The recent study, published in the Public Journal of Entomology, found 71 percent of counties in the 48 contiguous states were suitable for the aegypti species and 75 percent could support albopictus species.
Researchers found that the dengue, chikungunya and Zika viruses in particular represented a “growing public health threat in parts of the United States where they are established,” according to the journal’s report.
The maps show the CDC’s “best estimate” of potential ranges of where Ae. aegypti and Ae. albopictus mosquitoes could survive and reproduce if introduced. The maps do not show where the mosquitoes are currently nor where there is a risk of transmission, Rebecca Eisen, a research biologist with the CDC, said in a statement.
“In other words, these maps show areas where CDC predicts Aedes aegypti and albopictus mosquitoes could survive and reproduce if introduced to an area during the months when mosquitoes are locally active,” Eisen told the publication.
Temperature is a key factor. If there were just one day in winter on average when the temperature exceeds 50 degrees Fahrenheit, the chances that the area would be suitable for mosquitoes increased. Areas with consistently cold temperatures, however, have reduced chances that the insects’ eggs would sustain through the winter, specifically for aegypti, according to Eisen. Rainfall had a significant influence on albopictus, as it relies more on water courses filled by rainwater to lay its eggs than aegypti.
“Surveillance efforts can be focused in counties where Aedes aegypti and albopictus could survive and reproduce if introduced to an area during the months when mosquitoes are locally active or at least survive during summer months if introduced,” Eisen said.