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Amoebiasis; Entamoeba histolytica; Parasitic infection; Intestinal Amoebiasis; Extraintestinal Amoebiasis; Dysentery; Amoebic liver abscess; Fecal-oral transmission; Stool test; Antiparasitic drugs; Metronidazole; Tinidazole; Prevention of amoebiasis; Hygiene practices; Safe drinking water; Food safety

Introduction

Amoebiasis, also known as amebiasis, is an infectious disease caused by the parasite Entamoeba histolytica. It primarily affects the intestines but can spread to other organs, such as the liver, lungs, and brain, causing severe complications [1]. The disease is prevalent in tropical and subtropical regions, particularly in areas with poor sanitation. According to the World Health Organization (WHO), amoebiasis is responsible for approximately 50,000 to 100,000 deaths worldwide each year [2]. Amoebiasis, also known as amoebic dysentery, is a parasitic infection caused predominantly by Entamoeba histolytica, a protozoan that colonizes the human gastrointestinal tract [3]. The disease is most commonly transmitted via the fecal-oral route, often through ingestion of contaminated water or food, making it a significant public health concern in regions with inadequate sanitation and limited access to clean water. Although amoebiasis is found worldwide, it is particularly prevalent in developing countries in tropical and subtropical climates, where the conditions for transmission are more conducive [4]. The clinical manifestations of amoebiasis can vary widely, ranging from asymptomatic colonization to severe, life-threatening illness. In many cases, infected individuals remain symptom-free, unknowingly becoming carriers who contribute to the spread of the parasite [5]. When symptoms do occur, they often include abdominal pain, diarrhea (sometimes with blood or mucus), and cramping. In more serious instances, the parasite invades the intestinal wall, leading to ulceration, hemorrhage, and potentially an amoebic liver abscess, a complication that arises when the parasite spreads beyond the intestines [6]. Diagnosing amoebiasis can be challenging due to the nonspecific nature of its symptoms and the morphological similarities between E. histolytica and non-pathogenic species such as E. dispar. Modern diagnostic methods such as stool antigen detection, PCR, and serological tests have improved diagnostic accuracy and allow for more timely and effective treatment [7]. Management of amoebiasis typically involves the use of antiparasitic medications, with metronidazole or tinidazole being the drugs of choice for tissue-invasive disease, often followed by a luminal agent like paromomycin to eradicate cysts and prevent recurrence. Prevention strategies play a vital role in controlling the spread of amoebiasis, particularly in endemic regions. Key preventive measures include promoting good hygiene practices such as regular handwashing, ensuring the safety of drinking water, and proper sanitation infrastructure to reduce fecal contamination. Public health education and improvements in community-level sanitation remain critical components in reducing the incidence and burden of this parasitic disease [8].

Causes and transmission

The causative agent of amoebiasis, Entamoeba histolytica, is a single-celled protozoan parasite. It exists in two forms:

Trophozoites: The active, invasive form that causes tissue damage.

Cysts: The dormant, infective form that can survive outside the host in soil, water, or on contaminated surfaces. Amoebiasis is primarily transmitted through the fecal-oral route, which occurs in the following ways:

Contaminated food and water: Consuming food or water tainted with E. histolytica cysts.

Poor sanitation: Lack of proper sewage disposal and hygiene practices.

Person-to-person contact: Direct contact with infected individuals, such as through anal-oral sexual activities.

Flies and cockroaches: These insects can spread the cysts by contaminating food.

Symptoms of amoebiasis

The symptoms of amoebiasis vary depending on the severity of the infection. They range from mild gastrointestinal issues to severe systemic complications.

• Diarrhea (may contain blood and mucus)
• Abdominal pain and cramping
• Nausea and vomiting
• Fatigue and weight loss
• Flatulence and bloating

Extraintestinal amoebiasis

When the parasite spreads beyond the intestines, it can lead to:

Amoebic liver abscess, characterized by fever, right upper abdominal pain, and jaundice.

Pulmonary amoebiasis, cough, chest pain, and breathing difficulties.

Cerebral amoebiasis, rare but fatal; presents with neurological symptoms such as confusion, seizures, and coma.

Diagnosing amoebiasis requires a combination of clinical evaluation, laboratory tests, and imaging.

Microscopic identification of E. histolytica cysts or trophozoites in stool samples.

Stool antigen detection tests or PCR (polymerase chain reaction) for higher accuracy.

Serology tests to detect antibodies, especially in extraintestinal amoebiasis.

Elevated white blood cell count and liver enzymes in cases of liver involvement.

Ultrasound or CT scan, detects liver abscesses or other complications.

Colonoscopy or sigmoidoscopy, may reveal ulcers or inflammation in the colon.

Prevention of amoebiasis

Preventing amoebiasis relies on effective hygiene practices and sanitation measures:

Wash hands thoroughly with soap and water before eating and after using the toilet.

Avoid consuming unwashed fruits and vegetables.

Practice safe sex, especially during oral-anal contact.

If left untreated, amoebiasis can lead to severe complications, including:

Peritonitis – rupture of an abscess causing a life-threatening infection. Bowel perforation – intestinal damage leading to leakage of contents into the abdominal cavity. Sepsis – a systemic infection due to bacterial spread. Death – in rare cases, untreated amoebiasis can be fatal, especially when the liver, brain, or lungs are involved.

Recent advances in amoebiasis research

Vaccines and Immunotherapy – Experimental vaccines targeting E. histolytica antigens are under development.

New Antimicrobials – Research is underway to develop more effective and less toxic drugs.

Genetic and Molecular Studies – Advances in understanding the parasite's genome to develop targeted therapies.

Conclusion

Amoebiasis remains a major parasitic disease with significant public health implications, particularly in regions with poor sanitation and limited access to clean water. Early diagnosis, effective treatment with antiparasitic drugs, and preventive measures such as hygiene practices and safe drinking water are essential to reduce its burden. Continued research into vaccines, new therapeutics, and improved diagnostic tools offers hope for better control and eventual eradication of this disease. Strengthening public health infrastructure and community awareness will be key to minimizing transmission and safeguarding populations worldwide.

References

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