E. acervuline

Location: Found in duodenum of poultry

Morphology/ identification features

• Oocysts are ovoid, smooth, measuring average of 18×14 µm.
• Micropyle or residuum are absent but polar granules are present.
• Sporocysts are ovoid, with stiedo body and without residuum.
• A generation of asexual stage occurs:

1. First generation meronts measure 9-11 µm long and mature in 36-48 hours to produce 8-16 merozoites, with small residuum.
2. Second generation meronts mature in 41-56 hours to produce 16 merozoites with no residuum.
3. Third generation meronts mature 56-72 hours after inoculation to produce eight merozoites with residuum.
4. Fourth generation meronts mature 80-96 hours after inoculation and produce 32 merozoites with large residuum.

• Macrogamonts : 14.5 -19 µm
• Microgamonts: 7-8 µm. They later produce tri-flagellate
• Microgametes : 2-3 µm long

Life cycle

• Sporocyst emerge from oocyst in gizzard. Sporozoites are activated and release in small intestine. Most of them enter duodenum where they undergo 4 merogony generations.
• 1^st generation meronts: lie at base of the glands of the crypts of duodenum.
• 2^nd generation meronts: Found at the neck of glands.
• 3^rd generation lie at base of villi.
• 4^th generation meronts lie on side and tips of villi.
• Sexual stage found above the host cell nuclei, in the epithelial cells of villi ad seen after 4 days of infection. Gamonts takes 40 hours to mature.
• Pre-patent period: 89 hours
• Sporulation time: 24 hours.

Clinical signs/ pathogenesis

• These species are moderately pathogenic. These cause chronic disease with birds showing poor weight gains but little mortality.
• Clinical signs appear after 2 days of ingestion of large number of sporulated oocyst.
• Symptoms include: Diarrhea, Dejection, Ruffled feathers, Dropping wings, Inappetence, Weight loss and depressed weight gain.
• Lesions are concentrated mainly in duodenum. White transverse streaks in duodenum and upper small intestine. In heavy infection, lesion coalesce and intestinal wall becomes thickened and congested with marked whitish mucoid exudate.

Lesions are scored +1 to +4 as follows

• +1: scattered white plague-like lesions containing developing oocyst confined to duodenum. Lesions are elongated with longer axis transversely oriented on thickened intestinal walls like rungus of ladder. Birds don not show clinical signs and weight gain are also not affected.
• +2: Lesions are closer together but not coalescent and may extend below duodenum in young birds. Intestinal wall is not thickened and gut contents are normal. Birds would show depression in weight gain.
• +3 : Lesions are clearly recognizable and form mucosal and several surface. More numerous and begins to coalesce. Intestinal wall is thickened and intestinal contents are watery due to excessive mucus secretion. Birds have diarrhea and their weight gains are decreased.
• +4: Mucosal wall is greyish with colonies, completely coalesced in extremely heavy infections, entire mucosa may be bright red in color. Typical ladder-like lesion appears in middle part of intestine. Intestinal wall is very much thickened, and intestine is filled with creamy exudate. Birds shows diarrhea, severe weight loss, poor feed conversion and skin dyspigmentation.