Entamoeba histolytica

Classification

Kingdom: Protista
Phylum: Entamoebidae
Class: Archamoebae
Order: Amoebida
Family: Entamoebidae
Genus: Entamoeba
Species: Entamoeba histolytica

Morphology

Shape: Round, amoeboid form
Size: ~10-20 μm (trophozoites), ~10-15 μm (cysts)
Staining: Giemsa or trichrome stain
Arrangement: Found as trophozoites (active form) in the colon and cysts in feces
Motility: Motile via pseudopodia
Special Features: Produces cysts that are resistant to environmental conditions

Habitat & Distribution

Natural Habitat: Human colon and large intestine
Geographic Distribution: Worldwide, particularly in developing countries with poor sanitation
Host Association: Obligate parasite, infects humans
Transmission: Fecal-oral route, through ingestion of cysts in contaminated food, water, or hands

Entamoeba histolytica is the causative agent of amebiasis, an intestinal infection that can lead to dysentery and systemic complications like liver abscesses.

Virulence Factors: Proteolytic enzymes, ability to invade intestinal mucosa, cyst formation for survival in harsh environments
Associated Diseases: Amebic dysentery, amebic liver abscess, amebic colitis
Clinical Symptoms: Diarrhea, abdominal pain, weight loss, blood in stool, fever (in severe cases)
High-Risk Groups: Individuals in poor sanitation areas, immunocompromised patients, travelers to endemic regions

Amebiasis is a major health issue in developing countries, but it can be treated with proper medication, including metronidazole and other amoebicidal drugs.

The diagnosis of Entamoeba histolytica infection is based on stool examination, serology, and imaging in cases of extra-intestinal involvement.

Diagnostic Methods

Stool Microscopy: Identification of trophozoites or cysts in stool samples
Antigen Detection: Enzyme immunoassays for detecting E. histolytica antigens
Serology: Detection of antibodies for invasive disease
Imaging: Ultrasound or CT for liver abscess detection

Treatment Approaches

First-line Treatments: Metronidazole for invasive disease, followed by luminal agents (paromomycin)
Alternative Therapies: Tinidazole, nitazoxanide
Supportive Care: Rehydration, nutrition, and symptom management for diarrhea

Prevention Strategies

Proper hand hygiene and sanitation
Safe drinking water and food handling
Avoiding unprotected contact with feces

Preventing Entamoeba histolytica infection involves improving sanitation, access to clean water, and practicing proper hygiene.

Global Impact

Entamoeba histolytica is endemic in regions with poor sanitation, affecting millions annually in developing countries.

~50M

Approximately 50 million cases of amebiasis occur each year, with significant mortality in untreated cases.

Despite treatment options, amebiasis remains a significant health concern, especially in resource-limited regions.