Characterization of a Strain of Eimeria meleagridis from the Turkey

Abstract

An isolate of Eimeria meleagridis Tyzzer, 1927 was obtained by harvesting oocysts from the ceca of a turkey from northwest Arkansas and a pure line was established by infecting birds with a single oocyst. Oocysts were first produced in the ceca of infected birds from 102 to 108 hr after inoculation and were of similar size (mean length X width, 24.9 X 17.0 microm) to those of Eimeria adenoeides Moore and Brown, 1951 and Eimeria gallopavonis Hawkins, 1952. The line was identified as E. meleagridis based upon the development of large schizonts in the midintestine, and small schizonts in the ceca. Two generations of large schizonts were found 48 and 72 hr after infection, and at least two generations of small schizonts were found from 60 to 108 hr after infection. An inoculum of 2 X 10(5) oocysts was found to cause a significant reduction in weight gain from days 0-3 and 0-6 after infection, suggesting that the significance of this species of Eimeria as a pathogen of turkeys should be reassessed.

Coccidiosis in the turkey

“…According to Hawkins (1952), schizonts and gametocytes of E. meleagridis develop in the caeca, but Clarkson (1959a) found first-generation schizonts in the small intestine either side of the yolk sac diverticulum. Matsler & Chapman (2006) also found firstgeneration schizonts in the small intestine, initially in the upper and mid-ileum, but subsequently at these locations and the mid-jejunum. Later generations and gametogony occur in the caeca with some development in the rectum and lower ileum.…”

“…Two asexual schizont generations were described for E. meleagridis (Hawkins, 1952;Clarkson, 1959a), but whereas Hawkins considered both small in size, Clarkson found that the first and second generations were large and small, respectively. Clarkson's observations were confirmed by Matsler & Chapman (2006), who identified two generations of large schizont and at least another two generations of small schizont. According to Clarkson, first-generation schizonts develop mainly near the base of the villi.…”

“…It is possible, therefore, that the fewer oocysts produced in older birds may have been due to ''crowding'' in the intestine that occurs if large numbers are given. This has been widely recorded from the chicken, and reported from the turkey (Matsler & Chapman, 2006).…”

“…Second-generation schizonts and gametocytes also develop at this location, but small numbers are present in the deep glands (crypts of Lieberkü hn). Matsler & Chapman (2006) observed schizonts in epithelial cells at the sides of the villi, but none were found in the crypts.…”

“…Thus, Clarkson (1958) was unable to compare his isolate of E. adenoeides with that described by Moore & Brown (1951) because Moore had informed him that there was no longer a viable strain of this species in the USA. Similarly, Matsler & Chapman (2006) could not obtain an isolate of E. meleagridis to compare with their strain.…”