Evaluation of an immunoassay-based algorithm for screening and identification of giardia and cryptosporidium antigens in human faecal specimens from Saudi Arabia

An immunoassay-based algorithm,involving three commercial kits,was introduced and evaluated for screening and identification of giardia/cryptosporidium antigens in human stool specimens. initially,giardia/cryptosporidium chek kit (techlab),an enzyme-linked immunosorbent assay (elisa),was adopted for screening. the elisa-positive reactions were subsequently characterised by rida quick giardia and rida quick cryptosporidium immunochromatographic kits (r-biopharm). a gold standard test comprising pcr and microscopy was used for preparing control samples. performance of individual kits was tested against these samples which included 50 giardia-positive,40 cryptosporidium-positive,and 70 cryptosporidium/giardia-negative. for cryptosporidium,specificities of the elisa and rida quick cryptosporidium kits were 95.71% and 100%,respectively. both kits demonstrated sensitivity of 95%. for giardia,the elisa and rida quick giardia kits showed sensitivities of 100% and 97.5%,respectively. specificities obtained by the elisa and rida quick giardia were 95.7% and 100%,respectively. based on the results of two reference pcrs,on 250 random samples,the algorithm exhibited sensitivity,specificity,positive predictive value,and negative predictive value of 97.06%,100.00%,100.00%,and 98.91%,respectively. in conclusion,this immunoassay-based algorithm can be used as routine test in diagnostic laboratories for screening and identification of a large number of samples. © 2014 yousry hawash.