The testing method used to diagnose cryptosporidiosis is the microscopic examination of stool samples. The stool specimens are examined microscopically using different techniques such as acid-fast staining, direct fluorescent antibody (DFA), and/or enzyme immunoassays for detection of Cryptosporidium sp. antigens. Immunofluorescence microscopy is the method of choice for greatest sensitivity and specificity, followed closely by enzyme immunoassays. Molecular methods such as polymerase chain reaction (PCR) are increasingly used in reference diagnostic labs since they can be used to identify Cryptosporidium at the species level. However, these methods are mainly a research tool and are not routinely done in most laboratories. It is important to note that tests for Cryptosporidium are not routinely done in most laboratories, so healthcare providers should specifically request testing for this parasite.