The onset and prevalence of Campylobacter colonization in broilers and layers at commercial farms with low biosecurity in tropical climates were tested. Despite the presence of positive animals at the same farms, the broiler flocks tested negative until, on average, 21 days. Prelaying flocks showed a higher prevalence than laying flocks.
Campylobacter jejuni and C. coli are identified as major causes of food-borne disease in humans worldwide (1). Epidemiological studies have shown that handling and consumption of poultry meat are important risk factors for campylobacteriosis in humans (2).Newly hatched chickens are free of Campylobacter. Campylobacter colonization of commercial broiler flocks could be detected after 1 to 2 weeks of age (3). As reasons for this lag phase in colonization, other than the likelihood of exposure to an infective dose of Campylobacter, the presence of maternal immunity (4) and a shift in the composition of the gut flora over time (5) have been suggested. In laying hens and broilers, both shedding and the fraction of colonized animals decline over time, with acquired immunity suggested as a reason (6, 7).Studies in temperate countries have associated maternal immunity, acquired immunity, climatic conditions, poultry management systems, and the level of the biosecurity with the colonization and persistence of Campylobacter in chickens (5). Data on Campylobacter in poultry reared in tropical climates with open housing systems are scarce, and such data will add to the understanding of Campylobacter epidemiology. Hence, this study aimed to investigate the initial Campylobacter colonization of broilers and the prevalence of Campylobacter in laying hens under field conditions in commercial farm settings with low biosecurity in Sri Lanka, a tropical country in southern Asia.As in many other tropical countries, in Sri Lanka, the deeplitter open-house system is commonly used in the poultry industry. Poultry, either broilers or laying hens, is reared in houses with half walls (approximately 0.5 m), with food and water provided inside the pen. Wire mesh is used to complete the walls and confine the birds in the pen to protect them from predators. However, contact with rodents, insects, wild birds, and other wild animals is unavoidable.All farms, either broiler or layer, included in this study used the deep-litter open-house system, and the average number of animals per flock varied from 100 to 1,000. The management practices that were already in place were not changed to support this study. This included the use of commercially available feeds containing nonspecified coccidiostats and antibiotic growth promoters. The use of antibiotics otherwise was not monitored. Campylobacter colonization or shedding was tested by collecting cloacal swabs from a minimum of 10 birds selected randomly from each flock. Duplicate floor samples from each of five spots (four corners and the middle) in each pen were collected by using cotton swabs moistened with sterile saline before the chicks were introduced into the...