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Association between Poultry Density and Salmonella Infection in Commercial Laying Flocks in Iran using a Kernel Density
Fereshteh Ansari1, Hadi Pourjafar2*, Saeed Bokaie3, Seyed Mostafa Peighambari4, Mahmood Mahmoudi5, Mohammad Hosein Fallah6, Farshad Tehrani7, Abolfazl Rajab7, Seyed Ali Ghafouri7 and Maryam Shabani7
1Research Center for Evidence Based Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; 2Department of Public Health, Maragheh University of Medical Sciences, Maragheh, Iran; 3Department of Food Hygiene; 4Department of Avian Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran; 5Epidemiology and Biostatistics Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; 6Department of Poultry Diseases Researches, Razi Vaccine and Serum Research Institute, Karaj, Iran; 7Iranian Veterinary Organization
*Corresponding author:;


Salmonellosis in laying flocks is one of the major health concerns worldwide and the size of the flock has been introduced as an important risk-factor associated with increased risk of Salmonella. In this study a total of 113 holdings was selected using simple random sampling, stratified by active layer holdings in each province of Iran. Two pooled fecal samples were obtained from each flock of holding and information of sampled holdings was acquired from Geographic Information System (GIS). The prevalence of Salmonella contamination in laying hen holdings was 3.5% and the risk of Salmonella contamination was associated with the size of the poultry-holding (OR=5.6; CI95%=1.35, 23.57; P=0.018). None of the positive farms were in high density surface at farm level. Two of the positive farms were at the density surface of more than 13 flocks per square kilometer and all the positive farms were in the regions with poultry density of more than 319,000 per square kilometer. According statistical and spatial analysis keeping large number of poultries in a certain area is an important risk factor for Salmonella contamination.

Key words: Kernel density, Laying farms, Salmonella infection, Spatial analysis


ISSN 0253-8318 (Print)
ISSN 2074-7764 (Online)