[The use of ELISA systems for control of epizootics: safety of test standards using batch assays]

One of the advantages of ELISA techniques is to achieve a higher degree of safety by standardization. Bases of these standardizations should be, if available, international or national standards in combination with cutoff definitions. The cutoff definitions should be expressed, separate for the main kinds of samples, defined as a dilution of the standard. Those definitions can replace the mostly awkward and involved test descriptions as usual in official regulations. To guarantee a high grade of reliability it is a matter of urgent necessary to test (if possible by the producer) each serial (lot) of ELISA and to describe their capacities with regard of sensitivity and specificity. Separate pretests may be done with the main kinds of samples with well known reactions (negative and weak positive). The results are to compare to those of the cutoff-related dilutions of the standard in the same matrix. These descriptions of the capacities of each serial (lot) are safe bases for use of the serial. Key concepts are the quotients of the minimum positive value divided by the maximum negative or alternatively the mean value of the positive minus the threefold standard deviation divided by the mean value of the negative plus the threefold standard deviation.