# Molecular Detection of Bartonella henselae in Healthy Cats from Portugal (2015–2025): One Health Context and Implications for Transfusion Medicine

## TL;DR

This study found that 17.4% of healthy cats in Portugal carry Bartonella henselae, a zoonotic bacterium, highlighting its endemic presence and implications for cat blood donation safety.

## Contribution

The study provides the first comprehensive molecular epidemiological data on B. henselae in Portuguese cats over an 11-year period.

## Key findings

- B. henselae was detected in 17.4% of healthy cats in Portugal.
- Infection was more common in younger cats but not linked to sex or breed.
- The bacterium is endemic in Portugal at levels similar to other European regions.

## Abstract

Bartonella henselae is a flea-borne zoonotic bacterium for which domestic cats constitute the principal reservoir. However, contemporary molecular epidemiological data from Portugal remain scarce. This retrospective laboratory study analysed EDTA-stabilised blood samples from apparently healthy cats submitted for routine screening by 74 veterinary centres across mainland Portugal and autonomous regions over an 11-year period (2015–2025). DNA extracts were tested using a species-specific TaqMan qPCR assay for B. henselae with an internal extraction control, and a subset of samples was subsequently confirmed by nested PCR followed by Sanger sequencing (ribC). Among 270 cats, 47 tested positive, yielding a qPCR prevalence of 17.4% (95% confidence interval [CI] 13.1–22.5). Submissions were predominantly from Northern Portugal, and infection status was not statistically associated with the Nomenclature of Territorial Units for Statistics (NUTS) level 2 region (p = 0.478). Infection was more frequent in younger cats (median age 2 years, interquartile range [IQR] 1–5; p = 0.037), while sex (p = 0.103) and breed (p = 0.730) were not significantly associated with infection status. These findings support endemic circulation of B. henselae in Portuguese cats at levels comparable to other temperate European regions. The detection of subclinical infection in apparently healthy cats is relevant to transfusion medicine and supports the inclusion of B. henselae qPCR screening in donor selection protocols.