Clinical Infections and Vaccine

U.S. Olympians Brought Home Mosquito-Borne Diseases, But Not Zika

U.S. Olympic and Paralympic athletes and staff who went to Rio in 2016 brought back a variety of mosquito-borne viral infections, including West Nile virus, Dengue fever, and chikungunya virus, but not Zika say researchers at the University of Utah (U of U).  The team analyzed staff and athlete blood samples as part of a rapid response effort to monitor Olympic participants who traveled to Brazil, the epicenter of the outbreak, not long after the outbreak peaked.

Approximately 2,000 people traveled to Rio as official participants or Olympic and Paralympic staff members in the summer of 2016.  The U of U team enrolled 950 of them in the study, and 457 ended up providing blood samples after they returned.  Only 32 people out of the 457 (7%) became infected with mosquito-borne viruses: 27 with West Nile, 3 with chikungunya, and two with Dengue fever.  No one contracted Zika.  Only three travelers (two with chikungunya and one with West Nile) reported symptoms, including body aches and rashes, and they were mild.  The symptoms emerged within two weeks after the travelers returned to the U.S. and resolved quickly.  Participants who tested positive for any of the viruses were sent a letter explaining their results and recommending that they consult with their health care provider.

“Everyone was concentrating on Zika and ignoring that there could be other infections caused by mosquito bites.  We did not expect to find so many with these other infections,” said U of U Health Infectious Disease specialist Krow Ampofo, who presented the study on October 7 at the IDWeek conference held in San Diego.

“We were thrilled that there were no cases of Zika,” said lead investigator Carrie Byington.  “One of the reasons we think that post-travel diagnostic [studies] are really important is because multiple things can cause a similar picture and it’s important to know what you had.”

“We all had our Hollywood sunglasses on, and they blinded us to other possibilities,” said Marc Couturier, medical director at ARUP Laboratories that led the testing.

Caption: Blood samples were drawn from US Olympic and Paralympic athletes and staff before and after the Rio Games in 2016 and tested for Zika, West Nile Virus, and other tropical infectious diseases.
Credit:Charlie Ehlert, University of Utah Health
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For more information, go to the IDWeek post-meeting tools web site at, where you can read the abstract or watch the presentation in the digital library.