Via The Lancet, a letter: Is Zika a substantial risk for visitors to the Rio de Janeiro Olympic Games? Click or tap through for the documentation.
On May 20, 2016, 150 physicians, bioethicists, and scientists from several countries (including Brazil) posted an open letter suggesting WHO Director-General Margaret Chan exert pressure on Olympics authorities to delay or relocate the Rio de Janeiro Games because of public health concerns over the risk of Zika virus infection for tourists and athletes.
The same concern was raised in 2013 about the risk of dengue infection for tourists and athletes intending to travel to Brazil during the 2014 World Cup. At the time we estimated that the individual risk of dengue for visitors would vary from around 6 × 10−5 to around 4 × 10−4, which represented an expected number of infections among tourists between three and 59 cases. The reported number of dengue cases among tourists after the Games was three.
Here we provide a risk estimation for tourists and athletes intending to visit Rio de Janeiro during the summer Olympics in August. Aedes mosquitoes have a strong seasonal pattern with highest abundance in the summer months (from January to February in Rio de Janeiro) and lowest in the winter (from July to August), and Burattini and colleagues estimated the individual risk of being bitten by an Aedes egypti mosquito in Rio de Janeiro during the 3 weeks of the Olympic Games at 3·5 × 10−2. The individual risk of dengue infection for tourists in the same period was estimated by Ximenes and colleagues to be about 5 × 10−4.
Although the actual numbers of Zika virus infection in Brazil are still unknown, it is estimated between 500 000 and 1·5 million cases of infection; with these estimates, we calculated the risk of infection in August to be between 9 × 10−6 and 3 × 10−5. The risk of Zika virus infection is therefore more than 15 times less than that for dengue.
Although the risk of Zika virus infection during the time of the Olympic Games is extremely low, we think that pregnant women should avoid visiting any region of the world where Zika virus circulation has been reported, including Rio de Janeiro, a recommendation in line with international and national public health guidelines.