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amoebiasis

amoebiasis

introduction

  • infection caused by the amoeba Entamoeba histolytica
  • usually transmitted by the fecal-oral route
  • amoebiasis is estimated to cause 70,000 deaths per year world wide
  • it is often endemic in regions of the world with limited modern sanitation systems, including Mexico, Central America, western South America, South Asia, and western and southern Africa.

clinical pictures

asymptomatic carriers

  • 90% are asymptomatic
  • can remain latent in an infected person for several years

gastroenteritis

  • 10% develop gastroenteritis after an incubation period usually 2-4 weeks, which ranges from mild diarrhoea to severe dysentery (severe ulceration of the gastrointestinal mucosal surfaces occurs in less than 16% of symptomatic cases)
  • it is an uncommon cause of traveller's diarrhoea

intestinal granulomas

  • a granulomatous mass (known as an amoeboma) may form in the wall of the ascending colon or rectum due to long-lasting immunological cellular response
  • NB. inflammatory caecal area masses in returned travellers may be due to:
    • ameboma
    • helminthoma
    • ascaris - usually pulmonary symptoms in 1st 2 weeks with cough, wheeze, maybe eosinophilia
    • hookworm may cause eosinophilic enteritis
    • strongyloidiasis may rarely cause eosinophilic oophoritis
    • appendiceal abscess
    • Crohn's disease
    • malignancy
    • etc.

hepatic amoebiasis

  • 10% of invasive cases result in spread to almost any organ, but in particular, the liver.
  • complications include:
    • subdiaphragmatic abscess
    • perforation of diaphgram to pericardium and pleural cavity
    • perforation to abdominal cavital (amoebic peritonitis)
    • perforation of skin (amoebic cutis)

cutaneous amoebiasis

  • can occur at skin around site of colostomy wound, perianal region, region overlying visceral lesion and at the site of drainage of liver abscess

urogenital

  • urogenital tract amoebiasis derived from intestinal lesion can cause amoebic vulvovaginitis (May's disease), rectovesicle fistula and rectovaginal fistula.

other invasive spread

pulmonary amoebiasis

  • can occur from hepatic lesion by haemotagenous spread and also by perforation of pleural cavity and lung.
  • may cause lung abscess, pulmono pleural fistula, empyema lung and broncho pleural fistula.

brain

  • amoebic meningoencephalitis
  • amoebic intracerebral abcess

diagnosis

  • stool microscopy - cysts shed in stool but may need 3 samples to detect as shedding is not constant
  • serologic tests are available - positive after 2wks of infection

Rx

  • infections occur in both the intestine and in the intestinal wall and/or liver.
  • Thus, two different classes of drugs are needed to treat the infection, one for each location.
amoebiasis.txt · Last modified: 2014/12/19 11:17 (external edit)