Useful For

The differential diagnosis of community acquired and travel associated acute and chronic diarrhea.

Reflex Tests

Testing Algorithm

Specimens are tested concurrently for the presence of Giardia cysts and Cryptosporidium oocysts. All specimens are simultaneously stained with Trichrome and Iodine wet mount to search for other intestinal parasites.

Indications for Testing

Community acquired diarrheal disease.

Clinical Information

Giardia lamblia is an intestinal flagellate protozoan that infects the biliary tract and upper small intestine of both humans and animals. It is the most common cause of intestinal parasitosis in humans worldwide and is the causative organism of Giardiasis, sometimes known as “beaver fever.”

After an incubation period of approximately 12 – 20 days, patients can experience nausea, chills, low-grade fever, pigastric pain, and a sudden onset of watery diarrhea. Diarrhea is often explosive and presents as foul smelling without the presence of blood, cellular exudates, or mucus. Individuals can develop subacute or chronic infections with symptoms such as recurrent diarrhea, abdominal discomfort and distention, belching, and heartburn.

Humans are the principal reservoir but Giardia organisms can infect beavers, dogs, cats, and other animals. These animals can contaminate water with feces containing cysts that are infectious for humans. A Giardia vaccine is available for dogs and cats and may affect the prevalence in human infections.

Giardiasis is passed via the fecal-oral route. People become infected directly by ingestion of cysts from the feces of an infected person or indirectly by ingestion of fecally contaminated water or food. Person-to-person transmission is common where personal hygiene may be poor. Children who are not toilet trained are often linked to day care and family outbreaks.

The mean annual incidence reported in Canada from 2000 to 2004 was 14.6 per 100,000 population and for the same period the mean incidence rate in Newfoundland Labrador was 7.8 per 100,000.

Reference Values

NO OVA CYSTS AND PARASITES DETECTED

Interpretation

The majority of individuals infected with Giardia intestinalis/lamblia are asymptomatic. However, acute giardia may mimic other protozoan, viral, and bacterial pathogens. Diarrhea is typically eplosive and presents as foul smelling without the presence of blood, cellular exudate, or mucus. Individuals can develop subacute or chronic infections with symptoms such as recurrent diarrhea, abdominal discomfort and distention, belching, and heartburn. In patients with chronic cases of giardiasis, diarrhea can lead to dehydration, malabsorption, and impairment of pancreatic function.

References

White Jr., A. C. 2010. Cryptosporidium Species, p. 3547-3560. In Mandell, D., Bennett, J. E., and Dolin, R. 2010. Principles and practice of infectious diseases, 7^th ed., vol. 2. Churchill Livingstone, Elsevier, Philadelphia, PA.

Xiao, L., and Cama, V. 2007. Crytosporidium, p. 2122-2132. In Murray, P. R., Baron, E. J., Jorgensen, J. H., Landry, M. L., and Pfaller, M. A. Manual of Clinical Microbiology, 9^th ed., vol. 2. ASM Press, American Society for Microbiology, Washington, DC.

Meridian Biosciences Inc. 2008. MerIFluor Cryptosporidium/Giardia: Package insert. Meridian Biosciences Inc. Cincinnati, OH.