Tularemia – I decided to make a video based on a real patient of mine.
65-year-old man, previously healthy, retired from farm life. In his free time, he likes to hunt, and he is a local country singer, a regular weekend star at the bar. Not a smoker or a drinker. He comes to the clinic today because of a fever of 103 F, with muscle aches, a little bit of cough, feeling a little short of breath, respirations 23, Oxygen saturation 94 percent, and COVID 19 negative. He ends up getting much sicker, requiring an intensive care unit. Can doctors save his life?
Differential diagnosis includes tuberculosis (Mycobacterium tuberculosis), anthrax (Bacillus anthracis), bubonic plague (Yersinia pestis), and tularemia (Francisella tularensis).
Tularemia is a zoonotic infection, meaning it has a close relationship with animals. The bacteria that causes Tularemia is called Francisella tularensis. This is a very unusual bacteria. It’s an aerobic and fastidious gram-negative bacterium. In other words, it likes oxygen and is a pain to grow in the microbiology lab.
Human infection occurs following contact with infected animals or invertebrate vectors—usually rodents and rabbits.
Tularemia sometimes goes by other names, like Francis disease, deer fly fever, rabbit fever, market men disease, water rat trappers disease, wild hare disease (yato-byo), and Ohara disease.
Tell me you’ve heard of yato-byo. They didn’t talk too much about that name in med school.
The clinical manifestations of Tularemia may range from asymptomatic illness to septic shock and death, in part depending on the virulence of the infecting strain, portal of entry, the number of bacteria you get in your body, and how well your immune system works.
Pneumonic tularemia refers to clinical presentation-dominated lung involvement. The pneumonic disease is more common in adults but can affect any age group. Out of 190 cases in Missouri between 2000 and 2007, pneumonic disease accounted for 39% of adult cases and 24% of tularemia cases. Pneumonic and ulceroglandular tularemia were equally common in Colorado, Nebraska, South Dakota, and Wyoming during 2015, when there was a significant increase in the number of tularemia cases in these states.
The pneumonic disease can be categorized as primary or secondary, based on the route of transmission.
The primary pneumonic disease results from direct inhalation of the bacteria into the lungs. Do you know who is at a higher risk of getting this? People who work as farmers, sheep shearers, landscapers, and laboratory workers.
The initial symptoms are systemic, like fever, headache, malaise, myalgias, nausea, and appetite loss.
Then, as if that’s not bad enough, you develop more fever, chest pain, and cough with little phlegm production. Patients sometimes complain of substernal or pleuritic chest pain.
And this might be a further clue that they have a pleural effusion.
Doctor Mike Hansen, MD
Internal Medicine | Pulmonary Disease | Critical Care Medicine