam (Leukocytosis)

3. Proctoscopy/Sigmoidoscoppy

Diagnosis of amoebiasis can be very difficult.

One problem is that other parasites and cells can look

very similar to E. histolytica when seen under a microscope. Therefore, sometimes people are

told that they are infected with E. histolytica even though they are not.Entamoeba histolytica and

another ameba, Entamoeba dispar, which is about 10 times more common, look the same when

seen under a microscope. Unlike infection with E. histolytica, which sometimes makes people

sick, infection with E. dispar does not make people sick and therefore does not need to be

treated. If you have been told that you are infected with E. histolytica but you are feeling fine,

you might be infected with E. dispar instead. Unfortunately, most laboratories do not yet have

the tests that can tell whether a person is infected with E. histolytica or with E. dispar. Until these

tests become more widely available, it usually is best to assume that the parasite is E. histolytica.

A blood test is also available but is only recommended when your health care provider

thinks that your infection may have spread beyond the intestine (gut) to some other organ of your

body, such as the liver. However, this blood test may not be helpful in diagnosing your current

illness because the test may still be positive if you had amoebiasis in the past, even if you are no

longer infected now.


Complications:

1. Amebic colitis

Fulminant or necrotizing colitis

Toxic megacolon

Ameboma

Rectovaginal fistulas

2. Amebic liver abscess

Intrathoracic or intraperitoneal rupture with or without secondary bacterial infection

Direct extension to pleura or pericardium

3. Brain abscess

Treatment:

1. Metronidazole (Flagyl) 800mg TID X 5 days

2. Tetracyline 250 mg every 6 hours

3. Ampicillin, quinolones sulfadiazine

4. Streptomycin SO4, Chloramphenicol

5. Lost fluid and electrolytes should be replaced

Several antibiotics are available to treat amoebiasis. Treatment must be prescribed by

a physician. You will be treated with only one antibiotic if your E. histolytica infection

has not made you sick. You probably will be treated with two antibiotics (first one and then the

other) if your infection has made you sick.


Nursing Management:

1. Observe isolation and enteric precaution

2. Provide health education and instruct patient to

Boil water for drinking or use purified water

Avoid washing food from open drum or pail

Cover leftover food

Wash hands after defacation and before eating

Avoid ground vegetables (lettuce, carrots, and the like)

3. Proper collection of stool specimen

4. Never give paraffin or any oil preparation for at least 48 hours prior to collection of

specimen.

5. Instruct patient to avoid mixing urine with stools.

6. If whole stool cannot be sent to laboratory, select as much portion as possible containing

blood and mucus.

7. Send specimen immediately to the laboratory; stool that is not fresh is nearlyuseless for

examination. Label specimen properly.

8. Skin care

9. Cleanliness, freedom from wrinkles on the sheet will be helpful with all the usual

precautionary measures against pressure sores.

a. Mouth care

b. Provide optimum comfort.

Patient should be kept warm. Dysenteric patient should never be allowed to feel,

even for a moment.

Diet-During the acute stage, fluids should be forced.


In the beginning of an attack, cereal and strained meat broths without fat should

be given.

Chicken and fish maybe added when convalescence is established.

Bland diet without cellulose or bulk-producing food should be maintained for a

long time.

Common Nursing Diagnosis:

1. Altered nutrition: Less than body requirement

2. Alteration in bowel elimination

3. High risk for infection

4. Anxiety

5. Altered body temperature

Methods of Prevention:

1. Health education

2. Sanitary disposal of feces

3. Protect, chlorinate, and purify drinking water

4. Observe scrupulous cleanliness in food preparation and food handling

5. Detection and treatment of carriers

6. Fly control (they can serve as vector)


PUBLIC HEALTH PREVENTION

One important public health strategy is to make sure to treat infected individuals who

appear asymptomatic, since these people also pass cysts in their stool and thus

contributed to spreading the disease.

Good sanitation and water facilities are also important in preventing the disease.

Food handlers, childcare workers, and health care workers with amoebiasis should not be

allowed to work until their symptoms are gone.

If children have symptoms, they should not attend childcare centers or schools until their

symptoms are gone.

In general, people should practice good hygiene, since the fecal matter from those

infected could contaminate food and water that is then transferred to others. This includes

careful hand washing with soap and hot running water for at least 10 seconds after going

to the toilet, as well as practice frequent hand washing in general to eliminate any parasite

that one may have picked up throughout the day.

Travelers should take precaution

Clean bathrooms and toilets often.

Boil water

Avoid uncooked foods

Practice safe food storage and handling: thoroughly cook all raw foods, thoroughly wash

raw vegetables and fruits, and reheat food until the internal temperature of food reaches

at least 167°F.


HOME PREVENTION

Avoidance of drinking unboiled or unbottled water in endemic areas.

Uncooked food such as fruit and vegetables that may have been washed in local water

should also not be consumed.

Amoebic cysts are resistant to chlorine at the levels used in water supplies, but

disinfection with iodine may be effective.

Wash hands with soap and warm water after going to the toilet and before eating or

preparing food.

Proper food storage and preventing its contamination with feces, flies, and contaminated

water

Avoiding sexual practices that may lead to fecal-oral contact.

Case Study of Amoebiasis

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