You are here:
METHODS FOR DETECTION OF CRYPTOSPORIDIUM SP. AND GIARDIA SP.
Citation:
Lindquist, H.D A. METHODS FOR DETECTION OF CRYPTOSPORIDIUM SP. AND GIARDIA SP. Presented at ORSANCO Annual Meeting, Cincinnati, OH, October 21, 1999.
Impact/Purpose:
1) Refine new, practical methods for the detection of CCL-related and emerging waterborne human protozoa.
2) Perform field tests of devices or methods that have been developed under this task.
3) Evaluate these methods or devices in a variety of water matrices and parasite concentrations.
This work in this task supports CCL2 and 3 and is expected to be completed by 9/07.
Description:
There have been several waterborne outbreaks of giardiasis caused by infection with Giardia lamblia, and cryptosporidiosis, caused by infection with Cryptosporidium parvum. These outbreaks have created a need to detect these organisms in source and finished drinking water. The principal problems with detecting C. parvum and G. lamblia are their small size, their relatively low density in the water, and the difficulty of culturing these organisms from water samples. Hence, methods have been developed that rely on identification of low numbers of cysts and oocysts in large volume water samples. The initial attempt to quantify G. lamblia cysts and C. parvum oocysts involved filtration of the water sample, differential sedimentation, and identification of organisms by fluorescent antibody staining. This method is time consuming, has low recovery, especially of C. parvum oocysts, and it is difficult to confirm that cysts or oocysts are indeed cysts or oocysts from disease causing organisms, and that they may potentially cause disease. Newer methods have reduced the volume sampled, used different filtration media, and substituted immunomagnetic separation for differential sedimentation. Problems of identification and concentration have also been addressed by the introduction of flow cytometry, cell culture methods, genetic amplification methods, and fluorescent in situ hybridization.