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Patterns of geographic expansion of Aedes aegypti in the Peruvian Amazon.

Guagliardo SA, Barboza JL, Morrison AC, Astete H, Vazquez-Prokopec G, Kitron U - PLoS Negl Trop Dis (2014)

Bottom Line: To better understand Ae. aegypti spread, we compared characteristics of communities, houses, and containers in infested and uninfested communities.Our results suggest that urban development and oviposition site availability drive Ae. aegypti colonization along roads.Along rivers, boat traffic is likely to drive long-distance dispersal via unintentional transport of mosquitoes on boats.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America.

ABSTRACT

Background and objectives: In the Peruvian Amazon, the dengue vector Aedes aegypti is abundant in large urban centers such as Iquitos. In recent years, it has also been found in a number of neighboring rural communities with similar climatic and socioeconomic conditions. To better understand Ae. aegypti spread, we compared characteristics of communities, houses, and containers in infested and uninfested communities.

Methods: We conducted pupal-demographic surveys and deployed ovitraps in 34 communities surrounding the city of Iquitos. Communities surveyed were located along two transects: the Amazon River and a 95 km highway. We calculated entomological indices, mapped Ae. aegypti presence, and developed univariable and multivariable logistic regression models to predict Ae. aegypti presence at the community, household, or container level.

Results: Large communities closer to Iquitos were more likely to be infested with Ae. aegypti. Within infested communities, houses with Ae. aegypti had more passively-filled containers and were more often infested with other mosquito genera than houses without Ae. aegypti. For containers, large water tanks/drums and containers with solar exposure were more likely to be infested with Ae. aegypti. Maps of Ae. aegypti presence revealed a linear pattern of infestation along the highway, and a scattered pattern along the Amazon River. We also identified the geographical limit of Ae. aegypti expansion along the highway at 19.3 km south of Iquitos.

Conclusion: In the Peruvian Amazon, Ae. aegypti geographic spread is driven by human transportation networks along rivers and highways. Our results suggest that urban development and oviposition site availability drive Ae. aegypti colonization along roads. Along rivers, boat traffic is likely to drive long-distance dispersal via unintentional transport of mosquitoes on boats.

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Related in: MedlinePlus

Geographic border of Ae. aegypti colonization along the Iquitos-Nauta highway.The distance between the southernmost positive community, 5 de Abril, and the next community, San José, is approximately 6.49 km. The space between these two communities is characterized by forest cover with no human settlements (and therefore no oviposition sites). This forested area likely acts as a barrier to Ae. aegypti dispersal.
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pntd-0003033-g005: Geographic border of Ae. aegypti colonization along the Iquitos-Nauta highway.The distance between the southernmost positive community, 5 de Abril, and the next community, San José, is approximately 6.49 km. The space between these two communities is characterized by forest cover with no human settlements (and therefore no oviposition sites). This forested area likely acts as a barrier to Ae. aegypti dispersal.

Mentions: The contrast between the spatial pattern of Ae. aegypti establishment along rivers vs. the highway is noteworthy. Genetic studies have suggested that Ae. aegypti spreads along transportation networks [51]–[53], but few studies to date have used field collections to identify areas where Ae. aegypti has become successfully established following introduction from a known source [13], [14], [54]. We propose that urbanization is responsible for the linear pattern observed along the highway, due to the high density of settlements relatively close to Iquitos and immediately adjacent to the highway. Short-distance active dispersal of Ae. aegypti mosquitoes is driven by availability of oviposition sites [32], and as urbanization continues southward, ovisposition sites become more abundant. The community 5 de Abril represents the geographic limit of Ae. aegypti along the highway, approximately 19 km south of Iquitos. This is most likely due to the ∼6.5 km gap between 5 de Abril and the next community to the south, San José (Figure 5). Prior to that point, each community is distanced <3.1 km from the next settlement along the highway.


Patterns of geographic expansion of Aedes aegypti in the Peruvian Amazon.

Guagliardo SA, Barboza JL, Morrison AC, Astete H, Vazquez-Prokopec G, Kitron U - PLoS Negl Trop Dis (2014)

Geographic border of Ae. aegypti colonization along the Iquitos-Nauta highway.The distance between the southernmost positive community, 5 de Abril, and the next community, San José, is approximately 6.49 km. The space between these two communities is characterized by forest cover with no human settlements (and therefore no oviposition sites). This forested area likely acts as a barrier to Ae. aegypti dispersal.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4125293&req=5

pntd-0003033-g005: Geographic border of Ae. aegypti colonization along the Iquitos-Nauta highway.The distance between the southernmost positive community, 5 de Abril, and the next community, San José, is approximately 6.49 km. The space between these two communities is characterized by forest cover with no human settlements (and therefore no oviposition sites). This forested area likely acts as a barrier to Ae. aegypti dispersal.
Mentions: The contrast between the spatial pattern of Ae. aegypti establishment along rivers vs. the highway is noteworthy. Genetic studies have suggested that Ae. aegypti spreads along transportation networks [51]–[53], but few studies to date have used field collections to identify areas where Ae. aegypti has become successfully established following introduction from a known source [13], [14], [54]. We propose that urbanization is responsible for the linear pattern observed along the highway, due to the high density of settlements relatively close to Iquitos and immediately adjacent to the highway. Short-distance active dispersal of Ae. aegypti mosquitoes is driven by availability of oviposition sites [32], and as urbanization continues southward, ovisposition sites become more abundant. The community 5 de Abril represents the geographic limit of Ae. aegypti along the highway, approximately 19 km south of Iquitos. This is most likely due to the ∼6.5 km gap between 5 de Abril and the next community to the south, San José (Figure 5). Prior to that point, each community is distanced <3.1 km from the next settlement along the highway.

Bottom Line: To better understand Ae. aegypti spread, we compared characteristics of communities, houses, and containers in infested and uninfested communities.Our results suggest that urban development and oviposition site availability drive Ae. aegypti colonization along roads.Along rivers, boat traffic is likely to drive long-distance dispersal via unintentional transport of mosquitoes on boats.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America.

ABSTRACT

Background and objectives: In the Peruvian Amazon, the dengue vector Aedes aegypti is abundant in large urban centers such as Iquitos. In recent years, it has also been found in a number of neighboring rural communities with similar climatic and socioeconomic conditions. To better understand Ae. aegypti spread, we compared characteristics of communities, houses, and containers in infested and uninfested communities.

Methods: We conducted pupal-demographic surveys and deployed ovitraps in 34 communities surrounding the city of Iquitos. Communities surveyed were located along two transects: the Amazon River and a 95 km highway. We calculated entomological indices, mapped Ae. aegypti presence, and developed univariable and multivariable logistic regression models to predict Ae. aegypti presence at the community, household, or container level.

Results: Large communities closer to Iquitos were more likely to be infested with Ae. aegypti. Within infested communities, houses with Ae. aegypti had more passively-filled containers and were more often infested with other mosquito genera than houses without Ae. aegypti. For containers, large water tanks/drums and containers with solar exposure were more likely to be infested with Ae. aegypti. Maps of Ae. aegypti presence revealed a linear pattern of infestation along the highway, and a scattered pattern along the Amazon River. We also identified the geographical limit of Ae. aegypti expansion along the highway at 19.3 km south of Iquitos.

Conclusion: In the Peruvian Amazon, Ae. aegypti geographic spread is driven by human transportation networks along rivers and highways. Our results suggest that urban development and oviposition site availability drive Ae. aegypti colonization along roads. Along rivers, boat traffic is likely to drive long-distance dispersal via unintentional transport of mosquitoes on boats.

Show MeSH
Related in: MedlinePlus