Francisella tularensis: Understanding Reported Occupational Exposures and Laboratory Methods Used for the...

Francisella tularensis, the causative agent of tularemia, is a HHS Tier 1 select agent. Tularemia is the most commonly reported human and animal infection caused by a bacterial select agent in the United States. Because of the rarity of disease, low clinical suspicion, and the organism's low infectious dose, F. tularensis poses a hazard for unsuspecting laboratorians, particularly those who handle cultures outside a biological safety cabinet or without use of appropriate personal protective equipment (PPE). We examined Form 4s and Form 3s submitted to the Federal Select Agent Program between 2011 and 2015 to assess laboratory methods used in the identification of F. tularensis and categorize reported occupational exposures. Culture, which is used in a confirmatory identification, was the primary method used in clinical laboratories. Reported occupational exposures in clinical, veterinary, and reference laboratories occurred at a rate of 33.8, 14.0, and 0.4/100 isolates, respectively. The number of exposed workers in clinical, reference, veterinary, and research laboratories was 3.2, 2.4, 5.1, and 0.9 workers per reported incident, respectively. Most reported occupational exposures occurred in clinical laboratorians working on the bench at BSL-2 conditions with isolated cultures with no suspicion that the organism was F. tularensis; the fewest occurred in research laboratories at BSL-3 where occupational exposures were prevented by prior knowledge that the organism was F. tularensis and the PPE that was used in these laboratories.