The development of Haemonchus contortus in vitro

Abstract

The development of the exsheathed third-stage larva of Haemonchus contortus to the fourth stage in vitro has been investigated in half-strength Ringer's solution and in solutions with ionic concentrations similar to those found in the abomasum during normal secretion of acid and during heavy infestations of Haemonchus. The concentration of carbon dioxide required for the optimum development of the larva has been shown to be dependent on the pH of the medium. At a low pH the optimum pC02 is low and the larva is less sensitive to a range of carbon dioxide concentrations than at a pH near neutrality. Gastric mucin and histamine have been shown to have an inhibiting and a potentiating effect, respectively, on development, in media at pH 6.