Zoonotic bacteria and vector-borne protozoa in troglophilus bat colonies in Sicily (southern Italy): a biomolecular survey

Bats, belonging to the order Chiroptera, play a significant ecological role, occupying a high position in the food chain and are specialized in using different types of habitats. Bats, like other taxa, can also act as natural reservoirs and carriers of numerous zoonotic bacteria and viruses, often remaining immune to the pathogens they harbor. Human-bat interactions can be frequent in some geographical areas, primarily driven by anthropogenic modifications to their habitats, leading bats to seek alternative roosting sites even though interaction with other animals is not direct due to the different niches frequented. Understanding the pathogens harbored by bats can be important for public health, given the potential risks associated with such interactions. This study aimed to investigate the presence of potential zoonotic pathogens across different anatomical niches of insectivorous troglophilus bat colonies in some caves within the Ragusa and Syracuse provinces of Sicily, Italy. A comprehensive panel of biomolecular tests targeting bacterial and parasitic zoonotic agents, including Bartonella henselae, Borrelia spp.,Coxiella burnetii, Leptospira spp., Chlamydia spp., Rickettsia spp., Anaplasma phagocythopilum, and Babesia spp., was employed. Samples collected between 2020 and 2023 encompassed oral swabs, oculoconjunctival swabs, urine, feces, guano, and ectoparasites from 149 individuals belonging to six species. Zoonotic bacteria, particularly Bartonella henselae, Leptospira spp. and Chlamydia spp., were identified in the examined samples. Analysis revealed notable positivity for Bartonella henselae in three oral swabs and one oculoconjunctival swab, as well as for Leptospira in one oral swab. Notably, Bartonella henselae, typically associated with arthropod vectors and droppings, was found in saliva, indicating an alternative potential transmission route through biting and grooming behaviors within bat populations. Chlamydia spp. was detected in multiple samples, including four urine samples, one fecal sample, one guano sample, one oral swab, and one oculoconjunctival swab. The simultaneous detection of Chlamydia in multiple body habitats within the same individual suggests potential acute infection. Conversely, Borrelia spp., Coxiella burnetii, Rickettsia spp., and Anaplasma phagocytophilum were not detected in any samples. Furthermore, 10 feces sample and 5 bat ectoparasites were positive for Babesia spp. The positivity found in the fecal samples could result from either the ingestion of vector insects or from the infection of the bats. In conclusion, this study offers valuable insights into the range of pathogens excreted within throglophile bat communities. It highlights the potential of bats as reservoirs for bacteria and vector-borne protozoa, stressing the importance of various anatomical samples, such as saliva, ocular secretions, and urine, in evaluating their role as vectors of zoonotic infectious agents. These findings enhance our comprehension of bat-related zoonoses and guide public health strategies aimed at reducing risks linked to human-bat interactions. Further research is necessary to clarify the dynamics of zoonotic pathogen transmission within bat populations and their implications for disease prevention and control measures.