Field studies on coccidiosis in the ring-neck pheasants of eastern Washington

Abstract

1. An average incidence of infection of 38 % was found in thirty-seven ring-neck pheasants over a period of 7 months.2. There was a drop in the incidence from 70 % in October to 30 % in November. The incidence remained at 30 % during February and March and jumped to 67 % in April.3. Three species ofEimeriawere identified:E. phasianiTyzzer and two new species,E. pacificaandE. megalostomata.A fourth type designated as type IV was seen but not described because of an insufficiency of specimens.4. All infections observed were light. Histopathological studies showed little damage to the intestine and there was no significant difference between the weights of infected and non-infected birds.5. Oocysts ofE. pacificasporulated at temperatures from 8 to 30.5° C. The latter is the optimum temperature. Intracellular organization prior to sporulation was indicated in oocysts ofE. pacificakept at 8° C.6. A temperature of 37.5° C. was lethal to oocysts ofE. pacifica.Degenerative changes in the oocysts were first observed 9 days after being placed at that temperature.This work was done in the Zoology laboratory of Washington State College, Pullman, Washington. I wish to acknowledge my indebtedness to Dr R. F. MacLennan, of that Institution, for suggesting the problem, for his help and co-operation in the prosecution of the work, and to Dr F. S. Henika for assistance in the collection of specimens. I also wish to acknowledge my indebtedness to Dr Victor Burke and the Dairy Department for the use of the apparatus. Acknowledgement is also made to the Washington State Department of Game for permission to collect pheasants.