Detection of Borrelia in Ixodes scapularis ticks by silver stain, immunohistochemical and direct immunofluorescent methods

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

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

Identification of Hard Ticks in the United States: A Practical Guide for Clinicians and Pathologists

ABSTRACT

According to guidelines published by the Infectious Disease Society of America, Lyme disease prophylaxis is possible if a tick can be identified as Ixodes scapularis (nymphal or adult) within 72 hours of tick removal. However, a recent survey of medical practitioners indicates generally poor proficiency in tick identification. In this study, we provide a simple, practical guide to aid medical practitioners in identifying the most commonly encountered human biting ticks of North America.

Dermanyssus gallinae: the long journey of the poultry red mite to become a vector

The possibility that Dermanyssus gallinae, the poultry red mite, could act as a vector of infectious disease-causing pathogens has always intrigued researchers and worried commercial chicken farmers, as has its ubiquitous distribution. For decades, studies have been carried out which suggest that there is an association between a wide range of pathogens and D. gallinae, with the transmission of some of these pathogens mediated by D. gallinae as vector. The latter include the avian pathogenic Escherichia coli (APEC), Salmonella enterica serovars Enteritidis and Gallinarum and influenza virus. Several approaches have been adopted to investigate the relationship between D. gallinae and pathogens. In this comprehensive review, we critically describe available strategies and methods currently available for conducting trials, as well as outcomes, analyzing their possible strengths and weaknesses, with the aim to provide researchers with useful tools for correctly approach the study of the vectorial role of D. gallinae.

Cutaneous Involvement in Plasma Cell Myeloma

OBJECTIVES

Plasma cell myeloma (PCM) involving skin is rare and occurs in 1% to 4% of patients with PCM. We evaluated the clinicopathologic features, cytogenetic findings and clinical follow-up in a series of PCM cases with cutaneous involvement.

METHODS

Cases of PCM with cutaneous involvement were retrospectively reviewed with clinical data.

RESULTS

Skin involvement in PCM occurred in older individuals (mean, 75 years) and was more frequent in men (7/10 patients). All cases showed bone marrow involvement preceding the cutaneous lesions. Histopathologically, the infiltrate was plasmacytic (n = 5) or primitive or plasmablastic (n = 4), and 1 case showed predominantly lymphoplasmacytic features with cyclin D1 immunoreactivity and CCND1 gene rearrangement. Concurrent amyloid deposition was seen in one biopsy, and another case demonstrated coexisting squamous cell carcinoma. The most common immunophenotype was CD138+, CD20-, and CD56+ with light chain restriction. Cytogenetic analysis (available for 7 cases) showed multiple hyperdiploid abnormalities. Follow-up was available for 8 cases (mean, 42 months; range, 11-156 months) and showed short-term disease-related death in 7 of 8 patients.

CONCLUSIONS

Cutaneous involvement in PCM demonstrates a diverse cytomorphologic spectrum with plasmacytic, plasmablastic, or lymphoplasmacytic features and may show concurrent amyloid deposition or neoplasms such as squamous cell carcinoma. Cutaneous involvement typically occurs late in the course of the disease and likely portends poor outcome.