Portal de Periódicos da CAPES

Zika virus at the games: is it safe?

2016; Elsevier BV; Volume: 16; Issue: 6 Linguagem: Inglês

10.1016/s1473-3099(16)30069-x

1474-4457

The Lancet Infectious Diseases,

Mosquito-borne diseases and control

In a notorious scene in the film Marathon Man, a runner (played by Dustin Hoffman) is repeatedly asked by the Nazi dentist character (played by the late Laurence Olivier), “Is it safe?” With the Olympic Games due to start on Aug 5 and Paralympic Games on Sept 7, in Rio de Janeiro, Brazil, a country experiencing an outbreak of Zika virus infection, athletes from a plethora of sports, officials, and spectators will be asking themselves the same question. Already the South Korean Olympic team has announced that its athletes' uniforms will be coated with mosquito repellent. To answer the question of risk to games participants from Zika virus, several lines of evidence need to be considered. First, the Zika virus outbreak in Brazil and the associated excess of microcephaly cases are concentrated in the Northeast Region (92% of confirmed cases), well away from Rio in the Southeast Region. Zika virus transmission and associated microcephaly is occurring in the Southeast Region, but the incidence of microcephaly is no greater than that before the outbreak. Second, a rise in cases of Guillain-Barré syndrome (GBS) after Zika virus infection has been reported. However, data from the Zika virus outbreak in French Polynesia in 2013–14 suggest that the risk of GBS is no greater than that after campylobacter infection, a common food-borne disease found worldwide. Third, there was concern about the risk of dengue virus transmission—a disease endemic in Brazil—during the Brazil FIFA World Cup 2 years ago. In reality just three exported cases were detected, according to a risk assessment published by the European Centre for Disease Prevention and Control (ECDC), probably because the football tournament (as will the Olympic and Paralympic games) took place at a time of year unsuitable for the Aedes aegypti mosquito vectors of dengue and Zika viruses. Fourth, the settings of the games must be considered. Athletes and spectators are likely to spend their time in places purged of mosquito breeding sites and sprayed heavily with insecticide. A aegypti are poor flyers, so games participants are unlikely to encounter mosquitoes unless they travel well away from “official” sites. In summary, available evidence indicates that for games participants, risk of exposure to Zika virus and subsequent adverse health outcomes will be low, in a relatively low-risk part of Brazil at a low-risk time of year. To quote the ECDC risk assessment: “the density of dengue cases in Brazil is very low in the southern hemisphere, from mid-June to mid-September. Therefore, a low risk of vector-borne transmission of Zika virus infection during the Olympic Games is expected by analogy with dengue transmission involving the same vectors.” Just how low is shown in a modelling study published in April, which puts the risk of Zika virus infection for tourists visiting Rio during the 3 weeks of the Olympic Games at 1·8 per million tourists, which equates to one or two cases among games visitors, although the model does not account for the potential for sexually transmitted infection. It might be argued that a surge in visitor numbers caused by the games risks spreading the Zika virus worldwide. However, the experience of recent host cities is that the absolute number of visitors changes little compared with previous years, because regular tourists and business travellers are discouraged from visiting during the games. Besides which, the dissemination horse has already bolted, with local Zika virus transmission reported in 49 countries or territories in the past 9 months. Note also that WHO recommends no travel restrictions to Brazil. It is essential that athletes and visitors to the games be given evidence-based advice on the risk of Zika virus infection (and other mosquito-borne diseases), on sensible precautions to avoid mosquito bites, on contraception for women of child-bearing age, and on prevention of sexual transmission, for which WHO, the International Olympic Committee, and local organisers need to take responsibility. The ECDC has stated that it will publish a risk assessment ahead of the games, and the US Centers for Disease Control and Prevention has issued travel advice. Despite Laurence Olivier's repeated probing, Dustin Hoffman's runner was unable to answer the question “is it safe?” By contrast, unless new data emerge before August, we can say that compared with the risks usually associated with travel, such as gastrointestinal infections (on which we have written previously), traffic accidents, and falls, Zika virus represents a minimal threat to games visitors. For more on Zika virus and microcephaly by region of Brazil see MMWR Morb Mortal Wkly Rep 2016; 65: 242–47For the PAHO/WHO Zika Epidemiological Update see http://www.paho.org/hq/index.php?option=com_content&view=article&id=11599&Itemid=41691&lang=enFor ECDC risk assessment see http://ecdc.europa.eu/en/publications/_layouts/forms/Publication_DispForm.aspx?List=4f55ad51-4aed-4d32-b960-af70113dbb90&ID=1434For risk of Zika virus infection for tourists during the Olympic Games see Epidemiol Infect 2016; published online April 4. DOI:10.1017/S0950268816000649For CDC travel advice see http://www.cdc.gov/media/releases/2016/s0226-summer-olympic-games.html For more on Zika virus and microcephaly by region of Brazil see MMWR Morb Mortal Wkly Rep 2016; 65: 242–47 For the PAHO/WHO Zika Epidemiological Update see http://www.paho.org/hq/index.php?option=com_content&view=article&id=11599&Itemid=41691&lang=en For ECDC risk assessment see http://ecdc.europa.eu/en/publications/_layouts/forms/Publication_DispForm.aspx?List=4f55ad51-4aed-4d32-b960-af70113dbb90&ID=1434 For risk of Zika virus infection for tourists during the Olympic Games see Epidemiol Infect 2016; published online April 4. DOI:10.1017/S0950268816000649 For CDC travel advice see http://www.cdc.gov/media/releases/2016/s0226-summer-olympic-games.html Guillain-Barré Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control studyThis is the first study providing evidence for Zika virus infection causing Guillain-Barré syndrome. Because Zika virus is spreading rapidly across the Americas, at risk countries need to prepare for adequate intensive care beds capacity to manage patients with Guillain-Barré syndrome. Full-Text PDF Concerns raised over water quality at the Rio OlympicsA recent investigation by Associated Press on water quality at aquatic venues for the 2016 Olympic Games in Rio de Janeiro, Brazil, has raised concerns about the risk to the health of athletes who will compete next year. The article says that athletes “will be swimming and boating in waters so contaminated with human faeces that they risk becoming violently ill and unable to compete”. In fact, it goes on to say that competitors have already fallen ill while training in Rio in preparation for the games. Full-Text PDF Zika virus and the 2016 Olympic Games – Editors' replyAmir Attaran makes some valuable points in his response to our Editorial on the Zika virus risk associated with the 2016 Olympic and Paralympic Games in Rio de Janeiro, Brazil.1 Full-Text PDF