Zika virus and the 2016 Olympic Games – Editors' reply

Abstract

Amir 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.1The Lancet Infectious DiseasesZika virus at the games: is it safe?.Lancet Infect Dis. 2016; 16: 619Summary Full Text Full Text PDF PubMed Scopus (9) Google Scholar We agree that Rio de Janeiro state has more probable Zika virus cases than any other state of Brazil. However, the 92% figure cited in the Editorial related to the proportion of confirmed cases of Zika virus-associated microcephaly found in the Northeast Region. Latest figures show that 86% of such cases are in the Northeast Region, whereas only 6·6% are in the Southeast Region, of which Rio is part.2Ministério da Saúde BrazilMinistério da Saúde confirma 1.656 casos de microcefalia.http://portalsaude.saude.gov.br/index.php/cidadao/principal/agencia-saude/24437-ministerio-da-saude-confirma-1-656-casos-de-microcefalia%20Google Scholar This disparity between numbers of cases of Zika virus infection and of microcephaly suggests variations in case detection or notification, or, perhaps, that unknown cofactors contribute to manifestation of microcephaly. The only Nazi reference in the Editorial is to a fictional character. We see no issues of taste in accurate description of that character. The Editorial clearly considers the risk that the games pose for global dissemination of Zika virus, reaching the conclusion that the games represent little additional risk compared with routine travel. By contrast, Attaran contends that “Rio's Olympics are a risk to global health” because, among other reasons, “Olympic visitors have unsurpassed disease-spreading capacity because they come from every country in the world”. Fortunately, an objective, evidence-based approach can throw light on this difference of opinion. In the Editorial we cited a modelling study by Burattini and colleagues,3Burattini MN Coutinho FAB Lopez LF et al.Potential exposure to Zika virus for foreign tourists during the 2016 Carnival and Olympic Games in Rio de Janeiro, Brazil.Epidemiol Infect. 2016; 144: 1904-1906Crossref PubMed Scopus (25) Google Scholar which calculated the risk of Zika virus infection for visitors to Rio during the 3 weeks of the Olympic Games at 1·8 per million tourists. The model was based on the particularly bad 2008 dengue virus (a virus related to Zika and also transmitted by the Aedes aegypti mosquito) season in Rio, when new infections peaked at more than 25 000 per week. Some of the same authors have since published an updated estimate of Zika virus infection in August in Rio of about one to three per 100 000.4Massad E Coutinho FAB Wilder-Smith A Is Zika a substantial risk for visitors to the Rio de Janeiro Olympic Games?.Lancet. 2016; 388: 25Summary Full Text Full Text PDF PubMed Scopus (22) Google Scholar Thus, up to 15 of the 500 000 visitors to the Olympic Games might contract Zika virus, of whom some might carry the virus back to their home countries. As Attaran points out, it takes just one infected traveller to start an outbreak in a country with suitable conditions. Grills and colleagues5Grills A Morrison S Nelson B Miniota J Watts A Cetron MS Projected Zika virus importation and subsequent ongoing transmission after travel to the 2016 Olympic and Paralympic Games—country-specific assessment, July 2016.MMWR Morb Mortal Wkly Rep. 2016; (published online July 13.)https://doi.org/10.15585/mmwr.mm6528e1Crossref PubMed Scopus (20) Google Scholar have assessed the question of which countries are susceptible to ongoing Zika virus transmission resulting from introduction by a single traveller to the games.5Grills A Morrison S Nelson B Miniota J Watts A Cetron MS Projected Zika virus importation and subsequent ongoing transmission after travel to the 2016 Olympic and Paralympic Games—country-specific assessment, July 2016.MMWR Morb Mortal Wkly Rep. 2016; (published online July 13.)https://doi.org/10.15585/mmwr.mm6528e1Crossref PubMed Scopus (20) Google Scholar Four countries—Chad, Djibouti, Eritrea, and Yemen—were estimated to be uniquely at risk because “they do not have a substantial number of travelers to any country with local Zika virus transmission, except for anticipated travel to the Games”.5Grills A Morrison S Nelson B Miniota J Watts A Cetron MS Projected Zika virus importation and subsequent ongoing transmission after travel to the 2016 Olympic and Paralympic Games—country-specific assessment, July 2016.MMWR Morb Mortal Wkly Rep. 2016; (published online July 13.)https://doi.org/10.15585/mmwr.mm6528e1Crossref PubMed Scopus (20) Google Scholar To answer the issue of additional global health risk posed by the games, Grills and colleagues state: “With the exception of four countries, attendance at the Games does not pose a unique or substantive risk for mosquito-borne transmission of Zika virus in excess of that posed by non-Games travel”. Thus, for the four countries, the games represent a relative increased risk compared with routine travel, but, based on the estimate given above,4Massad E Coutinho FAB Wilder-Smith A Is Zika a substantial risk for visitors to the Rio de Janeiro Olympic Games?.Lancet. 2016; 388: 25Summary Full Text Full Text PDF PubMed Scopus (22) Google Scholar the absolute risk of any traveller from these countries being infected with Zika virus during the games is miniscule: Grills and colleagues project a total delegation, including athletes, from the four countries of just 79 people.5Grills A Morrison S Nelson B Miniota J Watts A Cetron MS Projected Zika virus importation and subsequent ongoing transmission after travel to the 2016 Olympic and Paralympic Games—country-specific assessment, July 2016.MMWR Morb Mortal Wkly Rep. 2016; (published online July 13.)https://doi.org/10.15585/mmwr.mm6528e1Crossref PubMed Scopus (20) Google Scholar The debate over whether the Olympic and Paralympic Games will spur global dissemination of Zika virus (and other infectious diseases from similar mass gatherings) can perhaps be distilled into two points of view. First, through rapid, global travel, the opportunities for spread are already so great that additional games-related travel make no meaningful difference, a view supported by the risk assessments described above. An alternative argument is that however small the risk, the potential harm outweighs the benefits of holding the games and the risk should not be taken. But the ultimate conclusion of the latter viewpoint is to ban all travel to and from Zika-affected countries. In the end, we do not think that any country should be penalised because of a disease outbreak taking place within its territory. Such penalties discourage rapid and complete reporting and ultimately do nothing to aid disease control. We declare no competing interests. Zika virus and the 2016 Olympic GamesA recent Editorial1 in The Lancet Infectious Diseases used erroneous reasoning to argue that Zika virus poses no worry for the Rio de Janeiro Olympics—namely, that 92% of Zika cases are far away from Rio (wrong: Rio de Janeiro state has 29% of probable Zika cases, more than anywhere else in Brazil2); that campylobacter is more dangerous (irrelevant: so is dynamite); that just three known travellers were infected with dengue virus during Brazil's 2014 World Cup (glib: Brazil's ruinous Zika virus outbreak began with just one infected traveller3); and that worrying is pointless anyway because Zika virus is already found in dozens of countries (fatalistic: by that logic it would never be worth intervening to slow a disease's spread). Full-Text PDF Zika virus at the games: is it safe?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. Full-Text PDF