Key points
- Francisella tularensis is highly infectious when grown in culture, and laboratory-acquired infections have been documented.
- The isolation of F. tularensis from clinical specimens, especially if unanticipated, can generate concern among laboratory workers about possible exposure.
Managing potential exposures
Management options for potentially exposed workers include a "fever watch" or antimicrobial prophylaxis. During a fever watch, workers monitor their temperature with instructions to seek immediate treatment for tularemia if they develop a fever (usually defined as a single oral temperature above 101 °F or 38.5 °C).
There are no set criteria for determining who should be managed by fever watch and who would benefit from immediate prophylaxis. Factors to consider when making this decision include:
- Nature of the exposure — Workers who report sniffing a culture plate or conducting procedures that generate aerosols are probably at greater risk than those who simply worked with the organism on the bench.
- Incubation period - The typical incubation period for tularemia is 3-7 days (range 1-14 days). Much of this period may have passed by the time the organism is positively identified, in which case, the remaining risk of infection is low.
- Level of concern — Some laboratory workers may be very anxious regarding their risk of infection, while others may be more concerned about taking medications unnecessarily.
Doxycycline (100 mg orally BID X 14 days) is generally recommended for prophylaxis in adults. Ciprofloxacin (500 mg orally BID) is not FDA-approved for prophylaxis of tularemia but has demonstrated efficacy in various studies, and may be an alternative for patients unable to take doxycycline.
Fact sheet: Managing potential laboratory exposures to Francisella tularensis