title: Effects of location for collection of air samples on a farm and time of day of sample collection on airborne concentrations of virulent Rhodococcus equi at two horse breeding farms.
abstract: OBJECTIVE
  To determine whether airborne concentrations of virulent Rhodococcus equi at 2 horse breeding farms varied on the basis of location, time of day, and month.
  
  
  METHODS
  2 farms in central Kentucky with recurrent R equi-induced pneumonia in foals.
  
  
  METHODS
  From February through July 2008, air samples were collected hourly for a 24-hour period each month from stalls and paddocks used to house mares and their foals. Concentrations of airborne virulent R equi were determined via a modified colony immunoblot technique. Differences were compared by use of zero-inflated negative binomial methods to determine effects of location, time, and month.
  
  
  RESULTS
  Whether mares and foals were housed predominantly in stalls or paddocks significantly affected results for location of sample collection (stall vs paddock) by increasing airborne concentrations of virulent R equi at the site where horses were predominantly housed. Airborne concentrations of virulent R equi were significantly higher from 6:00 pm through 11:59 pm than for the period from midnight through 5:59 am. Airborne concentrations of virulent R equi did not differ significantly between farms or among months.
  
  
  CONCLUSIONS
  Airborne concentrations of virulent R equi were significantly increased when horses were predominantly housed at the site for collection of air samples (ie, higher in stalls when horses were predominantly housed in stalls and higher in paddocks when horses were predominantly housed in paddocks). Concentrations of virulent R equi among air samples collected between the hours of 6:00 am and midnight appeared similar.
authors.affiliation: Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Kyle R
authors.initials: KR
authors.lastname: Kuskie
authors.forename: Jacqueline L
authors.initials: JL
authors.lastname: Smith
authors.forename: Naisyin
authors.initials: N
authors.lastname: Wang
authors.forename: Craig N
authors.initials: CN
authors.lastname: Carter
authors.forename: M Keith
authors.initials: MK
authors.lastname: Chaffin
authors.forename: Nathan M
authors.initials: NM
authors.lastname: Slovis
authors.forename: Randolph S
authors.initials: RS
authors.lastname: Stepusin
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Cattoi
authors.forename: Shinji
authors.initials: S
authors.lastname: Takai
authors.forename: Noah D
authors.initials: ND
authors.lastname: Cohen
mesh_terms: D000391:Air Microbiology; D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D006799:Housing, Animal; D006813:Humidity; D016929:Rhodococcus equi / Q000302:isolation & purification* / Q000472:pathogenicity; D013696:Temperature; D013997:Time Factors; D014774:Virulence; D014919:Wind