Giardia Lamblia - Manifestation of Infection

Manifestation of Infection

Nomenclature of Giardia species is difficult, as humans and animals appear to have morphologically identical parasites.

Colonization of the gut results in inflammation and villous atrophy, reducing the gut's absorptive capability. In humans, infection is symptomatic only about 50% of the time, and protocol for treating asymptomatic individuals is controversial. Symptoms of infection include (in order of frequency) diarrhea, malaise, excessive gas (often flatulence or a foul or sulphuric-tasting belch, which has been known to be so nauseating in taste that it can cause the infected person to vomit), steatorrhoea (pale, foul smelling, greasy stools), epigastric pain, bloating, nausea, diminished interest in food, possible (but rare) vomiting which is often violent, and weight loss. Pus, mucus and blood are occasionally present in the stool. It usually causes "explosive diarrhea" and while unpleasant, is not fatal. In healthy individuals, the condition is usually self-limiting, although the infection can be prolonged in patients who are immunocompromised, or who have decreased gastric acid secretion.

People with recurring Giardia infections, particularly those with a lack of the immunoglobulin A antibody, may develop chronic disease.

Lactase deficiency may develop in an infection with Giardia, but this usually does not persist for more than a few weeks, and a full recovery is the norm.

Some studies have shown giardiasis should be considered as a cause of vitamin B₁₂ deficiency as result of the problems caused within the intestinal absorption system.