Emerging zoonoses: the role of cats

The global landscape of infectious diseases is witnessing a significant surge in zoonotic infections, driven by a complex interplay of factors at the interface between humans, animals, and pathogens. Among extrinsic drivers, anthropogenic envi- ronmental changes, most notably climate change and biodiver- sity loss, play a major role in reshaping disease ecology. In the contemporary era, the distribution of mammalian biomass has faced dramatic changes: humans, livestock, and companion an- imals now constitute over 90% of the world’s total mammalian biomass, with wild mammals only accounting for less than 4%. To mitigate future health threats, public health strategies must move beyond traditional approaches and focus on the whole system involving humans, domestic species, and the remain- ing wildlife populations, reevaluating the entire disease trans- mission chain. Within this framework, the domestic cat (Felis catus) emerges as a species of significant epidemiological im- portance. Due to their millennia-long association with human civilization and their adaptability as invasive predators, cats are among the most widespread and numerous mammals on Earth. Their role in the maintenance and transmission of zoonotic dis- eases is multifaceted. Cats function not only as direct reservoirs but also as “bridge hosts,” facilitating the spread of infectious agents from wildlife reservoirs into human environments. Their role for emerging infections, even if as simple sentinels, is deep- ly influenced by their diverse lifestyles, which range from strictly indoor pets to free-roaming populations. This spectrum of be- havior ensures their proximity to humans while simultaneous- ly allowing for frequent interactions with livestock and wildlife in different settings. Cats are implicated in the transmission of several pathogens, including those with pandemic potential and antimicrobial-resistant (AMR) strains. These include viral, bac- terial, fungal, and parasitic agents transmitted through all prima- ry ecological routes, including direct contact (bites/scratches), the fecal-oral or respiratory route, and vector-borne pathways. To address the risks associated with zoonoses, this study pres- ents the results of a literature review designed to update the list of zoonotic pathogens associated with Felis catus. Several crit- ical case studies were selected for in-depth analysis, including high-impact viruses (i.e. Lyssaviruses, Orthopoxviruses, Orthoc- oronavirinae, Orthohantaviruses, Orthoflaviviruses, and Influen- za virus), bacterial infection (i.e. Bartonella spp., Leptospira spp, Borrelia spp., Francisella tularensis, and Yersinia spp.) other than parasites (i.e. Toxoplasma gondii, Echinococcus multilocu- laris). For each case study, the current epidemiological situation is discussed alongside a detailed evaluation of the cat’s specif- ic role in the pathogen’s life cycle and transmission to humans, providing a foundation for integrated “One Health” surveillance and intervention strategies.