Physiological responses of chicken gut tissue to infection with Eimeria acervulina.

Although Eimeria acervulina parasitizes primarily the duodenum of chickens, in heavy infections the entire small intestine may become distended. This reaction was measured in terms of length, fresh weight, dry weight, and moisture in relation to time postinfection (PI) and dose. Increases in percent moisture were apparently associated with numbers of infection sites, because higher doses caused increased moisture in the more distal portions of the small intestine. The first gross intestinal response to infection with 2 X 10(6) sporulated oocysts (SO)/bird was an increase in ileal length at 4 days PI. This response was followed by increases in fresh weight and dry weight by 7 days PI. At 7 days PI, inoculation with 10(4) and 10(5) SO/bird was associated not only with increases in fresh and dry weights of ileal segments but with those of jejunal segments as well. Infection with 10(6) SO/bird apparently caused sufficient increases in jejunal infection sites to overcome the hypertrophy or hyperplasia seen at lower doses. At 7 days PI, more mucosal cells could be scraped from ileal segments from infected chicks than from controls. Whole cells, as well as mitochondrial preparations of these cells, oxidized octanoic acid at higher rates than did controls. It is suggested that increased mass and metabolic activity of the more distal portions of the small intestine provide a means for compensatory absorption of nutrients during E. acervulina infection.