ABSTRACT
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.
ABSTRACT
Echinococcosis is a neglected zoonosis that uses dogs and sheep as its main hosts in Chile. The Eg95 vaccine against sheep infection has been included in some control programs. Here, we assess the efficacy of the vaccination program in the hyperendemic Alto Biobío commune after 3 years of execution. Fisher's test and generalized linear models were used in the assessment. The program tried to offer a first dose at 2 months of age, a booster 1 month later, and yearly vaccination. Given logistic difficulties, important delays in vaccination occurred, and most animals did not receive the first booster. Dog deworming was not included in the program. Likely due to the aforementioned factors, the overall frequency of infection was not lower, but the proportion of large (>5 mm) cysts and fertile cysts was smaller after the program. The frequency of infection and/or the number of cysts were lower when the age at first dose was younger and the first booster was administered 1 month after the first dose. The results suggest that vaccination affects both cyst development after the larvae reach the target organs, as well as the development of the protoscolex once the cysts start developing.
ABSTRACT
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.
