Infectious Disease Compendium

Francisella tularensis

Microbiology

A little gram negative rod (aka coccobacillus) that can have bipolar staining. Francisella tularensis, has 4 subspecies, but nearly all cases of are due to subspecies tularensis (type A), the most virulent typefound in North America, and subspecies holarctica (type B), which is the most widespread species in Europe.

Epidemiologic Risks

All over the Northern Hemisphere and Europe. Get it from skinning and eating rodents and lagomorphs (bunny rabbits) or being in contact with their excrement.

Ticks (a common vector in the Southern US around Missouri), biting flies and mosquitoes can also spread disease as can drinking water.

In Sweden, Francisella tularensis holarctica is spread by mosquitos (PubMed) and hares, has been a major problem in Norway (PubMed), in what they call the rodent years. I remember that show. And in Australian it is in ringtailed possums.

And, if you happen to be within 5 meters of hares that you are hosing down after skinning and disemboweling them, you can get pneumonic tularemia (PubMed). So be careful splitting hares.

There was a fatal case of pneumonic tularemia where the patient aquired the infection from her rabbit killing dog. Yet another reason you should not your dog lick you. (PubMed) People get plague from their dogs and cats the same way.

There are about 10 cases a year in the US (MMWR), there have been increased cases in Colorado, Nebraska, South Dakota, and Wyoming in 2015 (MMWR).

The best outbreak was pneumonic tularemia from rabbits being aerosolized by a lawn mower (PubMed); I had a similar case.

Now sing along with me. "Over in the gorge/Many many months ago,/ Me Mither killed a rabbit /In the mower it did go./ It aerosolized the bunny /In the good ould Toro way,/ Sending bacteria into the air/ To be sucked into the lung to stay. /Chorus: "Too-ra-loo-ra-le-mia, /Too-ra-loo-ra-li, /Too-ra-loo-ra-le-mia,/ now you are going to die /Too-ra-loo-ra-le-mia,/ Too-ra-loo-ra-li, /Too-ra-loo-ra-le-mia, /that's an ID lullaby."

In the Midwest, cats are the vector (PubMed).

And there was a water bourne outbreak in Turkey.

And a case in a immunocompetent white, non-Hispanic woman aged 67 years from Sherburne County, Minnesota from a fish hook injury from Francisella holarctica (type B) (PubMed).

Syndromes

a) typhoidal: A febrile, low pulse illness, non focal, lasting for a month. A cause of Faget's.

b) ulceroglandular: look for a necrotic ulcer at the site of inoculation. Can mimic herpes with a blister (PubMed).

c) glandular: many inflamed lymph nodes.

d) oculoglandular (after skinning a rabbit, try not to stick your finger in your eye).

e) pharyngeal.

f) pneumonic.  A problem in Sweden (PubMed).

Treatment

Streptomycin 7.5 to 10 mg/kg intramuscularly every 12 hours for 7 to 14 days is the classic therapy, gentamicin is an acceptable substitute.

Third-generation cephalosporins, carbapenems, other aminoglycosides, quinolones work in the test tube but little clinical experience.

In Missouri, where they had a bunch of mostly misdiagnosed cases, accidental ciprofloxacin worked well (PubMed).

Do not use tetracycline. "169 isolates (92 type A and 77 type B) from North America were tested against seven antimicrobial agents (streptomycin, gentamicin, tetracycline, doxycycline, ciprofloxacin, levofloxacin, and chloramphenicol) used for the treatment of tularemia. The MICs for all of the isolates fell within the susceptible range (PubMed)."

Notes

The organisms can survive for long periods of time in the environment. (:There are people fool enough to eat ill animals, as they are easy to catch. Mmmmmmmm, good:). It is a biohazard so warn the lab as they need special media to grow. Best way to make the diagnosis is serology.