EIMERIA - EFFECT OF METICLORPINDOL AND METHYL BENZOQUATE ON ENDOGENOUS STAGES IN CHICKEN

Meticlorpindol and methyl benzoquate had no action on the sporozoites of Eimeria brunetti in vitro. The drugs exert an inhibitory action on the sporozoites after invasion of the intestinal mucosa when the sporozoites have completed their migration. Some drug must be absorbed from the intestine since chicks treated with meticlorpindol in the food were protected from an infection induced via the blood-stream. The drugs may have an effect on later stages of the life cycle of some species of Eimeria, but not with others. Sporozoites of E. tenella, E. mivati and E. acervulina could develop even after treatment for 60 days with meticlorpindol, whereas other species (E. maxima) did not develop after 21 days of exposure to the drug. Possible reasons for the differences in survival of sporozoites of different species are discussed in relation to the turnover of intestinal epithelial cells and to the role of macrophages in the transport of sporozoites within the intestinal tissues. Chickens treated with meticlorpindol for 70 days did not exhibit latent infection after drug withdrawal, but were susceptible to infection with species of Eimeria used initially. This indicates that the presence of inhibited sporozoites did not stimulate resistance to reinfection. © 1968.