A new species of hemiuroidean trematode from Hatcheria macraei (Siluriformes, Trichomycteridae) and Heleobia hatcheri (Gastropoda, Cochliopidae) in a Patagonian River.

A new hemiuroidean species, Genarchella pichileufuensis n. sp. (Derogenidae: Halipeginae), was found in the stomach of the siluriform freshwater fish, Hatcheria macraei (Girard, 1855), in the Pichileufu River, Patagonia, Argentina. Its rediae with immature cystophorous cercariae were found in the snail Heleobia hatcheri (Pilsbry, 1911) in the same site. The present new species is morphologically featured by having a cyclocoel in the hindbody unlike the other species of the genus. The characteristics of this species allowed us to amend the diagnosis of the genus Genarchella as follows: cyclocoel present or absent; testes symmetrical to tandem; ootype pouch present. In the phylogenetic analysis, G. pichileufuensis forms a well-supported clade with Genarchella spp. recovered from Mexican freshwater fishes. This clade is included in the cluster of representatives of the subfamily Halipeginae. So far, three hemiuroidean species, Thometrema patagonica (Szidat, 1956), Derogenes lacustris Tsuchida, Flores, Viozzi, Rauque et Urabe, 2021 and G. pichileufuensis n. sp., have been reported from freshwater fishes in Argentinean Patagonia.

Tenencia responsable de perros y salud humana en barrios de San Carlos de Bariloche, Argentina / Responsible ownership of dogs and human health in neighborhoods of San Carlos de Bariloche, Argentina

La relación entre el hombre y el perro se asocia a numerosos y variados beneficios sobre la salud humana; sin embargo también presenta importantes riesgos. El objetivo de este trabajo es describir parámetros demográficos y características de la tenencia de perros con implicancias sobre la salud humana y evaluar la prevalencia de mordeduras y accidentes de tránsito causados por perros. Se realizó una encuesta en los barrios Nuestras Malvinas y Nahuel Hue de San Carlos de Bariloche. Se estimó el porcentaje de viviendas con al menos un perro, la media de perros por vivienda, la prevalencia de mordeduras de perro y de accidentes de tránsito causados por perros y el conocimiento de la población sobre zoonosis transmitidas por perros. Respecto de la tenencia, se evaluó el grado de esterilización, vacunación y desparasitación y el porcentaje de perros con libre acceso a la calle. Se realizaron 141 entrevistas. En 87% de las viviendas había al menos un perro (promedio 2.2 perros/vivienda). En 26% de las viviendas alguien había sufrido un accidente de tránsito causado por perros y en 41% alguien había sido mordido. El 83% de los perros fueron desparasitados en los últimos 12 meses, en promedio 1.4 veces (óptimo: 6 veces/año), 51% estaban esterilizados, 55% tenían libre acceso a la calle. Este estudio muestra una situación preocupante respecto de la población canina de los barrios evaluados. El número de perros sueltos en la calle y el bajo nivel de desparasitación y esterilización proveen condiciones ideales para que se propaguen zoonosis.

Human relationship with dogs associates with numerous and varied benefits on human health; however, it also presents significant risks. The goal of this study was to describe demographic parameters and characteristics of dog ownership with possible implications on human health and to evaluate the prevalence of dog bites and traffic accidents due to dogs. Interviews were conducted in the neighborhoods of Nuestras Malvinas and Nahuel Hue in San Carlos de Bariloche. The percentage of homes with at least one dog, the average number of dogs per home, the prevalence of dog bites and traffic accidents due to dogs and the general awareness of the population on dog transmitted zoonoses were estimated. Regarding ownership characteristics, the degree of sterilization, vaccination and parasite control and the percentage of dogs allowed to roam freely in public places were evaluated. A total of 141 interviews were conducted; 87% of the households had at least one dog, with an average of 2.2 dogs. In 26% of the households someone had suffered a traffic accident caused by dogs and in 41% someone had been bitten. Antiparasite treatment was administered to 83% of the dogs in the last 12 months, on average 1.4 times (recommended 6 times), 51% were sterilized, 55% were allowed to roam freely. This study shows a disturbing situation regarding the canine population of the evaluated neighborhoods. The number of dogs allowed to roam freely and the low level of parasite control and sterilization provide suitable conditions for the spread of zoonoses.

Parasite volume as an indicator of competition: the case of Acanthocephalus tumescens and Pseudocorynosoma sp. (Acanthocephala) in their intermediate host.

In Lake Mascardi (Patagonia), 2 acanthocephalan species, Acanthocephalus tumescens and Pseudocorynosoma sp., share an amphipod intermediate host but have different definitive hosts. Because both acanthocephalan species are potentially capable of manipulating amphipod behavior, one of the parasites may, therefore, have no opportunity to complete its life cycle; accordingly, negative interactions between them can be expected. The purpose of the present work was to examine the possibility of competition in the intermediate host through a comparison of A. tumescens and Pseudocorynosoma sp. cystacanth volume. Specimens of the amphipod Hyalella patagonica were collected monthly over almost 2 yr. Amphipods were measured (total length), necropsied, and cystacanths collected. Cystacanths were also measured, and their volume was calculated. Size of both acanthocepalan species was positively associated with amphipod total length. Competition, during 3 different infection periods, was assessed: high level of Pseudocorynosoma sp. infection (HP), high level of A. tumescens infection (HA), and high level of mixed infection (HM). In Pseudocorynosoma sp., intra-specific competition in HM was the only interaction found. In contrast, in A. tumescens, inter-specific competition in HP, intra-specific competion in HA, and intra- and inter-specific competition in HM were found. We suggest that Pseudocorynosoma sp. is a non-plastic species mostly found in single infections, while A. tumescens is a more variable species occurring more frequently in co-infections.

Effects of two acanthocephalan species on the reproduction of Hyalella patagonica (Amphipoda, Hyalellidae) in an Andean Patagonian Lake (Argentina).

The aim of the present study was to evaluate alterations in the reproduction induced by acanthellae and cystacanths of the acanthocephalans Acanthocephalus tumescens and Corynosoma sp. in the amphipod Hyalella patagonica from Lake Mascardi. Specimens of H. patagonica were separated in two categories: paired amphipods (joined specimens during precopulatory mate guarding period until fertilization) and unpaired amphipods (alone specimens). Different analyses were performed: first with paired (n=406) and unpaired (n=375) amphipods, and second only with female amphipods (n=1949), that were classified into three categories (without internal oocytes and eggs, only with internal oocytes, and with eggs). Also, carotenoid extraction was performed of amphipods uninfected (n=75) and infected (n=105) by cystacanths of Corynosoma sp. Unpaired amphipods had significantly higher prevalence of cystacanths of both acanthocephalan species than paired ones; but such differences were not found in prevalence of acanthellae. Female amphipods without internal oocytes and eggs showed significantly higher prevalence of cystacanths of both acanthocephalan species than the two other female categories; while females with eggs had significantly higher prevalence of A. tumescens acanthellae. Amphipods infected by Corynosoma sp. showed lower carotenoid concentration than uninfected ones. In Lake Mascardi, there is indirect evidence of both reduced mating success and female fecundity of H. patagonica provoked by both cystacanths species (A. tumescens and Corynosoma sp.). However, infections by acanthellae seem to have no effects.