Laboratory diagnosis ofcryptosporidiosi s

andthinsection electronmicroscopy provide definitive identification. Vomiting canbeanimportant clinical feature of gastroenteritis, andthefirst description ofoocysts invomitisreported. Preliminary findings, after more thantwoyearsofstudy showthatCryptosporidium isanimportant pathogenic agent in gastroenteritis, confirm theincreased incidence inchildren, andsuggest apossible seasonal trend. Thecoccidian protozoan parasite Cryptosporidium spisnowwidely accepted asacause ofacute gastroenteritis. Insomenormal subjects thesymptoms may be bothsevereandpersistent, whilein immunocompromised patients theinfection maybe lifethreatening.' Various methodshavebeen recommended forstudying cryptosporidia using light andtransmission electron microscopy. These varyfromtheexamination ofwetfilms tonegative staining bytransmission electron microscopy. Since beginning ourstudy early in1983wehavesupplied manylaboratories withpositive material andguidance, andinthis paper wemakerecommendations fortheroutine diagnostic examination offaecal samples. A comparison ofthemethods studied has shownthatthefluorescence staindescribed, together withmodified formol-ether concentrations whenappropriate, aresignificantly moresensitive thanother methods (p< 0-001).