Molecular detection of Hepatozoon species (Apicomplexa: Hepatozoidae) infecting snakes in the Northeastern region of Argentina.

The genus Hepatozoon Miller (1908) contains a wide range of obligate parasitic organisms with complex life cycles involving vertebrates and hematophagous invertebrates. Despite over 300 species being described, only a small percentage has been characterized in snakes using morphological and molecular techniques. The prevalence of these parasites in snakes is significant, highlighting the need for molecular descriptions in such elusive hosts. Thus, the objective of this study was to determine molecularly the presence of Hepatozoon species in snakes from the Northeastern region of Argentina. Thirty-two specimens of eight snake species (Bothrops alternatus, Dryophylax hypoconia, Erythrolamprus jaegeri coralliventris, Erythrolamprus poecilogyrus, Erythrolamprus semiaureus, Philodryas olfersii latirostris, Pseudablabes (ex Philodryas) patagoniensis and Palusophis (ex Mastigodryas) bifossatus were collected and examined. PCR analysis of the 18S rRNA locus detected four samples (12% prevalence) positive for the presence of Hepatozoon DNA. Phylogenetic analysis positioned the 18S rRNA Hepatozoon sequences obtained in three different clades, one with Hepatozoon musa, another with sequences of Hepatozoon cuestensis, while the third was placed as a sister taxon to a clade including Hepatozoon cevapii and Hepatozoon massardi. This study presents the first documentation of Hepatozoon infecting snakes in Argentina, thereby expanding their distribution within southern South America. Additionally, B. alternatus and Pa. bifossatus are reported as new hosts of Hepatozoon.

Natural infection of free-ranging capybaras (Hydrochoerus hydrochaeris) with Anaplasmataecea and Rickettsiaceae bacteria in the Iberá wetlands ecoregion, Argentina.

The current work assessed the infection with Ehrlichia and Anaplasma species, and exposure to Rickettsia spp. in free-ranging capybaras in the Iberá wetlands ecoregion in Argentina. By indirect immunofluorescence assay, 37 out of 51 (73%) capybara sera were seropositive to Rickettsia spp., with 23.5% and 4% samples considered homologous to Rickettsia parkeri and Rickettsia bellii, respectively (or very closely related serotypes). Anaplasmataceae DNA was found to be highly prevalent in capybaras, with 33 out of 62 samples positive for Anaplasma sp. with Ct values of 28.64 ± 0.35 (average ± standard error), and 12 samples positive for Ehrlichia sp. with Ct values of 31.74 ± 0.87. Anaplasma sp. from capybaras was closely related to Anaplasma sp. reported to infect Amblyomma dubitatum in Iberá wetlands and to Anaplasma odocoilei, while the detected Ehrlichia sp. was closely related to "Candidatus Ehrlichia hydrochoerus" previously reported to infect capybaras in Brazil and A. dubitatum in Iberá wetlands. Structures compatible with Anaplasma morulae were observed in the cytoplasm of platelets from Anaplasma-positive capybaras. Our findings show that capybaras from the Iberá wetlands were exposed to Rickettsia species related to R. bellii and to the pathogen R. parkeri, and were infected with "Ca. Ehrlichia hydrochoerus" and a novel Anaplasma species, herein named "Candidatus Anaplasma capybara".

A new dracunculus species (Nematoda: Dracunculoidea) in neotropical otters (Lontra longicaudis) from Argentina: morphological and molecular characterization.

A new species of Dracunculus is described in wild neotropical otters, Lontra longicaudis, occurring in Corrientes, Argentina, based on morphological and molecular characteristics. Worms were located in the subcutaneous tissue from two of five investigated otters. Dracunculus jaguape n. sp. is differentiated from the 14 species of Dracunculus described from mammals and reptiles by the prominent dorsal and ventral papillae on the head; deirids posterior to nerve ring; male with long needlelike spicules and presence of gubernaculum; and long first stage larva. Phylogenetic analysis using the 18S rRNA positioned Dracunculus jaguape n. sp. in an anterior position to the rest of Dracunculus sequences available and COI positioned it in a separated clade sister to Dracunculus lutrae sequences. This is the first report on the presence of this nematode in Lontra longicaudis in Argentina.

Anaplasmataceae presence in Amblyomma calcaratum associated with anteaters (Tamandua tetradactyla) in the rainforest ecoregion, Argentina.

Bacteria of the sister genera Ehrlichia and Anaplasma (Anaplasmataceae) are obligate intracellular Alphaproteobacteria that are transmitted mostly through arthropod vectors. These agents can infect different vertebrate cells, depending on the species involved, and can cause diseases in animals and humans. In this study, we evaluated the presence of Anaplasmataceae bacteria in Amblyomma calcaratum ticks collected from a road-killed Tamandua tetradactyla in the Rainforest ecoregion in Argentina. All samples were screened for Anaplasmataceae DNA using a real-time PCR assay targeting the 16S rRNA gene. Evidence of Anaplasmataceae DNA was detected in three out of thirty-nine Am. calcaratum ticks. Phylogenetic analysis of a portion of 16S rRNA gene positioned one sample (Ehrlichia sp. strain Ac124) with Ehrlichia sequences and the other two samples with Anaplasma sequences; Anaplasma sp. strain Ac145 close to Anaplasma odocoilei and Anaplasma sp. strain Ac152 in an ancestral position to most Anaplasma species. The groEL sequence obtained showed that Ehrlichia sp. strain Ac124 was phylogenetically related to Ehrlichia sp. strain Iberá reported infecting Amblyomma tigrinum from Iberá wetlands in Argentina. Phylogenetic analysis using the rpoB sequence positioned Anaplasma sp. strain Ac145 close to the canine pathogen Anaplasma platys, while Anaplasma sp. strain Ac152 was positioned close to the bovine pathogen Anaplasma marginale. In this study, three Anaplasmataceae agents were detected in adults of Am. calcaratum associated with a T. tetradactyla. These results suggest that the number of Anaplasmataceae species, as well as their distribution, is largely unknown.

Capybara density and climatic factors as modulators of Ehrlichia prevalence in questing ticks in the Iberá wetlands, Argentina.

We evaluated the presence of Ehrlichia spp. in unfed capybara ticks, Amblyomma dubitatum, and explored its association with capybaras density, ticks density and environmental variables. We observed that in the Iberá wetlands ecoregion A. dubitatum is infected by "Candidatus Ehrlichia hydrochoerus" and in a lesser extent with an Ehrlichia species closely related to Ehrlichia chaffeensis. The frequency of "Ca. Ehrlichia hydrochoerus" presence in A. dubitatum was not associated with vector abundance, but the probability of finding "Ca. Ehrlichia hydrochoerus"-infected ticks increased when the density of capybaras was low two months before. We hypothesize that when the density of capybaras decreases, A. dubitatum immature stages may seek out alternative hosts one of which could exhibit high realized reservoir competence for "Ca. Ehrlichia hydrochoerus", leading to an increased prevalence of this ehrlichiae in questing A. dubitatum. High minimum temperatures and high cumulative rainfall in the time period previous to tick collection (15 to 60 days) were positively correlated with the prevalence of "Ca. Ehrlichia hydrochoerus" infection in A. dubitatum. Our results suggest that a combination of factors (both biological and abiotic) could raise the risk of human exposure to tick-borne Ehrlichia in the Iberá wetlands ecoregion.

Ecological factors shaping the ectoparasite community assembly of the Azara's Grass Mouse, Akodon azarae (Rodentia: Cricetidae).

Parasites are integral members of the global biodiversity. They are useful indicators of environmental stress, food web structure and diversity. Ectoparasites have the potential to transmit vector-borne diseases of public health and veterinary importance and to play an important role in the regulation and evolution of host populations. The interlinkages between hosts, parasites and the environment are complex and challenging to study, leading to controversial results. Most previous studies have been focused on one or two parasite groups, while hosts are often co-infected by different taxa. The present study aims to assess the influence of environmental and host traits on the entire ectoparasite community composition of the rodent Akodon azarae. A total of 278 rodents were examined and mites (Mesostigmata), lice (Phthiraptera), ticks (Ixodida) and fleas (Siphonaptera) were determined. A multi-correspondence analysis was performed in order to analyze interactions within the ectoparasite community and the influence of environmental and host variables on this assembly. We found that environmental variables have a stronger influence on the composition of the ectoparasite community of A. azarae than the host variables analyzed. Minimum temperature was the most influential variable among the studied. In addition, we found evidence of agonistic and antagonistic interactions between ticks and mites, lice and fleas. The present study supports the hypothesis that minimum temperature plays a major role in the dynamics that shape the ectoparasite community of A. azarae, probably through both direct and indirect processes. This finding becomes particularly relevant in a climate change scenario.

Anaplasma species infecting questing ticks in the Iberá wetlands ecoregion, Argentina.

The present study evaluated the presence of Anaplasma species in questing ticks from six sites with opposing land usage (i.e., protected natural areas or livestock establishments) within the Iberá wetlands ecoregion in Argentina. The ticks were determined as Amblyomma dubitatum (n = 15,096), Rhipicephalus microplus (n = 399), Amblyomma triste (n = 134), Haemaphysalis juxtakochi (n = 5), and Amblyomma tigrinum (n = 1). Using a real-time PCR assay targeting the 16S rRNA gene, Anaplasma sp. was detected in A. dubitatum samples (one nymph, three nymph pools and one larvae pool) and one R. microplus larvae pool. The overall minimum infection rate (MIR) for Anaplasma sp. in questing A. dubitatum nymphs was 0.169% (0.175% in protected natural areas and 0% in livestock establishments). For R. microplus, overall Anaplasma sp. MIR was 0.25% (0.52% in protected natural areas and 0% in livestock establishments). Phylogenetic analysis positioned the Anaplasma sp. from A. dubitatum in the same clade as Anaplasma odocoilei, whereas the Anaplasma sp. from R. microplus was related to Anaplasma platys. In conclusion, these results support a possible role of A. dubitatum in the ecology of the Anaplasma agent reported to infect capybaras in the region.

Cattle Farming and Plantation Forest are Associated with Bartonella Occurrence in Wild Rodents.

Bartonella spp. are intracellular hemotropic bacteria primarily transmitted by arthropod vectors to various mammalian hosts, including humans. In this study, we conducted a survey on wild populations of sigmodontine rodents, Akodon azarae and Oxymycterus rufus, inhabiting the Paraná River delta region. The study involved eight grids organized in a crossed 2 × 2 design, where four of the grids were exposed to cattle while the other four were not, and four grids were located in implanted forest while the remaining four were in natural grasslands. Our objective was to examine whether the occurrence of Bartonella spp. in rodents was associated with silvopastoral activities (cattle raising associated with timber production) conducted in the region. Additionally, we evaluated the associations between Bartonella infection and other environmental and host factors. We present compelling evidence of a significant positive association between Bartonella prevalence and the presence of implanted forests and cattle. Furthermore, we identified the presence of a Bartonella genotype related to the pathogen Bartonella rochalimaea, infecting both A. azarae and Ox. rufus. These findings suggest that anthropogenic land-use changes, particularly the development of silvopastoral practices in the region, may disrupt the dynamics of Bartonella.

Mesostigmatid mites (Acari: Mesostigmata) at the domestic-wildlife interface: Poultry and passerine birds of central Argentina.

Wild birds may be considered a possible source of parasitic mesostigmatid mites for poultry, but only few studies explored this hypothesis. In addition, there is very little information about the parasitic mites present in commercial poultry systems from southern South America. To contribute with data on parasitic mesostigmatid mites at the domestic-wildlife interface, we conducted a study in which samples were systematically collected from laying hens and wild birds (adults and nestlings), for two years at three commercial laying hen farms. The occurrence of mesostigmatid mites were compared among hosts. A proportion of the collected mites were morphologically identified to the species level, finding that host preference varied greatly depending on mite species: laying hens were only parasitized by Ornithonyssus sylviarum, wild bird nestlings were mostly parasitized by Ornithonyssus bursa, and in small proportion, by O. sylviarum, while adult passerines were parasitized by both Ornithonyssus species, and sporadically by Pellonyssus cf. reedi and Dermanyssus cf. triscutatus. In laying hens, there was intra- and inter-annual variability in mite occurrence, but no consistent seasonal pattern, whereas in adult wild birds, mites showed the highest prevalence in spring and the lowest in summer. Not coinciding with this general pattern, the occurrence of O. bursa matched the reproductive activity of wild birds. A phylogenetic analysis based on a fragment of the 16S rRNA gene was carried out for a subsample of the mites collected, showing that the O. sylviarum mites present on adult wild birds and laying hens had the same haplotype (100% identity). Additionally, mites obtained from wild birds morphologically identified as O. bursa presented two distinctive haplotypes (89.8% identity), one phylogenetically related to O. sylviarum and the other to O. monteiroi. These findings show that in central Argentina commercial laying hens are parasitized mainly by O. sylviarum while wild birds are also hosts to other mite species. Adult wild passerines, especially house sparrows, may be a source of O. sylviarum for commercial poultry.

Novel Ehrlichia Strain Infecting Cattle Tick Amblyomma neumanni, Argentina, 2018.

In 2018, we detected a novel Ehrlichia strain infecting Amblyomma neumanni ticks in Argentina. The novel strain is phylogenetically related to the ruminant pathogen E. ruminantium and represents a potential risk for veterinary and public health because A. neumanni ticks parasitize domestic and wild ruminants and bite humans.

A putative novel strain of Ehrlichia infecting Amblyomma tigrinum associated with Pampas fox (Lycalopex gymnocercus) in Esteros del Iberá ecoregion, Argentina.

The current work evaluated road-killed Pampas foxes (Lycalopex gymnocercus) and their ticks for the presence of vector-borne agents in the ecoregion Esteros del Iberá in northeastern Argentina. Spleen, lung and blood samples and Amblyomma tigrinum adult ticks collected from the foxes were tested by polymerase chain reaction (PCR) assays targeting bacteria of the genera Ehrlichia, Anaplasma, and Rickettsia. All foxes tested were negative for the three genera, but evidence of Ehrlichia and Rickettsia infection was detected in the ticks. One A. tigrinum (out of 12 tested) was infected by an ehrlichial agent, here named Ehrlichia sp. strain Iberá, related to ehrlichial agents recently detected in platypuses in Tasmania (Ornithorhynchus anatinus) and in voles (Myodes rutilus and Myodes rufocanus) and shrews (Sorex araneus) in the Russian Far East. Regarding Rickettsia, all A. tigrinum ticks (100%) were infected by ´Candidatus Rickettsia andeanae´, a member of the spotted fever group rickettsia of unknown pathogenicity. Further research is necessary to unveil the ecology of Ehrlichia sp. strain Iberá as well as its zoonotic relevance. The species of the genus Ehrlichia are known to be pathogenic to mammals, including humans and domestic animals, thus the presence of this ehrlichial agent in A. tigrinum is a potential risk for veterinary and public health, as the adults of A. tigrinum are common parasites of dogs in rural and peri-urban environments, and humans are also frequently bitten by this tick species.

Orthohantavirus genotype Lechiguanas in Oligoryzomys nigripes (Rodentia: Cricetidae): New evidence of host-switching.

To identify and predict situations of increased risk of orthohantavirus infection in humans, it is necessary to study the relationships between the virus and its rodent hosts. The present study investigated orthohantavirus infection in an assemblage of wild Sigmodontinae rodents of the Paraná Delta, Argentina, and providing new evidence of host-switching events. Rodents belonging to the species Oxymycterus rufus (n = 187), Akodon azarae (n = 82), Oligoryzomys flavescens (n = 80), Oligoryzomys nigripes (n = 47), Scapteromys aquaticus (n = 38), Deltamys kempi (n = 7) and Holochilus brasiliensis (n = 2) were captured at 4 sampling sites during 20 trapping sessions. Blood samples were analyzed by IgG ELISA and livers by a nested reverse transcription PCR for the diagnosis of orthohantavirus infection. The amplified products of the S and M orthohantavirus genomes were sequenced and analyzed to determine similarities with species of the Orthohantavirus genus. The species of the Oligoryzomys positive to the virus were confirmed by amplifying and sequencing the complete cyt b gene. Of the 443 serum samples analyzed by IgG ELISA, A. azarae presented the highest host-specific prevalence value (10/82, 12.2%) followed by Ol. nigripes (4/47, 8.5%) and Ox. rufus (1/187, 0.5%). All the sero-positive Ol. nigripes (n = 4) were positive to the amplification of the S and M segments of the Lechiguanas genotype (98% nucleotide identity for both segments). This is surprising given that Ol. nigripes has been previously associated with Juquitiba genotype, not Lechiguanas. The latter is generally associated with Ol. flavescens, which in our study were all sero-negative. In addition, the association Ox. rufus - Pergamino genotype found here is, to our knowledge, novel and another potential evidence of host-switching considering that Pergamino has been originally associated with A. azarae. These findings contribute to the building evidence that contradicts the one-genotype-one-reservoir species premise in the association between rodent reservoirs and orthohantaviruses, and supports the hypothesis that the community structure of sympatric host species may contribute to orthohantavirus dynamics.

A new Trichuris species (Nematoda: Trichuridae) from capybaras: Morphological-molecular characterization and phylogenetic relationships.

A new species of Trichuris (Nematoda: Trichuridae) is described from the capybara, Hydrochoeris hydrochaeris (Rodentia: Caviidae), from two localities of Corrientes Province, based on morphological characteristics and ITS1 and ITS2 of nuclear rDNA region sequences. This species present morphological differences with 28 species of the genus described from North and South American rodents. Also, the new species is molecularly characterized and differentiated from those species from Muridae, Cricetidae and Myocastoridae rodents recorded from North and South America, Europe and Africa. Trichuris cutillasae n. sp. constitutes the ninth record from rodents of Argentina, and the second record for Caviidae. The phylogenetic analysis showed that the specimens of new species are in the same clade, and separated from specimens of T. myocastoris (ITS1and ITS2), T. navonae, T. bainae, Trichuris sp. and T. pardinasi (ITS2). Similarly, analysis of concatenated sequences ITS1 and ITS2 added further evidence that T. cutillasae n. sp. is a different species from those previously analyzed.

Detection of Ehrlichia sp. strain San Luis and Candidatus Rickettsia andeanae in Amblyomma parvum ticks.

Owing to the sanitary importance of the tick Amblyomma parvum, this study evaluated the infection by Ehrlichia, Anaplasma and Rickettsia species of questing A. parvum collected in northwestern Argentina. Our results showed that A. parvum ticks in this region are infected with the recently reported Ehrlichia sp. strain San Luis, closely related to Ehrlichia chaffeensis. A high prevalence of Candidatus Rickettsia andeanae was observed. Most of the infected ticks presented rickettsial loads lower than those previously reported for other spotted fever group rickettsiae. The presence of Ehrlichia sp. strain San Luis in A. parvum is a potential risk for public health as the principal hosts of this tick are domestic mammals in rural areas and humans are frequently bitten by this tick species.

Calodium hepaticum (Nematoda: Capillariidae) in wild rodent populations from Argentina.

Calodium hepaticum (Nematoda; Capillariidae) is a parasitic nematode of mammals with a cosmopolitan distribution. Adults of this nematode can infect the liver of many mammalian species, including humans, but the main hosts are members of the superfamily Muroidea. Among these, Rattus spp. have the highest apparent prevalences reported worldwide. There are only two reports of C. hepaticum infecting Sigmodontinae species (Muroidea: Cricetidae). In this survey, we examined the occurrence of C. hepaticum in two assemblages of Sigmodontinae rodents from Argentina (Santa Fe and Entre Ríos provinces). The diagnosis was made by morphological features, histopathological exam, and molecular characterization of 18S ribosomal RNA gene region. Here, we show that C. hepaticum is a common parasite of Sigmodontinae. We report the infection in six species (all new hosts): Akodon azarae, Calomys callidus, Calomys venustus, Oligoryzomys flavescens, Oligoryzomys nigripes, and Oxymycterus rufus. This is the first report of C. hepaticum in Sigmodontinae rodents from Argentina and the second record in this subfamily for South America. It is also the first confirmation of C. hepaticum infection in Sigmodontinae by molecular diagnosis. The genetic findings and the prevalences observed, together with the existing information on C. hepaticum, lead us to propose that Rattus spp. brought C. hepaticum to the New World exposing Sigmodontinae rodents, which are frequently infected by this parasite. The high prevalence of infection in A. azarae (41.2%) suggests that this host may be playing an important role in C. hepaticum dynamics in the New World.

Primer informe de Leptospira interrogans en el roedor sigmodontino Scapteromys aquaticus

[RESUMEN]. La leptospirosis es una enfermedad zoonótica de distribución mundial que puede transmitirse por contacto directo o indirecto con orina o tejidos de animales infectados. En Argentina, la leptospirosis es endémica en la provincia de Santa Fe y presenta brotes epidémicos durante las inundaciones. Sin embargo, se sabe muy poco sobre el papel que cumplen los roedores silvestres en la diseminación de la enfermedad en el país. El objetivo de este estudio fue identificar las especies hospederas de leptospiras patógenas entre los roedores presentes en un asentamiento ribereño de la provincia de Santa Fe. Se realizó un muestreo de roedores durante octubre de 2015. Los riñones de los animales capturados se analizaron por real-time PCR para el gen LipL32 de leptospiras patógenas. En los animales que resultaron positivos, se realizó test de microaglutinación (MAT) y tipificación molecular por amplificación del gen 16S rRNA y dos esquemas de MLST. Se capturaron 37 roedores de las especies Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus rattus y Scapteromys aquaticus. En el análisis por real-time PCR resultó positivo un macho de Scapteromys aquaticus. El suero de este individuo y del resto de los S. aquaticus capturados (n = 18) se analizaron por test de microaglutinación (MAT), y fueron no reactivos para los 10 serovares probados. La amplificación del gen 16S rRNA identificó la especie infectante como Leptospira interrogans, mientras que no se obtuvo amplificación para los dos esquemas de MLST. El hallazgo de este estudio aporta nueva información acerca de presencia de leptospiras patógenas en roedores silvestres, que es relevante para la zona por tratarse de una especie ampliamente distribuida en ambientes pantanosos e inundables de América del Sur.

[ABSTRACT]. Leptospirosis is a globally distributed zoonosis that can be transmitted through direct or indirect contact with the urine or tissues of infected animals. In Argentina, leptospirosis is endemic in the province of Santa Fe and epidemic outbreaks occur during floods. However, very little is known about the role that wild rodents play in the spread of the disease in Argentina. The objective of this study was to identify the host species of pathogenic Leptospira among rodents in a riverine settlement in the province of Santa Fe. We conducted a trapping session in October 2015. Kidneys of the captured animals were analyzed by real-time PCR for the LipL32 gene of pathogenic Leptospira. Animals that were positive were subjected to microscopic agglutination test (MAT) and molecular typing by amplification of the 16S rRNA gene and two multilocus sequence typing (MLST) schemes. A total of 37 rodents of the species Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus rattus, and Scapteromys aquaticus were captured. Real-time PCR found one male Scapteromys aquaticus that was positive. The serum of this individual and of the rest of the S. aquaticus captured (n = 18) were analyzed by MAT and were non-reactive for the 10 serovars tested. Amplification of the 16S rRNA gene identified the infective species as Leptospira interrogans, while amplification could not be obtained for the two MLST schemes. The findings of this study contribute new information concerning the presence of pathogenic Leptospira in wild rodents, which is relevant in this region because the species is widely distributed in swampy and flood-prone environments of South America.

[RESUMO]. A leptospirose é uma doença zoonótica de distribuição mundial transmitida pelo contato direto ou indireto com a urina ou os tecidos de animais infectados. Na Argentina, a leptospirose é endêmica na Província de Santa Fé com surtos epidêmicos ocorrendo com as enchentes. Sabe-se pouco sobre o papel dos roedores silvestres na propagação da doença no país. O objetivo deste estudo foi identificar as espécies hospedeiras de leptospiras patogênicas em roedores encontrados em um núcleo de povoamento ribeirinho na Província de Santa Fé. A amostragem dos roedores foi feita no mês de outubro de 2015. Os tecidos dos rins dos animais capturados foram analisados com a técnica de reação em cadeia da polimerase em tempo real (PCR-RT) quanto à presença do gene LipL32 de leptospiras patógenas. Para os animais com resultados positivos, foi realizado o teste de microaglutinação (MAT) e tipagem molecular baseada na amplificação do gene 16S rRNA e dois esquemas de tipagem por sequenciamento de locos múltiplos (MLST). Ao todo, foram capturados 37 roedores das espécies Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus e Scapteromys aquaticus. O ensaio de PCR-RT foi positivo em um roedor macho da espécie Scapteromys aquaticus. Os soros deste animal e dos outros S. aquaticus capturados (n = 18) foram analisados com o MAT e os resultados foram não reagentes para os 10 sorovares testados. A amplificação do gene 16S rRNA permitiu identificar a espécie infetante como sendo Leptospira interrogans e não houve amplificação nos dois esquemas de MLST. O achado deste estudo fornece um novo dado quanto à presença de leptospiras patogênicas em roedores silvestres, importante para esta área por se tratar de uma espécie de ampla distribuição em terras pantanosas e inundáveis da América do Sul.

[First report on Leptospira interrogans in the sigmodontine rodent Scapteromys aquaticusPrimeiro relato da presença de Leptospira interrogans em roedores sigmodontíneos Scapteromys aquaticus]. / Primer informe de Leptospira interrogans en el roedor sigmodontino Scapteromys aquaticus.

Leptospirosis is a globally distributed zoonosis that can be transmitted through direct or indirect contact with the urine or tissues of infected animals. In Argentina, leptospirosis is endemic in the province of Santa Fe and epidemic outbreaks occur during floods. However, very little is known about the role that wild rodents play in the spread of the disease in Argentina. The objective of this study was to identify the host species of pathogenic Leptospira among rodents in a riverine settlement in the province of Santa Fe.We conducted a trapping session in October 2015. Kidneys of the captured animals were analyzed by real-time PCR for the LipL32 gene of pathogenic Leptospira. Animals that were positive were subjected to microscopic agglutination test (MAT) and molecular typing by amplification of the 16S rRNA gene and two multilocus sequence typing (MLST) schemes.A total of 37 rodents of the species Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus rattus, and Scapteromys aquaticus were captured. Real-time PCR found one male Scapteromys aquaticus that was positive. The serum of this individual and of the rest of the S. aquaticus captured (n = 18) were analyzed by MAT and were non-reactive for the 10 serovars tested. Amplification of the 16S rRNA gene identified the infective species as Leptospira interrogans, while amplification could not be obtained for the two MLST schemes.The findings of this study contribute new information concerning the presence of pathogenic Leptospira in wild rodents, which is relevant in this region because the species is widely distributed in swampy and flood-prone environments of South America.

A leptospirose é uma doença zoonótica de distribuição mundial transmitida pelo contato direto ou indireto com a urina ou os tecidos de animais infectados. Na Argentina, a leptospirose é endêmica na Província de Santa Fé com surtos epidêmicos ocorrendo com as enchentes. Sabe-se pouco sobre o papel dos roedores silvestres na propagação da doença no país. O objetivo deste estudo foi identificar as espécies hospedeiras de leptospiras patogênicas em roedores encontrados em um núcleo de povoamento ribeirinho na Província de Santa Fé.A amostragem dos roedores foi feita no mês de outubro de 2015. Os tecidos dos rins dos animais capturados foram analisados com a técnica de reação em cadeia da polimerase em tempo real (PCR-RT) quanto à presença do gene LipL32 de leptospiras patógenas. Para os animais com resultados positivos, foi realizado o teste de microaglutinação (MAT) e tipagem molecular baseada na amplificação do gene 16S rRNA e dois esquemas de tipagem por sequenciamento de locos múltiplos (MLST).Ao todo, foram capturados 37 roedores das espécies Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus e Scapteromys aquaticus. O ensaio de PCR-RT foi positivo em um roedor macho da espécie Scapteromys aquaticus. Os soros deste animal e dos outros S. aquaticus capturados (n = 18) foram analisados com o MAT e os resultados foram não reagentes para os 10 sorovares testados. A amplificação do gene 16S rRNA permitiu identificar a espécie infetante como sendo Leptospira interrogans e não houve amplificação nos dois esquemas de MLST.O achado deste estudo fornece um novo dado quanto à presença de leptospiras patogênicas em roedores silvestres, importante para esta área por se tratar de uma espécie de ampla distribuição em terras pantanosas e inundáveis da América do Sul.

Primer informe de Leptospira interrogans en el roedor sigmodontino Scapteromys aquaticus / First report on Leptospira interrogans in the sigmodontine rodent Scapteromys aquaticus / Primeiro relato da presença de Leptospira interrogans em roedores sigmodontíneos Scapteromys aquaticus

RESUMEN La leptospirosis es una enfermedad zoonótica de distribución mundial que puede transmitirse por contacto directo o indirecto con orina o tejidos de animales infectados. En Argentina, la leptospirosis es endémica en la provincia de Santa Fe y presenta brotes epidémicos durante las inundaciones. Sin embargo, se sabe muy poco sobre el papel que cumplen los roedores silvestres en la diseminación de la enfermedad en el país. El objetivo de este estudio fue identificar las especies hospederas de leptospiras patógenas entre los roedores presentes en un asentamiento ribereño de la provincia de Santa Fe. Se realizó un muestreo de roedores durante octubre de 2015. Los riñones de los animales capturados se analizaron por real-time PCR para el gen LipL32 de leptospiras patógenas. En los animales que resultaron positivos, se realizó test de microaglutinación (MAT) y tipificación molecular por amplificación del gen 16S rRNA y dos esquemas de MLST. Se capturaron 37 roedores de las especies Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus rattus y Scapteromys aquaticus. En el análisis por real-time PCR resultó positivo un macho de Scapteromys aquaticus. El suero de este individuo y del resto de los S. aquaticus capturados (n = 18) se analizaron por test de microaglutinación (MAT), y fueron no reactivos para los 10 serovares probados. La amplificación del gen 16S rRNA identificó la especie infectante como Leptospira interrogans, mientras que no se obtuvo amplificación para los dos esquemas de MLST. El hallazgo de este estudio aporta nueva información acerca de presencia de leptospiras patógenas en roedores silvestres, que es relevante para la zona por tratarse de una especie ampliamente distribuida en ambientes pantanosos e inundables de América del Sur.(AU)

ABSTRACT Leptospirosis is a globally distributed zoonosis that can be transmitted through direct or indirect contact with the urine or tissues of infected animals. In Argentina, leptospirosis is endemic in the province of Santa Fe and epidemic outbreaks occur during floods. However, very little is known about the role that wild rodents play in the spread of the disease in Argentina. The objective of this study was to identify the host species of pathogenic Leptospira among rodents in a riverine settlement in the province of Santa Fe. We conducted a trapping session in October 2015. Kidneys of the captured animals were analyzed by real-time PCR for the LipL32 gene of pathogenic Leptospira. Animals that were positive were subjected to microscopic agglutination test (MAT) and molecular typing by amplification of the 16S rRNA gene and two multilocus sequence typing (MLST) schemes. A total of 37 rodents of the species Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus rattus, and Scapteromys aquaticus were captured. Real-time PCR found one male Scapteromys aquaticus that was positive. The serum of this individual and of the rest of the S. aquaticus captured (n = 18) were analyzed by MAT and were non-reactive for the 10 serovars tested. Amplification of the 16S rRNA gene identified the infective species as Leptospira interrogans, while amplification could not be obtained for the two MLST schemes. The findings of this study contribute new information concerning the presence of pathogenic Leptospira in wild rodents, which is relevant in this region because the species is widely distributed in swampy and flood-prone environments of South America.(AU)

RESUMO A leptospirose é uma doença zoonótica de distribuição mundial transmitida pelo contato direto ou indireto com a urina ou os tecidos de animais infectados. Na Argentina, a leptospirose é endêmica na Província de Santa Fé com surtos epidêmicos ocorrendo com as enchentes. Sabe-se pouco sobre o papel dos roedores silvestres na propagação da doença no país. O objetivo deste estudo foi identificar as espécies hospedeiras de leptospiras patogênicas em roedores encontrados em um núcleo de povoamento ribeirinho na Província de Santa Fé. A amostragem dos roedores foi feita no mês de outubro de 2015. Os tecidos dos rins dos animais capturados foram analisados com a técnica de reação em cadeia da polimerase em tempo real (PCR-RT) quanto à presença do gene LipL32 de leptospiras patógenas. Para os animais com resultados positivos, foi realizado o teste de microaglutinação (MAT) e tipagem molecular baseada na amplificação do gene 16S rRNA e dois esquemas de tipagem por sequenciamento de locos múltiplos (MLST). Ao todo, foram capturados 37 roedores das espécies Akodon azarae, Cavia aperea, Oligoryzomys flavescens, Rattus e Scapteromys aquaticus. O ensaio de PCR-RT foi positivo em um roedor macho da espécie Scapteromys aquaticus. Os soros deste animal e dos outros S. aquaticus capturados (n = 18) foram analisados com o MAT e os resultados foram não reagentes para os 10 sorovares testados. A amplificação do gene 16S rRNA permitiu identificar a espécie infetante como sendo Leptospira interrogans e não houve amplificação nos dois esquemas de MLST. O achado deste estudo fornece um novo dado quanto à presença de leptospiras patogênicas em roedores silvestres, importante para esta área por se tratar de uma espécie de ampla distribuição em terras pantanosas e inundáveis da América do Sul.(AU)

Prevalence and infection intensity of Rickettsia massiliae in Rhipicephalus sanguineus sensu lato ticks from Mendoza, Argentina.

Rickettsia massiliae belongs to the spotted fever group and in the New World is commonly associated with the brown dog tick, Rhipicephalus sanguineus. Herein we investigate the presence of R. massiliae in Rh. sanguineus sensu lato ticks in a location near the Andean foothills (Mendoza, Argentina), to provide a prevalence estimate and to assess the infection intensity of this pathogen. Rickettsia massiliae infection was found in 5.1% of the Rh. sanguineus s.l ticks analyzed, all with high infection intensities. Molecular analysis determined that all R. massiliae-infected Rh. sanguineus s.l. ticks belonged to the temperate lineage.

Ecology of the interaction between Ixodes loricatus (Acari: Ixodidae) and Akodon azarae (Rodentia: Criceridae).

The present study explores associations of different factors (i.e. host parameters, presence of other ectoparasites and [mainly biotic] environmental factors) with burdens of Ixodes loricatus immature stages in one of its main hosts in Argentina, the rodent Akodon azarae. For 2 years, rodents were trapped and sampled monthly at 16 points located in four different sites in the Parana River Delta region. Data were analysed with generalized linear mixed models with a negative binomial response (counts of larvae or nymphs). The independent variables assessed were (a) environmental: trapping year, presence of cattle, type of vegetation, rodent abundance; (b) host parameters: body length, sex, body condition, blood cell counts, natural antibody titers and (c) co-infestation with other ectoparasites. Two-way interaction terms deemed a priori as relevant were also included in the analysis. Most of the associations investigated were found significant, but in general, the direction and magnitude of the associations were context-dependent. An exception was the presence of cattle, which was consistently negatively associated with both larvae and nymphs independently of all other variables considered and had the strongest effect on tick burdens. Mites, fleas and Amblyomma triste were also significantly associated (mostly positively) with larval and nymph burdens, and in many cases, they influenced associations with environmental or host factors. Our findings strongly support that raising cattle may have a substantial impact on the dynamics of I. loricatus and that interactions within the ectoparasite community may be an important-but generally ignored-driver of tick dynamics.