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An Overview Cryptosporidium/Giardia Antigen Detection by DFA (See also Cryptosporidium Antigen detection by EIA and Giardia Antigen Detection by EIA)
Summary Giardia lamblia is the protozoan parasite responsible for the disease giardiasis. Symptoms of acute giardiasis include diarrhea, nausea, weight loss, malabsorption, abdominal cramps, flatulence and anemia. The disease may manifest itself as an acute, chronic or as an asymptomatic infection. Giardiasis is the most prevalent parasitic disease in the United States and is responsible for an estimated 100 million mild infections and 1 million severe infections each year.
The mode of transmission of Giardia is through fecal-oral ingestion of cysts. Epidemics of giardiasis have been documented in day care centers and by drinking contaminated water. Day care centers may be directly or indirectly responsible for 45% of diagnosed Giardia infections in the United States. One study found 54% of the children at a day care center were infected.
Another important source of Giardia infection is among homosexual men. Prevalence rates of 5 to 19% for this population have been reported.
Cryptosporidium is a coccidian parasite that is recognized as an important enteric pathogen. The organism causes an acute, though self-limiting infection in immunocompetent individuals. Incubation periods of 1 to 12 days have been reported with most oocyst shedding ending by day 21. Symptoms range from mild to severe diarrhea with a variety of complications.
The infection in immunocompromised patients is much more severe and may often be life threatening. Passage of fluid, up to 12 liters per day, has been reported.
Multiple pathways of Cryptosporidium transmission have been implicated. These include animal to human, water contamination and person-to-person. The latter may include contact between members of the same household, day care centers, and homosexual men.
Principle of Procedure This assay utilizes the principle of direct immunofluorescence. The conjugate contains a mixture of FITC-labeled monoclonal antibodies directed against Cryptosporidium oocysts and Giardia cysts, which, if present, are affixed to the slide. The slide is then rinsed to remove unbound conjugate and examined under a fluorescent microscope looking for an apple-green color and the characteristic morphology of the Cryptosporidium oocysts and the Giardia cysts. |