Objectives: To understand where transmission of Zika virus has the highest likelihood to occur in the contiguous United States with regard to its transmission both sexually and via Aedes aegypti mosquito bites.
Methods: We evaluated the 2 routes of transmission risk with predictors of sexually transmitted infections (percentage women of childbearing age, birthrate, gonorrhea and chlamydia rates, concentrated disadvantage) as a surrogate for unprotected sexual activity and the demographic distribution of the A. aegypti mosquito across 3108 counties in the contiguous United States.
Results: We found that 507 counties had the highest risk of virus exposure via mosquito vector or unprotected sexual activity; these were concentrated in southern states extending northward along the Atlantic coast and southern California, with the highest predicted risk in Mississippi counties.
Conclusions: Identifying areas with higher transmission risk can inform prevention strategies and vector control, and assist in planning for diagnosis and treatment.