Co-authored by Donald Thea and George Annas
As the Olympics draw near, is it time to reassess the Zika risks of holding them in Brazil, or even to initiate a travel ban on Rio? 100 "experts" seem to think so. On May 27, they released an open letter to the World Health Organization urging that the Olympics, scheduled for August, be postponed or moved "in the name of public health." They are entitled to their opinion, but they have no special warrant to speak in the name of public health. Their letter is naked fear mongering, and their call to isolate Rio from the rest of the world should be ignored.
The duty of public health officials is to act objectively and scientifically to assess the risks to health, and then propose actions to prevent or mitigate these risks. There is now no doubt that Zika is a health risk to pregnant women and their fetuses, as well as to a very small minority of non-pregnant adults. Certainly pregnant women should be counseled to avoid traveling to areas where Zika is present and to take precautions against mosquitoes if they must travel to these places. While it is clear that Brazil has recently experienced a very real Zika virus epidemic, there are numerous social, epidemiological, biological and insect-related factors that determine whether the 500,000 or so estimated global visitors who will visit the Olympics in Brazil will create a risk of substantially accelerating the spread of this epidemic to the far corners of the world. There are also indications that the force of the epidemic is beginning to dissipate in Brazil. The July-August summer months during which the games will be played are low season for mosquitos, and the Brazilian military has been mobilized to diminish mosquito populations in urban areas through area-wide fogging with insecticides.
We thought the WHO overreacted to Zika by declaring it a public health emergency of international concern earlier this year. We continue to believe that invoking a "public health emergency" label is based on little new science informing us of the extent of quantifiable risk to individuals, and serves to incite both public health and health professionals to overreact.
Their fundamental justification to move the Olympics is that the half million or so visitors to Brazil will become human reservoirs and bring the virus back to their home countries to spread. But this assertion is not based on a good understanding of the dynamics of this disease. Zika is really a problem of poverty. Zika's explosive spread in Latin America has largely occurred among the poor populations and in areas where the built environment is very poorly developed. These physically disorganized urban slum areas have much standing water where the mosquitos can reproduce, and few functional screens or air conditioning to provide human-insect barriers, thus optimizing vector breeding and human exposure to infected mosquitos.
Visitors who can afford to attend the Olympics have a very small chance of becoming infected during their short stay. Moreover, even if they are infected, they will return to their homes -- in relatively wealthy environments where they will likely face little exposure to biting mosquitoes -- and this will be an epidemic "dead end." Dengue, a virus similar to Zika that is transmitted by the same vector, can teach us much about this. While it has raged in Central America and the Caribbean, it has not established a beachhead in the U.S. (except a very limited outbreak in Key West in 2010) -- largely because of these factors. Similarly, rich people visiting the Olympics from poor countries will not be the main transit route into their country for Zika -- that will happen, as is occurring throughout Latin America today, by the vast transmigration between countries by the general population.
Moreover, it is worthwhile from a public health perspective to contrast the non-threat of Zika at the Olympics with the real threat of the mass "migration" of old world infectious disease (e.g. polio, measles, MDR tuberculosis, and leishmaniasis) via the total breakdown of health services in Syria and now the mass migration of Syrian refugees to bordering states and up into Europe.
If one really believed that Zika's spread by travelers to Rio could create a global health crisis, the remedy is not to move the Olympics, but to shut down all tourism to Rio. To call off the Olympics because of the anticipated but false threat of accelerated dissemination of Zika by the relatively few visitors from each country risks substantial economic damage to Brazil's already fragile economy, as well as to the hard-fought dreams of countless elite athletes.
The head of the CDC, Tom Frieden, is correct in concluding that "there is no public health reason to cancel or delay the Olympics." The Brazilian Society of Bioethics recently voiced a similar opinion, stating in an open letter written in response to the call to move the games, that they did not "see at the moment scientific grounds to suspend or postpone" the Olympics. Common sense public health reasonably concludes that as of today it is safe for men and non-pregnant women to attend the Olympics in Brazil this summer, as long as they take reasonable precautions to avoid getting bitten by mosquitoes.
Don Thea, MD, is Professor of Global Health and Director of the Center for Global Health and Development, George Annas, JD, MPH, is the William Fairfield Warren Distinguished Professor and Director of the Center for Health Law, Ethics, and Human Rights, and Sandro Galea, MD, DrPH, is the Robert A Knox Professor and Dean, all at the Boston University School of Public Health.