Intrinsic and extrinsic factors related to pathogen infection in wild small mammals in intensive milk cattle and swine production systems

Abstract

BackgroundUnderstanding the ecological processes that are involved in the transmission of zoonotic pathogens by small mammals may aid adequate and effective management measures. Few attempts have been made to analyze the ecological aspects that influence pathogen infection in small mammals in livestock production systems. We describe the infection of small mammals with Leptospira spp., Brucella spp., Trichinella spp. and Cysticercus fasciolaris and assess the related intrinsic and extrinsic factors in livestock production systems in central Argentina at the small mammal community, population and individual levels.Methodology/Principal findingsTen pig farms and eight dairy farms were studied by removal trapping of small mammals from 2008 to 2011. Each farm was sampled seasonally over the course of one year with cage and Sherman live traps. The 505 small mammals captured (14,359 trap-nights) included three introduced murine rodents, four native rodents and two opossums. Leptospira spp., anti-Brucella spp. antibodies and Trichinella spp. were found in the three murine rodents and both opossums. Rattus norvegicus was also infected with C. fasciolaris; Akodon azarae and Oligoryzomys flavescens with Leptospira spp.; anti-Brucella spp. antibodies were found in A. azarae. Two or more pathogens occurred simultaneously on 89% of the farms, and each pathogen was found on at least 50% of the farms. Pathogen infections increased with host abundance. Infection by Leptospira spp. also increased with precipitation and during warm seasons. The occurrence of anti-Brucella spp. antibodies was higher on dairy farms and during the winter and summer. The host abundances limit values, from which farms are expected to be free of the studied pathogens, are reported.Conclusions/SignificanceMurine rodents maintain pathogens within farms, whereas other native species are likely dispersing pathogens among farms. Hence, we recommend preventing and controlling murines in farm dwellings and isolating farms from their surroundings to avoid contact with other wild mammals.

PathogenicLeptospiraspecies are widely disseminated among small mammals in Atlantic Forest biome

“…Nevertheless, some reports indicate lower rates of carriers, mainly those conducted on temperate biomes. In Chile, 4.4% of wild rodents were positive (Correa et al., ) and from small mammals in Argentina, 13.4% (Lovera et al., ). Similarly, in small mammals from Germany a positivity rate of 13.3% was observed (Fischer et al., ).…”

“…In a recent review, Vieira, Pinto, and Lilenbaum () highlighted the need to understand the role of wildlife on the epidemiology of leptospirosis and its impact on livestock and public health, especially regarding direct detection and molecular characterization of the agent. It has increasingly been conducted in other countries, as Germany (Fischer et al., ; Obiegala et al., ), regions of Africa (Dietrich et al., ), France (Ayral et al., ), Chile (Correa, Bucarey, Cattan, Landaeta‐Aqueveque, & Ramírez‐Estrada, ) and Argentina (Lovera et al., ). In this context, and considering the One health approach, the purpose of the present study was to detect wild animals from Atlantic Forest biome that might be acting as carriers of Leptospira spp.…”

Seroprevalence of leptospiral antibodies in rodents from riverside communities of Santa Fe, Argentina

“…Murid rodents of the species Mus musculus, Rattus norvegicus and Rattus rattus (Muridae: Murinae) are maintenance hosts of the serovars Icterohaemorrhagiae, Copenhageni and Ballum [4,5]. In recent years, some species of South American sigmodontine rodents (Cricetidae: Sigmodontinae) were also reported as renal carriers of Leptospira [6][7][8][9][10][11][12]. Introduced and native rodent species usually cohabit and seek food and shelter in the proximity of households, becoming an important source of infection for humans and domestic animals [4,6].…”

“…Several species of rodents reside in this area, including cavys (Cavia aperea), sigmodontines, murines, and the introduced squirrel Callosciurus erythraeus (Sciuridae) [21,22]. Leptospiral infection was reported in Argentina for the four introduced species [7,14,[23][24][25][26][27][28] and for the native sigmodontines Akodon azarae, Holochilus vulpinus, Oligoryzomys flavescens, Oligoryzomys nigripes and Scapteromys aquaticus [7,10,23]. In a previous publication, we reported renal carriage of Leptospira interrogans in one individual of S. aquaticus from Santa Fe [11].…”

“…Given that this pathogen is transmitted by a wide diversity of host species, identifying the factors that influence their infection probabilities is key for guiding surveillance efforts that target a broad host range. However, only two studies analyzed factors that could influence over prevalence [7,23]. In the work of Vanasco et al (2003) [23], the authors found associations with species and age in rodents from different environmental settings of the city of Santa Fe.…”