In this paper further information concerning the ecological and biogeographical aspects of scorpionism is presented. Some of the information already outlined in three previous publications(10,14,16) is assessed, and new data given concerning the pattern of distribution presented by Tityus serrulatus in Brazil. Some new ideas are also proposed regarding the possible evolutionary advantages and disadvantages of parthenogenesis versus sexuality in both the short-term and the long-term
Summaryobjective To determine the influence of climate and of environmental vector control with or without insecticide on Aedes aegypti larval indices and pupae density.methods An 18-month longitudinal survey of infestation of Ae. aegypti immature stages was conducted for the 1015 residences (premises) of Vila Planalto, an area of Brasilia where the Breteau Index was about 40 before the study. This area was divided into five zones: a control zone with environmental management alone and four zones with insecticide treatment (methoprene, Bti, temephos). We tested for significant differences between infestation levels in the control and insecticidetreated areas, for relationships between climatic variables and larval indices, and to determine risk factors of infestation for certain types of premises and containers.results Environmental vector control strategies dramatically decreased infestation in the five areas. No significant differences could be detected between control strategies with insecticide and without. Some premises and container types were particularly suitable for breeding. The influence of climate on the emergence of Ae. aegypti adults for the area is described.conclusion In a moderately infested area such as Brasilia, insecticides do not improve environmental vector control. Rather, infestations could be further reduced by focusing on residences and containers particularly at risk. The nature of the link between climate and larval population should be investigated in larger-scale studies before being used in forecasting models.
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.
This retrospective analysis considered the number of adults and nymphs of each species collected and infected in both intradomicile and peridomicile. Results: A total of 754 triatomines were collected in 252 reported domiciles. Panstrongylus megistus was the most frequent species (65%), followed by T. pseudomaculata (14%). Of the 309 examined insects, only 3 (1%) specimens of P. megistus were infected with flagellates morphologically similar to Trypanosoma cruzi. The spatial occurrence indicated a higher diversity of triatomines and frequency of T. sordida in rural areas. Moreover, there was a predominance of P. megistus in urban areas. The number of records of P. megistus in the rainy season was two times higher than that during the dry season. The largest number of triatomines was collected in November. Conclusions: The presence of P. megistus specimens infected with trypanosomes in domiciles, shows the potential risk of human infection in DF. Thus, it is essential to continue entomological surveillance, intensifying it in the rainy season and in regions of greater occurrence. Keywords: Chagas disease control. Entomological surveillance. Synanthropic triatomines. Federal District. Brazil. triatomines. Furthermore, the invasion and/or colonization of infected triatomines from wild ecotopes may represent the risk of vectorial transmission with the installation of peridomiciliary and domiciliary cycles of T. cruzi 6,7 . In this context, the objective of this paper is to analyze the spatial and temporal occurrence of triatomine species collected in DF, as well as their indices of natural infection with trypanosomes to direct actions of entomological surveillance of Chagas disease coordinated by SES-DF. RESUMO 72 METHODS RESULTS Maeda MH et al -Occurrence of triatomines in DF Study areaThe Federal District of Brazil is geographically located between the parallels 15º30' and 16º03' south latitude, and between meridians 47°25' and 48°12' west longitude, in Central Brazil, one of the highest areas of the region, the Central Plateau. According to 2010 Census results, the population comprises 2,563,963 people in an area of 5,787,784km 2 divided into 30 administrative regions 8 . The area is filled with plateaus over 1,000m in altitude. The average annual rainfall is around 1,600mm, and the average annual temperature ranges between 18°C and 20°C with two distinct seasons, the dry season from May to September and the rainy season from October to April, the latter season with the highest temperature records 9 . Triatomine collection and natural infectionThe insects were collected in intradomiciliary and peridomiciliary environments by residents and then taken to the PITs. Each PIT receives a kit with materials for insect storage, a notepad to keep notes containing the address and location of collection, and tweezers for the handling of specimens.After notification, the SES-DF public health agents did active searches in these houses and their annexes. The materials used for triatomine collection were metal tweezers and fl...
BackgroundNeotropical primates are important sylvatic hosts of Trypanosoma cruzi, the etiological agent of Chagas disease. Infection is often subclinical, but severe disease has been described in both free-ranging and captive primates. Panstrongylus megistus, a major T. cruzi vector, was found infesting a small-primate unit at Brasília zoo (ZooB), Brazil. ZooB lies close to a gallery-forest patch where T. cruzi circulates naturally. Here, we combine parasitological and molecular methods to investigate a focus of T. cruzi infection involving triatomine bugs and Neotropical primates at a zoo located in the Brazilian Savannah.MethodsWe assessed T. cruzi infection in vectors using optical microscopy (n = 34) and nested PCR (n = 50). We used quantitative PCR (qPCR) to examine blood samples from 26 primates and necropsy samples from two primates that died during the study. We determined parasite lineages in five vectors and two primates by comparing glucose-6-phosphate isomerase (G6pi) gene sequences.ResultsTrypanosoma cruzi was found in 44 vectors and 17 primates (six genera and eight species); one Mico chrysoleucus and one Saguinus niger had high parasitaemias. Trypanosoma cruzi DNA was detected in three primates born to qPCR-negative mothers at ZooB and in the two dead specimens. One Callithrix geoffroyi became qPCR-positive over a two-year follow-up. All G6pi sequences matched T. cruzi lineage TcI.ConclusionsOur findings strongly suggest vector-borne T. cruzi transmission within a small-primate unit at ZooB – with vectors, and perhaps also parasites, presumably coming from nearby gallery forest. Periodic checks for vectors and parasites would help eliminate T. cruzi transmission foci in captive-animal facilities. This should be of special importance for captive-breeding programs involving endangered mammals, and would reduce the risk of accidental T. cruzi transmission to keepers and veterinarians.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1334-7) contains supplementary material, which is available to authorized users.
ObjectiveTo study the susceptibility status of Aedes aegypti to the organophosphate insecticide temephos. Methods Samples of Ae. aegypti larvae were obtained, using ovitraps, from eight cities of the Federal District, central Brazil, in 2000 and 2001. Larvae were submitted to the diagnostic dose of 0.012 mg/l temephos, as recommended by standard World Health Organization methodology. Field populations were tested in parallel with reference strains Rockefeller and DIVAL, from the Environmental Surveillance Directory (DIVAL) insectary. The concentration and purity of temephos solutions were verified by gas chromatography. Correlation calculations were performed using StatView -SAS Institute Inc., version 5. Student's t test was used for detecting differences in susceptibility, with significance levels of α=0.05. ResultsIn 2000, Ae. aegypti larvae populations from Taguatinga, Guará, and Núcleo Bandeirante showed resistance to temephos, with mortality ranging from 54.1 to 63.4%. The populations from Gama, Planaltina, and Sobradinho showed altered levels of susceptibility (mortality ranging from 83.6 to 92.8%). The population from Ceilândia was the only susceptible one, with 98% mortality. In 2001, all populations tested were resistant (44.4 to 66.4% mortality). No significant correlation was found between the susceptibility of populations and the distance between the cities of origin, or the amount of insecticide applied in the years preceding the study. Conclusions Ae. aegypti susceptibility to temephos is changing in the Federal District. It is essential to continue monitoring the resistance of this vector to insecticides in order to ensure the efficiency of programs aimed at vector control and at the protection of human health.
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 identifi ed 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.
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