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Amoebiasis

Amoebiasis is an infection caused by Entamoeba histolytica, a single-celled parasite that colonises the large intestine. It is widespread in areas where contaminated water and food remain common routes of exposure. Most people who pick up the parasite carry it without symptoms, but in some cases it causes significant illness.

Ornidazole Tablets

Ornidazole

500mg

Ornidazole 500mg tablets, used for trichomoniasis, amoebiasis and giardiasis. A nitroimidazole that disrupts DNA synthesis in protozoa.

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Key points

  • Entamoeba histolytica can live in the gut for a long time without producing any symptoms in the person carrying it.
  • Symptoms, when they appear, range from mild loose stools to bloody dysentery with cramping and a persistent urge to go.
  • A full course of an antiparasitic such as ornidazole is needed, since stopping early can leave cysts behind and allow relapse.

What the infection looks like

Symptomatic amoebiasis typically presents as diarrhoea, often with blood or mucus, accompanied by abdominal cramping and urgency. Symptoms can appear days to weeks after exposure and range from mild loose stools to a more severe bloody dysentery. In a small proportion of cases the parasite migrates beyond the gut, most often to the liver, causing an amoebic abscess with fever and right-sided abdominal pain. This extraintestinal form warrants prompt medical attention.

Treating amoebiasis

Intestinal amoebiasis responds well to nitroimidazole antiparasitic agents. Ornidazole is one of the options used; it belongs to the broader antiparasitic drug class and works by disrupting the parasite’s DNA. A full treatment course is important even when symptoms ease early, as incomplete treatment can leave cysts behind. Seek medical assessment if symptoms are severe, if fever is high, or if there is no improvement within a few days.

Further reading

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