Patterns of Gastrointestinal Helminth Infections in Rattus rattus, Rattus norvegicus, and Mus musculus in Chile.

Few studies have assessed the patterns of parasite populations of rodents over a longitudinal gradient in Chile. In this work, the gastrointestinal helminthic fauna of invasive rodents in Chile was examined to assess the association between their presence/absence and abundance with latitude, host sex, and host body condition, and to assess the coexistence and correlation of the abundance between parasite species. Rodents were obtained from 20 localities between 33 and 43°S. Helminths were extracted from the gastrointestinal tract and identified morphologically. Overall, 13 helminth taxa were obtained. The most frequently identified parasite species was Heterakis spumosa, and the most abundant was Syphacia muris, while Physaloptera sp. was the most widely distributed. No locality presented with a coexistence that was different from that expected by chance, while the abundance of five helminthic species correlated with the abundance of another in at least one locality, most likely due to co-infection rather than interaction. Host sex was associated with parasite presence or abundance, and female sex-biased parasitism was notably observed in all cases. Body condition and latitude presented either a positive or negative association with the presence or abundance of parasites depending on the species. It is notable that the likely native Physaloptera sp. is widely distributed among invasive rodents. Further, gravid females were found, suggesting spillback of this species to the native fauna. The low frequency and abundance of highly zoonotic hymenolepid species suggest that rodents are of low concern regarding gastrointestinal zoonotic helminths.

Survey of Trichinella in American minks (Neovison vison Schreber, 1777) and wild rodents (Muridae and Cricetidae) in Chile.

Trichinellosis is a zoonosis with worldwide distribution. Several hosts have been recognized around the world; however, there is a lack of knowledge of the role of feral mammals in Chile in its transmission. Herein, we tested muscle samples from 555 individuals among American minks (Neovison vison Schreber, 1777. n = 100) and several myomorph rodent species (Muridae and Cricetidae. n = 455) from southern Chile by artificial digestion to detect Trichinella larvae and identified the larvae at the species level through molecular analyses. Rodents were captured in agricultural and wild protected areas of several administrative regions (hereafter: region), while minks were captured in agricultural areas of the Los Ríos region. Trichinella spiralis larvae were detected in a synanthropic black rat (0.24%) of the Ñuble region and in seven minks (7%) trapped in agricultural areas of the Los Ríos region. The present results suggest that T. spiralis circulation is restricted to synanthropic rodents and minks living in agricultural areas where the parasite circulates among domesticated pigs. This study represents the first record of T. spiralis in a mustelid mammal in South America, increasing the number of feral species that could participate in the reservoir.

Morphological and molecular identification with frequency analysis of Calicophoron microbothrioides in central Chile / Identificação morfológica e molecular com análise de frequência de Calicophoron microbothrioides na região central do Chile

Abstract This research aimed to determine the presence of paramphistomids in cattle slaughtered in a slaughterhouse of the Ñuble Region of Chile, to identify flukes and to analyze the frequency of these parasites in the Maule, Ñuble, and Biobío administrative regions of Chile. Between October of 2016 and April of 2017, rumens of 494 cattle were examined for flukes in the forestomachs. Worms were identified morphologically and, in addition, molecular analysis of the internal transcriber spacer region 2 of the fluke's DNA was done and phylogenetic analyses were performed with Bayesian inference in 14 worms. The frequency was analyzed by locality (low- or highlands) and age. The overall frequency was 11.24%. The district with the highest frequency of presentation was Chillán Viejo (30.8%). Districts in the lowlands had similar frequencies to those in the mountain lands (p=0.1). The frequency of flukes was significantly higher in adult animals than in young ones (p<0.01). We obtained a 460 bp-length fragment of DNA that was identical to the sequences previously identified as Paramphistomum cervi and Calicophoron microbothrioides, and performed morphological analyses confirmed that our samples belonged to C. microbothrioides. This is the first published study of C. microbothrioides in Chile.

Resumo Este trabalho teve como objetivo determinar a presença de paramphistomídeos em bovinos abatidos em um matadouro da Região do Ñuble do Chile, para identificar parasitas e analisar a frequência desses parasitos nas regiões administrativas de Maule, Ñuble e Biobío, no Chile. Entre outubro de 2016 e abril de 2017, rúmens de 494 bovinos foram examinados à procura de vermes no pré-estômago. Os vermes foram identificados morfologicamente e, além disso, a análise molecular da região interna do espaçador do transcritor 2 do DNA e análises filogenéticas foram realizadas com inferência bayesiana em 14 vermes. A frequência foi analisada pela altitude da localidade (baixa ou alta) e idade. A frequência geral foi de 11,24%. O distrito com as maiores frequências de parasitismo foi Chillán Viejo (30,8%). Os distritos das terras baixas tinham frequências semelhantes às encontradas nas terras das montanhas (p=0,17). A frequência foi significativamente maior em animais adultos do que em jovens (p<0.01). Obtivemos um fragmento de DNA de 460 pb que era idêntico às sequências anteriores identificadas como Paramphistomum cervi e Calicophoron microbothrioides, e realizamos análises morfológicas que permitiram confirmar que nossas amostras pertenciam a C. microbothrioides. Este é o primeiro estudo publicado sobre C. microbothrioides no Chile.

Morphological and molecular identification with frequency analysis of Calicophoron microbothrioides in central Chile.

This research aimed to determine the presence of paramphistomids in cattle slaughtered in a slaughterhouse of the Ñuble Region of Chile, to identify flukes and to analyze the frequency of these parasites in the Maule, Ñuble, and Biobío administrative regions of Chile. Between October of 2016 and April of 2017, rumens of 494 cattle were examined for flukes in the forestomachs. Worms were identified morphologically and, in addition, molecular analysis of the internal transcriber spacer region 2 of the fluke's DNA was done and phylogenetic analyses were performed with Bayesian inference in 14 worms. The frequency was analyzed by locality (low- or highlands) and age. The overall frequency was 11.24%. The district with the highest frequency of presentation was Chillán Viejo (30.8%). Districts in the lowlands had similar frequencies to those in the mountain lands (p=0.1). The frequency of flukes was significantly higher in adult animals than in young ones (p<0.01). We obtained a 460 bp-length fragment of DNA that was identical to the sequences previously identified as Paramphistomum cervi and Calicophoron microbothrioides, and performed morphological analyses confirmed that our samples belonged to C. microbothrioides. This is the first published study of C. microbothrioides in Chile.