Tularemia in a Psoriasis Patient on Biologic Therapy After Relocation to Western South Dakota.

Abstract

Background: Francisella tularensis is an aerobic, gram negative coccobacillus bacterium that causes tularemia. F. tularensis spreads primarily through ticks, biting flies, droplet inhalation, contaminated mud or water, or infected animal bites, and it can survive in animal carcasses with the most common mode of transmission occurring via inoculation into the skin and inhalation/ingestion. Individuals on biologics or immunosuppressive medications are at an increased risk for infections such as tularemia, particularly when moving geographically to regions where it is endemic.

Case description: We describe a case of tularemia presenting in a South Dakota resident. The patient, who was on long term adalimumab, presented with persistent fever, chills, fatigue, night sweats and anorexia for 6 days. The patient had recently moved from eastern South Dakota to western South Dakota onto a farm that is mostly pasture land. Chest imaging showed bilateral nodular densities, and lymph node biopsy was diagnostic for F. tularensis. A diagnosis of tularemia was made based on her biopsy results and exposure to rabbit carcasses while mowing grass on her ranch. She was started on antibiotic therapy, and her symptoms and imaging improved. She followed up with internal medicine and infectious disease clinic, and her symptoms resolved and imaging cleared with transition to ciprofloxacin in the outpatient setting; additionally, she continues to do well with no evidence of recurrence of active infection.

Conclusions: It is important that clinicians recognize the geographical dimension in infectious disease risk for immunosuppressed individuals. The patient's experience with tularemia following her relocation from eastern to western South Dakota highlights how geographic transitions can introduce new infectious exposures and risks. For patients on immunosuppressive therapies, healthcare providers must consider potential infections endemic to the new region and adopt proactive management strategies. Early recognition, targeted therapy, and adjustments in immunosuppression are critical in managing such cases effectively. This case illustrates the importance of detailed travel histories, patient education, and coordination between specialists to ensure comprehensive care and optimal outcomes for immunocompromised patients in new environments.