Key factors that can combine to produce a Zika virus outbreak are expected to be present in a number of U.S. cities during peak summer months, new research shows.
[Photo: Dr. Kacey Ernst]
The Aedes aegypti mosquito, which is spreading the virus in much of Latin America and the Caribbean, will likely be increasingly abundant across much of the southern and eastern United States as the weather warms, according to a new study by lead author Dr. Andrew Monaghan, a scientist at the National Center for Atmospheric Research and senior author Dr. Kacey Ernst, associate professor of epidemiology at the University of Arizona Mel and Enid Zuckerman College of Public Health. The study was published in PLOS Currents Outbreaks in March.
Summertime weather conditions are favorable for populations of the mosquito along the East Coast as far north as New York City and across the southern tier of the country as far west as Phoenix and Los Angeles, according to computer simulations conceived and run by researchers at NCAR and the NASA Marshall Space Flight Center.
Spring and fall conditions can support low to moderate populations of the Aedes aegypti mosquito in more southern regions of its U.S. range. Wintertime weather is too cold for the species outside southern Florida and southern Texas, the study found.
By analyzing travel patterns from countries and territories with Zika outbreaks, the research team further concluded that cities in southern Florida and impoverished areas in southern Texas may be particularly vulnerable to local virus transmission.
Although the study does not include a specific prediction for this year, the authors note that long-range forecasts for this summer point to a 40–45 percent chance of warmer-than-average temperatures over most of the continental United States. This could lead to increased suitability for Aedes aegypti in much of the South and East, although above-normal temperatures would be less favorable for the species in the hottest regions of Texas, Arizona, and California.
“The results of this study are a step toward providing information to the broader scientific and public health communities on the highest risk areas for Zika emergence in the United States,” said Dr. Ernst. “We hope that others will build on this work as more information becomes available. All areas with an environment suitable to the establishment of Aedes aegypti should be working to enhance surveillance strategies to monitor the Aedes aegypti populations and human populations for disease emergence.”