Eimeria Ninakohlyakimovae

Synonyms: Eimeria galouzoi (pro parte), E. nina-kohl-yakimovi Yakimoff and Rastegaieff, 1930.

Hosts: Sheep, goat, Rocky Mountain bighorn sheep, mouflon (Ovis musimon), O. orientalis, Siberian ibex (Capra ibex sibirica), Barbary sheep (Ammo tragus lervia), Persian gazelle (Gazella subgutturosa).

Location: Small intestine, especially the posterior part,and also cecum and colon.

Geographic Distribution: Worldwide.

Prevalence: This species is fairly common. Christensen (1938a) found it in 3% of 100 sheep from Maryland and Idaho. Jacob (1943) found it in 5% of 100 sheep in Germany. Balozet (1932) found it in 35% of 63 sheep and 34% of 41 goats in Tunisia. Svanbaev (1957) found it in 52% of 302 sheep and 31% of 48 goats in Kazakhstan.

Morphology: This species has been described by Yakimoff and Rastegaieff (1930), Balozet (1932) and Christensen (1938a). The oocysts are usually ellipsoidal, sometimes spherical, occasionally slightly ovoid. They are 16 to 27 by 13 to 22 u with means of 23.1 by 18.3 u (Christensen) or 19.8 by 16.5 u (Balozet). Their length-width ratio is 1.1 to 1.5 with a mean of 1.27 according to Christensen (1938). The oocyst wall is 1 to 1.5 u thick, transparent, almost colorless to pale brownish yellow, and composed of two layers of which the outer is half as thick as the inner. A micropyle is absent or imperceptible (occasionally visible under bright light if the oocyst is tilted, according to Christensen). There is no micropylar cap. An oocyst polar granule and oocyst residuum are absent. The sporocysts are ovoid; 4 to 11 by 4 to 6 u. A sporocyst residuum is present. The sporozoites have one end slender and pointed and the other thick and rounded; they measure 4 to 5 by 2 u and lie lengthwise, head to tail, in the sporocysts. The sporulation time is 1 to 2 days according to Christensen (1938a) or 3 to 4 days according to Balozet (1932).

Life Cycle: The life cycle of this species has been described by Balozet (1932) in the goat and briefly by Lotze (1954) in the sheep. Their accounts differ, and are given separately below.

Lotze (1954) found in sheep that the sporozoites enter the epithelial cells ati the base of the glands of Lieberkuehn in the small intestine, where they form schizonts about 300 u in diameter containing thousands of merozoites. The sexual stages occur in the epithelial cells of the ileum, cecum and upper part of the large intestine, appearing 15 days or more after infection.

Balozet (1932a) found in a kid killed 39 days after infection that the schizonts were only 15 to 35 u in diameter and contained only 40 to 200 merozoites. However, these schizonts were found very late in the infection. They were associated with macrogametes and microgametocytes, and it is possible either that they may have belonged to a second generation not mentioned by Lotze or that they may have belonged to some other species.

The prepatent period was found by Shumard (1957) to be 15 days in lambs and by Balozet (1932) to be 10 to 13 days.

Pathogenesis: This is one of the most pathogenic species of coccidium in sheep. Lotze (1954) found that as few as 50,000 oocysts caused diarrhea in a 3-month-old lamb, and as few as 500,000 oocysts caused death. Dysentery was produced in a 2-year-old sheep by inoculation with as few as 1 million oocysts.

Lotze (1954) found that in lambs the feces became soft in 12 to 17 days after experimental infection. They became watery a day or 2 later and remained so for a week or more. In the more heavily infected lambs, the feces contained bloodstained mucus beginning the 15th day after infection or soon thereafter. In those animals which recovered, the feces remained soft for some weeks.

The lambs with severe diarrhea lost their appetites at first, altho they appeared to drink more. After about a week they drank very little. There was rapid loss of weight at the onset of diarrhea. If the lambs recovered, they gained weight about as rapidly as the controls, but of course had taken a setback in growth. About 2 months after severe coccidiosis, the wool began to break off over extensive areas, starting on the flanks; this may have been due to nutritional disturbance caused by the infection.

The diarrheic feces attracted flies, and affected animals quickly became flystruck. Some animals which would otherwise have recovered died of flystrike if they were not treated for this condition.

At necropsy, petechial hemorrhages were found in the small intestine 3 to 7 days after infection. The small intestine then became thickened and inflamed. Extensive hemorrhage was present in the posterior part of the small intestine of severely affected lambs by the 15th day. The cecum and upper part of the large intestine became thickened and edematous, and were hemorrhagic by the 19th day. In heavily infected lambs, vast areas of the posterior part of the small intestine were denuded of epithelium. Thus, one can say that the lesions consisted at first of petechial hemorrhages, followed by thickening, edema and inflammation, and finally by epithelial denudation. The small intestine, especially its posterior part, cecum and upper colon were affected.

Shumard (1957a) studied a somewhat less pathogenic strain. He reported lowered feed consumption, lassitude, generalized incoordination and slight diarrhea with some bleeding in lambs experimentally infected at 50 days of age with 7 million oocysts of E. ninakohlyakimovae and 100,000 oocysts of E. faurei. There was no decrease in water consumption. Clinical signs appeared on the 9th day after infection and ended about the 22nd day. One out of the 4 lambs died on the 15th day. There were decreases in percentage of feed protein digested and inorganic serum phosphorus, increases in serum globulins and blood glucose, and no significant changes in total serum protein, blood hemoglobin and hematocrit values. Oocysts of both species appeared in the feces on the 15th day, increased until the 21st day and then decreased gradually.

Balozet (1932) observed a case of mucosanguineous diarrhea followed by death in a naturally affected adult goat, and produced the disease experimentally in 2 newborn kids. A mucous diarrhea appeared on the 22nd day after infection, became bloody, and persisted until about the 39th day.

Remarks: In one of the very few cross-transmission experiments attempted with sheep and goat coccidia, Balozet (1932) was unable to infect a recently weaned lamb with E. ninakohlyakimovae from a goat, altho he did infect 2 newborn kids. He thought the lamb was too old.