Epidemiological investigation of an acute case of Chagas disease in an area of active transmission in Peruvian Amazon region

The study objective was to investigate an acute case of Chagas disease in the San Pedro de Shishita community, Pebas District, in the Peruvian Amazon basin, a non-endemic area. Both parents of the index case (acute case) were thoroughly interviewed, a seroepidemiological survey was carried out in the community, parasitological exams were carried out only in relatives of the index case, and triatomine bugs were searched for inside houses, peridomiciliary, and in wild environments. Seroprevalence for IgG anti-T. cruzi antibodies was 1/104 (0.96%), using an ELISA test and an indirect immunofluorescence assay. Panstrongylus geniculatus and Rhodnius pictipes adults were found. The index case is autochthonous from San Pedro de Shishita, but the source of transmission is unknown.O objetivo deste trabalho foi estudar caso da doença de Chagas aguda na comunidade indígena de San Pedro de Shishita, sem conhecimento da origem da transmissão. San Pedro de Shishita, distrito Pebas, região da Amazônia peruana é uma área não endêmica. Foram entrevistados os pais do paciente e feito inquérito soroepidemiológico dos participantes e estudos parasitológicos da família e procurou-se também triatomíneos no ambiente doméstico, peridomiciliar e silvestre. A soroprevalência de anticorpos IgG anti-T. cruzi foi 1/ 104 (0,96%) por ELISA e imunofluorescência indireta. Foram encontrados adultos de Panstrongylus geniculatus e Rhodnius pictipe

Arboviral Etiologies of Acute Febrile Illnesses in Western South America, 2000–2007

Over recent decades, the variety and quantity of diseases caused by viruses transmitted to humans by mosquitoes and other arthropods (also known as arboviruses) have increased around the world. One difficulty in studying these diseases is the fact that the symptoms are often non-descript, with patients reporting such symptoms as low-grade fever and headache. Our goal in this study was to use laboratory tests to determine the causes of such non-descript illnesses in sites in four countries in South America, focusing on arboviruses. We established a surveillance network in 13 locations in Ecuador, Peru, Bolivia, and Paraguay, where patient samples were collected and then sent to a central laboratory for testing. Between May 2000 and December 2007, blood serum samples were collected from more than 20,000 participants with fever, and recent arbovirus infection was detected for nearly one third of them. The most common viruses were dengue viruses (genera Flavivirus). We also detected infection by viruses from other genera, including Alphavirus and Orthobunyavirus. This data is important for understanding how such viruses might emerge as significant human pathogens

Oportunidad en el diagnóstico y tratamiento de la malaria en comunidades periurbanas de la amazonía peruana

Objetivos: Evaluar la capacidad del Ministerio de Salud (MINSA) para el diagnóstico y tratamiento oportuno de malaria en las comunidades periféricas de la ciudad de Iquitos. Materiales y métodos: En el año 2001 se entrevistó a pacientes febriles atendidos por promotores de salud debido a la sospecha de malaria, se contrastó lo obtenido en las entrevistas con las fichas de tratamiento y los registros de resultados de gota gruesa en los centros de salud de la jurisdicción. Resultados: Transcurrió un promedio de tres días entre la toma de la muestra y la obtención de resultado de gota gruesa por el promotor. De los 200 febriles encuestados, 71 (35%) tuvo resultado de gota gruesa positivo. Los promotores iniciaron tratamiento presuntivo en 28 (39%) de estos casos, pero el tratamiento fue adecuado a la especie sólo en 19 (26%). Asimismo, los promotores iniciaron tratamiento presuntivo para malaria a 13 (10%) febriles con gota gruesa negativa. Conclusiones: En las comunidades periféricas de Iquitos los pacientes con malaria tienen que esperar en promedio tres días para un tratamiento adecuado, los pacientes buscan atención rápidamente pero las demoras dependen de la organización de los servicios

Rickettsiosis, enfermedad emergente en Loreto. Evidencia serológica de 20 casos

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Mechanisms for gas-phase molecular formation of neutral formaldehyde (H

Context. Formaldehyde is a potential biogenic precursor involved in prebiotic chemical evolution. The cold conditions of the interstellar medium (ISM) allow H2CO to be reactive, playing a significant role as a chemical intermediate in formation pathways leading to interstellar complex organic molecules. However, gas-phase molecular formation mechanisms in cold regions of the ISM are poorly understood. Aims. We computationally determine the most favored gas-phase molecular formation mechanisms at local thermodynamic equilibrium conditions that can produce the detected amounts of H2CO in diffuse molecular clouds (DMCs), in dark, cold, and dense molecular clouds (DCDMCs), and in three regions of circumstellar envelopes of low-mass protostars (CELMPs). Methods. The potential energy surfaces, thermodynamic functions, and single-point energies for transition states were calculated at the CCSD(T)-F12/cc-pVTZ-F12 and MP2/aug-cc-pVDZ levels of theory and basis sets. Molecular thermodynamics and related partition functions were obtained by applying the Maxwell-Boltzmann quantum statistics theory from energies computed at CCSD(T)-F12/cc-pVTZ-F12 with corrections for zero-point energy. A literature review on detected abundances of reactants helped us to propose the most favorable formation routes. Results. The most probable reactions that produce H2CO in cold astrophysical regions are: 1CH2 + ⋅3O2 →1H2CO + O⋅(3P) in DMCs, ⋅3CH2 + ⋅3O2 →1H2CO + ⋅O(3P) in DCDMCs, and ⋅CH3 + ⋅O(3P) →1H2CO + ⋅H in region III, ⋅CH3 +⋅O(1D) →1H2CO + ⋅H in region II, and 1CH2 + ⋅3O2 →1H2CO + ⋅O(3P) in region I belonging to CELMPs. Conclusions. Quantum chemical calculations suggest that the principal carbonaceous precursors of H2CO in cold regions for the gas-phase are CH2(a1A1), and ⋅CH2(X3B1) combined with ⋅O2(3Σg) and ⋅CH3(2A”) + ⋅O(3P) / O(1D). Reactions based on more complex reagents yield less effective thermodynamics in the gas-phase H2CO molecular formation

Gas-phase molecular formation mechanisms of cyanamide (NH

Context. Cyanamide (NH2CN) and its tautomer carbodiimide (NHCHN) are believed to have been key precursors of purines and pyrimidines during abiogenesis on primitive Earth. The detection of guanine and cytosine in meteorites and comets provides evidence of their nonterrestrial formation. Although NH2CN has been found in several molecular clouds, NHCHN has only been detected in Sgr B2(N). Their possible molecular formation mechanisms in the gas phase and therefore their respective molecular precursors remain an open subject of investigation. Aims. The main objective of this paper is to determine which reactions can produce NH2CN and HNCNH in the amounts observed under the astrophysical conditions of Sgr B2(N). The determination of their most likely precursors could serve to provide new insights into possible routes to purine and pyrimidine synthesis, and by extension to nucleosides, under the astrophysical conditions of dense molecular clouds. Methods. Initially, we proposed 120 reaction mechanisms, 60 being dedicated to NH2CN formation and the remaining 60 to HNCNH. These mechanisms were constructed using 25 chemical species that were identified in outer space. We calculated the molecular energies of reactants and products at the CCSD(T)-F12/cc-pVTZ-F12 and MP2/aug-cc-pVDZ levels of theory, and defined the values of thermodynamic functions using the Maxwell-Boltzmann statistical quantum theory. Via an extensive literature review on the abundances of reactants and products in Sgr B2(N), in addition to a detailed kinetic study for a range of 20–300 K, we identify the most likely reaction mechanisms for both cyanamides of those proposed previously and presently. Results. From the 120 analyzed reactions, only nine for NH2CN and four for HNCNH could thermodynamically account for their synthesis in Sgr B2(N). The kinetic portion of our study shows that Ra60 (CH3NH2 +·CN → NH2CN +·CH3), with a modified Arrhenius expression of ${k_{\rm{T}}} = 1.22 \times {10^{ - 9}}{\left( {{T \over {300}}} \right)^{ - 0.038}}{\exp ^ - }\left( {{{ - 147.34} \over T}} \right) \rm{cm}^3 \rm{mol}^{-1} \rm{s}^{-1}$, is the most efficient reaction at low temperatures (<60 K). Above 60 K, no reaction with known reagents in Sgr B2(N) is efficient enough. In this way, Ra37-2 (·HNCN +·NH2 → NH2CN +3NH) appears to be the most likely candidate, showing a modified Arrhenius constant of ${k_{\rm{T}}} = 2.51 \times {10^{ - 11}}{\left( {{T \over {300}}} \right)^{ - 32.18}}{\exp ^ - }\left( {{{ - 1.332} \over T}} \right) \rm{cm}^3 \rm{mol}^{-1} \rm{s}^{-1}$. In the case of carbodiimide production, Rb18 (·H2NC +·NH2 → HNCNH +·H) is the most efficient reaction, fitting a rate constant of ${k_{\rm{T}}} = 4.70 \times {10^{ - 13}}{\left( {{{300} \over T}} \right)^{ - 3.24}}{\exp ^ - }\left( {{{36.28} \over T}} \right) \rm{cm}^3 \rm{mol}^{-1} \rm{s}^{-1}$ in Sgr B2(N). Conclusions. The detected gas-phase abundances of cyanamide (NH2CN) in Sgr B2(N) can be explained as: Ra60 (·CN +·CH3NH2) from 20 to 60 K; Ra5: (·CN +·NH2) from 60 to 120 K; and Ra37-2 (·HNCN +·NH2) from 120 to 300 K. The carbodiimide (HNCNH) synthesis could proceed via Rb18 (·H2NC +·NH2). Moreover, the presence of·HNCN and·H2NC in Sgr B2(N) are predicted here, making them viable candidates for future astronomical observations. The foreseen column density for the cyanomidil radical is ~1016 cm2 s−1 at 150 K or higher, while for amino methylidine, the value is a few 1013 cm2 s−1 at 100 K