Fast Five Quiz: Summer Health Concerns

Richard H. Sinert, DO


June 06, 2019

Standard treatment for giardiasis consists of antibiotic therapy. Metronidazole is the most commonly prescribed antibiotic for this condition. However, metronidazole use has been associated with significant failure rates in clearing parasites from the gut and with poor patient compliance. In addition, an increasing incidence of nitroimidazole-refractory giardiasis has been reported, particularly in travelers from India and other regions in Asia. An optimal treatment strategy for refractory giardiasis remains to be determined, and no standard treatment regimen for nitroimidazole-refractory giardiasis is available.

Waterborne transmission is responsible for a significant number of giardiasis epidemics, generally after ingestion of unfiltered surface water. Giardia cysts retain viability in cold water for as long as 2-3 months.

Most patients experience an insidious onset of symptoms, which are recurrent or resistant. A small number of persons develop abrupt onset of explosive, watery diarrhea, abdominal cramps, foul flatus, vomiting, fever, and malaise; these symptoms last 3-4 days before transition into the more common subacute syndrome.

Stool culture is not routinely used because of the difficulty of reproducibly isolating Giardia from patient fecal samples. However, stool cultures are beneficial in ruling out other pathogens as the cause of a patient's symptoms. Stool ova and parasite testing remains the diagnostic method with which other tests are compared. However, in more recent years, the advent of more objective techniques (eg, immunoassays, nucleic acid amplification techniques) has led to an increase in their use versus those that rely on subjective microscopic examination of fecal specimens for Giardia cysts.

Read more about giardiasis.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.