Evidence Hub

Decoding the Unexpected: How Cell-Free DNA Sequencing Unveiled an Elusive Tularemia Case

Watson JR, Syed RR, Salazar VM, Dahdouh G, Bursalyan J, English A, Ponce-Sanchez H, Urrutia F et al.

The Permanente journal, 2025

Abstract

Typhoidal tularemia is a rare form of Francisella tularensis infection with nonspecific systemic symptoms that pose diagnostic challenges. Microbial cell-free DNA (mcfDNA) sequencing offers promise for detecting difficult-to-diagnose pathogens, including tularemia. An 80-year-old woman presented with fever and acute encephalopathy, with in-hospital evaluation unrevealing of an identifiable source or pathogen. She was discharged with clinical improvement on empiric levofloxacin. Following her hospitalization, mcfDNA sequencing results detected Francisella tularensis, leading to diagnosis of typhoidal tularemia. This case demonstrated mcfDNA's utility for diagnosing rare zoonotic infections that would likely remain undiagnosed using conventional methods. The authors propose molecular testing should be considered for updated tularemia case definitions for public health surveillance. Clinicians should maintain suspicion for zoonotic diseases in patients with undifferentiated fever in California.

How strong is the evidence?

Evidence Hub reads this as a case report, done in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

Read the paper

Related studies

Go deeper in Evidence Hub

Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.

Open this study Sign up free