Coccidial Schizonts in Mesenteric Lymph Nodes of Sheep and Goats

Abstract

Coccidial schizonts were found in enlarged mesenteric lymph nodes of sheep and goats that, 13 to 18 days previously, had been fed sporulated oocysts of Eimeria arloingi, E. faurei, and E. ninaekohlyakimovi of ovine origin. The schizonts in the lymph nodes of the goats were somewhat abnormal in appearance and measured about 32 to 100 ,u in diameter; those in the lymph nodes of the sheep were more normal in appearance and measured about 30 to 360 ,u. Mature merozoites were not found in schizonts in the lymph nodes of either the sheep or the goats; merozoites that appeared to be approaching maturity were found in the larger schizonts in the lymph nodes of sheep. Enlargement of the lymph nodes was considered to be caused primarily by edema fluid. This report concerns the occurrence of coccidial schizonts in histologic sections prepared from enlarged mesenteric lymph nodes of sheep and goats in 1959 and 1960. These animals had been fed mixtures of sporulated oocysts of ovine origin of Eimeria arloingi, E. ninaekohlyakimovi, and E. faurei during investigations of the behavior of sheep coccidia in goats. MATERIALS AND METHODS The animals from which the mesenteric lymph nodes were taken for examination were two 2month-old goats, inoculated in 1959, and two goats and two sheep, 7 months old, inoculated in 1960. Each was obtained at the time of birth, kept under strict sanitary conditions, and bottle fed until old enough to consume solid feed. They were a part of a group of 70, all of which had been raised free of helminths and were either free of coccidia or had extremely light infections of either Eimeria arloingi or E. ninaekohlyakimovi, both of unknown source. At the time of inoculation, the 2-month-old goats weighed 22 and 23 lb, respectively, the two older goats weighed 51 and 38 lb, respectively, and each of the sheep weighed 43 lb. The experimental coccidial infections were produced by placing oocyst-bearing material from pooled cultures of oocysts of ovine origin in gelatin capsules and administering them per os by means Received for publication 30 September 1963. * Present address: Veterinary Medical Division, Food and Drug Administration, Beltsville, Maryland. t Present address: School of Public Health, Johns Hopkins University, Baltimore, Maryland. of a balling gun. This material was from cultures in plain tap water and in dichromate; the cultures were 2 to 5 months old. The inocula contained oocysts of three species in about the following percentages: Eimeria arloingi, 70; E. ninaekohlyakimovi, 25; and E. faurei, 5. Expressed in millions, the approximate total number of oocysts administered to each animal was: goat 382, 60; goat 386, 2; goat 437, 0.7; goat 449, 1.4; sheep 344, 0.7; and sheep 352, 0.7. One of the 2-month-old goats, no. 382, died on the 13th day after inoculation, and the other, no. 386, was killed at that time; one mesenteric lymph node was taken from each animal. Of the 7-month-old animals, goat no. 437 was killed on the 16th day after inoculation and one lymph node was taken; goat no. 449 was killed on the 17th day after inoculation and two lymph nodes were taken; sheep no. 352 was killed on the 16th day after inoculation and two lymph nodes were taken; and sheep no. 344 was killed on the 18th day after inoculation and one lymph node was taken. The lymph nodes were fixed in buffered 10% formalin and histologic sections, about 6 ,u in thickness, were made and stained in Harris's hematoxylin and eosin-y.