The infectivity ofEimeriasporozoites recovered from Monensin medicated chickens¹

Abstract

SUMMARYSporozoites of embryo-adapted lines olEimeria tenella, E. brunetti and E. necatrix were recovered from monensin medicated chickens. The viability of these sporozoites was compared with that of sporozoites recovered from unmedicated birds by assessing their infectivity in chicken embryos. Sporozoites of the three species of Eimeria recovered from 100 parts/10 6 monensin-medicated birds produced infections in embryos which were 94 to 98% less severe than infections resulting from the inoculation of sporozoites recovered from unmedicated chickens. A concomitant scanning electron microscope study revealed no apparent ultrastructural damage to the exposed sporozoites.Timed medication experiments in chickens showed that medication with monensin for the period covering sporozoite penetration in vivo was almost completely effective, being comparable to continuous medication. Medication started before infection (to ensure tissue concentrations of monensin) but terminating 5 to 7 hours before the oocysts were inoculated was ineffective.

Forty years of monensin for the control of coccidiosis in poultry

“…The action of monensin in vivo has been demonstrated by harvesting sporozoites from the intestinal contents of medicated birds, shortly after inoculation of oocysts, and inoculating them into chicken embryos when they were not as infective as sporozoites obtained from unmedicated chickens (Long et al, 1983).…”

First Divalent Metal Complexes of the Polyether Ionophore Monensin A:X-Ray Structures of [Co(Mon)2(H2O)2] and [Mn(Mon)2(H2O)2] and their Bactericidal Properties

“…Since its isolation in 1967 by Agtarap et al [1], significant attention has been paid to the polyether Monensin due to its antibiotic and anticoccidial properties [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The chemical structure of Monensin and other related compounds (Maduramycin, Salinomycin etc.)…”

Thomas K. Jeffers: pioneer of coccidiosis research

“…Further work by Long & Jeffers (1982) conducted in chicken embryos showed that these drugs exert their anticoccidial action primarily against the primary invasive stage (sporozoite) of Eimeria. Subsequently it was shown that sporozoites exposed to monensin in the intestine of medicated chickens accumulate sufficient drug to inhibit their ability to invade or develop in ovo (Long et al, 1983). These results confirm the importance of continuously maintaining an effective concentration of an ionophore in the lumen of the intestine to assure optimum anticoccidial activity.…”