Norway rat (Rattus norvegicus) ectoparasites in livestock production systems from central Argentina: Influencing factors on parasitism

Haematophagous ectoparasites are worldwide vectors of many zoonotic bacterial diseases, both emerging andre-emerging, whose incidences are rising. Livestock development alters different environmental characteristicssuch as the microclimate of a site, changing the availability, density and susceptibility of the hosts to pathogensand vectors, indirectly influencing the spread and persistence of a disease within an ecosystem. The Norway rat(Rattus norvegicus), the most abundant vertebrate pest species found on livestock farms from Argentina, is areservoir for several important zoonotic bacteria and may harbor ectoparasite species, which act as their vectors.Even though the Norway rat is widely known for its role as an ectoparasite host, the ecological characteristics oftheir ectoparasite communities and the related factors with parasitism on livestock farms have never been de-scribed. In the present study, we describe the ectoparasite community in Norway rats from central Argentinalivestock farms, while also depicting the influencing factors on both ectoparasite occurrence and abundance.Ectoparasites were collected from rats captured in 20 sites from Buenos Aires province, between the winter of2016 and the summer of 2018. A total of 1441 ectoparasite individuals were collected from 159 Norway ratindividuals  [Total  ectoparasite  prevalence  =  69.2%;  Mean  ectoparasite  specimen  abundance( ± CI)  =  9.06 ± 2.32  ectoparasite  individuals  per  rat;  Mean  ectoparasite  specimen  intensity( ± CI) = 13.10 ± 3.08 ectoparasite individuals per infested rat found]. Ectoparasite assemblage consisted offour cosmopolitan species, recognized for their sanitary relevance: mites (Laelapidae:Laelaps nuttalliandLaelapsechidninus), lice (Polyplacidae:Polyplax spinulosa) andfleas (Pulicidae:Xenopsylla cheopis). We observed higherNorway rat abundance in sites related to higher ectoparasite occurrence and abundance frequencies on the rats.Additionally, ectoparasites were more abundant on rats in warm seasons and on male individuals, over femalerats. Moreover, the geographical location of the studied sites influenced the ectoparasite assemblage structureobserved on the rats. This study broadens the knowledge on the role of Norway rats as zoonotic ectoparasiteshosts and analyzes the drivers influencing ectoparasite occurrence and abundance on the most populated regionof Argentina, which is also the region with the most intensive livestock farming. Therefore, this survey may assistin evaluating potential risks for humans and generate effective sanitary control strategies for ectoparasite-borneinfectious diseases