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Although the immunosuppressive effect of chronic stress has been established, a stress response that downregulates the whole immune system does not make biological sense, especially if an animal has to endure difficult times in which there is also increased infection risk. At high animal densities, animals are faced simultaneously with food restriction (FR), social conflict (SC), and greater parasite--pathogen exposure. We hypothesized that the stress response to chronic stressors that covary with infection risk is not entirely immunosuppressive. Our prediction was that a chronically stressed animal would respond by enhancing innate defenses, while reducing investment in acquired immunity. In a laboratory setting, rats were exposed to prolonged FR and/or SC, and natural and specific antibody levels were repeatedly measured. Our prediction was fulfilled only partly, as FR and SC interacted to enhance natural antibodies, but rats exposed to either or both stressors also showed significantly higher levels of specific antibodies. These results suggest that, in the rat, chronic stress results in a prioritization of both innate and acquired humoral defenses, which makes biological sense provided the stressors examined usually signal an increased infection risk. [ABSTRACT FROM AUTHOR]

Twenty-eight Capillariinae species have been recorded in rodents; 1 of these species was reported from a caviomorph rodent, Hydrochoeris hydrochaeris (capybara), and placed in the genus Echinocoleus by Moravec (1982). However, both original description and subsequent contributions of Echinocoleus hydrochoeri are poor and incomplete. In this paper, this species is redescribed, and a new geographical distribution is reported. The redescription is based on morphologic and morphometrical features; intestine ends in a cloaca beside ejaculatory duct, caudal bursa composed of 2 large ventrolateral lobes with a fleshy internal part and a membranous external part (they are not united dorsally with a membrane), 1 pair of caudal papillae, terminal part of cylindrical cirrus ornamented with thin and thick spines (and particular pattern distribution), sclerotized spicule in male, and vulvar appendage in female, and 3 bacillary bands (1 ventral and 2 lateral). Generic and specific analyses were performed to establish new standards for future studies on the systematic position of Capillariinae species. This study presents new morphological information and a new record of a capillariid species from Argentina. [ABSTRACT FROM AUTHOR]

The study of myiasis is important because they may cause problems to the livestock industry, public health, or wildlife conservation. The ecology of parasitic dipterans that cause myiasis is singular, as they actively seek their hosts over relatively long distances. However, studies that address the determinants of myiasis dynamics are very scarce. The genus Philornis include species that may be excellent models to study myiasis ecology, as they exclusively parasitize bird nestlings, which stay in their nests until they are fully fledged, and larvae remain at the point of entry until the parasitic stage is over, thus allowing the collection of sequential individual-level infection data from virtually all the hosts present at a particular area. Here we offer a stratified multi-level analysis of longitudinal data of Philornis torquans parasitism in replicated forest bird communities of central Argentina. Using Generalized Linear Models and Generalized Linear Mixed Models and an information theory approach for model selection, we conducted four groups of analyses, each with a different study unit, the individual, the brood, the community at a given week, and the community at a given year. The response variable was larval abundance per nestling or mean abundance per nestling. At each level, models included the variables of interest of that particular level, and also potential confounders and effect modifiers of higher levels. We found associations of large magnitude at all levels, but only few variables truly governed the dynamics of this parasite. At the individual level, the infection was determined by the species and the age of the host. The main driver of parasite abundance at the microhabitat level was the average height of the forest, and at the community level, the density of hosts and prior rainfall. This multi-level approach contributed to a better understanding of the ecology of myiasis. [ABSTRACT FROM AUTHOR]

Echinococcosis is a zoonosis caused by tapeworms of the genus Echinococcus . Echinococcus granulosus sensu lato (s. l.) has a world-wide distribution and its transmission is primarily maintained in a synanthropic cycle with dogs as definitive hosts and livestock species as intermediate hosts. However, many wild canids also function as definitive hosts for E. granulosus s. l. Echinococcosis in humans is mainly caused by E. granulosus sensu stricto (s. s.) G1 genotype. In the present work, we expanded the epidemiological study on echinococcosis reported cases in Pampas fox ( Lycalopex gymnocercus ) to provide a prevalence estimate for rural areas of southern Buenos Aires province, Argentina. Ninety-five whole intestines were analyzed using the sedimentation and counting technique with a result of 83 foxes (87.37%) harboring at least one helminth species. E. granulosus s. l. adults were found in one Pampas fox (1.05%). These adult helminthes were E. granulosus s. s. (G1) according to the genotyping analysis of a 450-bp region of the mitochondrial cytochrome c oxidase subunit 1 ( cox1 ) gene. [ABSTRACT FROM AUTHOR]

Echinococcosis is a zoonosis caused by tapeworms of the genus Echinococcus . Echinococcus granulosus sensu lato (s. l.) has a world-wide distribution and its transmission is primarily maintained in a synanthropic cycle with dogs as definitive hosts and livestock species as intermediate hosts. However, many wild canids also function as definitive hosts for E. granulosus s. l. Echinococcosis in humans is mainly caused by E. granulosus sensu stricto (s. s.) G1 genotype. In the present work, we expanded the epidemiological study on echinococcosis reported cases in Pampas fox ( Lycalopex gymnocercus ) to provide a prevalence estimate for rural areas of southern Buenos Aires province, Argentina. Ninety-five whole intestines were analyzed using the sedimentation and counting technique with a result of 83 foxes (87.37%) harboring at least one helminth species. E. granulosus s. l. adults were found in one Pampas fox (1.05%). These adult helminthes were E. granulosus s. s. (G1) according to the genotyping analysis of a 450-bp region of the mitochondrial cytochrome c oxidase subunit 1 ( cox1 ) gene. [ABSTRACT FROM AUTHOR]

Highlights: [•] The genus Spirometra is cosmopolitan and these parasites infect carnivores, specially felids and canids. [•] In Argentina, S. erinacei and S. mansonoides have been reported sporadically only in domestic definitive hosts. [•] This report describes the first finding of S. erinacei infecting Pampas fox expanding the list of definitive hosts. [•] Estimate prevalence of this cestode in rural areas from Argentina was calculated through adult of small intestinals and eggs identification. [ABSTRACT FROM AUTHOR]