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

BACKGROUND: Understanding 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 FINDINGS: Ten 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/SIGNIFICANCE: Murine 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.

[Morphological and molecular identification of Cysticercus fasciolaris isolated from rodent hosts (Rattus norvegicus) in Buenos Aires province (Argentina)]. / Identificación morfológica y molecular de Cysticercus fasciolaris aislado de un roedor (Rattus norvegicus) de la provincia de Buenos Aires (Argentina).

In a rodent (Rattus norvegicus) survey in Buenos Aires province, metacestodes of tapeworms were found encysted in the liver of the host. The aim of this work was the morphological and molecular identification of this parasite. To achieve the molecular characterization of the parasite, ribosomal (28S) and mitochondrial (COI) DNA were amplified and sequenced. Based on both morphological and molecular data using bioinformatic tools, the metacestode was identified as Cysticercus fasciolaris. The adult form of this tapeworm (Taenia taeniaeformis) commonly infects felid and canid mammalian hosts. This is the first report on the molecular identification of Cysticercus fasciolaris in Buenos Aires province (Argentina).

Identificación morfológica y molecular de Cysticercus fasciolaris aislado de un roedor (Rattus norvegicus) de la provincia de Buenos Aires (Argentina) / [Morphological and molecular identification of Cysticercus fasciolaris isolated from rodent hosts (Rattus norvegicus) in Buenos Aires province (Argentina)].

In a rodent (Rattus norvegicus) survey in Buenos Aires province, metacestodes of tapeworms were found encysted in the liver of the host. The aim of this work was the morphological and molecular identification of this parasite. To achieve the molecular characterization of the parasite, ribosomal (28S) and mitochondrial (COI) DNA were amplified and sequenced. Based on both morphological and molecular data using bioinformatic tools, the metacestode was identified as Cysticercus fasciolaris. The adult form of this tapeworm (Taenia taeniaeformis) commonly infects felid and canid mammalian hosts. This is the first report on the molecular identification of Cysticercus fasciolaris in Buenos Aires province (Argentina).

In vitro diagnosis of the first case of amitraz resistance in Rhipicephalus microplus in Santo Tomé (Corrientes), Argentina.

In Argentina, the cattle tick Rhipicephalus microplus has already developed resistance to organophosphates and synthetic pyrethroids. However, no cases of amitraz resistance have ever been recorded in this country despite its heavy use. A recent failure of amitraz to control ticks in a farm located in Santo Tomé, province of Corrientes, resulted in the collection of samples for acaricide resistance diagnosis. The modified Drummond adult immersion test (AIT) and the larval tarsal test (LTT) were performed separately in Argentina and Switzerland to evaluate efficacy of amitraz and other acaricides. The AIT showed that oviposition in the Santo Tomé field isolate was not inhibited when it was challenged to 250 and 500 ppm amitraz, and 50 ppm deltamethrin. However, oviposition was reduced by 90.6% when this field isolate was challenged to a combination of 400 ppm ethion and 100 ppm cypermethrin. To confirm the results obtained with the AIT, 2 additional tick samples were collected and shipped to Switzerland for resistance diagnosis of amitraz, cypermethrin and flumethrin, using the LTT. With this bioassay, the resistance ratios of the 2 field isolates were 32.5 and 57.0 for amitraz and between 5.9 and 27.2 for the synthetic pyrethroids. Both in vitro bioassays confirmed amitraz and synthetic pyrethroid resistance in the Santo Tomé samples. These results account for the first evidence of amitraz resistance in R. microplus in Argentina.

Identificación morfológica y molecular de Cysticercus fasciolaris aislado de un roedor (Rattus norvegicus) de la provincia de Buenos Aires (Argentina). / [Morphological and molecular identification of Cysticercus fasciolaris isolated from rodent hosts (Rattus norvegicus) in Buenos Aires province (Argentina)].

In a rodent (Rattus norvegicus) survey in Buenos Aires province, metacestodes of tapeworms were found encysted in the liver of the host. The aim of this work was the morphological and molecular identification of this parasite. To achieve the molecular characterization of the parasite, ribosomal (28S) and mitochondrial (COI) DNA were amplified and sequenced. Based on both morphological and molecular data using bioinformatic tools, the metacestode was identified as Cysticercus fasciolaris. The adult form of this tapeworm (Taenia taeniaeformis) commonly infects felid and canid mammalian hosts. This is the first report on the molecular identification of Cysticercus fasciolaris in Buenos Aires province (Argentina).