With less than one month until the ceremonial torch is passed in Rio, Zika has threatened to alter the course of the 2016 Summer Olympics, if not halt them altogether. Brazil has been battling a drastic rise in cases of Zika infection since public health authorities first confirmed transmission in May of 2015 within the Northeast region of the country. Shortly thereafter, Brazil reported an association between Zika virus and Guillian- Barré syndrome in July followed by an association between the virus and microcephaly in October of last year. Since then, scientific evidence has led to a consensus that Zika does in fact cause both conditions. As of May 28th of this year, Brazil had 161,241 confirmed cases of Zika, thirty-eight thousand of which occurred in the Rio de Janeiro state, the second-most affected state behind Bahia. Brazil has also experienced the majority of suspected microcephaly cases of all Zika-affected countries; the Ministry of Health reported 8,451 cases of microcephaly and other congenital brain malformations between October 22, 2015 and July 9, 2016. Thus far, 1,687 of these suspected cases have been confirmed. In the months leading up to the 2016 Summer Olympics, set to occur in Rio de Janeiro from August 5th to 21st, the Zika case load in Brazil has continued to rise at alarming rates while athletes and the global community as a whole have begun to question the safety of allowing travel to a region amidst a major outbreak. Many athletes, including pro-golfer Jason Day, currently ranked number-one in the world, have opted out of this year’s Olympics, citing concern for Zika transmission. Some individuals have also expressed apprehension over whether the Rio Olympics should occur at all. Are these concerns warranted?
The international scientific community is not in agreement. On May 28th, the WHO released a statement saying, “based on current assessment, canceling or changing the location of the 2016 Olympics will not significantly alter the international spread of Zika virus,” citing that Brazil is just one of 60 countries with Zika transmission and that frequent travel to and from these regions will occur regardless of the Games. The WHO has also openly maintained a persistent view that the risk of further international Zika spread from the Olympic Games is “very low.” In reaction to this statement, nearly 240 scientists from 40 countries have signed an open letter to WHO Director Dr. Margaret Chan urging that the WHO step in and revisit the idea of moving or postponing the Games due to Zika transmission concerns. However, Brazil’s Health Minister, Ricardo Barros, has also publicly stated that there is no scientific basis for postponing the Games and that lower mosquito rates due to Rio’s low temperature in August (Brazil’s winter) poses reduced threat of Zika transmission during the Olympics. Furthermore, Brazil has taken multiple steps to eradicate mosquitos, particularly within Rio, in the months leading up to the Summer Olympics, such as aerial spraying of insecticides and larvicides from planes, with the goal of preventing transmission during the Olympic Games.
Concern for Zika spread among Olympic athletes and spectators is warranted as Brazil is still amidst an ongoing outbreak and, despite winter weather in Rio, mosquitos will still be active. That being said, athletes, spectators, and the global community must be reminded that most people infected with the virus are asymptomatic or present only mild clinical symptoms. Unless currently pregnant or intending to reproduce in the immediate future, travelers to the Olympic games do not face substantial health risks from Zika infection. Individuals in Brazil for the Olympics who may acquire Zika infection, upon returning to their home country, could, however, transmit the infection to sexual partners or to local mosquitos. This could eventually result in local transmission in areas that have yet to report this type of spread (such as the continental U.S.), provided that the Aedes aegypti mosquitos are found in these areas.
In a newly released CDC report that assessed each of the 206 country sending Olympic athletes for the risk of subsequent sustained, local mosquito-borne Zika transmission, the CDC found that 19 countries without reported Zika cases have the environmental conditions and susceptible population to foster local transmission should a case be imported from the Games. Of those countries, however, only four (Chad, Yemen, Djibouti, and Eritrea) were found to have a heightened risk for Olympics-related transmission because, aside from travel for the Games, their populations do not experience frequent travel to areas currently experiencing Zika outbreaks. These four countries are predicted to send a total of 19 athletes, accounting for a small fraction of the nearly 350,000-500,000 visitors that may attend this summer’s Games. This fraction of transmission risk becomes even less significant when you consider the fact that Olympic travel will account for less than 0.25% of the total estimated 2015 travel to Zika-affected regions. The CDC report went on to agree with the WHO stating, “except for these four countries, the 2016 Olympic and Paralympic Games do not pose a unique or significant risk for further mosquito-borne transmissions of Zika virus in excess of that posed by non-Olympic travel.”
The major takeaways from the current state of the Zika epidemic? The Olympics should go on. We as a global community should listen to the resounding evidence presented by the WHO, CDC, and other leading global health scientists and take the appropriate precautions to reduce Zika transmission during the Games. While the risk of Zika transmission will be diminished during the Games due to Rio’s winter temperatures, August will bring peak mosquito weather to much of the United States, heightening the risk of Zika spread. Perhaps Americans in particular should shift their concern to the increased risk of Zika transmission in many regions of the U.S. in the coming months. As Dr. Peter Hotez, founding Dean of the National School of Tropical Medicine and Professor of Pediatrics and Molecular Virology & Microbiology at Baylor College of Medicine, explained in an interview with POLITICO’s “Pulse Check” podcast, “Rio de Janeiro may be one of the safest places in the Western Hemisphere for Zika this summer…the risk, sadly enough, may be far higher for pregnant women on the Gulf Coast.”