The use of poultry litter as a biological soil amendment presents a risk for the preharvest contamination of fresh produce bySalmonella. In order to properly assess this risk, it is important to understand the factors influencing the persistence ofSalmonellain poultry litter. This research was performed to investigate the influence of indigenous microflora on the survival ofSalmonellaTyphimurium in poultry litter. Microcosms of irradiated (sterilized) and natural poultry litter were inoculated withS. Typhimurium, adjusted to pH 8.0, 0.92 water activity (a_w), and stored at 30°C for 6 days.S. Typhimurium populations (log CFU g^-1) declined in both litter treatments and there were no significant differences (P> 0.05) in recovery between litter treatments on any sampling days (0 to 6). The pH of the natural litter significantly increased (P< 0.05) from 8.42 on day 0 to 9.00 on day 6. By day 6,S. Typhimurium populations in both litter treatments fell below the limit of detection (1 log CFU g^-1). The inactivation kinetics ofS. Typhimurium in both litter treatments were described by the Weibull model. Under the experimental conditions (pH 8.0, 0.92 a_w, 30°C), the presence or absence of poultry litter microflora did not significantly influence the survival ofS. Typhimurium. This study demonstrates that the mere presence of poultry litter microflora will not inhibitSalmonellasurvival. Instead, inhibitory interactions between various microorganisms in litter andSalmonellaare likely dependent on more favorable environmental conditions (e.g., a_w, pH) for growth and competition.

Recurring outbreaks of cyclosporiasis linked to fresh produce demonstrate the need to develop interventions to reduce C. cayetanensis in irrigation water. C. cayetanensis is resistant to commonly used irrigation water treatments, such as chemical sanitizers, making removal of oocysts by filtration the most suitable intervention. This study evaluated the reduction of Eimeria tenella and E. acervulina, as surrogates for C. cayetanensis, in water using filters packed with sand alone or mixtures of sand and zero-valent iron (ZVI). Water inoculated with Eimeria spp. oocysts was filtered through laboratory-scale (PVC column) and field-scale (swimming pool filter) filters packed with either 100% sand or 50% ZVI/50% sand (v/v). Filtered and backflush water was examined microscopically for oocysts. Laboratory-scale filters with 50% ZVI significantly (p < 0.05) reduced 99.9% of E. tenella oocysts compared to 55.3% with filters containing 100% sand. At the field-scale level, 50% ZVI filters significantly (p < 0.05) reduced 70.5% of E. acervulina oocysts compared to 54.5% by 100% sand filters. Filters were backflushed to examine the recovery of these parasites during routine filter-media cleaning procedures. Backflush recovery of oocysts ranged from 4.42–16.7%. The addition of ZVI significantly improved the reduction of Eimeria spp. oocysts at both filter scales. and should be further investigated as a potential irrigation water intervention to reduce C. cayetanensis.