Toxicological profile of deltamethrin in Triatoma brasiliensis (Hemiptera: Reduviidae) in State of Ceará, Northeastern Brazil

INTRODUCTION: Triatoma brasiliensis is the species of greatest epidemiological relevance in the semi-arid region of Brazil. This species is predominantly found in domestic environments, and it has the ability to build large colonies with high levels of natural infection via Trypanosoma cruzi. Thus, T. brasiliensis is one of the most efficient transmitters of Chagas disease (CD) to humans. Despite household spraying with residual insecticides, many areas report persistent reinfestations for reasons that remain poorly understood. Therefore, this study sought to characterize the toxicological profile of deltamethrin in T. brasiliensis from areas with persistent reinfestation in State of Ceará, Brazil. METHODS: The susceptibility reference lineage (SRL) was derived from Umari. Serial dilutions of deltamethrin were prepared and applied to the dorsal abdomen of first instar nymphs. The control group received only pure acetone. Mortality was evaluated after 72h. Qualitative tests assessed mortality in response to a diagnostic dose of 1xLD99 (0.851 nanograms of active ingredient per treated nymph) of the SRL. RESULTS: The susceptibility profile characterization of the T. brasiliensis populations revealed 50% resistance ratios (RR50) that ranged from 0.32 to 1.21. The percentage of mortality in response to the diagnostic dose was 100%. CONCLUSIONS: We demonstrated that T. brasiliensis was highly susceptible to deltamethrin. The control difficulties found might be related to the recolonization of the triatomines originating from neighboring environments and the possible operational failures related to the process of spraying that enabled specimens less susceptible to deltamethrin to survive.

Variability of susceptibility to deltamethrin in peridomestic Triatoma sordida from Triângulo Mineiro, State of Minas Gerais, Brazil

AbstractINTRODUCTION:Despite chemical and physical vector control strategies, persistent infestations of Triatoma sordida have been reported in a large part of Minas Gerais, Brazil, and the cause for this is little investigated. We aimed to characterize the deltamethrin toxicological profile in peridomestic T. sordidapopulations from Triângulo Mineiro area of Minas Gerais.METHODS:Susceptibility to deltamethrin was assessed in seventeen peridomestic T. sordida populations. Serial dilutions of deltamethrin in acetone (0.2µL) were topically applied on the first instar nymphs (F1; five days old; fasting weight, 1.2 ± 0.2mg). Dose response results were analyzed using Probit software, and the lethal doses, slope and resistance ratios were determined. Qualitative tests were also performed.RESULTS:The deltamethrin susceptibility profile of T. sordida populations revealed resistance ratios ranging from 0.84 to 2.8. The percentage mortality in response to a diagnostic dose was 100.0% in all populations.CONCLUSIONS:From our results, the lack of resistance to insecticides but persistent T. sordida infestations in the Triângulo Mineiro area may be because of: 1) environmental degradation facilitating dispersion of T. sordida , allowing colonization in artificial ecotopes; 2) operational failures; and 3) complexity of the peridomicile in the study area.These variables are being investigated.

Susceptibility of Triatoma sordida Stal, 1859 (Hemiptera: Reduviidae) to alpha-cypermethrin under natural climatic conditions

Abstract:INTRODUCTION:Despite the recommendations by interpretation of resistance ratios obtained in laboratory bioassays, little is known about the actual impact of these results in the effectiveness of vector control activities in the field. In this context, our objective was to determine the mean value of different resistance ratios obtained by laboratory bioassays performed as part of the chemical control strategies of Triatoma sordida in the field.METHODS:Field bioassays were developed in Monte Azul and Coração de Jesus (Southeast, Brazil). In each location, samples were formed with three domestic units treated with alpha-cypermethrin 20.0% (Alfatek (r) 200 SC). One day after spraying, 10 fifth-instar nymphs remained in contact with the surfaces treated (adobe with plaster, adobe without plaster, or wood) with insecticide in plastic cones for 72h. Three cones were exposed inside the intradomicile and the peridomicile. The insects in the control group were exposed to an insecticide-free piece of cardboard. Mortality was measured 72h after removal of the insects from the treated surfaces. The tests were realized in triplicate.RESULTS:Mortality was 100.0% in all locations, except for Monte Azul; Landinho (96.6%) and Coração de Jesus; Barriguda (96.6%).CONCLUSIONS:Although the resistant populations in laboratory tests proved to be susceptible in the field, this observation is not sufficient to suggest that the cut-off points used to justify the resistance ratio should be changed. In this sense, we recommend that laboratory and field bioassays are carried out with a greater number of Triatominae populations to allow more in-depth consideration of the subject.

Malaria in the State of Amazonas: a typical Brazilian tropical disease influenced by waves of economic development

In Brazil, more than 99% of malaria cases are reported in the Amazon, and the State of Amazonas accounts for 40% of this total. However, the accumulated experience and challenges in controlling malaria in this region in recent decades have not been reported. Throughout the first economic cycle during the rubber boom (1879 to 1912), malaria was recorded in the entire state, with the highest incidence in the villages near the Madeira River in the Southern part of the State of Amazonas. In the 1970s, during the second economic development cycle, the economy turned to the industrial sector and demanded a large labor force, resulting in a large migratory influx to the capital Manaus. Over time, a gradual increase in malaria transmission was observed in peri-urban areas. In the 1990s, the stimulation of agroforestry, particularly fish farming, led to the formation of permanent Anopheline breeding sites and increased malaria in settlements. The estimation of environmental impacts and the planning of measures to mitigate them, as seen in the construction of the Coari-Manaus gas pipeline, proved effective. Considering the changes occurred since the Amsterdam Conference in 1992, disease control has been based on early diagnosis and treatment, but the development of parasites that are resistant to major antimalarial drugs in Brazilian Amazon has posed a new challenge. Despite the decreased lethality and the gradual decrease in the number of malaria cases, disease elimination, which should be associated with government programs for economic development in the region, continues to be a challenge.

Epidemiology of infectious meningitis in the State of Amazonas, Brazil

INTRODUCTION: In the State of Amazonas, particularly in the capital Manaus, meningitis has affected populations of different cultures and social strata over the years. Bacterial meningitis is caused by several different species and represents a major issue of public health importance. The present study reports the meningitis case numbers with different etiologies in Amazonas from January 1976 to December 2012. METHODS: Since the 1970s, the (currently named) Tropical Medicine Foundation of Doutor Heitor Vieira Dourado [Fundação de Medicina Tropical Doutor Heitor Vieira Dourado (FMT-HVD)] has remained a reference center in Amazonas for the treatment of meningitis through the diagnosis and notification of cases and the confirmation of such cases using specific laboratory tests. RESULTS: The foundation has achieved coverage of over 90% of the state medical records for many years. Between 1990 and 2012, meningitis cases caused by Haemophilus influenzae decreased with the introduction of the H. influenzae vaccine. Meningococcal disease previously had a higher frequency of serogroup B disease, but starting in 2008, the detection of serogroup C increased gradually and has outpaced the detection of serogroup B. Recently, surveillance has improved the etiological definition of viral meningitis at FMT-HVD, with enteroviruses, Epstein-Barr virus (EBV) and varicella zoster virus (VZV) prevailing in this group of pathogens. With the advent of acquired immunodeficiency syndrome (AIDS), cryptococcal meningitis has become an important disease in Amazonas. Additionally, infectious meningitis is an important burden in the State of Amazonas. CONCLUSIONS: Changes in the epidemiological profile for the different etiology-defined cases are the result of continuous epidemiological surveillance and laboratory capacity improvements and control measures, such as Haemophilus influenzae vaccination.

Comparação da coronariografia de mulheres diabéticas e não-diabéticas com síndrome coronariana aguda sem supradesnivelamento de ST

OBJETIVO: Comparar o padrão hemodinâmico, angiográfico e a morfologia da lesão aterosclerótica em diabéticas e não-diabéticas com angina instável ou infarto agudo do miocárdio sem supradesnivelamento do segmento ST (AI/IAMSS). MÉTODOS: Dois hemodinamicistas determinaram a presença de lesão aterosclerótica grave, definida como > 70%, a morfologia da placa, de acordo com a classificação da American Heart Association, a presença de circulação colateral e as pressões ventriculares e aórticas. A fração de ejeção foi calculada pela angiografia ou pelo ecocardiograma. RESULTADOS: Em oito anos e meio, foram realizados 645 coronariografias em mulheres com AI/IAMSS. Foram analisadas 593 pacientes (215 diabéticas - 36%). Este grupo diferiu das não-diabéticas nos seguintes aspectos: idade mais alta (61 ± 10,6 x 58,1 ± 11,4), prevalência maior de mulheres pós-menopausa e menor prevalência de tabagismo. Lesão grave em três vasos foi significativamente mais freqüente nas pacientes diabéticas (28% x 10%), assim como vasos totalmente ocluídos: 51 (23%) x 54 (14.3%), p < 0.005.Fração de ejeção < 50% foi mais comum nas diabéticas. CONCLUSÃO: Estes achados confirmam o acometimento difuso da doença aterosclerótica em pacientes diabéticas, assim como maior deterioração da função ventricular, que pode estar relacionada ao pior prognóstico dessa população em curto e em longo prazo.

Fração de ejeção e volumes do ventrículo esquerdo medidos com eco 3D e com tomografia ultra-rápida

FUNDAMENTO: O ecocardiograma tridimensional em tempo real (ECO 3D) e a tomografia computadorizada ultra-rápida (CT) são dois novos métodos de análise da fração de ejeção e dos volumes do VE. OBJETIVO: Comparar as medidas da FEVE e dos volumes do VE aferidos pelo ECO 3D e pela CT ultra-rápida. MÉTODOS: Foram estudados pelo ECO 3D e pela CT ultra-rápida de 64 cortes, 39 pacientes consecutivos (27 homens, média etária de 57±12 anos). Foram analisados: FEVE e volumes do VE. Análise estatística: coeficiente de correlação (r: Pearson), teste de Bland & Altman, teste de regressão linear, 95 % IC, p<0,05. RESULTADOS: Medidas do ECO 3D: a FEVE variou de 56,1 a 78,6 (65,5±5,58)%; volume diastólico final variou de 49,6 a 178,2 (87±27,8)ml; volume sistólico final variou de 11,4 a 78 (33,1±13,6)ml. Medidas da CT: a FEVE variou de 53 a 86 (67,8±7,78)%; volume diastólico final variou de 51 a 186 (106,5±30,3) ml; volume sistólico final variou de 7 a 72 (35,5±13,4)ml. As correlações entre ECO 3D e CT foram: FEVE (r: 0,7888, p<0,0001, 95% IC 0,6301 a 0,8843); volume diastólico final (r: 0,7695, p<0,0001, 95% IC 0,5995 a 0,8730); volume sistólico final (r: 0,8119, p<0,0001, 95% IC 0,6673 a 0,8975). CONCLUSÃO: Nesta série, foi observada boa correlação entre as medidas da FEVE e entre os volumes ventriculares aferidos pelo ECO3D e pela CT ultra-rápida de 64 cortes.

Análise comparativa entre tipos de alimentação de Micrurus corallinus (Serpentes, Elapidae) em cativeiro

Micrurus corallinus (Merrem, 1820) kept in laboratory animal rooms swallow voluntarily various colubrid species. The most accepted species belong to the genera Sibynomorphus Fitzinger, 1843, Oxyrhopus Wagler, 1830 and Liophis Wagler, 1830. The voluntary feeding guaranteed resistance against pathogenic agents. The forced feeding was unsatisfactory due to stress resulting from handling, feeding frequency (30 days), susceptibility to pathogenic agents and high occurrence of pathologies.

Variação de peso e sobrevida de Micrurus corallinus sob diferentes condições de alimentação em biotério (Serpentes, Elapidae)

The weight variation in Micrurus corallinus (Merrem, 1820) during the first 60 days in laboratory animal rooms was very remarkable. This fact demonstrates the difficulty in adaptation of these animals to the captive environment. The weight loss was observed in animals under voluntary feeding as well as forced feeding. The survival rate was significantly higher in voluntarily fed animals. Sex differences were also observed with higher survival rates for males. Low survival rates were observed in both sexes under forced feeding.

Nota sobre os Ixodideos da Republica Argentina

A study of and addicional collection of Argentine ixodidae is made on material send to the Author by Professor Salvador Mazza of Departamento de pathologia do Norte - Jujuy and Professor Doello Jurado of the Museu Rivadavia. There was examined 37 lots of Ixodidae. Among them there were found the nymph of Ixodes auritulus Nn. and 3 other species already known on the South American fauna and from which there was til yet no record in Argentine; they are Ixodes ricinus, Amblyomma parvum and Amblyomma pseudo-concolor.

Population dynamics of Triatoma vitticeps (Stål, 1859) in Itanhomi, Minas Gerais, Brazil

Taxonomic markers (head structure morphometry, isoenzymes and randon amplified polymorphism of DNA - RAPD) were used to understand the population dynamics of Triatoma vitticeps, predominant triatomine species in Itanhomi district, using samples obtained from domestic, peridomiciliary and sylvatic habitats. Morphometric analysis revealed sexual dimorphism within the three samples although specimens could not be separated according to the habitat in which they were captured. Forty-two bands were analyzed from RAPD profiles generated using four primers. A dendrogram constructed from Dice's similarity coefficient values showed that migration of the insects between the habitats has occurred, without structuring of populations. Moreover, the dendrogram obtained from the genetic distance values showed an important gene flow between the sylvatic and domestic habitats. No polymorphism was found in the electrophoretic mobility of proteins for the ten enzymes studied. Our results revealed movement of triatomines between the three habitats, suggesting that the presence of T. vitticeps in houses should not be ignored. As invasion of houses by sylvatic insects is frequent and the natural infection indices of this species are among the highest known, epidemiological vigilance studies may reveal possible changes in T. vitticeps behaviour which could present future risks to public health.

Seasonal dynamics of Aedes aegypti (Diptera: Culicidae) in the northernmost state of Brazil: a likely port-of-entry for dengue virus 4

Roraima is the northernmost state of Brazil, bordering both Venezuela and Guyana. Appropriate climate and vector conditions for dengue transmission together with its proximity to countries where all four dengue serotypes circulate make this state, particularly the capital Boa Vista, strategically important for dengue surveillance in Brazil. Nonetheless, few studies have addressed the population dynamics of Aedes aegypti in Boa Vista. In this study, we report temporal and spatial variations in Ae. aegypti population density using ovitraps in two highly populated neighbourhoods; Centro and Tancredo Neves. In three out of six surveys, Ae. aegypti was present in more than 80% of the sites visited. High presence levels of this mosquito suggest ubiquitous human exposure to the vector, at least during part of the year. The highest infestation rates occurred during the peak of the rainy seasons, but a large presence was also observed during the early dry season (although with more variation among years). Spatial distribution of positive houses changed from a sparse and local pattern to a very dense pattern during the dry-wet season transition. These results suggest that the risk of dengue transmission and the potential for the new serotype invasions are high for most of the year.

Experimental chemotherapy for Chagas disease: 15 years of research contributions from in vivo and in vitro studies

Chagas disease, which is caused by the intracellular parasite Trypanosoma cruzi, is a neglected illness with 12-14 million reported cases in endemic geographic regions of Latin America. While the disease still represents an important public health problem in these affected areas, the available therapy, which was introduced more than four decades ago, is far from ideal due to its substantial toxicity, its limited effects on different parasite stocks, and its poor activity during the chronic phase of the disease. For the past 15 years, our group, in collaboration with research groups focused on medicinal chemistry, has been working on experimental chemotherapies for Chagas disease, investigating the biological activity, toxicity, selectivity and cellular targets of different classes of compounds on T. cruzi. In this report, we present an overview of these in vitro and in vivo studies, focusing on the most promising classes of compounds with the aim of contributing to the current knowledge of the treatment of Chagas disease and aiding in the development of a new arsenal of candidates with anti-T. cruzi efficacy.