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Distinct variation in vector competence among nine field populations of Aedes aegypti from a Brazilian dengue-endemic risk city.

Gonçalves CM, Melo FF, Bezerra JM, Chaves BA, Silva BM, Silva LD, Pessanha JE, Arias JR, Secundino NF, Norris DE, Pimenta PF - Parasit Vectors (2014)

Bottom Line: When the results were evaluated by a logistic model using IR as covariate, North, Barreiro, South-Central and Venda Nova showed the strongest association in 2009.When DIR data were analyzed by logistic regression models, Pampulha, South-Central, Venda Nova, West, Northeast and East (2009) as well as South-Central, Venda Nova and West (2011) were the districts showing the strongest associations.Further analysis should be conducted to better understand the reasons for this large variability in vector competence and how these parameters correlate with epidemiological findings in subsequent years.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Medical Entomology, René Rachou Research Centre- FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil. pimenta@cpqrr.fiocruz.br.

ABSTRACT

Background: In Brazil, dengue epidemics erupt sporadically throughout the country and it is unclear if outbreaks may initiate a sustainable transmission cycle. There are few studies evaluating the ability of Brazilian Aedes aegypti populations to transmit dengue virus (DENV). The aim of this study was to compare DENV susceptibility of field-captured Ae. aegypti populations from nine distinct geographic areas of the city of Belo Horizonte in 2009 and 2011. Infection Rate (IR), Vector Competence (VC) and Disseminated Infection Rate (DIR) were determined.

Methods: Aedes aegypti eggs from each region were collected and reared separately in an insectary. Adult females were experimentally infected with DENV-2 and the virus was detected by qPCR in body and head samples. Data were analyzed with the Statistical Package for the Social Sciences version 17.

Results: IR varied from 40.0% to 82.5% in 2009 and 60.0% to 100.0% in 2011. VC ranged from 25.0% to 77.5% in 2009 and 25.0% to 80.0% in 2011. DIR oscillated from 68.7% to 100.0% in 2009 and 38.4% to 86.8 in 2011. When the results were evaluated by a logistic model using IR as covariate, North, Barreiro, South-Central and Venda Nova showed the strongest association in 2009. In 2011, a similar association was observed for South-Central, Venda Nova, West and Northeast regions. Using VC as covariate, South-Central and Venda Nova showed the most relevant association in 2009. In 2011, South-Central, Venda Nova and Barreiro presented the greatest revelation associations. When DIR data were analyzed by logistic regression models, Pampulha, South-Central, Venda Nova, West, Northeast and East (2009) as well as South-Central, Venda Nova and West (2011) were the districts showing the strongest associations.

Conclusions: We conclude that Ae. aegypti populations from Belo Horizonte exhibit wide variation in vector competence to transmit dengue. Therefore, vector control strategies should be adapted to the available data for each region. Further analysis should be conducted to better understand the reasons for this large variability in vector competence and how these parameters correlate with epidemiological findings in subsequent years.

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Schematic map of the city of Belo Horizonte showing graphics of the vector competence of the Ae. aegypti populations in the years 2009 and 2011. The city of Belo Horizonte is divided in 9 regional districts.
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Figure 2: Schematic map of the city of Belo Horizonte showing graphics of the vector competence of the Ae. aegypti populations in the years 2009 and 2011. The city of Belo Horizonte is divided in 9 regional districts.

Mentions: In 2009, the DIR was very similar among the regional districts, varying from 84.7% to 100%, except for the Northwest region for which a significantly lower DIR was calculated (68.7%) (p = 0.003). The mosquito populations of North, Pampulha, South-Central, Venda Nova, West, Northwest and East presented DIRs significantly higher than Barreiro and Northwest districts (p ≤ 0.009). However, this profile was not observed in 2011 when the DIR varied from 38.4% (Barreiro) to 86.8% (West). The mosquitoes of North, Pampulha, South-Central, Venda Nova, West, and Northeast presented DIRs significantly higher than Barreiro and East districts (p ≤ 0.009) (Table 1). Figure 2 summarizes the IRs, VCs and DIRs found in all regional districts of Belo Horizonte showing plots directly superposed over the city map.


Distinct variation in vector competence among nine field populations of Aedes aegypti from a Brazilian dengue-endemic risk city.

Gonçalves CM, Melo FF, Bezerra JM, Chaves BA, Silva BM, Silva LD, Pessanha JE, Arias JR, Secundino NF, Norris DE, Pimenta PF - Parasit Vectors (2014)

Schematic map of the city of Belo Horizonte showing graphics of the vector competence of the Ae. aegypti populations in the years 2009 and 2011. The city of Belo Horizonte is divided in 9 regional districts.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4230638&req=5

Figure 2: Schematic map of the city of Belo Horizonte showing graphics of the vector competence of the Ae. aegypti populations in the years 2009 and 2011. The city of Belo Horizonte is divided in 9 regional districts.
Mentions: In 2009, the DIR was very similar among the regional districts, varying from 84.7% to 100%, except for the Northwest region for which a significantly lower DIR was calculated (68.7%) (p = 0.003). The mosquito populations of North, Pampulha, South-Central, Venda Nova, West, Northwest and East presented DIRs significantly higher than Barreiro and Northwest districts (p ≤ 0.009). However, this profile was not observed in 2011 when the DIR varied from 38.4% (Barreiro) to 86.8% (West). The mosquitoes of North, Pampulha, South-Central, Venda Nova, West, and Northeast presented DIRs significantly higher than Barreiro and East districts (p ≤ 0.009) (Table 1). Figure 2 summarizes the IRs, VCs and DIRs found in all regional districts of Belo Horizonte showing plots directly superposed over the city map.

Bottom Line: When the results were evaluated by a logistic model using IR as covariate, North, Barreiro, South-Central and Venda Nova showed the strongest association in 2009.When DIR data were analyzed by logistic regression models, Pampulha, South-Central, Venda Nova, West, Northeast and East (2009) as well as South-Central, Venda Nova and West (2011) were the districts showing the strongest associations.Further analysis should be conducted to better understand the reasons for this large variability in vector competence and how these parameters correlate with epidemiological findings in subsequent years.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Medical Entomology, René Rachou Research Centre- FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil. pimenta@cpqrr.fiocruz.br.

ABSTRACT

Background: In Brazil, dengue epidemics erupt sporadically throughout the country and it is unclear if outbreaks may initiate a sustainable transmission cycle. There are few studies evaluating the ability of Brazilian Aedes aegypti populations to transmit dengue virus (DENV). The aim of this study was to compare DENV susceptibility of field-captured Ae. aegypti populations from nine distinct geographic areas of the city of Belo Horizonte in 2009 and 2011. Infection Rate (IR), Vector Competence (VC) and Disseminated Infection Rate (DIR) were determined.

Methods: Aedes aegypti eggs from each region were collected and reared separately in an insectary. Adult females were experimentally infected with DENV-2 and the virus was detected by qPCR in body and head samples. Data were analyzed with the Statistical Package for the Social Sciences version 17.

Results: IR varied from 40.0% to 82.5% in 2009 and 60.0% to 100.0% in 2011. VC ranged from 25.0% to 77.5% in 2009 and 25.0% to 80.0% in 2011. DIR oscillated from 68.7% to 100.0% in 2009 and 38.4% to 86.8 in 2011. When the results were evaluated by a logistic model using IR as covariate, North, Barreiro, South-Central and Venda Nova showed the strongest association in 2009. In 2011, a similar association was observed for South-Central, Venda Nova, West and Northeast regions. Using VC as covariate, South-Central and Venda Nova showed the most relevant association in 2009. In 2011, South-Central, Venda Nova and Barreiro presented the greatest revelation associations. When DIR data were analyzed by logistic regression models, Pampulha, South-Central, Venda Nova, West, Northeast and East (2009) as well as South-Central, Venda Nova and West (2011) were the districts showing the strongest associations.

Conclusions: We conclude that Ae. aegypti populations from Belo Horizonte exhibit wide variation in vector competence to transmit dengue. Therefore, vector control strategies should be adapted to the available data for each region. Further analysis should be conducted to better understand the reasons for this large variability in vector competence and how these parameters correlate with epidemiological findings in subsequent years.

Show MeSH
Related in: MedlinePlus