No abstract

The incidence of intestinal spirochaetes was determined using direct fluorescent antibody microscopy on faecal and mucosal samples from chickens. Of 134 flocks with intestinal disorders 27.6% were found to be positive, but only 4.4% (of 45 flocks) were positive where signs of enteritis were absent. Flocks housed in cages or with access to litter were equally affected. No evidence was found for pigs as an aetiological factor.

Broiler parent hens were inoculated with avian intestinal spirochaetes several weeks before the onset of egg production. The infection persisted, wet droppings developed, and egg production, mean egg weight and carotenoid contents of the eggs were decreased. Hatching eggs were collected and incubated. In broilers which hatched from these eggs, reduced gain in body weight at 2 and 3 weeks of age, wet droppings, low plasma carotenoid concentration and elevated alkaline phosphatase activity in the blood plasma were observed. Spirochaetes were not detected in these broilers. These findings demonstrated the deleterious effects on chick quality of parental infection with avian intestinal spirochaetes. Avian intestinal spirochaetosis was diagnosed in about 2.5% of all submissions from reproductive flocks in 1991.

SUMMARY Three SPF-laying hens were inoculated into the crop with avian intestinal spirochaetes which previously had been passaged in broiler chicks by oral inoculation (isolate 1380). Mild persisting gastrointestinal disorder developed; at nine months post inoculation spirochaetes were readily demonstrated in caecal faeces. Histologic examination of the caecal mucosa revealed many spirochaetes covering the mucosal surface and filling up the crypts lumina. Spirochaetes were found in intra-and subepithelial locations and in gaps running through the epithelium. These gaps often opened into subepithelial cavities crowded with spirochaetes ('gaplike lesions'). These lesions were seen mostly on the tips of the villi and in the deeper parts of the crypts. Massive erosion or desquamation of epithelium heavily infested by spirochaetes occurred. These findings indicate colonisation of the mucosal surface and of the crypts, penetration of the mucosa and colonisation of subepithelial compartments with spirochaetes in poultry suffering from intestinal spirochaetosis.

Laying hens of 20 weeks of age were infected with avian intestinal spirochaetes (isolate 1380). After 20 weeks it was found that most infected birds shed 10(7) or more spirochaetes/ml caecal faeces. Faecal dry matter content was not significantly influenced by the infection, but the amount of crude fat in the faecal dry matter increased by more than 25%.