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United States Department of Agriculture

Agricultural Research Service

Title: Influence of relative humidity on transmission of Campylobacter jejuni in broiler chickens.

Author
item Line, John

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 23, 2006
Publication Date: July 1, 2006
Citation: Line, J.E. 2006. Influence of relative humidity on transmission of Campylobacter jejuni in broiler chickens.. Poultry Science. 85:1145-1150.

Interpretive Summary: Campylobacter continues to be an important human pathogen and its epidemiological link to poultry as a source is well defined. Improved control measures to prevent contamination of broilers during production are needed to ensure increased safety of raw processed chicken so that food safety risks associated with undercooking or cross-contamination are mitigated. Transmission of Campylobacter jejuni among broiler chickens has been documented; however, the influence of relative humidity (RH) on transmission rates is an important factor that has not been extensively studied. The purpose of our experiments was to determine if there were differences in the rate of C. jejuni colonization among groups of broilers raised in microbiological isolation under high (approximately 80%) and low (approximately 30%) RH conditions. Day-of-hatch chicks (n = 100 per group) were placed on wood shavings in high and low humidity controlled pens and challenged with C. jejuni by introducing two seeder birds orally inoculated with C. jejuni into each group. The rate of colonization was monitored by analyzing ceca from 10 chicks from each group at days 1, 2, 3, 4, and 7. After three weeks the remaining chickens were removed and 100 newly hatched chicks were placed on the contaminated litter and a second trial was conducted with the litter as the only inoculum source. Trials were repeated in this manner with the time between removing birds and placing newly hatched chicks extended to 6h, 24h, and one week. Significant differences in Campylobacter colonization rates were observed between chickens raised under the high and low RH conditions. A delay in colonization was observed in birds raised under the low RH conditions which increased with the increased time between removal of birds and placement of newly hatched chicks. This research is useful because these experiments demonstrate the importance of humidity in transmission of Campylobacter from litter and could lead to practical applications to help reduce Campylobacter colonization in broilers. For example, the importance of maintaining a minimum lag time of at least one week between flocks for sufficient reduction of campylobacters in commercial houses was suggested and the study further demonstrates the potential value in drying the litter to help prevent cross contamination between flocks. Reduction of RH in poultry rearing houses through ventilation and water handling practices that promote dryer litter have been suggested as primary considerations for Salmonella reduction during production and the results of our studies suggest that such practices should also help reduce exposure of chicks to viable Campylobacter in the litter environment. These results should be of interest to poultry producers, food safety specialists and researchers in industry, academia and government.

Technical Abstract: Horizontal transmission of Campylobacter jejuni among broiler chickens has been documented; however, the influence of relative humidity (RH) on transmission rates is an important factor that has not been extensively studied. The purpose of our experiments was to determine the rate of C. jejuni colonization among groups of broilers raised in microbiological isolation under high (approximately 80%) and low (approximately 30%) RH conditions. Day-of-hatch chicks (n = 100 per group) were placed on wood shavings in high and low humidity controlled pens and challenged with C. jejuni by introducing two seeder birds orally inoculated with C. jejuni into each group. The rate of colonization was monitored by analyzing ceca from 10 chicks from each group at days 1, 2, 3, 4, and 7. After three weeks the remaining chickens were removed and 100 newly hatched chicks were placed on the contaminated litter and a second trial was conducted with the litter as the only inoculum source. Trials were repeated in this manner with the time between removing birds and placing newly hatched chicks extended to 6h, 24h, and one week. Significant differences in Campylobacter colonization rates were observed between chickens raised under the high and low RH conditions. A delay in colonization was observed in birds raised under the low RH conditions which increased with the increased time between removal of birds and placement of newly hatched chicks. These experiments demonstrate the importance of humidity in transmission of Campylobacter from litter and could lead to practical applications to help reduce Campylobacter colonization in broilers.Horizontal transmission of Campylobacter jejuni among broiler chickens has been documented; however, the influence of relative humidity (RH) on transmission rates is an important factor that has not been extensively studied. The purpose of our experiments was to determine the rate of C. jejuni colonization among groups of broilers raised in microbiological isolation under high (approximately 80%) and low (approximately 30%) RH conditions. Day-of-hatch chicks (n = 100 per group) were placed on wood shavings in high and low humidity controlled pens and challenged with C. jejuni by introducing two seeder birds orally inoculated with C. jejuni into each group. The rate of colonization was monitored by analyzing ceca from 10 chicks from each group at days 1, 2, 3, 4, and 7. After three weeks the remaining chickens were removed and 100 newly hatched chicks were placed on the contaminated litter and a second trial was conducted with the litter as the only inoculum source. Trials were repeated in this manner with the time between removing birds and placing newly hatched chicks extended to 6h, 24h, and one week. Significant differences in Campylobacter colonization rates were observed between chickens raised under the high and low RH conditions. A delay in colonization was observed in birds raised under the low RH conditions which increased with the increased time between removal of birds and placement of newly hatched chicks. These experiments demonstrate the importance of humidity in transmission of Campylobacter from litter and could lead to practical applications to help reduce Campylobacter colonization in broilers.Horizontal transmission of Campylobacter jejuni among broiler chickens has been documented; however, the influence of relative humidity (RH) on transmission rates is an important factor that has not been extensively studied. The purpose of our experiments was to determine the rate of C. jejuni colonization among groups of broilers raised in microbiological isolation under high (approximately 80%) and low (approximately 30%) RH conditions. Day-of-hatch chicks (n = 100 per group) were placed on wood shavings in high and low humidity controlled pens and challenged with C. jejuni by introducing two seeder birds orally inoculated with C. jejuni into each group. The rate of colonization was monitored by analyzing ceca from 10 chicks from each group at days 1, 2, 3, 4, and 7. After three weeks the remaining chickens were removed and 100 newly hatched chicks were placed on the contaminated litter and a second trial was conducted with the litter as the only inoculum source. Trials were repeated in this manner with the time between removing birds and placing newly hatched chicks extended to 6h, 24h, and one week. Significant differences in Campylobacter colonization rates were observed between chickens raised under the high and low RH conditions. A delay in colonization was observed in birds raised under the low RH conditions which increased with the increased time between removal of birds and placement of newly hatched chicks. These experiments demonstrate the importance of humidity in transmission of Campylobacter from litter and could lead to practical applications to help reduce Campylobacter colonization in broilers.

Last Modified: 9/1/2014
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