CS#13

You work in a small family practice in rural Virginia, (much better than Texas!). A man in his early 50s comes in with a complaint of intermittent fever (102-103 F) and headache for the past two weeks. The physician examines him and takes a history. The only clinical finding is a wound about the size of a quarter on his right thumb. Axillary lymph nodes are swollen and tender. The man says he cut himself while skinning a rabbit three days ago. On the basis of these observations the physician prescribes streptomycin and asks the man to call if his symptoms don’t improve in three days.

The physician asks you to draw blood and tells the patient he should return in four weeks for another blood sample. She says there is no need to culture the wound.

1. On the basis of the limited information above, the physician has obviously made a diagnosis. What is it? What does the causative organism look like when gram stained?
2. What is the most likely reservoir for the causative organism in this case?
3. Why draw blood twice?
4. Why not culture the wound to look for the bacterium?
5. What are four other common infections that humans acquire from animals?

1. Based on the limited information the physician’s diagnosis is Tularemia. Humans can acquire this illness through getting a bite from an infected (blood-sucking)tick, horsefly, or mosquito, inhaling infected dirt or plant material, eating infected meat which is very rare, but in this case with the information given about the patients etiology the most likely way that the man acquired this illness is through direct physical contact through the cut in his skin with the infected rabbit (other animals that this illness can be acquired from in this way most often include muskrat, beaver, or squirrel).The incubation period is usually 3-5 days after coming in contact with the bacterium. The