# Turning urban wildlife mortality into a surveillance tool: Detection of vector-borne pathogens in carcasses of hedgehogs, squirrels, and blackbirds

## TL;DR

This study shows that dead urban animals like hedgehogs and squirrels can help track tick-borne diseases, offering a new way to monitor public health risks.

## Contribution

The study introduces urban wildlife carcasses as a practical and overlooked resource for surveillance of tick-borne pathogens.

## Key findings

- Carcasses of urban wildlife provide reliable biological material for detecting tick-borne pathogens.
- Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Bartonella spp., and Rickettsia helvetica were the most prevalent pathogens detected.
- Ear and skin tissues are the most effective for pathogen detection, and multi-tissue sampling increases detection rates.

## Abstract

Tick-borne zoonoses pose a major challenge to human and animal health, driving efforts to monitor the distribution, intensity, and diversity of their causative agents. Within the One Health framework, which links human, animal, and environmental health, integrated surveillance strategies are increasingly needed. However, most studies focus on tick vectors, while vertebrate reservoirs are often overlooked due to labour-intensive sampling, the need for specialized skills, and legislative or species protection constraints.

This study evaluated whether carcasses of accidentally killed wildlife (primarily roadkill) can serve as a source of biological material for vector-borne pathogen surveillance, with a focus on urban habitats due to their public health relevance. Hedgehogs, squirrels, and blackbirds were selected as synanthropic species that thrive in cities, are commonly infested by ticks, and act as hosts for zoonotic tick-borne pathogens (TBPs).

A total of 268 carcasses (125 hedgehogs, 55 squirrels, and 88 blackbirds) were collected across multiple Czech cities with public assistance. Overall, 1836 tissue samples were analyzed using multiplex real-time PCR assays targeting over ten microorganisms. Detection efficiency was compared across tissues, with ear and skin consistently the most reliable and versatile sample types. Individual pathogen-host-tissue combinations reached 65–93% efficiency, highlighting the value of multi-tissue sampling. The most prevalent TBPs detected were Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Bartonella spp., and Rickettsia helvetica.

In conclusion, carcasses of accidentally killed urban wildlife provide a practical and valuable resource for TBP surveillance, complementing vector-focused methods. This approach supports One Health principles by integrating wildlife monitoring into urban disease surveillance efforts.

•Urban wildlife carcasses enable host-based surveillance of tick-borne pathogens.•Hedgehogs, squirrels, and blackbirds serve as sentinels for urban TBPs circulation.•Anaplasma, Borrelia, Bartonella, and Rickettsia were the most prevalent pathogens.•Ear and skin tissues are most reliable; multi-tissue sampling boosts detection.•Pathogen detection is robust across cadaver autolysis grades, supporting surveillance.

Urban wildlife carcasses enable host-based surveillance of tick-borne pathogens.

Hedgehogs, squirrels, and blackbirds serve as sentinels for urban TBPs circulation.

Anaplasma, Borrelia, Bartonella, and Rickettsia were the most prevalent pathogens.

Ear and skin tissues are most reliable; multi-tissue sampling boosts detection.

Pathogen detection is robust across cadaver autolysis grades, supporting surveillance.