Going Viral: Zika Transmission at Rio 2016

In the build-up to Rio 2016, Brazil’s efforts to control the ongoing Zika virus outbreak have become the focus of many high-profile debates over the safety of athletes and tourists alike. It is easy to understand why people are nervous. Individuals travel from all over the world to attend an event as prestigious as the Olympics, where they will be clustered together in confined spaces for extended periods of time, likely share food, drinks, and accommodation, and indulge in risky sexual behaviour. Half a million people descending en masse to a single location is a public health challenge under any circumstances. However adding the mosquito-borne Zika virus, whose potential health complications have been the focus of numerous international media reports, has made many people and athletes question the wisdom of going forward with the Olympics at all. Several renowned tennis and golf players have even withdrawn their participation in the 2016 Olympics, citing their concern over the Zika virus outbreak in Brazil. 

However, the risk of contracting the virus is low. For individuals who are not pregnant or trying to conceive, concerns over the Zika virus are largely unfounded. A number of public health experts and organisations, including the World Health Organisation and both the European and US Centres for Disease Control and Prevention, have released statements indicating that the risk of catching the virus while traveling to Rio is very low. There are a number of factors mitigating the risk of Zika virus transmission during the Olympics. Firstly, the games will take place during Brazil’s winter, when the cooler, drier air is significantly less hospitable to mosquitos. In addition, the highest number of reported Zika virus cases have occurred in Brazil’s Amazonas, Mato Grosso, Tocantins and Bahia states, the nearest of which is approximately 1,000km north of Rio de Janeiro. Tourists and athletes visiting Brazil for the Olympics will also likely be spending most of their time in air-conditioned accommodation and insecticide-treated Olympic venues, where Zika virus-carrying mosquitos are highly unlikely to come near. 

In an attempt to estimate potential Zika virus transmission at the 2016 Olympics, international researchers modelled potential transmission on that of a 2008 outbreak of Dengue fever, another mosquito-borne disease. Based on this model, researchers noted that the probability of any individual traveller being bitten by the Zika virus-carrying A. aegypti mosquito over the three-week course of the 2016 Olympics was approximately three to five percent. This model therefore predicts a best-case scenario of roughly 1.8 Zika virus cases per one million visitors to Rio de Janeiro, or a worst-case scenario of approximately 3.2 cases per 100,000 visitors. Given that Rio de Janeiro is anticipating approximately 500,000 tourists and 10,500 athletes for the Olympic Games, the worst-case scenario predicts about 16 cases of Zika virus transmission for the duration of the Olympics. 

While the likelihood of anyone contracting the Zika virus during the Rio de Janeiro Olympics is very low, unborn foetuses remain the most at risk of complications from the virus. Individuals who plan to conceive shortly after the Olympics should also take precautions, and bear in mind that the Zika virus has been shown to be transmitted sexually and can remain viable in bodily fluids for up to 62 days from infection.