Eimeria Dispersa

Hosts: Turkey, bobwhite quail, ringnecked pheasant, ruffed grouse (?), sharptailed grouse (?).

This species was first described by Tyzzer (1929) from the bobwhite quail. He also found it in the ring-necked pheasant, Hawkins (1952) first found it in the turkey. Boughton (1937) reported it from the ruffed grouse (Bonasa umbellus) and sharp-tailed grouse (Pedioecetes phasianellus campestris). Tyzzer (1929) transmitted it from the bobwhite to the turkey, chicken (producing a light infection) and possibly to the pheasant. Venard (1933) and Patterson (1933) were unable to infect chickens with strains from the bobwhite. Tyzzer (1929) transmitted it from the pheasant to the bobwhite. Hawkins (1952) infected the bobwhite and Hungarian partridge (Perdix perdix) with E. dispersa from the turkey, but was unable to infect the pheasant or chicken. Moore and Brown (1952) infected the bobwhite with a turkey strain, but, according to Moore (1954), were unable to infect the pheasant.

Location: Primarily duodenum, but also small intestine.

Geographic Distribution: North America.

Prevalence: Presumably relatively uncommon.

Morphology: The morphology of this species was studied especially by Tyzzer (1929) and Hawkins (1952). The oocysts are broadly ovoid, smooth, 22 to 31 by 18 to 24 u with a mean of 26 by 21 u. The oocyst wall is composed of a single layer and lacks a micropyle. An oocyst polar granule and oocyst residuum are absent. The sporocysts are ovoid, with a Stieda body. The sporulation time is 2 days.

Life Cycle: Tyzzer (1929) and Hawkins (1952) studied the endogenous stages of this species. They are found above the nuclei of the epithelial cells near the tips of the villi. There are apparently two types of first generation schizonts. Much the commoner is a small type about 6 u in diameter which produces 15 or fewer merozoites each 4 to 6 u long and 1 u wide. The other type measures up to 24 by 18 u and produces at least 50 merozoites. The first generation merozoites are formed by the end of the second day of infection.

The second generation schizonts are about 11 to 13 u in diameter and produce 18 to 23 merozoites each 5 to 6 u long and 1.5 to 2 u wide about 4 days after infection.

There are a few third generation schizonts and merozoites, but most of the second generation merozoites develop into sexual stages. The macrogametes are 18 to 20 u in diameter when mature, and the microgametocytes are slightly smaller. The microgametes have 2 flagella. Oocysts first appear in the feces late on the fifth or on the sixth day after infection.

Pathogenesis: This species is only slightly pathogenic in the turkey. Hawkins (1952) found the most severe lesions on the fifth and sixth days after experimental infection. The entire small intestine was markedly dilated and the duodenum and anterior jejunum were creamy white when seen thru the serosal surface. The anterior half of the small intestine was filled with creamy, yellowish, sticky, mucoid material. The wall of the anterior intestine was edematous, but there was little epithelial sloughing. The intestinal tract was virtually normal by the eighth day after infection.

The only signs Hawkins saw in infected turkeys were a slight tendency to produce somewhat liquid feces and a slight depression in weight gains.

Immunity: According to Hawkins (1952), turkeys which have recovered from infection are strongly immune to reinfection.