RESUMEN

BACKGROUND: The Gran Chaco ecoregion is a well-known hotspot of several neglected tropical diseases (NTDs) including Chagas disease, soil-transmitted helminthiasis and multiparasitic infections. Interspecific interactions between parasite species can modify host susceptibility, pathogenesis and transmissibility through immunomodulation. Our objective was to test the association between human co-infection with intestinal parasites and host parasitaemia, infectiousness to the vector and immunological profiles in Trypanosoma cruzi-seropositive individuals residing in an endemic region of the Argentine Chaco. METHODS: We conducted a cross-sectional serological survey for T. cruzi infection along with an intestinal parasite survey in two adjacent rural villages. Each participant was tested for T. cruzi and Strongyloides stercoralis infection by serodiagnosis, and by coprological tests for intestinal parasite detection. Trypanosoma cruzi bloodstream parasite load was determined by quantitative PCR (qPCR), host infectiousness by artificial xenodiagnosis and serum human cytokine levels by flow cytometry. RESULTS: The seroprevalence for T. cruzi was 16.1% and for S. stercoralis 11.5% (n = 87). We found 25.3% of patients with Enterobius vermicularis. The most frequent protozoan parasites were Blastocystis spp. (39.1%), Giardia lamblia (6.9%) and Cryptosporidium spp. (3.4%). Multiparasitism occurred in 36.8% of the examined patients. Co-infection ranged from 6.9% to 8.1% for T. cruzi-seropositive humans simultaneously infected with at least one protozoan or helminth species, respectively. The relative odds of being positive by qPCR or xenodiagnosis (i.e. infectious) of 28 T. cruzi-seropositive patients was eight times higher in people co-infected with at least one helminth species than in patients with no such co-infection. Trypanosoma cruzi parasite load and host infectiousness were positively associated with helminth co-infection in a multiple regression analysis. Interferon-gamma (IFN-γ) response, measured in relation to interleukin (IL)-4 among humans infected with T. cruzi only, was 1.5-fold higher than for T. cruzi-seropositive patients co-infected with helminths. The median concentration of IL-4 was significantly higher in T. cruzi-seropositive patients with a positive qPCR test than in qPCR-negative patients. CONCLUSIONS: Our results show a high level of multiparasitism and suggest that co-infection with intestinal helminths increased T. cruzi parasitaemia and upregulated the Th2-type response in the study patients.

Asunto(s)

Enfermedad de Chagas , Coinfección , Helmintiasis , Parasitosis Intestinales , Trypanosoma cruzi , Humanos , Trypanosoma cruzi/inmunología , Trypanosoma cruzi/genética , Trypanosoma cruzi/aislamiento & purificación , Coinfección/parasitología , Coinfección/epidemiología , Coinfección/inmunología , Enfermedad de Chagas/epidemiología , Enfermedad de Chagas/complicaciones , Enfermedad de Chagas/parasitología , Enfermedad de Chagas/sangre , Enfermedad de Chagas/inmunología , Animales , Adulto , Estudios Transversales , Masculino , Femenino , Parasitosis Intestinales/epidemiología , Parasitosis Intestinales/parasitología , Parasitosis Intestinales/complicaciones , Parasitosis Intestinales/inmunología , Persona de Mediana Edad , Helmintiasis/complicaciones , Helmintiasis/parasitología , Helmintiasis/epidemiología , Helmintiasis/inmunología , Adulto Joven , Adolescente , Argentina/epidemiología , Estudios Seroepidemiológicos , Strongyloides stercoralis/inmunología , Strongyloides stercoralis/aislamiento & purificación , Parasitemia/parasitología , Parasitemia/epidemiología , Células Th2/inmunología , Niño , Estrongiloidiasis/epidemiología , Estrongiloidiasis/parasitología , Estrongiloidiasis/complicaciones , Estrongiloidiasis/inmunología , Estrongiloidiasis/sangre , Anciano , Citocinas/sangre , Anticuerpos Antiprotozoarios/sangre

RESUMEN

BACKGROUND: The emergence of pyrethroid resistance has threatened the elimination of Triatoma infestans from the Gran Chaco ecoregion. We investigated the status and spatial distribution of house infestation with T. infestans and its main determinants in Castelli, a municipality of the Argentine Chaco with record levels of triatomine pyrethroid resistance, persistent infestation over 2005-2014, and limited or no control actions over 2015-2020. METHODS: We conducted a 2-year longitudinal survey to assess triatomine infestation by timed manual searches in a well-defined rural section of Castelli including 14 villages and 234 inhabited houses in 2018 (baseline) and 2020, collected housing and sociodemographic data by on-site inspection and a tailored questionnaire, and synthetized these data into three indices generated by multiple correspondence analysis. RESULTS: The overall prevalence of house infestation in 2018 (33.8%) and 2020 (31.6%) virtually matched the historical estimates for the period 2005-2014 (33.7%) under recurrent pyrethroid sprays. While mean peridomestic infestation remained the same (26.4-26.7%) between 2018 and 2020, domestic infestation slightly decreased from 12.2 to 8.3%. Key triatomine habitats were storerooms, domiciles, kitchens, and structures occupied by chickens. Local spatial analysis showed significant aggregation of infestation and bug abundance in five villages, four of which had very high pyrethroid resistance approximately over 2010-2013, suggesting persistent infestations over space-time. House bug abundance within the hotspots consistently exceeded the estimates recorded in other villages. Multiple regression analysis revealed that the presence and relative abundance of T. infestans in domiciles were strongly and negatively associated with indices for household preventive practices (pesticide use) and housing quality. Questionnaire-derived information showed extensive use of pyrethroids associated with livestock raising and concomitant spillover treatment of dogs and (peri) domestic premises. CONCLUSIONS: Triatoma infestans populations in an area with high pyrethroid resistance showed slow recovery and propagation rates despite limited or marginal control actions over a 5-year period. Consistent with these patterns, independent experiments confirmed the lower fitness of pyrethroid-resistant triatomines in Castelli compared with susceptible conspecifics. Targeting hotspots and pyrethroid-resistant foci with appropriate house modification measures and judicious application of alternative insecticides with adequate toxicity profiles are needed to suppress resistant triatomine populations and prevent their eventual regional spread.

Asunto(s)

Enfermedad de Chagas , Resistencia a los Insecticidas , Insecticidas , Piretrinas , Triatoma , Animales , Triatoma/efectos de los fármacos , Triatoma/fisiología , Piretrinas/farmacología , Argentina , Insecticidas/farmacología , Enfermedad de Chagas/transmisión , Enfermedad de Chagas/epidemiología , Humanos , Estudios Longitudinales , Insectos Vectores/efectos de los fármacos , Insectos Vectores/fisiología , Vivienda , Ecosistema , Control de Insectos

RESUMEN

The South American Dry Diagonal, also called the Diagonal of Open Formations, is a large region of seasonally dry vegetation extending from northeastern Brazil to northern Argentina, comprising the Caatinga, Cerrado, and Chaco subregions. A growing body of phylogeography literature has determined that a complex history of climatic changes coupled with more ancient geological events has produced a diverse and endemic-rich Dry Diagonal biota. However, the exact drivers are still under investigation, and their relative strengths and effects are controversial. Pleistocene climatic fluctuations structured lineages via vegetation shifts, refugium formation, and corridors between the Amazon and Atlantic forests. In some taxa, older geological events, such as the reconfiguration of the São Francisco River, uplift of the Central Brazilian Plateau, or the Miocene inundation of the Chaco by marine incursions, were more important. Here, we review the Dry Diagonal phylogeography literature, discussing each hypothesized driver of diversification and assessing degree of support. Few studies statistically test these hypotheses, with most support drawn from associating encountered phylogeographic patterns such as population structure with the timing of ancient geoclimatic events. Across statistical studies, most hypotheses are well supported, with the exception of the Pleistocene Arc Hypothesis. However, taxonomic and regional biases persist, such as a proportional overabundance of herpetofauna studies, and the under-representation of Chaco studies. Overall, both Pleistocene climate change and Neogene geological events shaped the evolution of the Dry Diagonal biota, though the precise effects are regionally and taxonomically varied. We encourage further use of model-based analyses to test evolutionary scenarios, as well as interdisciplinary collaborations to progress the field beyond its current focus on the traditional set of geoclimatic hypotheses.

Asunto(s)

Filogeografía , Cambio Climático , América del Sur , Biodiversidad , Clima Tropical

RESUMEN

PURPOSE: Cosmocercids are common nematodes that parasitize the digestive tract and lungs of amphibians and reptiles around the world. They are commonly found in leptodactylid and bufonid anurans in South America, primarily in Brazil and Argentina. This paper describes a new species of genus Cosmocerca based on specimens collected in a microhylid from the Dry Chaco ecoregion. METHODS: A total of 18 specimens of Elachistocleis haroi were collected in October 2011 in Chaco province and in December 2021 and March 2022 in Formosa province, Argentina, both areas of the Dry Chaco ecoregion. The morphology of the nematodes was studied in detail using light microscopy and scanning electron microscopy. RESULTS: One hundred and fifty-one nematodes were collected from the large intestines of E. haroi. Based on the morphology of the caudal papillae (rosette papillae and plectanes), the presence of two spicules and the absence of caudal alae in males, and the presence of two prodelphic ovaries in females, these specimens were allocated to the genus Cosmocerca. However, they presented unique characteristics that differentiate them from all known species. Cosmocerca wichiorum sp. nov. is similar to C. archeyi, C. australis, C. sardiniae, C. zugi, and C. leytensis by having four pairs of plectanes, but can be easily distinguished from all of them by the type, number, and arrangement of the precloacal (non-plectanes), adcloacal and postcloacal papillae, by the length of the spicules and by its different zoogeographical distribution. CONCLUSION: This is the 14th species of the genus Cosmocerca described in South America and the first one for the microhylid E. haroi from the Dry Chaco ecoregion.

Asunto(s)

Microscopía Electrónica de Rastreo , Animales , Masculino , Femenino , Argentina , Microscopía Electrónica de Rastreo/veterinaria , Anuros/parasitología , Anfibios/parasitología , Intestino Grueso/parasitología

RESUMEN

BACKGROUND AND AIMS: Whole-plant performance in water-stressed and disturbance-prone environments depends on a suitable supply of water from the roots to the leaves, storage of reserves during periods of shortage, and a morphological arrangement that guarantees the maintenance of the plants anchored to the soil. All these functions are performed by the secondary xylem of roots. Here, we investigate whether different growth forms of Fabaceae species from the seasonally dry Neotropical environment have distinct strategies for water transport, mechanical support and non-structural carbon and water storage in the root secondary xylem. METHODS: We evaluated cross-sections of root secondary xylem from species of trees, shrubs and subshrubs. We applied linear models to verify the variability in secondary xylem anatomical traits among growth forms. KEY RESULTS: Secondary xylem with larger vessels and lower vessel density was observed in tree species. Vessel wall thickness, vessel grouping index, potential hydraulic conductivity and cell fractions (vessels, fibres, rays and axial parenchyma) were not statistically different between growth forms, owing to the high interspecific variation within the groups studied. CONCLUSION: Our results showed that the variability in anatomical traits of the secondary xylem of the root is species specific. In summary, the cellular complexity of the secondary xylem ensures multiple functional strategies in species with distinct growth forms, a key trait for resource use in an environment with strong water seasonality.

Asunto(s)

Fabaceae , Xilema/anatomía & histología , Árboles/anatomía & histología , Hojas de la Planta/anatomía & histología , Agua

RESUMEN

BACKGROUND: The Gran Chaco region is a major hotspot of Chagas disease. We implemented a 9-year program aimed at suppressing house infestation with Triatoma infestans and stopping vector-borne transmission to creole and indigenous (Qom) residents across Pampa del Indio municipality (Argentine Chaco). The aim of the present study was to assess the intervention effects on parasite-based transmission indices and the spatial distribution of the parasite, and test whether house-level variations in triatomine infection with Trypanosoma cruzi declined postintervention and were influenced by household ethnicity, persistent infestation linked to pyrethroid resistance and other determinants of bug infection. METHODS: This longitudinal study assessed house infestation and bug infection with T. cruzi before and after spraying houses with pyrethroids and implemented systematic surveillance-and-response measures across four operational areas over the period 2007-2016. Live triatomines were individually examined for infection by optical microscopy or kinetoplast DNA (kDNA)-PCR and declared to be infected with T. cruzi when assessed positive by either method. RESULTS: The prevalence of infection with T. cruzi was 19.4% among 6397 T. infestans examined. Infection ranged widely among the study areas (12.5-26.0%), household ethnicity (15.3-26.9%), bug ecotopes (1.8-27.2%) and developmental stages (5.9-27.6%), and decreased from 24.1% (baseline) to 0.9% (endpoint). Using random-intercept multiple logistic regression, the relative odds of bug infection strongly decreased as the intervention period progressed, and increased with baseline domestic infestation and bug stage and in Qom households. The abundance of infected bugs and the proportion of houses with ≥ 1 infected bug remained depressed postintervention and were more informative of area-wide risk status than the prevalence of bug infection. Global spatial analysis revealed sharp changes in the aggregation of bug infection after the attack phase. Baseline domestic infestation and baseline bug infection strongly predicted the future occurrence of bug infection, as did persistent domestic infestation in the area with multiple pyrethroid-resistant foci. Only 19% of houses had a baseline domestic infestation and 56% had ever had ≥ 1 infected bug. CONCLUSIONS: Persistent bug infection postintervention was closely associated with persistent foci generated by pyrethroid resistance. Postintervention parasite-based indices closely agreed with human serosurveys at the study endpoint, suggesting transmission blockage. The program identified households and population subgroups for targeted interventions and opened new opportunities for risk prioritization and sustainable vector control and disease prevention.

Asunto(s)

Enfermedad de Chagas , Piretrinas , Triatoma , Trypanosoma cruzi , Animales , Humanos , Triatoma/parasitología , Prevalencia , Estudios Longitudinales , Insectos Vectores/parasitología , Enfermedad de Chagas/epidemiología , Enfermedad de Chagas/prevención & control , Piretrinas/farmacología , ADN de Cinetoplasto , Argentina/epidemiología

RESUMEN

A combination of tiletamine-zolazepam, medetomidine, and azaperone was used to immobilize captive Chacoan peccaries (Catagonus wagneri) for health assessments and biological sample collection at the Centro Chaqueño para la Conservación e Investigación (CCCI) in the Paraguayan Chaco during July in 2017 and 2018. In total, 83 peccaries kept in 0.25-1.50 hectare enclosures were immobilized via dart-administered anesthetic. Mean animal weight was 33.89±3.74 kg (standard deviation; n=77). The mean intramuscular (IM) anesthetic drug and dosages were 0.03±0.00 mg/kg of medetomidine, 0.91±0.10 mg/kg of Zoletil 50 (tiletamine-zolazepam), and 0.30±0.03 mg/kg azaperone. The mean time to recumbency after darting was 6.07±2.65 min. The mean time to reach the anesthetic plane postdarting was 10.00±2.00 min. Muscle relaxation was adequate to allow minor veterinary procedures. A mean dosage of 0.15±0.02 mg/kg of atipamezole was given IM to reverse the medetomidine. Recoveries were smooth and animals were standing by 59.17±30.18 min postreversal. Full recovery and release back to enclosures occurred 90±30 min postreversal. A single dose of this drug combination provided adequate anesthesia for 88% of adult Chacoan peccaries; 12% needed a supplemental dose of tiletamine-zolazepam because of failure to receive the full dose from the anesthetic dart. Sex and age did not impact the dosage required to achieve immobilization. Confinement during recovery from anesthesia is required with this protocol. Aside from mild hypoxemia, no adverse effects from anesthesia were observed. However, oxygen supplementation as a part of this protocol is recommended to support circulatory and respiratory capacity.

Asunto(s)

Anestésicos , Artiodáctilos , Animales , Medetomidina/farmacología , Tiletamina , Zolazepam , Azaperona/farmacología , Oxígeno , Paraguay , Combinación de Medicamentos , Artiodáctilos/fisiología , Terapia por Inhalación de Oxígeno/veterinaria , Inmovilización/veterinaria , Inmovilización/métodos , Hipnóticos y Sedantes , Anestésicos Disociativos

RESUMEN

In this paper, we developed an innovative and plural methodology for a socio-cultural assessment of ecosystem services (ES). This methodology was performed using diverse and interdependent tools applied within the framework of ethnoecology and post-normal science, with the aim of identifying ES from the perspective of local communities that inhabit different socio-ecosystems, highlighting the relevance of Indigenous and Local Knowledge (ILK). As examples of how this methodology works, we analyzed a multiple case study performed in three peasant communities of the Dry Chaco eco-region, Argentina. We identified ES in all the categories and their fundamental contributions to the particular way of life in this area. The method is flexible enough to be used in other socio-ecosystems with different environmental and social features.

Asunto(s)

Ecosistema , Conocimiento , Argentina , Conservación de los Recursos Naturales/métodos

RESUMEN

Chagas disease is more prevalent in socially vulnerable communities in the Gran Chaco Eco-region. The study evaluated the seroprevalence of Chagas disease and associated factors between May 2014 and September 2015, in indigenous communities of Santa Fe, Argentina, in the southern Chaco. Lysate ELISA and indirect hemagglutination tests were used to detect antibodies against Trypanosoma cruzi, and recombinant ELISA was used in the case of disagreement. Household surveys were conducted with the head of household about risk factors for the disease. Serological tests were conducted on 298 people from three indigenous communities, 127 male and 171 female. Seroprevalence was 18.5%. A total of 64 surveys were conducted; 82.8% of the heads of household were male, with a median age of 39 years, and 61.0% had not completed primary school. In 35.9% of the households, there was at least one member of the cohabiting group infected with T. cruzi. The level of education of the head of household showed a statistically significant association with Chagas disease (OR = 3.43), among all the risk factors studied. The prevalence of infection is lower than that of other indigenous communities of the Gran Chaco, probably because environmental conditions are moderating and disfavoring the establishment of the insect vector in homes, but also because of socioeconomic differences with the rest of the eco-region. Beyond this, serological controls are needed to prevent vertical transmission.

RESUMEN

In order to provide a reassessment of the Neotropical genus Pseudonannolene Silvestri, 1895, a cladistic analysis, biogeographic analysis, and taxonomic review were conducted in the present work. For the cladistic approach, 91 morphological characters were scored for 53 terminals as the ingroup and 10 as the outgroup. Three synapomorphies support the monophyly of the genus: presence of a longitudinal suture on the promentum, penial bases partially fused, and the internal branch of the gonopods surrounding the telopodite; and two homoplastic transformations: the lateral lobe of the collum densely striated and setae present up to the apical portion of the prefemoral process on the first leg-pair of males. The genus Pseudonannolene is recovered as sister-group of Epinannolene Brölemann, 1903 (Pseudonannoleninae). A total of 226 occurrence points were recorded for Pseudonannolene, with the majority of records from the Chacoan subregion, composed by Araucaria Forest, Atlantic, and Parana Forest provinces. The biogeographical searches using the Geographically explicit Event Model recovered two biogeographic reconstructions (cost of 79 000), with the vicariance events occurring more frequently in the deep clades, whereas sympatry and points of sympatry occurred in more inclusive clades. The first reconstruction recovered four vicariances, 13 sympatries, 4 points of sympatry, and 21 founder events, and the second reconstruction recovered four vicariances, 12–13 sympatries, 4–5 points of sympatry, and 21 founder events. The genus Pseudonannolene comprises 56 species, including 8 new species herein described: P. alata sp. nov., P. aurea sp. nov., P. bucculenta sp. nov., P. curvata sp. nov., P. granulata sp. nov., P. insularis sp. nov., P. morettii sp. nov., and P. nicolau sp. nov.; P. brevis Silvestri, 1902 and P. rugosetta Silvestri, 1897 are regarded as species inquirendae; a neotype of P. alegrensis Silvestri, 1897 is here proposed with male described for the first time. The following taxa are synonymized: P. canastra Gallo & Bichuette, 2020 and P. saguassu Iniesta & Ferreira, 2013 with P. ambuatinga Iniesta & Ferreira, 2013; P. marconii Iniesta & Ferreira, 2013 with P. longicornis (Porat, 1888); P. chaimowiczi Fontanetti, 1996, P. gogo Iniesta & Ferreira, 2013, P. rosineii Iniesta & Ferreira, 2014, P. taboa Iniesta & Ferreira, 2014, and P. longissima Iniesta & Ferreira, 2014 with P. microzoporus Mauriès, 1987; P. tricolor gracilis Brölemann, 1902 and P. tricolor rugosus Schubart, 1945 with P. tricolor Brölemann, 1902; P. auguralis Silvestri, 1902 with P. rocana Silvestri, 1902; and P. abbreviata Silvestri, 1902 with P. typica Silvestri, 1895. P. inops Brölemann, 1929 is proposed here as new status from P. bovei inops. A dichotomous identification key is presented to facilitate the species identification.

RESUMEN

This article analyzes bottom-up institution-building processes in a region considered deforestation and environmental degradation hotspot. Utilizing the constitutionality approach developed by Haller, Acciaioli, and Rist (2016), we examine two recent cases of bottom-up institution-building in the department of Rivadavia, Chaco Salteño, Argentina. We highlight the similarities and differences between both constitutionality processes and identify various weaknesses in the two cases. We argue that constitutionality, understood as a process, has occurred to different (incomplete) degrees in each case. Finally, we show that external catalyzing agents play a decisive role in enabling or hampering the constitutionality process. Our study contributes to the literature on common-pool resource governance by highlighting how collective action can lead to participatory-development processes.

RESUMEN

In the Gran Chaco region, the Pan American Health Organization (PAHO) declared the interruption of vector transmission of Chagas Disease in Paraguay and some district of Argentina.After a bibliographic search, by using the words "Chagas, prevalence, children, Chaco", on scientiphic articles indexed in Pubmed and Lilacs during the 2010-2021 period, we found nine studies which dealt with entomological data seroprevalence surveys of Chagas Disease in Argentine children and three studies in Bolivian children.More field studies need to be published to better understand the epidemiological situation in children from the region. Due to its social and ecological characteristics, the Gran Chaco region remains a hotspot for Chagas Disease affecting disproportionally rural communities and certain vulnerable ethnics groups.

Asunto(s)

Enfermedad de Chagas , Trypanosoma cruzi , Enfermedad de Chagas/diagnóstico , Enfermedad de Chagas/epidemiología , Niño , Humanos , Prevalencia , Población Rural , Estudios Seroepidemiológicos

RESUMEN

BACKGROUND: Triatomine elimination efforts and the interruption of domestic transmission of Trypanosoma cruzi are hampered by pyrethroid resistance. Fluralaner, a long-lasting ectoparasiticide administered to dogs, substantially reduced site infestation and abundance of pyrethroid-resistant Triatoma infestans Klug (Heteroptera: Reduviidae) in an ongoing 10-month trial in Castelli (Chaco Province, Argentina). We assessed the effects of fluralaner on vector infection with T. cruzi and blood meal sources stratified by ecotope and quantified its medium-term effects on site infestation and triatomine abundance. METHODS: We conducted a placebo-controlled, before-and-after efficacy trial of fluralaner in 28 infested sites over a 22-month period. All dogs received either an oral dose of fluralaner (treated group) or placebo (control group) at 0 month post-treatment [MPT]. Placebo-treated dogs were rescue-treated with fluralaner at 1 MPT, as were all eligible dogs at 7 MPT. Site-level infestation and abundance were periodically assessed by timed manual searches with a dislodging aerosol. Vector infection was mainly determined by kDNA-PCR and blood meal sources were determined by enzyme-linked immunosorbent assay. RESULTS: In fluralaner-treated households, site infestation dropped from 100% at 0 MPT to 18-19% over the period 6-22 MPT while mean abundance plummeted from 5.5 to 0.6 triatomines per unit effort. In control households, infestation dropped similarly post-treatment. The overall prevalence of T. cruzi infection steadily decreased from 13.8% at 0-1 MPT (baseline) to 6.4% and subsequently 2.3% thereafter, while in domiciles, kitchens and storerooms it dropped from 17.4% to 4.7% and subsequently 3.3% thereafter. Most infected triatomines occurred in domiciles and had fed on humans. Infected-bug abundance plummeted after fluralaner treatment and remained marginal or nil thereafter. The human blood index of triatomines collected in domiciles, kitchens and storerooms highly significantly fell from 42.9% at baseline to 5.3-9.1% over the period 6-10 MPT, increasing to 36.8% at 22 MPT. Dog blood meals occurred before fluralaner administration only. The cat blood index increased from 9.9% at baseline to 57.9-72.7% over the period 6-10 MPT and dropped to 5.3% at 22 MPT, whereas chicken blood meals rose from 39.6% to 63.2-88.6%. CONCLUSION: Fluralaner severely impacted infestation- and transmission-related indices over nearly 2 years, causing evident effects at 1 MPT, and deserves larger efficacy trials.

Asunto(s)

Enfermedad de Chagas , Insecticidas , Piretrinas , Triatoma , Trypanosoma cruzi , Animales , Argentina/epidemiología , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/prevención & control , Enfermedad de Chagas/veterinaria , Perros , Humanos , Insectos Vectores , Insecticidas/farmacología , Isoxazoles , Piretrinas/farmacología

RESUMEN

Several species of reptiles and mammals have components in their sera that can neutralize toxic components present in snake venoms. In this manuscript, we studied the neutralizing capacity of Chaco eagle's (Buteogallus coronatus) serum. This South American bird of prey eats snakes as a regular part of its diet and has anatomical features that protect from snakes' bites. The neutralizing potency of the Chaco eagle's serum was tested on lethal, hemorrhagic, procoagulant, and phospholipase activities of the venom of "yarará grande" (Bothrops alternatus) and on phospholipase activity of "yarará ñata" (Bothrops ammodytoides) venom; both snakes are known to be the prey of Chaco eagle. Sera of crested caracara (Caracara plancus-a scavenger, omnivorous pan-American bird of prey), secretary bird (Saggitarius serpentarius-an omnivorous bird of prey from Africa that can include venomous snakes in its diet), common hen (Gallus gallus), rat (Rattus norvegicus), mouse (Mus musculus), horse (Equus caballus), and dog (Canis lupus familiaris) were also tested to compare the inhibitory capacity of neutralization. To test isologous and xenologous neutralization, sera from Bothrops alternatus and white-eared opossum (Didelphis albiventris), respectively, were used due to their known inhibitory activity on Bothrops venoms. As a control for the neutralization activity, antibothropic antivenom was used. Chaco eagle's serum neutralized hemorrhagic and phospholipasic activity and slightly neutralized the coagulation and the lethal activity of Bothrops spp. venom. The neutralizing capacity was present in the non-immunoglobulin fraction of the serum, which showed components of acidic characteristics and lower molecular weight than IgY, in correspondence with the characteristics of PLA2s and SVMPs inhibitors described in sera from some snakes and mammals. These studies showed that Chaco eagle's serum neutralizes all toxic activities tested at a higher level than sera from animal species in which inhibitors of snake venoms have not been described (p < 0.05), while it is lower or similar in neutralizing capacity to white-eared opossum and B. alternatus sera.

Asunto(s)

Bothrops , Venenos de Crotálidos , Águilas , Mordeduras de Serpientes , Animales , Antivenenos/farmacología , Pollos , Venenos de Crotálidos/toxicidad , Perros , Femenino , Hemorragia , Caballos , Mamíferos , Ratones , Pruebas de Neutralización , Fosfolipasas , Ratas , Venenos de Serpiente , Serpientes

RESUMEN

The aims were to study the epidemiology and the effect of gastrointestinal nematodes (GINs) on yearling cattle in a semiarid region in Argentina and to evaluate the mineral serum levels. Ten- to twelve-month-old calves were monitored between November and April 2019. Animals were divided into three groups: untreated control (CONG; n = 20); group treated with moxidectin (MXD, 200 µg/kg) every 30-40 days (MXDG; n = 20); group equally MXD treated and mineral supplementation administered in November and January (MMG; n = 20). Individual GIN egg counts (epg) and fecal cultures were made every 30-40 days. Animal live weight gain was determined. On 7-11-18, 25-1-19, and 3-4-19, serum levels of Se, Cu, Zn, Mg, and Ca were determined by atom absorption spectrophotometry. At the start of the trial, epg values were low (x̄ = 5.5), which increased only in CONG towards the end of the assay (x̄ = 229). In both GMXD and MMG, epg remained very low (x̄ = 4.1). Cooperia spp. (81%) prevailed over Haemonchus spp. (9%) and Oesophagostomum spp. (9%). Deficiency of Se ranged between marginal and important, except for MMG, although mean values were always below normal. Cu was marginally deficient in CONG and MXDG on the first two sampling dates, whereas MMG had normal values after treatment. Mg had low values in the three groups (x̄ = 1.5 mg/dl), whereas Ca and Zn exhibited normal values. Live weight gain (LWG) was higher in MMG than in MXDG, with significant differences (p < 0.05) by mid-January and then, when epg increased, dewormed groups showed higher LWG (p < 0.034) than CONG. A negative effect of GINs on LWG was observed, as well as low to marginal levels of Se, Cu, and Mg.

Asunto(s)

Enfermedades de los Bovinos , Nematodos , Infecciones por Nematodos , Animales , Argentina/epidemiología , Bovinos , Enfermedades de los Bovinos/epidemiología , Heces , Tracto Gastrointestinal , Infecciones por Nematodos/epidemiología , Infecciones por Nematodos/veterinaria , Recuento de Huevos de Parásitos/veterinaria

RESUMEN

The Bajos Submeridionales (BBSS) (Argentina) is a 54,800 km2 hydrological system located at the distal part of the Salado-Juramento Fluvial Megafan (SJRM). Its climate evolves from humid-subtropical in the east to semiarid in the west. Its hydrogeological system is typical of extensive plains, topography locally imposes vertical flows and neotectonic elements define system boundaries and drains. These characteristics and poor data availability represent a major challenge for identifying a hierarchical subsurface flow system and the influence of neotectonics. This work characterizes the hydrogeology of the BBSS and proposes a conceptual model based on integrated systematic information including 453 water level, 145 hydrochemical, and 99 δ18O- δD data. Four hydrogeological units are identified (HU1-HU4), two of which are divided into sub-units based on their sedimentary sequence. The main chemical types are Na-Cl, Na-Cl/SO4, Na-HCO3/Cl, Na-Cl/HCO3, and HCO3-Na. Dominant ions are Na, Cl, and SO4. Measured electrical conductivity reaches values as high as 132,000 µS/cm. Water chemistry modifying processes include halite, gypsum, and carbonate dissolution; ion exchange; inter-HU water mixing; and evapo-concentration. δ18O-δD and EC-δ18O suggest the existence of subsurface flow sectors. In the south, shallow and medium depth groundwater flows respond to the current circulation of the SJRM. Recharge occurs in the sub-Andean Ranges and point discharges, at the western lakes and some lakes of the Golondrina-Calchaquí system. Precipitation recharges shallow flows locally in the north, center, and east. Extreme west HU2 and HU1 receive deep upward thermal flows through structural lineaments. Thus, the Otumpa Hills morpho-structure would be a barrier to shallow HU1 flow, though not to deep regional HU2 and HU4 flows. Regional groundwater flow is from NW to SE and both local and regional flows would discharge in the Paraná River. The new conceptual model developed helps to further understand the groundwater system of a large plain in South America.

Asunto(s)

Agua Subterránea , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Agua Subterránea/química , Ríos , Sodio , Agua , Contaminantes Químicos del Agua/análisis

RESUMEN

Home to more than twenty indigenous languages belonging to six linguistic families, the Gran Chaco has raised the interest of many linguists from different backgrounds. While some have focused on finding deeper genetic relations between different language groups, others have looked into similarities from the perspective of areal linguistics. In order to contribute to further research of areal and genetic features among these languages, we have compiled a comparative wordlist consisting of translational equivalents for 326 concepts - representing basic and ethnobiological vocabulary - for 26 language varieties. Since the data were standardized in various ways, they can be analyzed both quantitatively and qualitatively. In order to illustrate this in detail, we have carried out an initial computer-assisted analysis of parts of the data by searching for shared lexicosemantic patterns resulting from structural rather than direct borrowings.

RESUMEN

We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid-resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo-controlled before-and-after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control-house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site-level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner-treated group, infestation dropped significantly from 100% at baseline to 19% over 6-10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8-0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0-14.7 - triatomines at 0-1 MPT to 4.0-4.2 over 6-10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site-level infestation and abundance of pyrethroid-resistant T. infestans and should be tested more widely in Phase III efficacy trials.

Asunto(s)

Enfermedad de Chagas , Enfermedades de los Perros , Insecticidas , Piretrinas , Triatoma , Trypanosoma cruzi , Animales , Argentina , Enfermedad de Chagas/prevención & control , Enfermedad de Chagas/veterinaria , Enfermedades de los Perros/prevención & control , Perros , Insectos Vectores , Insecticidas/farmacología , Isoxazoles , Piretrinas/farmacología

RESUMEN

We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid-resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo-controlled before-and-after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control-house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site-level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner-treated group, infestation dropped significantly from 100% at baseline to 19% over 6-10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8-0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0-14.7 - triatomines at 0-1 MPT to 4.0-4.2 over 6-10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site-level infestation and abundance of pyrethroid-resistant T. infestans and should be tested more widely in Phase III efficacy trials.

Asunto(s)

Piretrinas , Resistencia a los Insecticidas , Enfermedad de Chagas , Control de Vectores de las Enfermedades , Isoxazoles

RESUMEN

We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid-resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo-controlled before-and-after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control-house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site-level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner-treated group, infestation dropped significantly from 100% at baseline to 19% over 6-10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8-0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0-14.7 - triatomines at 0-1 MPT to 4.0-4.2 over 6-10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site-level infestation and abundance of pyrethroid-resistant T. infestans and should be tested more widely in Phase III efficacy trials.

Asunto(s)

Triatoma , Enfermedad de Chagas , Insecticidas , Enfermedad