New hosts for the mite Ornithonyssus bursa in Argentina.

The mite Ornithonyssus bursa (Berlese) (Mesostigmata: Macronyssidae) is considered a poultry pest causing important infestations in chickens and it is considered a potential vector of arbovirus. Despite being considered a common parasite in wild birds, there is scarce published information about its potential hosts and effects on them. Here we present new bird hosts for O. bursa, assess the presence of Alphavirus, Flavivirus and Bunyavirus in mites from three host species, and discuss its potential impact on wild bird populations. We found O. bursa infecting five raptor and six passerine wild bird species. For nine of these species, this is the first record of infection by O. bursa. Although all analysed mites were negative for the examined arboviruses, the small sample size of mites does not allow further conclusions at the present moment. Because of the general nature of this ectoparasite, its presence in migratory long dispersal and endangered bird species, and the seropositivity for arboviruses in some of the species studied here, we consider it critical to assess the role of O. bursa and other ectoparasites as vectors and reservoirs of pathogens and as potential deleterious agents in wild bird populations.

Colonizing the world in spite of reduced MHC variation.

The major histocompatibility complex (MHC), which harbours the most polymorphic vertebrate genes, plays a critical role in the host-pathogen coevolutionary arms race. However, the extent to which MHC diversity determines disease susceptibility and long-term persistence of populations is currently under debate, as recent studies have demonstrated that low MHC variability does not necessarily hamper population viability. However, these studies typically assayed small and decimated populations in species with restricted distribution, thereby making inferences about the evolutionary potential of these populations difficult. Here, we show that MHC impoverishment has not constrained the ecological radiation and flourishing of falcons (Aves: Falconidae) worldwide. We found two remarkably different patterns of MHC variation within the genus Falco. Whereas MHC variation in kestrels (the basal group within the genus) is very high, falcons exhibit ancestrally low intra- and interspecific MHC variability. This pattern is not due to the inadvertent survey of paralogous genes or pseudogenes. Further, patterns of variation in mitochondrial or other nuclear genes do not indicate a generalized low level of genome-wide variability among falcons. Although a relative contribution of genetic drift cannot be completely ruled out, we propose the falcons went through an evolutionary transition, driven and maintained by natural selection, from primarily highly variable towards low polymorphic and slow-evolving MHC genes with a very specific immune function. This study highlights that the importance of MHC diversity cannot be generalized among vertebrates, and hints at the evolution of compensatory immune mechanisms in falcons to cope with emerging and continuously evolving pathogens.

MC1R-dependent, melanin-based colour polymorphism is associated with cell-mediated response in the Eleonora's falcon.

Colour polymorphism in vertebrates is usually under genetic control and may be associated with variation in physiological traits. The melanocortin 1 receptor (Mc1r) has been involved repeatedly in melanin-based pigmentation but it was thought to have few other physiological effects. However, recent pharmacological studies suggest that MC1R could regulate the aspects of immunity. We investigated whether variation at Mc1r underpins plumage colouration in the Eleonora's falcon. We also examined whether nestlings of the different morphs differed in their inflammatory response induced by phytohemagglutinin (PHA). Variation in colouration was due to a deletion of four amino acids at the Mc1r gene. Cellular immune response was morph specific. In males, but not in females, dark nestling mounted a lower PHA response than pale ones. Although correlative, our results raise the neglected possibility that MC1R has pleiotropic effects, suggesting a potential role of immune capacity and pathogen pressure on the maintenance of colour polymorphism in this species.

Coprophagy: an unusual source of essential carotenoids.

The rare Egyptian vulture (Neophron percnopterus) stands out among the Old World vultures (Family Accipitridae) because of its brightly ornamented head, which is coloured yellow by carotenoid pigments, and its practice of feeding on faeces. Here we show that Egyptian vultures obtain these pigments from the excrement of ungulates. To our knowledge, this is the first demonstration that faeces can be used as a source of carotenoids by a vertebrate.

[Exercise-induced atrioventricular block]. / Bloqueo auriculoventricular inducido por el ejercicio.

Exercise-induced atrioventricular block in patients with normal atrioventricular conduction at rest is uncommon. Electrophysiologic studies have documented block distal to the atrioventricular node in these patients. Implantation of a permanent pacemaker is recommended because of a high incidence of subsequent symptomatic block. We report three symptomatic patients with exercise-induced atrioventricular block. Two patients showed a bundle branch block in the baseline electrocardiogram, suggesting a distal location of the block. In the remainder, with a normal QRS, the electrophysiologic study revealed AV block within the His bundle in response to atrial pacing.

[Anemia in the pregnancies followed-up at a health center]. / Estudio de la anemia en los embarazos controlados en un centro de salud.

We retrospectively evaluated the 134 pregnancies which were controlled in our health center in a 4-year period, so as to evaluate anemia in pregnancy and the factors influencing its development. In the study sample, 18.65% of the women had anemia. The age did not have any influence on the hemoglobin and packed red cell volume at the beginning of pregnancy, but it had at the end (p less than 0.01). He types of anemia were classified, and the normocytic-normochromic was the most common (68%). The investigations carried out for the etiological characterization of the anemias, the treatments and their results were evaluated. A lack of homogeneity in treatments, a small efficacy (32%), and a lack of specific investigations for the etiological evaluation were found (24%). Guidelines for the investigation and therapy of anemia during pregnancy are suggested.