Case Presentation: A 69 year old man presented with a two week history of high fevers and malaise after a spider bite behind his knee two weeks prior to admission. He also reported nausea, diarrhea, and crippling fatigue. His primary care doctor prescribed a course of amoxicillin-clavulanate but this had not helped. He lived in a wooded area on the Eastern Shore of Virginia and “did a lot of gardening.” He had a cat and had recently been in contact with dead rodents. Initial physical examination was significant for an ill appearing man with a temperature of 39.30 C and relative bradycardia. Skin examination revealed a 2.5 cm non-draining necrotic eschar in the right popliteal fossa and a tender 2 cm right inguinal lymph node. Blood cultures were drawn along with serologies for Rickettsia rickettsii, Francisella tularensis, Ehrlichiosis, Anaplasmosis, Coxiella burnetii, Lyme disease, typhus, and Bartonella henselae. He was started on a multidrug regimen including vancomycin, piperacillin-tazobactam, ciprofloxacin, and doxycycline in order to cover Staphylococcus aureus, Pseudomonas aeruginosa, and tick-borne infections in addition to tularemia. Rapid clinical improvement was noted over 24 hours and the regimen was narrowed to doxycycline and ciprofloxacin. Francisella tularensis IgG was positive with a titer of 1:640, confirming the diagnosis of ulceroglandular tularemia.

Discussion: Tularemia is a rare, highly virulent zoonotic disease caused by gram-negative bacterium Francisella tularensis. It is transmitted commonly through arthropods such as ticks and deer flies, as well as vertebrates such as rabbits. Though still quite rare, ulceroglandular disease is the most common form, frequently caused by tick or deerfly bites. Other forms of disease depend on the mode of acquisition, and include typhoidal, pneumonic, oculoglandular, glandular, and pharyngeal. A detailed social history is imperative as the diagnosis requires a high index of suspicion given its rarity. Frequently, patients attribute the classic eschar of ulceroglandular disease to a spider bite, however these bites are uncommon and rarely cause systemic symptoms. Unless a spider is seen, physicians should pursue other diagnoses. Additionally, many providers associate tularemia only with rabbit exposure, which is a common mistake and may lead to a delay in diagnosis. Since the decline in tularemia after the 1960’s, the most common mode of transmission in North America is through tick bites, specifically the dog tick (Dermacentor variabilis), wood tick (Dermacentor andersoni), and lone star tick (Amblyomma americanum).

Conclusions: Tularemia is a rare zoonotic disease which requires a high degree of suspicion for diagnosis. Detailed history can often lead to the diagnosis. Rabbit exposure is not the only hint in history as tick/insect bites are the most common mode of transmission.