Sewer-associated rodents in countries with lower human development, a time-bomb for zoonoses?

Sewer-associated rodents inhabiting urban and peri-urban areas constitute a potential infection source for many zoonotic pathogens at a global scale. However, there is a lack of scientific information about the implications of these micromammals in regions with fragile sanitary services, low economic resources and weak educational systems. Consequently, this study aimed to review the scientific knowledge about rodent-borne zoonoses in sewer-related environments from countries with lower Human Development Index (HDI). Our results revealed a low number of publications (n = 13) evaluating the epidemiology of sewer-associated rodents in countries with lower HDI, which were distributed across Central/South America (69.2 %; 9/13), Africa (23.1 %; 3/13) and Asia (7.7 %; 1/13). The most evaluated rodents were Rattus norvegicus -brown rat- (present in 10/13 articles), followed by Rattus rattus -black rat- (6/13) and Mus musculus -house mouse- (5/13). Fourteen zoonotic pathogens were assessed, specifically bacteria (n = 6 publications) and parasites (n = 7), with the highest prevalence described for Bartonella spp. (85.0 %), Calodium hepaticum (83.8 %), Rickettsia spp. (75.0 %), Leptospira spp. (68.0 %) and Hymenolepis nana (60.0 %). Most reviewed publications described the use of molecular methods and direct examination of samples to identify the pathogens studied (46.2 %; 6/13 each), followed by the MALDI-TOF technique (15.4 %; 2/13). The four clusters building the semantic network reinforced the pivotal role of sewer-associated rodents as reservoirs of both vector-borne pathogens and directly transmitted zoonoses. Our findings evidence a severe gap of knowledge in lower-resource areas about the role of sewer-associated rodents in the epidemiology of zoonotic diseases, which could impact on the sanitary system of not only the evaluated countries, but also in other developed and non-developed regions worldwide.