A Saint Louis University analysis of mosquito migration patterns and sexually transmitted diseases places the St. Louis region on a map of counties that could see an elevated risk for Zika infections this summer. The virus is spread by mosquitoes but can also be transmitted sexually for several months after symptoms occur.
However, the overall risk in the continental United States is still very low, study author Enbal Shacham said.
“I do not want to create alarm, but more to highlight the need for public health intervention, as well as considering how our resources are limited in researching further,” said Shacham, a behavioral science researcher for the university.
The virus is mild in most cases, and does not always present symptoms. However, it can cause severe birth defects, including microcephaly, if a pregnant woman is infected. It has also been linked to Guillian-Barre Syndrome in rare cases.
In the past year, 222 Zika cases transmitted by mosquitoes have been reported in South Florida and Brownsville, Texas. Sexual transmission has accounted for 45 cases in U.S. states.
Shacham calculates that “high risk” counties in her analysis would have a 17 to 25 percent higher risk of Zika infections than “low risk” counties. But at this point, researchers aren’t sure how efficiently Zika can pass from one person to another in bodily fluids.
“Until we know that, we can only model this type of behavior and estimate our risk,” Shacham said. “We need more research to do that.”
Whether the continental United States will see additional Zika cases over the summer is hard to predict, officials with the Centers for Disease Control and Prevention say.
“Based on last year’s activity and similar mosquito borne outbreaks, we wouldn’t be surprised to see small pockets of local transmission,” Benjamin Haynes, a CDC press officer.
Further south, the situation is much worse: 38,065 locally transmitted cases have been reported in Puerto Rico, American Samoa and the U.S. Virgin Islands since the beginning of the outbreak.
Earlier this month, the CDC added four countries to list of countries where travelers should take precautions to protect themselves against the virus.
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