Giardiasis-CDCreport

Giardiasis

ICD-10 A07.1
Identification

Case classification:
• Suspected case: A protozoan infection principally of the upper small intestine; it can be asymptomatic; or bring on acute, self-limited diarrhea; or lead to intestinal symptoms such as chronic diarrhea.
• Probable case: steatorrhea, abdominal cramps, bloating, frequent loose and pale greasy stools, fatigue, malabsorption (of fats and fat-soluble vitamins) and weight loss. There is usually no extra intestinal invasion, but reactive arthritis and, in severe giardiasis, damage to duodenal and jejunal mucosal cells may occur.
• Confirmed case: identification of cysts or trophozoites in feces (to rule out the diagnosis at least 3 negative results are needed). Because Giardia infection is usually asymptomatic, the presence of G. lamblia (in stool or duodenum) does not necessarily indicate that Giardia is the cause of illness. Tests using ELISA or direct ?uorescent antibody methods to detect antigens in the stool, generally more sensitive than direct microscopy, are commercially available. Where results of stool examination and antigen assays are questionable, it may be useful to examine for trophozoites from duodenal ?uid (aspiration or string test) or mucosa obtained by small intestine biopsy.

Infectious agent

Giardia lamblia (G. intestinalis, G. duodenalis), a ?agellate protozoan.