What is the prognosis of giardiasis?

Updated: Oct 01, 2018
  • Author: Hisham Nazer, MBBCh, FRCP, DTM&H; Chief Editor: Burt Cagir, MD, FACS  more...
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The prognosis for patients with giardiasis is generally excellent. Most patients are asymptomatic, and most infections are self-limited. Giardiasis is not associated with mortality except in rare cases of extreme dehydration, primarily in infants or malnourished children.

Several antibiotic agents are available with good efficacy rates to shorten the disease course, although drug resistance has been observed in clinical experience. Untreated, giardiasis can last for weeks.

The parasite persists in the stool. [8, 26] Reinfection is possible.

Weight loss, disaccharidase deficiency, malabsorption, and growth retardation are possible complications. [50, 51]  G intestinalis has been implicated as the chief cause of growth retardation in infected children, even after other diarrhea-causing agents are controlled. [18, 26]

Some patients may experience persistent symptoms (eg, chronic diarrhea/steatorrhea, malabsorption) despite apparently effective antibiotic treatment, although these usually subside over weeks to months. [21, 39, 47] However, Hanevik et al found symptoms consistent with irritable bowel syndrome (IBS) and/or functional dyspepsia in 76 of 82 patients at least 6 months after eradication of Giardia infection. [52] Patients reported bloating, diarrhea, and abdominal pain, which were exacerbated by specific foods or by physical or mental stress. Another study by Hanevik and colleagues associated giardiasis with the presence of IBS and chronic fatigue even 6 years after infection. [53]

Similarly a longitudinal cohort study (2006-2010) of data from the MarketScan commercial database that evaluated the relationship between a diagnosis of giardiasis and that of IBS found that, even accounting for confounding factors, patients with giardiasis had a greater 1-year incidence of IBS than those without giardiasis. [1]  The study included a matched cohort of 3935 patients with giardiasis and 19,663 without giardiasis.

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