Kacey Ernst, one of the study’s coauthors, described the findings during testimony to a US House of Representatives subcommittee in Washington, DC, on May 25.
The Aedes aegypti mosquito, which is spreading the Zika virus in Latin America and the Caribbean, is expected to increase in numbers across much of the Southern and Eastern US as the weather warms, according to the study published in PLOS Currents Outbreaks.
The study’s results are a step toward providing information to the broader scientific and public health communities on the highest-risk areas for Zika emergence in the US, says Ernst, an associate professor and infectious disease epidemiologist at the University of Arizona. But more research is needed to determine the role of Aedes albopictus, which also is capable of transmitting the virus and has a broader geographic range but does not feed on humans as much as Aedes aegypti does.
Other gaps include the extrinsic incubation period of Zika virus and whether there is vertical transmission from infected Aedes aegypti females to their offspring, which might mean the virus could survive in eggs that would hatch the next year.
From the abstract in the study published in PLOS Currents Outbreaks, the authors makes the following points about the potential spread of Zika in the US:
“Meteorological conditions are largely unsuitable for Aedes aegypti over the U.S. during winter months (December-March), except in southern Florida and south Texas where comparatively warm conditions can sustain low-to-moderate potential mosquito abundance. Meteorological conditions are suitable for Aedes aegypti across all fifty cities during peak summer months (July-September), though the mosquito has not been documented in all cities. Simulations indicate the highest mosquito abundance occurs in the Southeast and south Texas where locally acquired cases of Aedes-transmitted viruses have been reported previously. Cities in southern Florida and south Texas are at the nexus of high seasonal suitability for Aedes aegypti and strong potential for travel-related virus introduction. Higher poverty rates in cities along the U.S.-Mexico border may correlate with factors that increase human exposure to Aedes aegypti”(Monaghan & et., al, 2016).
Read the full study here.
Study: Monaghan AJ, Morin CW, Steinhof DF, Wilhelm O, Hayden M, Quattrochi DA, Reiskind M, Lloyd AL, Smith K, Schmidt CA, Scalf PE, Ernst K. On the Seasonal Occurrence and Abundance of the Zika Virus Vector Mosquito Aedes Aegypti in the Contiguous United States. PLOS Currents Outbreaks. 2016 Mar 16 . Edition 1. dos: 10.1371/currents.outbreaks.50dfc7f46798675fc63e7d7da563da76.
Image: Aedes aegypti mosquito, Credit: US Department of Agriculture/Flickr