DETECTION OF OOCYSTS OF CRYPTOSPORIDIUM BY ENHANCED CHEMILUMINESCENCE

A modified enhanced chemiluminescent assay was assessed for its abilit y to detect oocysts of Cryptosporidium parvum using either X-ray film or a photomultiplier for imaging. The photomultiplier was able to dete ct a minimum theoretical number of 6.25 purified oocysts and did not a ppear to have a problem with the detection of false positives. However , because of the plate format of this system, it is not possible to co nfirm results by microscopy. When X-ray film was utilised for imaging, false positives were detected on 16% (4/25) occasions, but as few as two oocysts could be detected by this system. X-ray film was also used in the screening of environmental samples previously assessed by micr oscopy. Although 23% (3/13) of the negative samples were considered by BEC to be positive, all those samples which contained oocysts were al so found to be positive by this system. Until such time as this techni que can be refined by increasing the avidity of the monoclonal antibod y, enhanced chemiluminescence might provide a useful method for initia l screening of environmental and water samples for Cryptosporidium ooc ysts, with subsequent confirmation by microscopy of samples considered to be positive.