Some health professionals have lobbied to postpone the upcoming Olympics in Rio de Janeiro because of the Zika virus, which is spread by mosquitoes and—and less commonly—through sexual intercourse. Other experts disagree that Zika poses a significant enough threat to warrant changing the venue or date of the games, set for August 5 to August 21.
“The risk of Zika infection in Rio during the Olympics is very low,” says Uriel Kitron, chair of the environmental sciences department at Emory University and an expert on mosquito-borne diseases. “But if you are pregnant, or are thinking of getting pregnant right now as part of a couple, then you may want to consider even this low risk of transmission, given the potential serious complications.”
The Centers for Disease Control and Prevention is advising women who are pregnant “to consider not going to the Olympics,” due to the link between Zika infections and severe birth defects. It also recommends special precautions for men and women to practice safe sex following any possible exposure to the Zika virus.
When Zika popped up in Brazil last year, Kitron already had ongoing research projects in the country focused on how urban mosquitoes spread the viruses of dengue and chikungunya. People had no immunity to Zika and the virus swept like wildfire through the country. Researchers quickly expanded their research to include cases of Zika, which can cause a rash and relatively mild illness, although most of those infected have no symptoms at all. It was not until months later that the more insidious effects of the Zika virus became apparent.
Kitron and his colleagues published one of the first epidemiological studies, in Emerging Infectious Diseases, showing the strong link between the epidemic curve of the outbreak and a spike in cases of Guillain-Barré syndrome and babies born with smaller-than-normal heads, a condition known as microcephaly.
He discusses some of what is now known about the emerging infectious disease and why mosquito surveillance and control is currently the key to containing its spread.
Q. Why do you think the risk is low for Zika virus transmission during the Olympics?
The rates of Zika infection in Brazil have gone down drastically since last year, probably because the population now has herd immunity, so that further lowers the risk of transmission. Brazil is no longer the “hot spot” of the Zika pandemic. The horse has already left the barn as Zika has moved throughout Latin America and the Caribbean.
The US territory of Puerto Rico, where an outbreak began more recently, currently has high rates of new Zika infections and summer is the high season for transmission.
Q. What is the risk of contracting Zika virus from a mosquito in the United States?
In the past, we have seen a few cases of locally transmitted dengue fever and chikungunya in South Texas and South Florida. The Aedes aegypti mosquito, the main vector of dengue, chikungunya, and Zika, can be found in states bordering the Gulf of Mexico. The much more widespread Aedes albopictus, better known as the Asian tiger mosquito, has also shown that it can transmit these diseases, at least in a laboratory setting. Aedes albopictus, however, is not as effective as a vector.
