The antibody response to Cryptosporidium: development of a serological test and its use in a study of immunologically normal persons.

The demonstration of an immune response in the relatively newly recognised infection of human beings, cryptosporidiosis, is essential for assessing pathogenicity, for diagnostic purposes, and for epidemiological studies. In addition, serological methods may be applied to the detection and definitive identification of the parasite. Earlier reports were of histologically based methods with tissue from experimentally infected animals and did not define the nature of the response. The method described here is simple and rapid. It may be done in laboratories not equipped to perform the earlier methods. Results confirm that oocysts may be used to detect antibody in the blood of human beings, to determine when sero-conversion takes place and to define the nature of the response in terms of the class of immunoglobulin. Some sero-epidemiological observations have been made.