The opening ceremonies of the 2016 Olympics in Rio de Janeiro are just days away. But this year, fears of Zika have cast a shadow over festivities.
The Zika virus is the cause of an ongoing epidemic of birth defects first noticed in Brazil in late 2015. While the virus causes no symptoms in most people, infections of pregnant women can lead to microcephaly, blindness, spontaneous abortion or stillbirth of the fetus. Now affecting nearly all Latin American and Caribbean countries, the Zika outbreak has been declared a public health emergency of international concern by the World Health Organization (WHO).
As scientists and health agencies race to keep up with the epidemic, it’s no surprise that the threat of Zika during the Olympics has been in the news.
Over 200 international academics, led by Canadian law and medicine professor Amir Attaran, brought considerable attention to the issue in May, signing an open letter advocating that the Olympics should be postponed or relocated so that visitors do not import Zika virus to their home countries.
For its part, the WHO has maintained that canceling the Olympics or changing the location of the games will not lessen the risk of Zika spreading internationally. Meanwhile, the U.S. Centers for Disease Control and Prevention has pointed out that the Olympics will account for less than 0.25 percent of all travel to Zika-affected countries this year. Regular travel between the U.S., the Caribbean and Latin America has led to over 1,400 imported disease cases within U.S. states this year. However, local mosquito-borne transmission has not yet been reported within the 50 states, and only 15 cases of domestic sexually transmitted cases are known to have occurred.
These assurances have done little, however, to relieve public perceptions of risk in a news cycle dominated by announcements that some athletes will skip the Olympics over Zika fears.
As academic scientists working at the intersection of public health, medicine, operations research and human rights, my colleagues and I have been dismayed watching how this controversy played out over the airwaves. Policymakers and travelers need evidence to make sound decisions. Questions over Zika risk at the Olympics must be addressed scientifically.
To bring evidence into the Zika debate, we calculated how big a risk the virus poses for travelers visiting Rio for the Olympics as well as for the countries into which these individuals may import the virus. Our findings were published today in the Annals of Internal Medicine.
How Do the Numbers Play Out?
The state of Rio de Janeiro, Brazil saw between 15,918 and 143,985 Zika virus infections in the year 2015, in a population of 16.5 million. The precise number of infections is uncertain because most people who get infected never show symptoms. Even among those who do, the rash, fever, headache or joint pain that typically occur may not be severe enough to warrant a visit to the clinic, meaning many cases won’t appear in health statistics.
