Microbial pathogen survival study in a high plains feedyard playa

-Sixteen microbes and one enteric protozoal parasite were secured in screw- cap vials (CV) and dialysis tubes (DT) and placed in a feedyard shallow lak e (playa) in the West Texas High Plains, USA. They were removed weekly or m onthly depending on their susceptibility to the water environment. There we re two overlapping studies; one started in September 1996 and was terminate d 390 days later. The second study started in May 1997 and was terminated 1 88 days later. These controlled studies were used to determine the decrease in titers of 10 bacteria (Pasteurella haemolytica A1, Pasteurella multocid a A:3, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Acti nomyces pyogenes, Salmonella enterica serovar dublin, Bacillus thuringiensi s, Klebsiella pneumoniae and Pseudomonas aeruginosa); two fungi (Aspergillu s fumigatus and Aspergillus niger); four viruses (Infectious Bovine Rhinotr acheaitis (IBR), Bovine Virus:Diarrhea Virus (BVD), Bovine Respiratory Sync ytial Virus (BRSV), Bovine Parvovirus (BPV) and one protozoal parasite (Cry ptosporidium parvum), over time. The Pasteurella isolates died in both stud ies within seven to 35 days. Actinomyces pyogenes died within 84 days in th e 1996 study and survived for 188 days in the 1997 study. The remaining bac terial isolates in 1996 survived for 390 days with low titers, except for P . aeruginosa. Both fungal isolates died by 390 days in the 1996 study. All bacteria and fungi survived the 188 day study in 1997, except for the Paste urella isolates. The titers of the viruses decreased rapidly over 42 days, except for BPV in the 1996 study, and all viruses were inactivated by day 4 2 in the 1997 study. Cryptosporidium parvum survived the 1996 winter but lo st it's ability to infect infant mice during the month of May, 1997. Microb ial survival decreased more rapidly in DT samples compared to CV samples.