Detection of Cryptosporidium oocysts in soil samples by enzyme-linked immunoassay

An ELISA protocol was adapted for detection of Cryptosporidium parvum oocys ts in soil samples and the limit of detection of the test was determined. A modified indirect antigen capture ELISA protocol was developed using monoc lonal antibodies against the oocyst outer wall. The accuracy of the ELISA w as compared to spiked soil samples and measured in terms of sensitivity and specificity of the test. The performance of the ELISA was evaluated in fie ld soil samples and measured using the kappa -statistics. Similarly, the pe rformance of the ELISA was compared to the concentration flotation method, to a modified concentration flotation method and to a commercial ELISA (Pro SpecT(TM)) in held fecal and soil samples. The limit of detection of the test was selected to be 10,000 oocysts/g. At this limit of detection, the ELISA had a sensitivity of 95% and specificity of 100%. The agreement between the ELISA and the modified flotation-concen tration method in detecting Cryptosporidium oocysts in soil samples was 32% (kappa = 0.32). The ELISA had the same relative sensitivity (82%) in compa rison to both the flotation and ProSpecT(TM) in determining Cryptosporidium -infection status of an animal. The kappa -statistics was 0.26 for both tes ts. The developed ELISA proved to be a valuable diagnostic test for detecti ng oocysts in soil samples and has a potential application in determining t he infection status of animals. (C) 2001 Elsevier Science B.V. All rights r eserved.