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Potential Contamination of Food by Airborne Animal Waste


A recent publication* confirmed that proximity to a poultry farm resulted in contamination of soil foliage and almonds in an orchard.  The survey was conducted in California over a two-year period. E. coli was identified on leaf surfaces, on trees and nuts in 20 percent of samples in an orchard located 30 yards downwind from a poultry operation.  In contrast only one of 207 samples from an orchard surrounded by other almond orchards yielded E. coli


It was not possible to demonstrate the presence of Salmonella from 520 samples examined.  The isolation of E. coli in the orchard adjacent to the poultry farm was concentrated in a zone located near the common boundary of the orchard and the farm suggesting airborne transport.  It was also demonstrated that Staphylococcaceae generally associated with poultry were frequently recovered from trees close to the common boundary compared to trees 120 yards into the orchard.

Almond Orchard

Open-sided California House

The paper does not describe the population of chickens on the adjacent farm or the type of housing used, whether opened sided suspended cages or units with fan exhausts. It is intuitive that either wind or power ventilation would transport dust laden with bacteria of fecal origin over short distances resulting in contamination of adjacent areas, in this case an almond orchard. 


In 1996, STEC was associated with fruit used to make non-pasteurized Odwalla brand apple juice. An investigation showed that product was derived from blemished and fallen fruit that may have been contaminated by animal waste.  There is evidence that outbreaks of E.coli infection have occurred as a result of contaminated romaine lettuce. Irrigation water may have contained runoff from adjacent concentrated animal feeding operations including zero grazing dairy facilities.


*Theofel, C. G. et al Microorganisms move a short distance into an almond orchard from an adjacent upwind poultry operation. Applied and Environmental Microbiology. DOI: 10.1128/AEM.00573-20

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