St. Clair County and St. Louis City are among the areas considered at high risk for transmission of Zika infection, according to an early online article by Saint Louis University researchers in the American Journal of Public Health.
“The purpose of this study was not to create unwarranted alarm, but rather to enhance Zika prevention methods such as mosquito control, effective prevention message dissemination, and treatment and care preparation, in advance of a Zika epidemic in the contiguous U.S.,” said Enbal Shacham, associate professor of behavioral sciences and health education at Saint Louis University and the lead author of the study.
Shacham said significant planning and prevention is necessary to prevent Zika infection.
“Timely strategies to communicate risk, control mosquito populations, and prevent disease transmission are imperative to preventing a large-scale Zika epidemic in the United States,” Shacham said.
Zika poses the most serious threat to unborn babies who may die or develop devastating birth defects, such as brain damage, after their mothers contract Zika during pregnancy.
Shacham and her collaborators studied 3,108 counties in the United States. They determined 507 “high risk” areas for Zika transmission based on several factors — the presence of Aedes aegypti mosquitoes; high rates of sexually transmitted infections, which is an established surrogate marker for unprotected sex; number of women of child-bearing age; and an estimate of birth rates for each county.
Recent reports suggest the Zika virsus can survive within semen for a significant amount of time, Shacham said, meaning sexual transmission may be underestimated.
“The problem is especially concerning in our region, due to the high rates of gonorrhea and chlamydia and the increased likelihood of the mosquito that carries Zika virus being present in the city of St. Louis and St. Clair County,” Shacham said.
About 80 percent of those who contract Zika have no symptoms, which means they may engage in sexual activity without any indication they are at risk of transmitting the virus, she added.
Authors of “Potential High-Risk Areas for Zika Virus Transmission in the Continuous United States” are Shacham, Erik J. Nelson, Daniel F. Hoft, Mario Schootman and Alexander Garza. The paper was published online ahead of print March 21.