Histological staining of tick bite skin biopsies for spirochetes and Powassan virus RNA

• DOI: 10.1128/spectrum.00902-24
• Publication Date: 2025-01-10T14:50:52Z
• Authors: Jihane Oufattole; Anne Piantadosi; Sam R. Telford; Alvaro C. Laga; Isaac H. Solomon
• Keywords: immunohistochemistry; Lyme disease; tick-borne infection; in situ hybridization; Microbiology; QR1-502; Powassan virus; Research Article

ABSTRACT Ixodes scapularis is a vector of several human pathogens in the United States, including Borrelia burgdorferi, cause Lyme disease, and Powassan virus (POWV), an emerging severe encephalitis. Skin biopsies from tick bite sites are frequently collected tested for presence spirochetes ( spp.), which remain elusive. POWV testing not performed despite increasing incidence To determine utility staining skin tick-borne pathogens, formalin-fixed paraffin-embedded specimens 2010 to 2023 were examined by hematoxylin eosin, Warthin–Starry stain, spirochete immunohistochemistry, situ hybridization (ISH). These assays optimized histological sections whole ticks, detected two out 14 patient-derived specimens, RNA was multiple experimentally infected ticks. None 36 positive spirochetes, 20 with retained mouth parts six patients serology. ISH negative all biopsies, one laboratory confirmed case. Combining ticks n = 50), only 1/5 (20%) suspected erythema chronicum migrans (ECM). Although limited, our data suggest poor correlation between ECM detection findings concordance published literature. Similarly, absence detectable any or case, limited clinical use without further analysis larger sample size. IMPORTANCE Tick-borne infections, encephalitis, significant morbidity mortality challenging diagnose study humans. We bites look direct evidence microbes histochemical, immunohistochemical, stains. validate these assays, we also same stains on virus. Examination using similar tools may prove valuable studying pathogenesis diseases, such as southern tick-associated rash illness, causative pathogen has yet been identified.