42 Giardia
Paul Pottinger 21/09/18
Is a flagellate, kind of looks like trichomonas vaginalis
42.1 Giardiasis - Acute Diarrhoea
It is purely a gut bug.
Cysts become trophs in duodenum. They hold onto small bowel wall, onto the microvilli brush border.
Turn into cysts in colon. The cysts look a bit similar to a hookworm egg but they’ve got a big bar.
42.2 Epi
Anywhere in the world!
Fecal-oral spread. Also person to person. Also waterborne
42.3 Clinically
You’re more likely to get it with a low secretory IgA. So IgA deficiency more likely to get.
It can occasional cause duodenal ulcerations.
It can cause a lot of gas/bloating, especially with lactose containing foods.
Causes nasty buoyant diarrhoea, should not be bloody
42.4 Presentation
Most are asymptomatic (2/3)
Incubates of 1-3 weeks.
Then nasty diarrhoea.
Most are spontaneously cured within 4 weeks. But it can cause lactose deficiency life long.
42.5 Test
- String Test (don’t do)
- Duodenal Biopsy
- OCP stool (but NPV of this is poor, if you see nothing could still be giardia)
- Fecal Antigen - ELISA - (NPV and PPV is around 90%)
- Molecular Testing - PCR
42.6 Treat
- Tinidazole
- Metronidazole
- or Nitazoxanide or Albendazole if treatment failure
But after treatment leave them for 2 weeks, you get post infective diarrhoea