BackgroundRabies is a fatal infection of the central nervous system primarily transmitted by rabid animal bites. Rabies virus (RABV) circulates through two different epidemiological cycles: terrestrial and aerial, where dogs, foxes or skunks and bats, respectively, act as the most relevant reservoirs and/or vectors. It is widely accepted that insectivorous bats are not important vectors of RABV in Argentina despite the great diversity of bat species and the extensive Argentinean territory.MethodsWe studied the positivity rate of RABV detection in different areas of the country, and the antigenic and genetic diversity of 99 rabies virus (RABV) strains obtained from 14 species of insectivorous bats collected in Argentina between 1991 and 2008.ResultsBased on the analysis of bats received for RABV analysis by the National Rabies system of surveillance, the positivity rate of RABV in insectivorous bats ranged from 3.1 to 5.4%, depending on the geographic location. The findings were distributed among an extensive area of the Argentinean territory. The 99 strains of insectivorous bat-related sequences were divided into six distinct lineages associated with Tadarida brasiliensis, Myotis spp, Eptesicus spp, Histiotus montanus, Lasiurus blosseviilli and Lasiurus cinereus. Comparison with RABV sequences obtained from insectivorous bats of the Americas revealed co-circulation of similar genetic variants in several countries. Finally, inter-species transmission, mostly related with Lasiurus species, was demonstrated in 11.8% of the samples.ConclusionsThis study demonstrates the presence of several independent enzootics of rabies in insectivorous bats of Argentina. This information is relevant to identify potential areas at risk for human and animal infection.

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Bats are among the most diverse, widespread, and abundant mammals. In Argentina, 67 species of bats have been recorded, belonging to 5 families and 29 genera. These high levels of biodiversity are likely to complicate identification at fieldwork, especially between closely related species, where external morphology-based approaches are the only immediate means for a priori species assignment. The use of molecular markers can enhance species identification, and acquires particular relevance in capture-release studies. In this study, we discuss the extent of the use of the mitochondrial cytochrome b gene for species identification, comparing external morphology identification with a molecular phylogenetic classification based on this marker, under the light of current bat systematics. We analyzed 33 samples collected in an eco-epidemiological survey in the province of Santa Fe (Argentina). We further sequenced 27 museum vouchers to test the accuracy of cytochrome b -based phylogenies in taxonomic identification of bats occurring in the Pampean/Chacoan regions of Argentina. The cytochrome b gene was successfully amplified in all Molossid and Vespertilionid species except for Eptesicus, for which we designed a new reverse primer. The resulting Bayesian phylogeny was congruent with current systematics. Cytochrome b proved useful for species-level delimitation in non-conflicting genera (Eumops, Dasypterus, Molossops) and has infrageneric resolution in more complex lineages (Eptesicus, Myotis, Molossus). We discuss four sources of incongruence that may act separately or in combination: 1) molecular processes, 2) biology, 3) limitations in identification, and 4) errors in the current taxonomy. The present study confirms the general applicability of cytochrome b -based phylogenies in eco-epidemiological studies, but its resolution and reliability depend mainly, but not solely, on the level of genetic differentiation within each bat genus.

The first outbreak of acute flaccid myelitis associated to enterovirus D68 is reported in Argentina. Active epidemiological surveillance will help to determine the true incidence, epidemiology and etiology of this disease.

In rabies diagnosis, it is essential to count on a rapid test to give a quick response. The combined sensitivity and robustness of the TaqMan RT-PCR assays (qRT-PCR) have made these methods a valuable alternative for rabies virus (RABV) detection. We conducted a study to compare the applicability of two widely used qRT-PCR assays targeting the nucleoprotein gene (LysGT1 assay) and leader sequences (LN34 qRT-PCR assay) of RABV genomes, in all variants circulating in Argentina. A total of 44 samples obtained from bats, dogs, cattle, and horses, that were previously tested for rabies by FAT and conventional RT-PCR, were used in the study. All variants were successfully detected by the pan-lyssavirus LN34 qRT-PCR assay. The LysGT1 assay failed to detect three bat-related variants. We further sequenced the region targeted by LysGT1 and demonstrated that the presence of three or more mismatches with respect to the primers and probe sequences precludes viral detection. We conclude that the LysGT1 assay is prone to yield variant-dependent false-negative test results, and in consequence, the LN34 assay would ensure more effective detection of RABV in Argentina.