Faecal samples (n 5 1786) from chickens in broiler breeder (n 5 28), layer (n 5 22) or broiler (n 5 19) ocks in the eastern states of Australia were cultured for intestinal spirochaetes. Overall, birds in 42.9% of broiler breeder and 68.2% of layer¯ocks were colonized with spirochaetes, but no birds in broiler¯ocks were infected. Colonization rates in infected¯ocks ranged from 10 to 100% of birds sampled. Faeces from colonized¯ocks were on average 14% wetter than those from non-colonized¯ocks. There was a highly signi® cant association between colonization with spirochaetes and the occurrence of wet litter and/or reduced production. A subset of 57 spirochaete isolates from birds in 16¯ocks were identi® ed to the species level using a panel of polymerase chain reaction tests. Isolates from nine (56%) of these¯ocks were spirochaetes that are known to be pathogens of poultry: Serpulina pilosicoli was isolated from birds from ® ve¯ocks, birds from two¯ocks were infected with Serpulina intermedia, and in two other¯ocks both species were identi® ed. Isolates from the other seven¯ocks belonged to other Serpulina species, which are currently of unknown pathogenicity. This study indicates that infections with intestinal spirochaetes are a common but currently under-diagnosed cause of wet litter and/or reduced egg production in broiler breeder and layer¯ocks in Australia.
This paper presents an overview of intestinal spirochete infections of chickens. It focuses particularly on studies in Australia, where recent surveys of 136 layer and broiler breeder flocks have revealed a high rate of infection (>40%) with intestinal spirochetes. Infection was not detected in broiler flocks. Approximately 50% of isolates from infected flocks were Brachyspira (Serpulina) intermedia or B. pilosicoli, with the other isolates being B. innocens, B. murdochii or the proposed species ‘B. pulli’. No isolates of B. alvinipulli were found. Intestinal spirochetes were significantly associated with wet litter problems and/or reduced egg production. Experimental infection of point-of-lay birds with either B. intermedia or B. pilosicoli caused reduced egg production, and, with B. intermedia, a significant increase in fecal moisture content. Infection with B. innocens caused no significant changes. In-water treatment of a flock with a mixed spirochete infection using lincospectin resulted in a slimy diarrhea lasting for 2–3 weeks, followed by absence of spirochetes for 3 months. Birds treated with tiamulin remained healthy, and had a reduced level of infection with intestinal spirochetes (30%) for 3 months. Trials are under way to test the efficacy of antimicrobials in point-of-lay chickens experimentally infected with either B. intermedia or B. pilosicoli.
The pathogenic potential of the anaerobic intestinal spirochaetes Brachyspira (Serpulina ) pilosicoli and Brachyspira innocens was evaluated in adult chickens. Thirty 17-week-old Cobb broiler breeder hens were individually caged in three groups of 10 birds. Control birds (group A) were sham inoculated with sterile broth medium. Birds in the other two groups (groups B and C) were inoculated, respectively, with an isolate of B. innocens or of B. pilosicoli. Birds were monitored daily, and killed at 41 weeks of age. Infection had no consistent effect on body weight gain, but inoculation with B. pilosicoli resulted in a transient increase in faecal water content. B. innocens infection had no effect on egg production, but B. pilosicoli infection caused a delayed onset of laying, and a highly significant reduction in egg production over the first 11 weeks of lay. This study confirms that B. pilosicoli can cause serious egg production losses in adult chickens, while B. innocens is not obviously pathogenic.
Objective To validate a polymerase chain reaction (PCR) based method, Enterobacterial Repetitive Intergenic Consensus‐PCR (ERIC‐PCR), for the fingerprinting of Haemophilus parasuis strains and to use that method to differentiate isolates from apparently related outbreaks of Glässers disease on three pig farms. Design ERIC‐PCR was evaluated by comparing 15 different strains that represented all 15 recognised serovars in the Kielstein‐Rapp‐Gabrielson (KRG) scheme for serotyping H parasuis. Next, ERIC‐PCR was used to examine 14 Australian field isolates of H parasuis; 12 collected from three farms suffering apparently related outbreaks of Glässers disease and two from two other farms with no known connection. Results The 15 serovar reference strains all gave unique, reproducible ERIC‐PCR fingerprints. The 12 isolates from the three apparently related outbreaks all gave a single fingerprint, which was distinct from any seen in the 15 serovar reference strains and the two other Australian field isolates in the studied farms. The confirmation that all 12 isolates were the same strain allowed the development of a prevention and control program that has prevented the emergence of any further outbreaks of Glässer disease on the three farms. Conclusion ERIC‐PCR is a suitable technique for the differentiation of unrelated strains of H parasuis. The finding that the 12 field isolates of H parasuis all shared the same fingerprint is strong evidence that there was a common source of infection on all three farms. This study has shown, for the first time, that ERIC‐PCR is a suitable technique for the sub‐typing of H parasuis and useful for studying the epidemiology of outbreaks of Glässers disease.
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