A 50 y.o. male was mowing grass for the highway department and developed a febrile illness.

The CT is shown

He has a cough and body aches; what do you notice on his CT?

Our patient had pulmonary nodules from pneumonic tularemia.  He had run over a nest of rabbits with his mower and inhaled the bacteria.

Tularemia was first isolated from ground squirrels in Tulare county  California and was named Bacterium tularense.  Edward Francis reviewed 800 cases in 1914 causing it to be renamed Francisella tularensis. Tularemia is a gram negative zoonotic illness which is spread from a reservoir in rodents and rabbits .  It is prevalent in the southwestern US and is also found in Arkansas and Missouri.  Tularemia causes disease which manifests in several ways

Ulceroglandular - the most common type with a skin ulcer at the site of the local infection and swelling of regional lymph nodes. Ticks most often cause this form.

Typhoidal- is also common and differs in that it does not involve regional nodes. It presents with an influenza-like illness with fever, headache and diarrhea.

Pneumonic tularemia- since rodents and rabbits are a reservoir of tularemia. They can be aerosolized when handling dead animals or hitting them with a mower. In Nebraska in 2003 workers mowing along the highway ran over a nest of rabbits. Two men developed pneumonic tularemia. Pneumonic tularemia was studied in WWII as a biological weapon because only ten organisms are needed to cause disease.

Glandular , oculoglandular and oropharyngeal tularemia are far less common.

less common forms of tularemia

The diagnosis depends having a high degree of suspicion and a good history since lab data can be delayed. Cultures are often negative because F tularensis requires a cysteine-rich medium to  grow and antibodies may not be detectable until the second week of illness. Streptomycin and gentamicin have cure rates of 86-97%. 

FUN FACTS

Tularemia was first studied in 1926 at the Astrakhan plague station in Russia.  it was thought to be first used as a weapon at the Battle of Stalingrad in 1942. Hundreds of cases were reported however this may have been due to a proliferation of rats instead of use as a bioweapon. 

Finding a nodule of CXR does not narrow the differential for febrile illness with cough. Infections (tuberculosis, histoplasmosis), hypersensitivity pneumonitis, vasculitis, chemical exposures (berylium) and cancer can all cause nodules and fever. 

Kraval A Pulmonary tularemia. TIDSSKRIFTET 2021 July 7 Vol 141 10.4045.

Alias T, Fallahzadeh M, Berhe M. Tularemia presenting as pulmonary nodules in an immunocompromised patient (Bayl Univ Med Cent) 2017 A[r;30(2):175-76.

Kravdal A, Stubhaug O, Wago A, et al. Pulmonary tularaemia: a differential diagnosis to lung cancer. ERJ Open Research 2020 6(2):00093-2019.

Dr. Gerald Diaz@Geraod MD https://www/omstagra,/cp,/grepmed/

Naughton M, Brown R, Adkins, DiPersio J. Tularemia-an unusual cause of a solitary pulmonary nodule in the post-transplant setting. Case Reports Bone Marrow Transplant.1999 July;24(2):197-199.

tularemia is also called rabbit fever