Giardiasis in Man: Review and Updates

Abstract

Giardia lamblia (known as G. duodenalis or G. intestinalis) is a microscopic flagellated organism. This protozoan parasite was described for the first time by van Leeuwenhoek in 1681 followed by Lambl in 1859. Giardia is one of the most common causes of diarrhea, with 280 million cases per year. It is included in the "˜Neglected Tropical Diseases" of the World Health Organization. The organism has two life forms; motile flagellated trophozoite, and a non-motile cyst. The mode of transmission is through ingestion of viable cysts from water, food and by faecal-oral route from person-to-person. Giardia infection may result in clinical aspects that range from the asymptomatic cyst passer state to acute or chronic diarrhea, malabsorption and failure to thrive. The reference method for giardiasis diagnosis is by microscopic detection of the diagnostic stages in faecal samples. Detection of coproantigen of Giardia by enzyme-linked immunosorbent assay or direct immunofluorescence may be helpful. Additionally, molecular techniques are able to detect and identify the parasite in stool. Duodenal biopsy and aspirate could be a useful tool in diagnosis. Human Giardia infections are unlikely to be ever eradicated, and thus, chemotherapy and other methods of control of the disease will always be required.