Intestinal spirochaetes (Brachyspiraspp.) colonizing flocks of layer and breeder chickens in Malaysia

Abstract

Avian intestinal spirochaetosis causes problems including delayed onset of lay and wet litter in adult chickens, and results from colonization of the caecae/rectum with pathogenic intestinal spirochaetes (genus Brachyspira). Because avian intestinal spirochaetosis has not previously been studied in South East Asia, this investigation was undertaken in Malaysia. Faecal samples were collected from 25 farms and a questionnaire was administered. Brachyspira species were detected by polymerase chain reaction in 198 of 500 (39%) faecal samples from 20 (80%) farms, including 16 (94%) layer and four (50%) breeder farms. Pathogenic Brachyspira pilosicoli was identified in five (29%) layer and two (25%) breeder farms whilst pathogenic Brachyspira intermedia was detected in nine (53%) layer and one (12.5%) of the breeder farms. Twelve (80%) layer farms had egg production problems and 11 (92%) were positive for Brachyspira: three (25%) for B. pilosicoli and six (50%) for B. intermedia. Of three breeder farms with egg production problems, one was colonized with B. pilosicoli. Three of ten layer farms with wet litter were positive for B. pilosicoli and six for B. intermedia. Of four breeder farms with wet litter, one was colonized with B. pilosicoli and one with B. intermedia. No significant associations were found between colonization and reduced egg production or wet litter, perhaps because so many flocks were colonized. A significant association (P = 0.041) occurred between a high prevalence of colonization and faecal staining of eggs. There were significant positive associations between open-sided housing (P = 0.006), and flocks aged >40 weeks (P < 0.001) and colonization by pathogenic species.

The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans

“…About 20% of these infected flocks contain chickens that are colonized with B. pilosicoli (63,65,67), and flocks with diarrhea or poor egg production are colonized more commonly than flocks with normal feces. Flocks with chickens that are over 40 weeks old are significantly more likely to be infected than flocks with younger chickens on the same farms (63,65,67,76), and multi-age farms have the highest risk of infection (75). This pattern is likely to reflect relatively increased cumulated opportunities for transmission of the spirochetes to chickens as they age.…”

“…Occasionally infection is reported in other poultry species, such as turkeys (30). Colonization and disease have been reported in many regions of the world (73)(74)(75)(76)(77). Infections can vary from being asymptomatic to severe, with increased mortality rates.…”

“…On the other hand, epidemiological surveys have shown that infection is common in flocks of laying and breeding chickens in Europe, Scandinavia, North and South America, Malaysia, and Australia (63)(64)(65)(66)(67)(68)(69)(70). Besides caged or housed flocks, outdoor free-range flocks and organic flocks with access to outside areas are commonly affected (71,72,76). In most regional studies, approximately 70% of laying flocks and 50% of breeding flocks contain chickens that are colonized by Brachyspira species.…”