Giardiasis

Giardia lamblia (syn. G. duodenalis, G. intestinalis ) is the most common parasitic cause of diarrheal illness. Human infection results from fecal–oral transmission, primarily water-borne, and is mostly human to human, but zoonotic transmission is also well documented. Symptomatic patients typically have a subacute diarrheal illness beginning 1 to 2 weeks after exposure and characterized by malabsorption and weight loss but without significant fluid loss. Fever and systemic toxicity are uncommon. The diagnosis can be confirmed by microscopic examination of a fecal specimen for Giardia cysts or trophozoites, or by antigen or nucleic acid–based testing. Nitroimidazoles such as metronidazole or tinidazole are the most commonly used agents. Albendazole is commonly used in situations where anti-helminthic activity is also needed. Irritable bowel syndrome is very common after symptomatic giardiasis and does not benefit from additional anti- Giardia treatment