title: Modeling the effect of seasonal variation in ambient temperature on the transmission dynamics of a pathogen with a free-living stage: example of Escherichia coli O157:H7 in a dairy herd.
abstract: To explore the potential role of ambient temperature on infection transmission dynamics for pathogens, we used Escherichia coli O157:H7 in a dairy herd and the surrounding farm environment as a model system. For this system, we developed a mathematical model in which a Susceptible-Infectious-Susceptible (SIS) model of infection spread through the host population is coupled with a metapopulation model of E. coli O157:H7 free-living stage in the environment allowing bacterial growth to be influenced by ambient temperature. Model results indicate that seasonal variation in ambient temperature could have a considerable impact on pathogen populations in the environment, specifically on barn surfaces and in water troughs, and consequently on the prevalence of infection in the host population. Based on model assumptions, contaminated drinking water was the most important pathway of E. coli O157:H7 transmission to cattle. Sensitivity analysis indicated that water-borne transmission is amplified during the warmer months if the amount of standing drinking water available to the cattle herd is high. This is because warmer ambient temperature favors faster pathogen replication which when combined with slower water replacement-rate due to high amount of available standing water leads to a greater pathogen load in drinking water. These results offer a possible explanation of the seasonal variation in E. coli O157:H7 prevalence in cattle and suggest that improved drinking-water management could be used for control of this infection in cattle. Our study demonstrates how consideration of ambient temperature in transmission cycles of pathogens able to survive and grow in the environment outside the host could offer novel perspectives on the spread and control of infections caused by such pathogens.
authors.affiliation: Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A & M University, College Station, TX 77843-4458, United States. rgautam@cvm.tamu.edu
authors.forename: Raju
authors.initials: R
authors.lastname: Gautam
authors.forename: Majid
authors.initials: M
authors.lastname: Bani-Yaghoub
authors.forename: William H
authors.initials: WH
authors.lastname: Neill
authors.forename: Dörte
authors.initials: D
authors.lastname: Döpfer
authors.forename: Charles
authors.initials: C
authors.lastname: Kaspar
authors.forename: Renata
authors.initials: R
authors.lastname: Ivanek
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission*; D003612:Dairying; D060766:Drinking Water / Q000382:microbiology; D004783:Environmental Microbiology; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000254:growth & development*; D005260:Female; D008954:Models, Biological; D012621:Seasons; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D060766:Drinking Water