Amoebic dysentery (intestinal amebiasis)

For a lay person:

Intestinal amoebiasis is an infection of the large bowel by a single-celled parasite spread through contaminated food and water. Many people have no symptoms, but it can cause bloody diarrhoea and abdominal pain, and occasionally spreads to the liver as an abscess.

For a trained medical person:

Caused by Entamoeba histolytica, acquired by faecal-oral ingestion of cysts; trophozoites invade the colonic mucosa causing flask-shaped ulcers, colitis, and rarely toxic megacolon, perforation or amoebic liver abscess. Diagnosis is by stool antigen or PCR, which distinguishes it from non-pathogenic Entamoeba species, and serology and imaging for liver abscess. Treatment is a nitroimidazole such as metronidazole followed by a luminal agent such as paromomycin.

In Chinese medicine:

Liu and Tseng's textbook differentiates this condition into these patterns: Damp-Heat Accumulating in Intestines Syndrome (Common Type); Excess Parasite Toxin Syndrome (Fulminant); Spleen and Stomach Deficient Cold; Zheng Qi Deficiency with Lingering Evil Pathogens. Treatment follows the pattern a patient presents with, not the Western diagnosis alone.

When to get help: See a doctor for bloody diarrhoea or diarrhoea after travel; get urgent care for high fever, severe abdominal pain or pain under the right ribs. It needs antiparasitic medicine and Chinese medicine is adjunctive at most.