Author Correction: Surveillance of vector-borne pathogens under imperfect detection: lessons from Chagas disease risk (mis)measurement.

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Surveillance of vector-borne pathogens under imperfect detection: lessons from Chagas disease risk (mis)measurement.

Vector-borne pathogens threaten human health worldwide. Despite their critical role in disease prevention, routine surveillance systems often rely on low-complexity pathogen detection tests of uncertain accuracy. In Chagas disease surveillance, optical microscopy (OM) is routinely used for detecting Trypanosoma cruzi in its vectors. Here, we use replicate T. cruzi detection data and hierarchical site-occupancy models to assess the reliability of OM-based T. cruzi surveillance while explicitly accounting for false-negative and false-positive results. We investigated 841 triatomines with OM slides (1194 fresh, 1192 Giemsa-stained) plus conventional (cPCR, 841 assays) and quantitative PCR (qPCR, 1682 assays). Detections were considered unambiguous only when parasitologists unmistakably identified T. cruzi in Giemsa-stained slides. qPCR was >99% sensitive and specific, whereas cPCR was ~100% specific but only ~55% sensitive. In routine surveillance, examination of a single OM slide per vector missed ~50-75% of infections and wrongly scored as infected ~7% of the bugs. qPCR-based and model-based infection frequency estimates were nearly three times higher, on average, than OM-based indices. We conclude that the risk of vector-borne Chagas disease may be substantially higher than routine surveillance data suggest. The hierarchical modelling approach we illustrate can help enhance vector-borne disease surveillance systems when pathogen detection is imperfect.

Synanthropic triatomines as potential vectors of Trypanosoma cruzi in Central Brazil

Abstract INTRODUCTION: Chagas disease surveillance requires current knowledge on synanthropic triatomines. We analyzed the occurrence and Trypanosoma cruzi infection rates of triatomine bugs in central Brazil, during 2012-2014. METHODS: Triatomines were collected inside or around houses, and T. cruzi infection was determined by optical microscopy and conventional/quantitative polymerase chain reaction. RESULTS: Of the 2706 triatomines collected, Triatoma sordida was the most frequent species in Goiás State, whereas Panstrongylus megistus predominated in the Federal District. Parasites identified were T. cruzi, T. rangeli, and Blastocrithidia sp. CONCLUSIONS: P. megistus and T. sordida sustained the risk of T. cruzi transmission to humans in central Brazil.

Synanthropic triatomines as potential vectors of Trypanosoma cruzi in Central Brazil.

INTRODUCTION: Chagas disease surveillance requires current knowledge on synanthropic triatomines. We analyzed the occurrence and Trypanosoma cruzi infection rates of triatomine bugs in central Brazil, during 2012-2014. METHODS: Triatomines were collected inside or around houses, and T. cruzi infection was determined by optical microscopy and conventional/quantitative polymerase chain reaction. RESULTS: Of the 2706 triatomines collected, Triatoma sordida was the most frequent species in Goiás State, whereas Panstrongylus megistus predominated in the Federal District. Parasites identified were T. cruzi, T. rangeli, and Blastocrithidia sp. CONCLUSIONS: P. megistus and T. sordida sustained the risk of T. cruzi transmission to humans in central Brazil.

Occurrence and characterization of Acanthamoeba similar to genotypes T4, T5, and T2/T6 isolated from environmental sources in Brasília, Federal District, Brazil.

Species of Acanthamoeba can cause keratitis and brain infections. The characterization of environmental isolates is necessary to analyze the risk of human infection. We aimed at identifying and genotyping Acanthamoeba isolates from soil, swimming pools, and water features in Brasília, Federal District, Brazil, as well as determining their physiological characteristics and pathogenic potential. Among the 18 isolates studied, eight were similar to genotype T5, five to T4, and one to T2/T6, classified by the sequence analysis of 18S rDNA. Genotypes of four isolates were not determined. Ten isolates (55%) grew at 37 °C and seven (39%) grew in media with 1.5M mannitol, which are the physiological parameters associated with pathogenic Acanthamoeba; also, four isolates from swimming pools presented high pathogenic potential. Our results indicate a widespread distribution of potentially pathogenic Acanthamoeba T4, T5, and T2/T6 in different environmental sources in Brasília, revealing the potential risk of human infection and the need of preventive measures.

[Comparative biology and feeding behavior of Rhodnius neglectus and Rhodnius robustus (Triatominae) under laboratory conditions]. / Biologia comparativa e comportamento alimentar de Rhodnius neglectus e Rhodnius robustus (Triatominae) sob condições de laboratório.

INTRODUCTION: The vector competence of triatomine insects is determined by studying their biology and feeding behavior under field and/or laboratory conditions. Factors including the number of bites, the amount of blood ingested and defecation time have implications for trypanosome transmission. The biological and behavioral parameters of Rhodnius neglectus and R. robustus were compared under experimental conditions to estimate differences in the potential transmission of trypanosomes. METHODS: The insects were observed daily to determine the period of nymphal development, mortality, detection of food source, number of bites, time of blood meal intake, amount of blood ingested, time elapsed between the end of the meal and the first defecation and the frequency of defecation. RESULTS: Although the nymphal development of R. neglectus (156.4 ± 25.05d) was lower than that of R. robustus (204.7 ± 13.22d), the mortality between species was similar (63.8 and 65% respectively).R. robustus and R. neglectus quickly located the food source, especially in the first instar (2.5 and 1.6 min, respectively). Although the time of blood meal intake was similar between the species, R. robustus ingested a larger amount of blood on average at all stages and exhibited higher values for the fifth instar. Nymphs of R. neglectus bit more frequently, and they defecated faster and more often than those of R. robustus. CONCLUSIONS: Under laboratory conditions, R. neglectus has a greater potential for transmission of Trypanosoma cruzi and T. rangeli than does R. robustus, an attribute that should be further evaluated in experimental infections.

Biologia comparativa e comportamento alimentar de Rhodnius neglectus e Rhodnius robustus (Triatominae) sob condições de laboratório / Comparative biology and feeding behavior of Rhodnius neglectus and Rhodnius robustus (Triatominae) under laboratory conditions

INTRODUÇÃO: A competência vetorial de triatomíneos é determinada a partir de estudos sobre biologia e comportamento alimentar em condições de campo e/ou laboratório. Fatores como número de picadas, quantidade de sangue ingerido e tempo de defecação têm implicações na transmissão de tripanosomatídeos. Parâmetros biológicos e comportamentais de Rhodnius neglectus e R. robustus foram comparados experimentalmente para estimar diferenças no potencial de transmissão de tripanosomatídeos. MÉTODOS: Os triatomíneos foram observados diariamente para determinar o período de desenvolvimento ninfal, mortalidade, detecção da fonte alimentar, número de picadas, tempo do repasto sanguíneo, quantidade de sangue ingerido, tempo entre o final do repasto e a primeira defecação e frequência de defecação. RESULTADOS: Apesar do período ninfal de R. neglectus (156,4 ± 25,05d) ter sido menor que o de R. robustus (204,7 ± 13,22d), a mortalidade foi similar entre as espécies (63,8 e 65%, respectivamente). R. robustus e R. neglectus detectaram rapidamente a fonte alimentar, especialmente no primeiro estádio (2,5 e 1,6min, respectivamente). Apesar do tempo de repasto sanguíneo ter sido similar entre as espécies, R. robustus ingeriu em média uma maior quantidade de sangue em todos os estádios, com maiores valores para as ninfas V. As ninfas de R. neglectus picaram mais vezes as fontes alimentares, defecaram mais rápido e mais frequentemente que as de R. robustus. CONCLUSÕES: Sob as condições de laboratório usadas, R. neglectus possui um maior potencial para transmissão de Trypanosoma cruzi e T. rangeli que R. robustus, atributo que deve ser avaliado em infecções experimentais.

INTRODUCTION: The vector competence of triatomine insects is determined by studying their biology and feeding behavior under field and/or laboratory conditions. Factors including the number of bites, the amount of blood ingested and defecation time have implications for trypanosome transmission. The biological and behavioral parameters of Rhodnius neglectus and R. robustus were compared under experimental conditions to estimate differences in the potential transmission of trypanosomes. METHODS: The insects were observed daily to determine the period of nymphal development, mortality, detection of food source, number of bites, time of blood meal intake, amount of blood ingested, time elapsed between the end of the meal and the first defecation and the frequency of defecation. RESULTS: Although the nymphal development of R. neglectus (156.4 ± 25.05d) was lower than that of R. robustus (204.7 ± 13.22d), the mortality between species was similar (63.8 and 65% respectively).R. robustus and R. neglectus quickly located the food source, especially in the first instar (2.5 and 1.6 min, respectively). Although the time of blood meal intake was similar between the species, R. robustus ingested a larger amount of blood on average at all stages and exhibited higher values for the fifth instar. Nymphs of R. neglectus bit more frequently, and they defecated faster and more often than those of R. robustus. CONCLUSIONS: Under laboratory conditions, R. neglectus has a greater potential for transmission of Trypanosoma cruzi and T. rangeli than does R. robustus, an attribute that should be further evaluated in experimental infections.

Predicting the potential geographical distribution of Rhodnius neglectus (Hemiptera, Reduviidae) based on ecological niche modeling.

Rhodnius neglectus is frequently found in palm trees and bird nests in sylvatic environments. However, adult specimens infected by Trypanosoma cruzi have been invading houses in central Brazil. Analyzing and predicting the geographical distribution of this species may improve vector surveillance strategies for Chagas disease. Ecological niche modeling using the genetic algorithm for rule-set production (GARP) was applied to predict the geographical distribution of R. neglectus from occurrence records and a set of 23 predictor variables (e.g., temperature, precipitation, altitude, and vegetation). Additionally, the geographical distribution of R. neglectus was compared with the geographical distribution of four species of palm trees and two species of birds from the study region. The models were able to predict, with high probability, the occurrence of R. neglectus as a regular (although nonendemic) species of the Cerrado biome in central Brazil. Caatinga, Amazonian savanna, Pantanal, and the Bolivian Chaco appear as areas with lower probabilities of potential occurrence for the species. A great overlap was observed between the distribution of R. neglectus, palm trees (Acrocomia aculeata and Syagrus oleracea), and birds (Phacellodomus ruber and Pseudoseisura cristata). By including new records for R. neglectus (from both sylvatic and domestic environments), our study showed a distribution increase toward the west and northeast areas of Brazil in the "diagonal of open/dry ecoregions of South America". These results should aid Chagas disease vector surveillance programs, given that household invasion by Rhodnius species maintains the risk of disease transmission and limits control strategies.

Triatomines (Hemiptera, Reduviidae) prevalent in the northwest of Peru: species with epidemiological vectorial capacity

The development of strategies for the adequate control of the vector transmission of Chagas disease depends on the availability of updated data on the triatomine species present in each region, their geographical distribution, natural infections by Trypanosoma cruzi and/or T. rangeli, eco-biological characteristics and synanthropic behavioral tendencies. This paper summarizes and updates current information, available in previously published reports and obtained by the authors our own field and laboratory studies, mainly in northwest of Peru. Three triatomine species exhibit a strong synanthropic behavior and vector capacity, being present in domestic and peridomestic environments, sometimes showing high infestation rates: Rhodnius ecuadoriensis, Panstrongylus herreri and Triatoma carrioni The three species should be given continuous attention by Peruvian public health authorities. P. chinai and P. rufotuberculatus are bugs with increasing potential in their role as vectors according to their demonstrated synanthropic tendency, wide distribution and trophic eclecticism. Thus far we do not have a scientific explanation for the apparent absence ofT. dimidiata from previously reported geographic distributions in Peru. It is recommended, in the Peruvian northeastern Amazon region, the development of field studies on species of the genus Rhodnius, as well as of other triatominae, to evaluate their present Trypanosomatidae vector capacity.

El desarrollo de estrategias adecuadas para el control de la transmisión vectorial de la Enfermedad de Chagas depende: de la disponibilidad de datos actualizados de las especies de triatominos presentes en cada región, de su distribución geográfica, infección natural por Trypanosoma cruzi ylo T. rangeli, características eco-biológicas y tendencias de comportamiento sinantrópico. Este trabajo resume y actualiza la información disponible en la literatura y aquella obtenida en nuestros estudios de campo y de laboratorio desarrollados en los últimos años por los autores, predominantemente, en la región Nor-Occidental del Perú. El resultado de esas observaciones es la detección de que, tres especies de triatominos presentan un importante comportamiento sinantrópico y capacidad vectorial, ocupando ambientes intradomiciliares y peridomiciliares: Rhodnius ecuadoriensis, Panstrongylus herreri y Triatoma carrioni. Las tres especies deben recibir constante atención por parte de las autoridades de Salud Pública Peruana. P. chinai y P rufotuberculatus tienen potencial creciente en su papel de vectores, por la comprobada tendencia sinantrópica, distribución geográfica y eclecticismo trófico. Se desconocen las causas de la aparente ausencia actual de Triatoma dimidiata, dada su presencia constatada anteriormente en el Perú. Se recomienda que en la región Nor-Oriental Amazónica Peruana se realicen en forma urgente estudios sobre las especies del genero Rhodnius y de otros triatominos que permitan evaluar la real capacidad vectorial de los Trypano-somatideos.

Estudo comparativo de técnicas de demonstraçao de amastigotas e isolamento de promastigotas no diagnóstico de leishmanione tegumentar americana

O PCR tem alta sensibilidade no diagnóstico da LTA, mas é caro e distante da prática. A cultura e o esfregaço são práticos, mas pouco sensíveis. O objetivo deste trabalho foi comparar os dois últimos métodos, buscando maior sensibilidade e menor custo.Foram comparados três meios de cultura no isolamento de leishmânia: Difco agar sangue + Schneider + soro bovino fetal (20 por cento); Difco agar sangue + Schneider + urina humana (2por cento); Schneider + urina humana (2por cento). Foram comparadas, também, duas técnicas de pesquisa de amastigotas: esfregaço realizado com biópsia, ou raspado através de palito (matchstick). Os índices de positividade e contaminação (29 a 33por cento e 8 a 11por cento, respectivamente, p>0.05) foram semelhantes na comparação dos cultivos. Os esfregaços com biópsia, ou palito também não tiveram diferenças significativas (14 e 19 por cento, respectivamente, p> 0,05). A Leishmania (Vianna) braziliensis predominou. No Brasil, a urina pode substituir o soro fetal bovino. Há vantagem na relação custo/benefício. A urina não tem custo enquanto 500ml de soro bovino fetal custa 185 dólares

Infecçöes por parasitas oportunistas em pacientes HIV/SIDA positivos, no Hospital Universitário de Brasília / Opportunistic infections in HIV/AIDS-positive patients at the Brasilia University Hospital

Objetivo: O presente trabalho visa determinar a frequência de parasitas oportunistas em pacientes HIV/SIDA positivos, do Hospital Universitário de Brasília, com ênfase aos Coccídios e Microsporídios, empregando técnicas simples e baratas de coloração para microscopia de luz. Material e métodos: Foram realizados dois estudos (restrospectivo e prospectivo). No estudo retrospectivo, foram aleatoriamente analisados prontuários médicos dos pacientes HIV/SIDA positivos, avaliados e acompanhados no Hospital Universitário de Brasília, e preenchida uma ficha clínica-epidemiológica. Paralelamente, foram realizadas duas avaliações, em períodos e populações diferentes, das amostras coprológicas que foram examinadas na Seção de Parasitologia, do Laboratório Central do hospital. Para o estudo prospectivo, foi implantado um ambulatório especial, onde foram avaliados e examinados os pacientes. No final de cada entrevista, uma ficha clínica-epidemiológica foi preenchida e amostras de fezes foram coletadas, em formalina a 10 por cento e a fresco, para posterior exame por meio de técnicas coprológicas de sedimentação, centrifugação e concentração, e técnicas específicas de coloração, para identificação e medição dos parasitas encontrados. Resultados: Os resultados revelaram a presença de protozoários intestinais, tais como: Isospora belli, Cryptosporidium sp e Cyclospora sp. O único helminto de destaque foi o Strongyloides stercoralis. Existe uma elevada frequência de protozoários intestinais nos pacientes HIV positivos, quando examinados apropriadamente por meio das técnicas de coloração recomendadas para microscopia de luz. Conclusão: Na nossa casuística, ainda não detectamos Microsporídios, fazendo suspeitar baixa prevalência, em nosso meio, ou de cepas pouco patogênicas e expressivas clinicamente ou, talvez consequência da terapia anti-retroviral aplicada. Esses são aspectos que focalizaremos na continuidade desta pesquisa