Detection of gastrointestinal nematodes by a coproantigen capture ELISA

An assay is described for the quantitative detection of excretory/secretory antigens liberated by the intestinal nematode Heligmosomoides polygyrus and voided in the host's faeces. A rabbit polyclonal antiserum to the antigens detected them in a dose-dependent manner and was sufficiently sensitive to recognise infection in mice carrying a mean worm burden of nine worms. The assay was specific, giving higher optical density readings with the faeces of mice infected with H polygyrus than with faeces from mice carrying patent infections with Trichuris muris, Hymenolepsis microstoma or the intestinal phase of Trichinella spiralis, or with faeces from rats carrying Hymenolepis diminuta or hamsters carrying Necator americanus or Ancylostoma ceylanicum. It detected the parasite antigens in faeces stored for eight weeks at -20, 4 or 20 degrees C and could detect prepatent infections. The assay has potential for the development of infection intensity-sensitive assays for gastrointestinal nematodes and for the detection of animals harbouring the arrested larvae of parasites.