Amoeba Parasitology

Amoeba Parasitology

Definition and Classification

• Amoebas are single-celled eukaryotic organisms belonging to the kingdom Protista
• Classified into two main groups:
  • Free-living amoebas: Found in soil, freshwater, and saltwater environments
  • Parasitic amoebas: Infect and live within host organisms, including humans

Parasitic Amoebas

• Entamoeba histolytica: Most common parasitic amoeba, causing amoebic dysentery and amoebic liver abscess
  • Infects approximately 50 million people worldwide
  • Transmission: Fecal-oral route, contaminated water, and food
• Acanthamoeba: Causes acanthamoebiasis, a rare but potentially fatal infection
  • Infects the eye, brain, and skin
  • Transmission: Contact lens use, contaminated water, and soil
• Balamuthia mandrillaris: Causes balamuthiasis, a rare and often fatal infection
  • Infects the brain and skin
  • Transmission: Unknown, but suspected to be through contaminated soil and water

Life Cycle

• Trofozoite stage: Active, motile stage that invades host cells
• Cyst stage: Dormant, resistant stage that can survive outside the host
  • Excystation: Process of cysts transforming into trophozoites
  • Encystation: Process of trophozoites forming cysts

Pathogenesis and Symptoms

• Entamoeba histolytica:
  • Causes intestinal ulcers, diarrhea, and abdominal pain
  • Can lead to amoebic liver abscess, a life-threatening condition
• Acanthamoeba:
  • Causes keratitis (eye infection), granulomatous amoebic encephalitis (brain infection), and skin lesions
• Balamuthia mandrillaris:
  • Causes granulomatous amoebic meningoencephalitis (brain infection) and skin lesions

Diagnosis and Treatment

• Microscopy: Identification of amoebas in stool, tissue, or cerebrospinal fluid samples
• Antibodies: Detection of anti-amoeba antibodies in serum or cerebrospinal fluid
• Antimicrobials: Metronidazole, tinidazole, and chloroquine used to treat amoebic infections