Rio de Janeiro, Brazil
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Montella I.R.,Instituto Oswaldo Cruz Fiocruz | Montella I.R.,Institute Biologia do Exercito | Schama R.,Instituto Oswaldo Cruz Fiocruz | Schama R.,Institute Biologia do Exercito | And 4 more authors.
Memorias do Instituto Oswaldo Cruz | Year: 2012

The use of chemical insecticides continues to play a major role in the control of disease vector populations, which is leading to the global dissemination of insecticide resistance. A greater capacity to detoxify insecticides, due to an increase in the expression or activity of three major enzyme families, also known as metabolic resistance, is one major resistance mechanisms. The esterase family of enzymes hydrolyse ester bonds, which are present in a wide range of insecticides; therefore, these enzymes may be involved in resistance to the main chemicals employed in control programs. Historically, insecticide resistance has driven research on insect esterases and schemes for their classification. Currently, several different nomenclatures are used to describe the esterases of distinct species and a universal standard classification does not exist. The esterase gene family appears to be rapidly evolving and each insect species has a unique complement of detoxification genes with only a few orthologues across species. The examples listed in this review cover different aspects of their biochemical nature. However, they do not appear to contribute to reliably distinguish among the different resistance mechanisms. Presently, the phylogenetic criterion appears to be the best one for esterase classification. Joint genomic, biochemical and microarray studies will help unravel the classification of this complex gene family.

Maciel-de-Freitas R.,Instituto Oswaldo Cruz | Avendanho F.C.,Secretaria de Vigilancia em Saude | Santos R.,Secretaria Estadual de Saude de Roraima | Sylvestre G.,Instituto Oswaldo Cruz | And 10 more authors.
PLoS ONE | Year: 2014

Background: During a dengue outbreak with co-circulation of DENV-1 and -2 in the city of Boa Vista, one patient was diagnosed with DENV-4, a serotype supposed absent from Brazil for almost 30 years. The re-emergence of DENV-4 triggered the intensification of mechanical and chemical Aedes aegypti control activities in order to reduce vector density and avoid DENV-4 dissemination throughout the country. Methods/Principal Findings: Vector control activities consisted of (a) source reduction, (b) application of diflubenzuron against larvae and (c) vehicle-mounted space spraying of 2% deltamethrin to eliminate adults. Control activity efficacy was monitored by comparing the infestation levels and the number of eggs collected in ovitraps before and after interventions, performed in 22 Boa Vista districts, covering an area of ∼80% of the city and encompassing 56,837 dwellings. A total of 94,325 containers were eliminated or treated with diflubenzuron. The most frequently positive containers were small miscellaneous receptacles, which corresponded to 59% of all positive breeding sites. Insecticide resistance to deltamethrin was assessed before, during and after interventions by dose-response bioassays adopting WHO-based protocols. The intense use of the pyrethroid increased fourfold the resistance ratio of the local Ae. aegypti population only six months after the beginning of vector control. Curiously, this trend was also observed in the districts in which no deltamethrin was applied by the public health services. On the other hand, changes in the resistance ratio to the organophosphate temephos seemed less influenced by insecticide in Boa Vista. Conclusions: Despite the intense effort, mosquito infestation levels were only slightly reduced. Besides, the median number of eggs in ovitraps remained unaltered after control activity intensification. The great and rapid increase in pyrethroid resistance levels of natural Ae. aegypti populations is discussed in the context of both public and domestic intensification of chemical control due to a dengue outbreak. © 2014 Maciel-de-Freitas et al.

Linss J.G.B.,Instituto Oswaldo Cruz | Linss J.G.B.,Institute Biologia Do Exercito | Brito L.P.,Instituto Oswaldo Cruz | Brito L.P.,Institute Biologia Do Exercito | And 12 more authors.
Parasites and Vectors | Year: 2014

Background: The chemical control of the mosquito Aedes aegypti, the major vector of dengue, is being seriously threatened due to the development of pyrethroid resistance. Substitutions in the 1016 and 1534 sites of the voltage gated sodium channel (AaNa§ssub§V§esub§), commonly known as kdr mutations, confer the mosquito with knockdown resistance. Our aim was to evaluate the allelic composition of natural populations of Brazilian Ae. aegypti at both kdr sites. Methods. The AaNa§ssub§V§esub§ IIIS6 region was cloned and sequenced from three Brazilian populations. Additionally, individual mosquitoes from 30 populations throughout the country were genotyped for 1016 and 1534 sites, based in allele-specific PCR. For individual genotypes both sites were considered as a single locus. Results: The 350 bp sequence spanning the IIIS6 region of the AaNa §ssub§ V §esub§ gene revealed the occurrence of the kdr mutation Phe1534Cys in Brazil. Concerning the individual genotyping, beyond the susceptible wild-type (Na§ssub§ V§esub§ §ssup§S§esup§), two kdr alleles were identified: substitutions restricted to the 1534 position (Na§ssub§ V§esub§ §ssup§R1§esup§) or simultaneous substitutions in both 1016 and 1534 sites (Na§ssub§V§esub§ §ssup§R2§esup§). A clear regional distribution pattern of these alleles was observed. The Na§ssub§V§esub§ §ssup§R1§esup§ kdr allele occurred in all localities, while Na§ssub§V§esub§ §ssup§R2§esup§ was more frequent in the Central and Southeastern localities. Locations that were sampled multiple times in the course of a decade revealed an increase in frequency of the kdr mutations, mainly the double mutant allele Na§ssub§V§ esub§ §ssup§R2§esup§. Recent samples also indicate that Na§ssub§V§esub§ §ssup§R2§esup§ is spreading towards the Northern region. Conclusions: We have found that in addition to the previously reported Val1016Ile kdr mutation, the Phe1534Cys mutation also occurs in Brazil. Allelic composition at both sites was important to elucidate the actual distribution of kdr mutations throughout the country. Studies to determine gene flow and the fitness costs of these kdr alleles are underway and will be important to better understand the dynamics of Ae. aegypti pyrethroid resistance. © 2014 Linss et al.; licensee BioMed Central Ltd.

Belinato T.A.,Instituto Oswaldo Cruz Fiocruz | Belinato T.A.,Institute Biologia Do Exercito | Martins A.J.,Instituto Oswaldo Cruz Fiocruz | Martins A.J.,Institute Biologia Do Exercito | And 5 more authors.
Parasites and Vectors | Year: 2013

Background: Resistance to traditional insecticides represents a threat to the control of disease vectors. The insect growth regulators (IGR) are a potential alternative to control mosquitoes, including resistant populations. The chitin synthesis inhibitors (CSI) are IGRs, which interfere with the insect molting process and represent one major class of compounds against Aedes aegypti populations resistant to the larvicide organophosphate temephos. In the present study, we evaluated the efficacy of the CSI triflumuron on Culex quinquefasciatus, Aedes albopictus and against several Ae. aegypti field populations. Methods. The efficacy of triflumuron, against Cx. quinquefasciatus and Ae. albopictus was evaluated with laboratory strains through dose-response assays. Additionaly, this CSI was tested against seven Ae. aegypti field populations exhibiting distinct resistance levels to both temephos and the pyrethroid deltamethrin. Aedes aegypti populations were exposed to both a dose that inhibits 99% of the adult emergence of mosquitoes from the susceptible reference strain, Rockefeller, (EI99 = 3.95 μg/L) and the diagnostic dose (DD), corresponding to twice the EI99. Results: Our results indicate that triflumuron was effective in emergence inhibition (EI) of Cx. quinquefasciatus (EI50= 5.28 μg/L; EI90= 12.47 μg/L) and Ae. albopictus (EI50= 1.59 μg/L; EI90= 2.63 μg/L). Triflumuron was also effective against seven Ae. aegypti Brazilian populations resistant to both temephos and deltamethrin. Exposure of all the Ae. aegypti populations to the triflumuron EI99 of the susceptible reference strain, Rockefeller, resulted in complete inhibition of adult emergence, suggesting no cross-resistance among traditional insecticides and this CSI. However, a positive correlation between temephos resistance and tolerance to triflumuron was observed. Conclusion: The results suggest that triflumuron represents a potential tool for the control of disease vectors in public health. Nevertheless, they point to the need of constant monitoring of the susceptibility status of vector populations to CSIs. © 2013 Belinato et al.; licensee BioMed Central Ltd.

Belinato T.A.,Instituto Oswaldo Cruz Fiocruz | Belinato T.A.,Institute Biologia do Exercito | Martins A.J.,Instituto Oswaldo Cruz Fiocruz | Martins A.J.,Institute Biologia do Exercito | And 3 more authors.
Memorias do Instituto Oswaldo Cruz | Year: 2012

In Brazil, decades of dengue vector control using organophosphates and pyrethroids have led to dissemination of resistance. Although these insecticides have been employed for decades against Aedes aegypti in the country, knowledge of the impact of temephos resistance on vector viability is limited. We evaluated several fitness parameters in two Brazilian Ae. aegypti populations, both classified as deltamethrin resistant but with distinct resistant ratios (RR) for temephos. The insecticide-susceptible Rockefeller strain was used as an experimental control. The population presenting the higher temephos resistance level, Aparecida de Goiânia, state of Goiás (RR95 of 19.2), exhibited deficiency in the following four parameters: blood meal acceptance, amount of ingested blood, number of eggs and frequency of inseminated females. Mosquitoes from Boa Vista, state of Roraima, the population with lower temephos resistance level (RR95 of 7.4), presented impairment in only two parameters, blood meal acceptance and frequency of inseminated females. These results indicate that the overall fitness handicap was proportional to temephos resistance levels. However, it is unlikely that these disabilities can be attributed solely to temephos resistance, since both populations are also resistant to deltamethrin and harbour the kdr allele, which indicates resistance to pyrethroids. The effects of reduced fitness in resistant populations are discussed.

da Silva I.M.,Institute Biologia do Exercito | da Silva I.M.,University Estadual do Amazonas | Tavares A.M.,Fundacao de Medicina Tropical Dr. Heitor Vieira Dourado
Revista da Sociedade Brasileira de Medicina Tropical | Year: 2012

Introduction: Snake bite, a problem in public health, generally occurs where there is no electric power. Methods: A comparative clinical study was conducted with 102 victims of Bothrops snake bite, from the state of Amazonas, Brazil; 58 victims were treated with liofilizated trivalent antivenom serum (SATL) and 44 victims treated with liquid bivalent and monovalent antivenom serum (SAMBL). Results: 17% (10/58) of patients presented adverse effects with the SATL and 25% (11/44) with the SAMBL. Conclusions: There was no statistic difference in number of adverse effects between the two types of snake bite antivenom.

Lima J.B.P.,Instituto Oswaldo Cruz Fiocruz | Lima J.B.P.,Institute Biologia do Exercito | Rosa-Freitas M.G.,Instituto Oswaldo Cruz Fiocruz | Rodovalho C.M.,Instituto Oswaldo Cruz Fiocruz | And 3 more authors.
Memorias do Instituto Oswaldo Cruz | Year: 2014

Distribution, abundance, feeding behaviour, host preference, parity status and human-biting and infection rates are among the medical entomological parameters evaluated when determining the vector capacity of mosquito species. To evaluate these parameters, mosquitoes must be collected using an appropriate method. Malaria is primarily transmitted by anthropophilic and synanthropic anophelines. Thus, collection methods must result in the identification of the anthropophilic species and efficiently evaluate the parameters involved in malaria transmission dynamics. Consequently, human landing catches would be the most appropriate method if not for their inherent risk. The choice of alternative anopheline collection methods, such as traps, must consider their effectiveness in reproducing the efficiency of human attraction. Collection methods lure mosquitoes by using a mixture of olfactory, visual and thermal cues. Here, we reviewed, classified and compared the efficiency of anopheline collection methods, with an emphasis on Neotropical anthropophilic species, especially Anopheles darlingi, in distinct malaria epidemiological conditions in Brazil.

Fontoura N.G.,Instituto Oswaldo Cruz Fiocruz | Fontoura N.G.,Institute Biologia do Exercito | Bellinato D.F.,Instituto Oswaldo Cruz Fiocruz | Bellinato D.F.,Institute Biologia do Exercito | And 4 more authors.
Memorias do Instituto Oswaldo Cruz | Year: 2012

The mosquito Aedes aegypti is the main focus of dengue control campaigns. Because of widespread resistance against conventional chemical insecticides, chitin synthesis inhibitors (CSIs) are considered control alternatives. We evaluated the resistance status of four Brazilian Ae. aegypti populations to both the organophosphate temephos and the pyrethroid deltamethrin, which are used in Brazil to control larvae and adults, respectively. All vector populations exhibited high levels of temephos resistance and varying rates of alterations in their susceptibility to pyrethroids. The effect of the CSI novaluron on these populations was also investigated. Novaluron was effective against all populations under laboratory conditions. Field-simulated assays with partial water replacement were conducted to evaluate novaluron persistence. Bioassays were continued until an adult emergence inhibition of at least 70% was attained. We found a residual effect of eight weeks under indoor conditions and novaluron persisted for five-six weeks in assays conducted in an external area. Our data show that novaluron is effective against the Ae. aegypti populations tested, regardless of their resistance to conventional chemical insecticides.

Ramos L.S.,Federal University of Rio de Janeiro | Figueiredo-Carvalho M.H.G.,Instituto Nacional Infectologia Evandro Chagas | Barbedo L.S.,Instituto Nacional Infectologia Evandro Chagas | Ziccardi M.,Federal University of Rio de Janeiro | And 8 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2015

Objectives: The emerging fungal pathogens comprising the Candida haemulonii complex (Candida haemulonii, Candida haemulonii var. vulnera and Candida duobushaemulonii) are notable for their antifungal resistance. Twelve isolates with phenotypic similarity to C. haemulonii were recovered from patients in Brazilian hospitals. Here we aimed to identify these isolates by a molecular approach, using the current classification of this fungal complex, and to evaluate their antifungal susceptibility profiles. Methods: The fungal isolates were rechecked to certify their authentication by mycology methodologies and then characterized by ITS1-5.8S-ITS2 gene sequencing. A susceptibility assay was performed using the broth microdilution method published by CLSI (M27-A3/M27-S3). Results: Based on biochemical tests, all Brazilian isolates were identified as C. haemulonii. After employing ITS sequencing, five isolates were identified as C. haemulonii, four as C. duobushaemulonii and three as C. haemulonii var. vulnera. All 12 clinical isolates were resistant to amphotericin B (MICs ranged from 2 to > 16 mg/L) and fluconazole (MICs ≥ 64 mg/L). One isolate of C. haemulonii var. vulnera and two isolates of C. duobushaemulonii were susceptible-dose dependent to itraconazole, while the remaining isolates (75%) were resistant to this antifungal. Eight out of 12 isolates (66.7%) were resistant to voriconazole (MICs ≥ 16 mg/L), while all isolates were susceptible to caspofungin (MICs ≤ 0.5 mg/L). Conclusions: Our results reinforce the importance of molecular identification in differentiating species of the C. haemulonii complex. Moreover, the antifungal multiresistant profile of clinical isolates of the C. haemulonii complex represents a challenge to the treatment of such infections. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

PubMed | University of North Texas Health Science Center, Institute Biologia do Exercito and Federal University of Rio de Janeiro
Type: Journal Article | Journal: Scandinavian journal of medicine & science in sports | Year: 2016

Human physical performance is a complex multifactorial trait. Historically, environmental factors (e.g., diet, training) alone have been unable to explain the basis of all prominent phenotypes for physical performance. Therefore, there has been an interest in the study of the contribution of genetic factors to the development of these phenotypes. Support for a genetic component is found with studies that shown that monozygotic twins were more similar than were dizygotic twins for many physiological traits. The evolution of molecular techniques and the ability to scan the entire human genome enabled association of several genetic polymorphisms with performance. However, some biases related to the selection of cohorts and inadequate definition of the study variables have complicated the already difficult task of studying such a large and polymorphic genome, often resulting in inconsistent results about the influence of candidate genes. This review aims to provide a critical overview of heritable genetic aspects. Novel molecular technologies, such as next-generation sequencing, are discussed and how they can contribute to improving understanding of the molecular basis for athletic performance. It is important to ensure that the large amount of data that can be generated using these tools will be used effectively by ensuring well-designed studies.

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