Exploring the Impact of Land Cover on the Occurrence of Ornithobacteriosis and Fowl Cholera: A Case-Case Study.

Ornithobacterium rhinotrachealis (ORT) and Pasteurella multocida (PM) are two major bacterial pathogens affecting the United States (US) commercial turkey industry. This retrospective observational case-case study aimed to investigate the association between land cover and confirmed disease occurrences attributed to PM or ORT in commercial turkey sites located in the Midwestern US A total of 65 farms from one poultry production company were included, where 28 had PM disease occurrences and 37 had ORT disease occurrences between 2014 and 2021. Risk factors of interest included land cover types (wetlands, forest, urban, pasture, herbaceous, barren, shrub), poultry-farm density in the area, and season and year of confirmed outbreak(s). A multivariable logistic regression model revealed that for every 1 m increase in distance from a farm to the nearest wetland, the odds of a confirmed disease occurrence related to PM decreased by approximately 0.24% compared to an ORT-related disease occurrence (p = 0.004). Meanwhile, PM occurrence during 2014-2017 was 98.5% higher than 2018-2019 and 93.2% higher than in 2020-2021. Broadly, the findings contribute to the dearth of research on land cover and turkey respiratory diseases and demonstrate that land cover is an important consideration for farm management and future study.