Climate-sensitive zoonotic diseases transmissible by companion animals: A scoping review protocol

PLOS One | https://doi.org/10.1371/journal.pone.0325568 June 10, 2025 2 / 8 will be collated and presented as a descriptive summary using graphical and tabular formats. Review registration Two separate protocols have been registered in Open Science Framework. The first review consolidates evidence in cat and dog populations (https://osf.io/ydgc2), while the second review is focused on human populations (https://osf.io/3cvx2). Introduction Zoonotic diseases are characterized by their ability to be transmitted between ani- mals and people, caused by pathogens that can infect both animals and humans [1]. Zoonotic pathogens are found across all major taxonomic groups, including fungi, helminths, protists, viruses, and bacteria [2]. Similar to other infectious pathogens, zoonotic pathogens can be climate-sensitive, and some may be more sensitive to climate than animal- or human-only diseases [2]. Climate-sensitive pathogens and diseases are characterized by their susceptibility to fluctuations in temperature, precipitation, and extreme weather events. Changes in temperature and precipitation can alter the distribution of disease vectors and reservoirs, while all three factors can further alter migration and mobility patterns [3–6]. Through these mechanisms, cli- mate change has enabled certain zoonotic pathogens to emerge in new geographic areas or re-emerge in previously established areas, increasing the risk of disease [7–9]. Climate change is expected to increase the risk of zoonotic diseases via

changes in temperature, precipitation patterns, extreme weather events, and other meteorological factors [2,7,8,10]. The impacts of climate change on various zoonotic diseases can be seen globally, across all taxonomic groups of pathogens, and multiple species including wildlife, domestic animals, and humans [2,10,11]. Examples of climate-sensitive zoonotic dis- eases include Lyme disease [7], leishmaniasis [12,13], rabies [14], leptospirosis [15], and anthrax [16]. Companion animals, restricted to cats (i.e., Felis catus) and dogs (i.e., Canis familiaris) for the purpose of this protocol, may act as sentinels for some zoonotic diseases. Their shared living environment with human owners, interactions with wildlife, and free-roaming nature in many areas worldwide underscores the poten- tial for zoonotic transmission between companion animals and humans [11,17,18]. Companion animals remain an overlooked source of zoonotic diseases, with over 70 pathogens capable of infecting humans [1]. National surveys reveal that approx- imately 46% and 26% of households in the United States own at least one dog or cat, respectively [19], with similar estimates observed in Canadian households [20]. These statistics indicate an inherent risk of zoonotic disease via companion animals, posing an important health concern. Despite the ability of companion animals to transmit pathogens to humans, they have received limited attention in the context of climate change. At present, our under- standing of climate-sensitive zoonotic diseases that are transmissible by companion

and reproduction in any medium, provided the original author and source are credited. Data availability statement: No datasets were generated or analysed during the current study. All relevant data from this study will be made available upon study completion. Funding: This work is supported by a grant to LEG from the Public Health Agency of Canada Infectious Disease and Climate Change Fund Program (2324-HQ-000026) (https://www. canada.ca/en/public-health.html). The funder played no role in study design, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist.