Amoebiasis

Amoebiasis is caused by Entamoeba histolytica (an amoeboid protozoan) and spread by the faecal-oral route. It is estimated that 10% of the world's population is chronically infected. Infection can be asymptomatic, cause mild diarrhoea or severe amoebic dysentery. Amoebiasis also causes liver and colonic abscesses..

Pathophysiology of amoebiasis

Amoebic dysentery

profuse, bloody diarrhoea
there may be a long incubation period
stool microscopy may show trophozoites if examined within 15 minutes or kept warm (known as a 'hot stool')
treatment
- oral metronidazole
- a 'luminal agent' (to eliminate intraluminal cysts) is recommended usually as well e.g. diloxanide furoate

Amoebic liver abscess

initial amoebic colitis → weeks later spreads via portal circulation → liver abscess
usually a single mass in the right lobe (may be multiple). The contents are often described as 'anchovy sauce'
features
- fever
- right upper quadrant pain
- systemic symptoms e.g. malaise
- hepatomegaly
investigations
- ultrasound
- serology is positive in > 95%
management
- oral metronidazole
- a 'luminal agent' (to eliminate intraluminal cysts) is recommended usually as well e.g. diloxanide furoate

+PassMedicine Notes

Amoebiasis is caused by Entamoeba histolytica (an amoeboid protozoan) and spread by the faecal-oral route. It is estimated that 10% of the world's population is chronically infected. Infection can be asymptomatic, cause mild diarrhoea or severe amoebic dysentery. Amoebiasis also causes liver and colonic abscesses..

Amoebic dysentery

profuse, bloody diarrhoea
there may be a long incubation period
stool microscopy may show trophozoites if examined within 15 minutes or kept warm (known as a 'hot stool')
treatment

oral metronidazole
a 'luminal agent' (to eliminate intraluminal cysts) is recommended usually as well e.g. diloxanide furoate

Amoebic liver abscess

initial amoebic colitis → weeks later spreads via portal circulation → liver abscess
usually a single mass in the right lobe (may be multiple). The contents are often described as 'anchovy sauce'
features