SUMMARYIn heavy breed layers a new syndrome was encountered, associated with impaired growth. The disease developed from 5 to 6 weeks onwards. Morbidity in most flocks was 1 to 4%, but in some cases up to 20%. The affected birds were smaller in size, made a peeping sound like that of younger chickens, and showed a characteristic stiff gait. The stifle and hock joints were swollen. At necropsy 12 out of 66 affected birds (18%) had bronze-coloured livers and 23 out of 66 (35%) had orange-coloured joint deposits. Histology indicated that these birds appeared to have amyloidosis. The amyloid was found to react positively with anti-duck and anti-bovine amyloid protein A antisera on PAP-staining, indicating it to be of the reactive type. The cause of the syndrome is unknown. A possible association with infectious agents (Streptococcus faecalis and reovirus) is discussed.

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Cecal samples from laying chickens from 25 farms with a history of decreased egg production, diarrhea, and/or increased feed conversion ratios were examined for anaerobic intestinal spirochetes of the genus Brachyspira. Seventy-three samples positive in an immunofluorescence assay for Brachyspira species were further examined using selective anaerobic culture, followed by phenotypic analysis, species-specific PCRs (for Brachyspira hyodysenteriae, B. intermedia, and B. pilosicoli), and a Brachyspira genus-specific PCR with sequencing of the partial 16S rRNA gene products. Brachyspira cultures were obtained from all samples. Less than half of the isolates could be identified to the species level on the basis of their biochemical phenotypes, while all but four isolates (5.2%) were speciated by using PCR and sequencing of DNA extracted from the bacteria. Different Brachyspira spp. were found within a single flock and also in cultures from single chickens, emphasizing the need to obtain multiple samples when investigating outbreaks of avian intestinal spirochetosis. The most commonly detected spirochetes were the pathogenic species B. intermedia and B. pilosicoli. The presumed nonpathogenic species B. innocens, B. murdochii, and the proposed "B. pulli" also were identified. Pathogenic B. alvinipulli was present in two flocks, and this is the first confirmed report of B. alvinipulli in chickens outside the United States. Brachyspira hyodysenteriae, the agent of swine dysentery, also was identified in samples from three flocks. This is the first confirmed report of natural infection of chickens with B. hyodysenteriae. Experimental infection studies are required to assess the pathogenic potential of these B. hyodysenteriae isolates.Avian intestinal spirochetosis (AIS) is a disease complex that affects commercial laying and meat breeder chickens, characterized by the colonization of the ceca by members of one or more species of anaerobic intestinal spirochetes of the genus Brachyspira (formerly Serpulina) (11,14,36). The condition is associated with delayed or reduced egg production and a chronic diarrhea in adult birds that can result in wet litter and fecal staining of eggshells. Moreover, reduced performance has been reported for broiler chicks hatched from eggs of breeder chickens infected with Brachyspira spp. (7,33). AIS was first clearly described in the 1980s, in both The Netherlands (5, 7, 8) and the United Kingdom (10), and subsequently has been reported in the United States (39, 43), Australia (24,35), and a number of other European countries (2, 3). The nonspecific nature of the disease and the lack of availability of simple and specific diagnostic tests for these anaerobic spirochetes from chickens may have resulted in the condition being greatly underreported (14).Studies using multilocus enzyme electrophoresis showed that intestinal spirochetes from chickens could be divided into at least six species groupings (25). These included the three species currently considered to be pathogenic to chickens, Brachys...

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.

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Colibacillosis results from infection with avian pathogenic Escherichia coli bacteria. Healthy broilers are resistant to inhaled E. coli, but previous infection with vaccine or virulent strains of Infectious Bronchitis Virus (IBV) predisposes birds for severe colibacillosis. The aim of this study was to investigate how IBV affects the course of events upon infection with E. coli. Broilers were inoculated with IBV H120 vaccine virus or virulent M41 and challenged 5 days later with E. coli 506. A PBS and E. coli group without previous virus inoculation were included. Sections of trachea, lung and airsacs were stained for CD4, CD8, gammadelta-TCR, alphabeta1-TCR, and for macrophages (KUL-01) and both pathogens. Changes in the mucociliary barrier of trachea, lung and airsacs did not predispose for bacterial superinfection. The disease in the lungs of the E. coli group and both IBV/E. coli groups was similar. Lesions in the airsacs were more pronounced and of longer duration in the IBV/E. coli groups. The immunocytological changes differed substantially between the E. coli group and both IBV/E. coli groups. In trachea, lungs and airsacs the CD4+ and CD8+ populations were significantly larger than in the E. coli and PBS groups. In the lungs and the airsacs the macrophages were more numerous in the IBV/E. coli and the E. coli groups than in the PBS group. The presence of high numbers of T cells and macrophages in IBV infected birds most likely induced an altered immune response, which is responsible for the enhanced clinical signs of colibacillosis.

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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.