Protozoa: Giardia lamblia

Giardiasis is the most common parasitic cause of diarrhea throughout the world. Human infections result from the ingestion of the environmentally stable cyst form, most commonly from the ingestion of contaminated water or direct fecal-oral transmission. When infection results from contaminated food, it is usually from infected food handlers or from washing food with contaminated water. Infection can be asymptomatic, or may result in prolonged diarrhea with malabsorption and weight loss. Even after successful treatment a quarter of patients have prolonged irritable bowel syndrome. The most effective prevention strategy is the maintenance of adequately pure sources of water used for consumption or recreational purposes. Food-borne transmission can be prevented by treatment of handlers known to be infected, by use of adequately purified water for washing food and by the appropriate use of hand washing and gloves by food handlers.