Amebiasis - Causes, Risk Factors, Symptoms, Diagnosis, Treatment, and Prevention

Introduction:

Amebiasis is an infection of the intestines caused by the microscopic parasite Entamoeba histolytica. It can affect both children and adults. Amebiasis occurs worldwide but is more commonly seen in developing countries due to poor sanitation and increased fecal contamination of water supplies. They are also called amebic dysentery, intestinal amebiasis, amebic colitis, diarrhea - amebiasis.

How Does Entamoeba Histolytica Infection Occur?

Entamoeba histolytica infection can occur when a person:

• Ingest anything into the mouth that has touched the feces of an infected person with entamoeba histolytica.

• Drinks water or swallows food that is contaminated with the parasite.

• Swallows cysts of entamoeba histolytica that are picked up from contaminated surfaces or fingers.

What Causes Amebiasis?

Entamoeba histolytica is a protozoan (single-celled) parasite causing amebiasis. It enters the human body when people ingest cysts contaminated with infected fecal matter or through contaminated food or water. Entamoeba histolytica exists in two forms - the cysts, which are the inactive form of the parasite, can live for several months in the soil deposited in feces. When cyst enters the digestive tract, they release an invasive, active form of the parasite called a trophozoite. The trophozoite enters the digestive tract and multiplies, attacking the intestinal wall. Transmission of the parasite is also possible during anal sex, oral-anal sex, and colonic irrigation.

What Are the Risk Factors for Severe Amebiasis?

• Drinking alcohol.

• Cancer.

• Malnutrition.

• Older or younger age.

• Pregnancy.

• Recent travel to a tropical region.

• Weak immune system.

What Are the Symptoms of Amebiasis?

Amebiasis is contagious from person to person. Only about 10 % to 20 % of people infected with Entamoeba histolytica become sick. Most people with amebiasis are asymptomatic. Symptomatic patients are further divided into intestinal and extraintestinal amebiasis. Intestinal amebiasis shows symptoms affecting the digestive system, whereas extraintestinal amebiasis includes the involvement of the liver, lungs, brain, spleen, skin, etc. If symptomatic, signs are seen seven to 28 days after the exposure to the parasite. A patient can spread the infection to others as long as the infected patient excretes cysts in their stools. If untreated, the disease can spread for weeks to many years.

The symptoms are often relatively mild and can include:

• Loose feces.

• Stomach pain and stomach cramping.

• Fatigue.

• Excessive gas.

• Rectal pain while having a bowel movement.

• Anemia.

• Increased white blood cell (WBC) count.

• Weight loss.

Amebic dysentery, a severe form of amebiasis, is associated with stomach pain, bloody stools (passage of ten to twenty stools per day), fever, and vomiting. In some cases, Entamoeba histolytica invades the liver and forms liver abscesses (a collection of pus). A liver abscess can develop within two to four weeks after the first infection and develops in less than four percent of patients. Liver abscess usually presents right upper quadrant pain, fever, and tenderness on palpation (pain on touch). Rarely, an amoebic liver abscess may rupture into the pleural cavity showing as pleural effusion or pericardium presenting as pericardial effusion.

How Is Amebiasis Diagnosed?

• Physical examination and travel history to tropical regions.

• Examination of the abdomen to rule out the tenderness in the stomach (typically in the right upper part of the abdomen).

• Blood tests may reveal the following:

• Elevated white blood cell (WBC) count.

• Eosinophilia.

• Elevated bilirubin and transaminase enzymes.

• Mild anemia.

• Elevated erythrocyte sedimentation rate (ESR).

• Liver ultrasound to rule out liver enlargement.

• Sigmoidoscopy to view the inside of the intestine.

• Stool test and examination of stool samples. The investigation is done with multiple samples of several days.

• Colonoscopy is done to check the presence of parasites in the large intestine.

How Can We Treat Amebiasis?

Asymptomatic infections are not usually treated. Treatment depends on the severity of the disease. For symptomatic patients, antibiotics are generally prescribed. If vomiting is present and medications can not be taken by mouth, medicines are given through a vein. After antibiotic treatment, the stool will be rechecked to ensure the infection has been cleared.

Entamoeba histolytica infection can be treated with luminal agents such as

• Paromomycin.

• Iodoquinol.

• Diloxanide furoate.

Paromomycin is given for a duration of seven days, diloxanide furoate for ten days, and iodoquinol for twenty days. Metronidazole or Tinidazole is recommended for amoebic liver abscesses (up to 10 cm) followed by a luminal agent. Chloroquine can be given to patients who do not respond to Metronidazole.

What Are the Home Remedies for Amebiasis?

The suggested home remedies for amebiasis include increased fluid intake, coconut water, buttermilk, black tea, herbal tea, oregano, and apple cider vinegar.

What Are the Possible Complications?

Complications of amebiasis may include:

• A liver abscess (collection of pus in the liver).

• Side effects of the medicines taken, including nausea.

• Gastrointestinal bleeding.

• Lung abscess.

• Brain abscess.

• Bloody dysentery.

• Toxic megacolon (abnormal dilation of the colon).

• Ameboma (cancer lesion).

How Can We Prevent Amebiasis?

When traveling in poor sanitation countries, drink purified or boiled water. Washing hands after eating and using the toilet can prevent the infection. Avoid eating uncooked food and unpeeled fruit.

The following items are not considered safe and to be avoided:

• Drinks with ice cubes.

• Unpeeled fruit or vegetables.

• Milk, cheese, or dairy products that are not pasteurized.

• Food or beverages sold by street vendors.

What Is the Differential Diagnosis for Amebiasis?

When examined under a microscope, Entamoeba histolytica and entamoeba dispar look similar, and they are found to be more common. Entamoeba histolytica infection can sometimes make people sick, whereas infection with entamoeba dispar never makes people sick and therefore does not need to be treated.

Conclusion:

Amebiasis is a relatively common parasitic infection with worldwide distribution. The Entamoeba histolytica cysts can not be prevented by water disinfection with chlorine. The risk of spreading disease is low. The outcome is usually good with treatment. Usually, the illness lasts about two weeks, but the chances of reinfection are more if not properly treated. Patient education plays an essential role in preventing infection.