Comparison of acarological risk metrics derived from active and passive surveillance and their concordance with tick-borne disease incidence

Tick-borne diseases continue to threaten human health across the United States. Both active and passive tick surveillance can complement human case surveillance, providing spatio-temporal information on when and where humans are at risk for encounters with ticks and tick-borne pathogens. However, little work has been done to assess the concordance of the acarological risk metrics from each surveillance method. We used data on Ixodes scapularis and its associated human pathogens from Connecticut (2019-2021) collected through active collections (drag sampling) or passive submissions from the public to compare county estimates of tick and pathogen presence, infection prevalence, and tick abundance by life stage. Between the surveillance strategies, we found complete agreement in estimates of tick and pathogen presence, high concordance in infection prevalence estimates for Anaplasma phagocytophilum, Borrelia burgdorferi sensu stricto, and Babesia microti, but no consistent relationships between actively and passively derived estimates of tick abundance or abundance of infected ticks by life stage. We also compared nymphal metrics (i.e., pathogen prevalence in nymphs, nymphal abundance, and abundance of infected nymphs) with reported incidence of Lyme disease, anaplasmosis, and babesiosis, but did not find any consistent relationships with any of these metrics. The small spatial and temporal scale for which we had consistently collected active and passive data limited our ability to find significant relationships. Findings are likely to differ if examined across a broader spatial or temporal coverage with greater variation in acarological and epidemiological outcomes. Our results indicate similar outcomes between some actively and passively derived tick surveillance metrics (tick and pathogen presence, pathogen prevalence), but comparisons were variable for abundance estimates.

Survey of white-footed mice in Connecticut, USA reveals low SARS-CoV-2 seroprevalence and infection with divergent betacoronaviruses

Diverse mammalian species display susceptibility to and infection with SARS-CoV-2. Potential SARS-CoV-2 spillback into rodents is understudied despite their host role for numerous zoonoses and human proximity. We assessed exposure and infection among white-footed mice (Peromyscus leucopus) in Connecticut, USA. We observed 1% (6/540) wild-type neutralizing antibody seroprevalence among 2020-2022 residential mice with no cross-neutralization of variants. We detected no SARS-CoV-2 infections via RT-qPCR, but identified non-SARS-CoV-2 betacoronavirus infections via pan-coronavirus PCR among 1% (5/468) of residential mice. Sequencing revealed two divergent betacoronaviruses, preliminarily named Peromyscus coronavirus-1 and -2. Both belong to the Betacoronavirus 1 species and are ~90% identical to the closest known relative, Porcine hemagglutinating encephalomyelitis virus. Low SARS-CoV-2 seroprevalence suggests white-footed mice may not be sufficiently susceptible or exposed to SARS-CoV-2 to present a long-term human health risk. However, the discovery of divergent, non-SARS-CoV-2 betacoronaviruses expands the diversity of known rodent coronaviruses and further investigation is required to understand their transmission extent.

An in vitro comparison of venom recovery methods and results on the box jellyfish, Chironex fleckeri

The emergence of novel venom extraction techniques over the last half-century has greatly facilitated advances in the field of cnidarian research. A new recovery protocol utilizing ethanol as the primary stimulant in nematocyst discharge was recently published, however in vitro examination of the venom on organic models was not performed. This present study reports an original comparison of the chemically-induced discharge technique in vitro with a commonly used saltwater extraction method. Size-exclusion chromatography revealed distinct differences in venom profiles between the two methods: the saltwater recovery method FPLC profile and SDS-PAGE gel were similar to previously published results, whereas the ethanol-induced method was not. SDS-PAGE gel revealed distinct 40-55 kDa bands of previously identified cardiotoxic proteins recovered from the saltwater method, whereas the ethanol-induced method yielded degraded venom protein bands. A concentration-response curve generated through xCELLigence Real-Time Cell Analysis (RTCA) revealed a dramatic decrease in human cardiomyocyte activity when venom recovered via saltwater discharge was applied to these cells. With the exception of one sample, all ethanol-induced recovered venom failed to prompt a concentration-dependent decrease in cell survival when applied to human cardiomyocytes, resulting in a significant difference in IC50 concentrations between the compared venom samples. The data presented here facilitates an improved understanding of the parameters and analyses that are essential when developing and utilizing novel techniques for future cnidarian venom extraction research and supports the conclusion that recovery of venom from the tentacles of the box jellyfish Chironex fleckeri by ethanol is not an effective, efficient, or comprehensive extraction method compared to the published method of saltwater degradation of tentacles and bead mill extraction.