Clinical features

The incubation period is highly variable, from a matter of days to up to a year. Three different clinical presentations may occur:

• history of gradual onset of mild intermittent diarrhoea with abdominal discomfort. Often the diarrhoea may be bloody and contain mucus. Accompanying the diarrhoea there may be headache, nausea, and anorexia. There may be right iliac fossa tenderness. If the entire colon is involved there will be generalised abdominal tenderness. There may be an amoeboma palpable and this must be differentiated from diverticular disease or carcinoma.
  
  
• acute amoebic dysentery - fever, malaise, abdominal pain and watery diarrhoea. As the disease progresses, bloody diarrhoea with mucus, tenesmus, faecal urgency and severe cramping abdominal pain become prominent.
  
  
• fulminating colitis