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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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The proportion of the analyzed characters of the DENV infection (IR, VC and DIR) is represented by the mean of the percentage found in the 9 districts during the years 2009 and 2011, which characterizes data from the entire Belo Horizonte city. *** Notice that there is only significance comparing the DIR between the two years.
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Figure 1: The proportion of the analyzed characters of the DENV infection (IR, VC and DIR) is represented by the mean of the percentage found in the 9 districts during the years 2009 and 2011, which characterizes data from the entire Belo Horizonte city. *** Notice that there is only significance comparing the DIR between the two years.

Mentions: Analysis across all nine districts of Belo Horizonte from the two collections, revealed dissimilarities in the characteristics related to experimental DENV-infection of the Ae. aegypti mosquitoes. The infection rates (IR) varied from 40.0% to 82.5% (60.6 ± 8.4) in 2009 and 60.0% to 100.0% (mean = 78.1 ± 6.1) in 2011. The vector competence (VC), infection of mosquito heads and salivary glands, ranged from 25.0% to 77.5% (mean = 54.7 ± 7.6) in 2009 and 25.0% to 80.0% (mean = 50.8 ± 8.2) in 2011. The disseminated infection rates (DIR) oscillated from 68.7% to 100.0% (mean = 91.1 ± 3.3) in 2009 and 38.4% to 86.8 (62.4 ± 6.1) in 2011. Despite these differences between the two collection years, the differences were only statistically significant for the DIR (p = 0.008) (Figure 1).


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)

The proportion of the analyzed characters of the DENV infection (IR, VC and DIR) is represented by the mean of the percentage found in the 9 districts during the years 2009 and 2011, which characterizes data from the entire Belo Horizonte city. *** Notice that there is only significance comparing the DIR between the two years.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: The proportion of the analyzed characters of the DENV infection (IR, VC and DIR) is represented by the mean of the percentage found in the 9 districts during the years 2009 and 2011, which characterizes data from the entire Belo Horizonte city. *** Notice that there is only significance comparing the DIR between the two years.
Mentions: Analysis across all nine districts of Belo Horizonte from the two collections, revealed dissimilarities in the characteristics related to experimental DENV-infection of the Ae. aegypti mosquitoes. The infection rates (IR) varied from 40.0% to 82.5% (60.6 ± 8.4) in 2009 and 60.0% to 100.0% (mean = 78.1 ± 6.1) in 2011. The vector competence (VC), infection of mosquito heads and salivary glands, ranged from 25.0% to 77.5% (mean = 54.7 ± 7.6) in 2009 and 25.0% to 80.0% (mean = 50.8 ± 8.2) in 2011. The disseminated infection rates (DIR) oscillated from 68.7% to 100.0% (mean = 91.1 ± 3.3) in 2009 and 38.4% to 86.8 (62.4 ± 6.1) in 2011. Despite these differences between the two collection years, the differences were only statistically significant for the DIR (p = 0.008) (Figure 1).

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