Abstract
Rattus norvegicus, the brown or Norway rat, is the most abundant mammal after humans in urban areas, where they live in close proximity to people. Among rodent-borne diseases, the reservoir role of Norway rats of zoonotic parasites in cities has practically been ignored. Considering the parasitic diseases in the One Health approach, we intended to identify and quantify the zoonotic intestinal protozoans (ZIP) in an urban population of R. norvegicus in the city of Barcelona, Spain. We studied the presence of ZIP in 100 rats trapped in parks (n = 15) as well as in the city’s sewage system (n = 85) in the winter of 2016/17. The protozoans were molecularly identified by means of a multiplex PCR (AllplexTM Gastrointestinal Panel-Parasite Assay). We also investigated the presence of co-infections among the species found. Four ZIP were identified, presenting significant prevalences in sewers, specifically Blastocystis (83.5%), Giardia duodenalis (37.7%), Cryptosporidium spp. (34.1%), and Dientamoeba fragilis (14.1%). Several co-infections among the detected ZIP were also detected. The reservoir role of ZIP that Norway rats play in cities as well as the role rats may play as sentinels of zoonotic parasites affecting humans in urban areas are strongly backed up by our findings. The increasing worldwide urbanization, climate change, and the COVID-19 pandemic are factors that are producing an increase in human–rat interactions. Our results should be considered a warning to the authorities to intensify rat control and surveillance in public health interventions.
Highlights
Rats captured in the sewage system did have a higher overall zoonotic intestinal protozoans (ZIP) prevalence than those captured in parks
This study reveals by molecular methods, and for the first time, significant Blastocystis, Giardia duodenalis, Cryptosporidium spp., and D. fragilis prevalences, as well as the occurrence of multiple ZIP co-infections in a population of R. norvegicus in an urban environment
R. norvegicus should be considered an effective reservoir of ZIP in urban areas for the following reasons: (i) its population in cities is the largest after that of humans; (ii) in absence of competitors or predators rats live longer in cities than in the wild; (iii) the high ZIP prevalences found, in rats from sewers; (iv) Norway rats in cities live in proximity to humans resulting in close interaction; (v) large rat populations live in sewers in close contact with human fecal disposal containing infective parasite forms; (vi) it is not possible to control the environmental contamination by rat feces; and (vii) a proper management of rat fecal waste is unfeasible
Summary
Rodents are hosts of a wide range of zoonotic pathogens. Zoonotic diseases can be transmitted to humans either directly, i.e., the infective agent contaminates the environment and, humans may become infected due to contaminated hands, food, water, or indirectly through the intervention of an arthropod vector that has become infected directly by the rodent. Among the diseases transmitted by rodents, those caused by bacteria or viruses tend to receive more attention than those caused by parasites The role of rodents as potential reservoirs of zoonotic parasites in rural or wild areas is well known. These can either be protozoans (Entamoeba histolytica, Giardia duodenalis, 4.0/)
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