Giardiasis (Giardia lamblia)

Giardia lamblia is a very common intestinal parasite and a frequent cause of diarrhoeal illness throughout the world. Although water remains the most common mode of transmission, there has been an increase in the number of person-to-person cases, especially related to children, as well as an increase in food-borne cases. Chronic diarrhoea and malabsorption are seen with persistent infection and since treatment is simple and effective, diagnosis by duodenal biopsy is important. New antigen detection tests for stool may ultimately replace histology in some situations. The greatest clinical experience in treatment is with the nitroimidazole drugs, i.e., metronidazole, tinidazole, and ornidazole, which are highly effective. A 5- to 7-day course of metronidazole can be expected to cure over 90% of individuals, and a single dose of tinidazole or ornidazole will cure a similar number.