A Wild Rabbit Chase: When Tularemia Hops into the Differential
College
College of Health Sciences
Presentation Type
Oral Presentation
Abstract
Case Presentation
A 43-year-old previously healthy male presented to the ED for four days of a painful skin lesion, which he had attributed to a suspected spider bite. He reported associated chills, myalgias, and headaches. The wound was cultured, and he was discharged on empiric cephalexin and trimethoprim-sulfamethoxazole. Five days later he returned to the ED with progressive symptoms, including high fevers, shortness of breath, nausea with emesis, diarrhea, blurry vision, and visual hallucinations. His exam was significant for an eschar at the left lower chest with surrounding erythema and pustules. Labs revealed neutrophilic leukocytosis, elevated transaminases, and hyponatremia. He was admitted for broad-spectrum antibiotics and additional work-up. Further testing including CT head, lumbar puncture, and routine blood cultures were negative. A CT chest revealed multiple pulmonary nodules concerning multifocal infection or septic emboli. A TTE did not show any valvular pathology or vegetations. A punch biopsy of the eschar showed epidermal ulceration, a dense dermal inflammatory infiltrate, and peri-eccrine inflammation, suggestive a spider bite. He improved and was discharged home on a short course of amoxicillin/clavulanic acid and doxycycline. His initial wound culture was ultimately sent to the state health department for further identification, and Francisella tularensis was diagnosed via PCR. The F. tularensis IgG drawn during his hospitalization also returned positive. Although he still had some residual symptoms, he declined re-admission for aminoglycoside therapy and was started on 10-day course of ciprofloxacin with near symptom resolution and interval reduction of pulmonary nodules on follow up CT chest.
Discussion
Tularemia may develop after the bite of an infected insect, such as a tick or deerfly. Individuals typically develop symptoms three to five days after a bite. Domestic animals, including dogs, can sometimes play a role in transmitting the pathogen to humans. Tularemia presents in six major clinical forms: glandular, ulceroglandular, oculoglandular, typhoidal, pneumonic, and oropharyngeal. Symptoms may be nonspecific, and patients may infrequently display features of several forms. Severe disease can occur in healthy, young adults and is not restricted to those with weakened immune systems or preexisting health conditions Approximately 200 cases of tularemia are reported annually in the United States, with the highest incidence in the southern and central states. In 2023, only two cases were reported in Virginia. Microbiology lab members should be alerted immediately with any concerns for tularemia due to the need for special culture media and biosafety precautions. Aminoglycosides remain gold standard therapy, though doxycycline or a fluoroquinolone may be prescribed for mild-moderate infections. This patient’s partial response to doxycycline may be attributed to the higher rates of treatment failure and relapse associated with doxycycline compared to fluoroquinolones in the treatment of tularemia. Tularemia is uncommon in the Southeast US, and disseminated tularemia with primary skin lesions is rare. A high index of suspicion and a careful review of exposure history are essential for more rapid diagnosis and appropriate treatment.
Keywords
Infectious disease
A Wild Rabbit Chase: When Tularemia Hops into the Differential
Case Presentation
A 43-year-old previously healthy male presented to the ED for four days of a painful skin lesion, which he had attributed to a suspected spider bite. He reported associated chills, myalgias, and headaches. The wound was cultured, and he was discharged on empiric cephalexin and trimethoprim-sulfamethoxazole. Five days later he returned to the ED with progressive symptoms, including high fevers, shortness of breath, nausea with emesis, diarrhea, blurry vision, and visual hallucinations. His exam was significant for an eschar at the left lower chest with surrounding erythema and pustules. Labs revealed neutrophilic leukocytosis, elevated transaminases, and hyponatremia. He was admitted for broad-spectrum antibiotics and additional work-up. Further testing including CT head, lumbar puncture, and routine blood cultures were negative. A CT chest revealed multiple pulmonary nodules concerning multifocal infection or septic emboli. A TTE did not show any valvular pathology or vegetations. A punch biopsy of the eschar showed epidermal ulceration, a dense dermal inflammatory infiltrate, and peri-eccrine inflammation, suggestive a spider bite. He improved and was discharged home on a short course of amoxicillin/clavulanic acid and doxycycline. His initial wound culture was ultimately sent to the state health department for further identification, and Francisella tularensis was diagnosed via PCR. The F. tularensis IgG drawn during his hospitalization also returned positive. Although he still had some residual symptoms, he declined re-admission for aminoglycoside therapy and was started on 10-day course of ciprofloxacin with near symptom resolution and interval reduction of pulmonary nodules on follow up CT chest.
Discussion
Tularemia may develop after the bite of an infected insect, such as a tick or deerfly. Individuals typically develop symptoms three to five days after a bite. Domestic animals, including dogs, can sometimes play a role in transmitting the pathogen to humans. Tularemia presents in six major clinical forms: glandular, ulceroglandular, oculoglandular, typhoidal, pneumonic, and oropharyngeal. Symptoms may be nonspecific, and patients may infrequently display features of several forms. Severe disease can occur in healthy, young adults and is not restricted to those with weakened immune systems or preexisting health conditions Approximately 200 cases of tularemia are reported annually in the United States, with the highest incidence in the southern and central states. In 2023, only two cases were reported in Virginia. Microbiology lab members should be alerted immediately with any concerns for tularemia due to the need for special culture media and biosafety precautions. Aminoglycosides remain gold standard therapy, though doxycycline or a fluoroquinolone may be prescribed for mild-moderate infections. This patient’s partial response to doxycycline may be attributed to the higher rates of treatment failure and relapse associated with doxycycline compared to fluoroquinolones in the treatment of tularemia. Tularemia is uncommon in the Southeast US, and disseminated tularemia with primary skin lesions is rare. A high index of suspicion and a careful review of exposure history are essential for more rapid diagnosis and appropriate treatment.