Rio Olympic Games: what are the medical journals saying on the eve of the event?

by Otávio Clark | Aug 4, 2016

Half a million tourists and over 10,000 athletes are expected in Rio de Janeiro for the Summer Olympic Games. This is the first time that the event will be held in South America, and the press has had a lot to say about it. Amid controversies that include health concerns, doubts about the readiness of infrastructure, political turmoil and an economic crisis, Rio will really be a sui generis setting for the Olympics.

A little more than a week before the official opening, we conducted a literature search to map what medical journals are saying about this event. Using the keywords (Olympics OR Olympic games OR Paralympic games) AND (Rio de Janeiro OR Rio OR Brazil) we found 50 articles that addressed some aspect of the competition. 1-55

Papers analyzed the signs of progress in physical activity report and monitoring by several countries since the London Olympics,10 the possibility that scheduling night competitions in the games might hinder athletes’ performances,11 and how genetic variations might influence the result of elite sprinters.14

The levels of air pollution in Rio de Janeiro’s slums and its impact on athletes’ health and performance,28,29 as well as the poor quality of physical activity resources in those areas32 and the appalling lack of sewage treatment contaminating the waters of Guanabara Bay,46,49 have all be closely examined.

Not surprisingly, though, roughly half of those articles focused on the Zika virus epidemic and other arboviruses, their likely consequences, and how athletes, visitors and the population in general should protect themselves.1-8,12,13,16,18,20-27,30,31,36,38,39

As early as 2014, there were already publications covering the health risks involved in travelling to Brazil.50,51,53,54 Gaines et al. searched the peer-reviewed and gray literature to provide travelers coming to the 2014 World Cup and later to the Olympic and Paralympic Games with a list of actions to be taken ahead of the travel.54 The article described the most common diseases in Brazil (including dengue), which vaccines were available, and which precautions should be taken to avoid illnesses.

The recent outbreak of Zika in Brazil brought ample attention to this and other arboviruses. The confirmation that the Zika virus was circulating in the northeast of Brazil happened in March 2015 after the report of several cases of a febrile exanthematic disease that did not fill the parameters for either dengue or chikungunya fever. 56

Detailed data on the incidence of Zika in every state and region can be found for 2016; however, official numbers regarding the impact of the disease in 2015 are still lacking because the mandatory report was only determined last February. The latest epidemiologic bulletin from the government states that between January 3 and June 11 there were 165,932 likely cases of Zika in Brazil, of which 66,180 had been confirmed by tests.9

Burattini et al. used a mathematical formula to calculate the risk of acquiring the Zika virus during the periods of Carnival and the Olympics.39 They used the 27,146 cases of the disease that were reported in 2015 as basis for their calculation. Results showed that the risk of contracting Zika would be 3.6 per 100,000 during Carnival (which is the hottest season and usually the peak of transmission for such diseases) and 1.8 per 1 million during the Olympics (a much drier and cooler season, often the nadir of transmission). However, if the total number of Zika infections in Brazil in 2015 was really 1.5 million cases (anecdotal information, as yet unconfirmed), then the respective risks would 1.3 per 1,000 and 3.2 per 100,000.

Another mathematical calculation was performed to evaluate the risk of contracting dengue fever during the Olympic Games.2 This stochastic model took into consideration all historic data on the disease from 2000 to 2015. The calculations predict that in the worst-case scenario (based on the worst month of August 2007) incidences of 5.75 symptomatic and 51.5 asymptomatic cases per 100,000 individuals will be expected. That would result in 23 and 206 cases, respectively.

Most authors did not support the postponement of the games, particularly because delaying the event would place it in the middle of summer, the hottest and most humid season when mosquito populations increase all over the country.21,35,36,38 An extensive review of data regarding mass gatherings around the world (sports-related or religious) summarized the lessons learned and the implications for the Olympics in Brazil.1 The virus is present in over 60 countries, and the risk of infection is real with or without the Olympics. The authors reinforced that any potential risks caused by mass gatherings can be lessened when they are previously recognized and planned for and emphasized that other events already occurred in the country without significant international spread.

About Dengue

Dengue is an infection caused by four distinct viral serotypes htat are transmitted by the female mosquito of the genus Aedes. The disease was reintroduced in Brazil during the early 1980s and became a widespread problem by the mid-1990s. Nowadays, the country has the highest number of dengue infections worldwide, with more than 7 million reported cases.57 Up to 6% of travelers who visit Brazil and report febrile sickness on return are affected by it.50

Dengue has a usual pattern of outbreaks during the year, with most of the cases concentrated during the hot and humid months of summer, when the proliferation of mosquitoes and their vectorial capacity are higher.52

Symptoms include mild, nonspecific febrile syndrome with headache and myalgia. About 5% of patients may present hemorrhagic dengue, a severe and life-threatening condition. As a new dengue vaccine58 is being introduced and monitored in countries where dengue is most prevalent, the general recommendation for infected patients is supportive treatment with rest and fluid ingestion and avoidance of non-steroidal anti-inflammatories and aspirin.  Preventive measures to avoid the infection are the same described for Zika below.

About Zika

Zika fever is another disease cause by an arbovirus (flavivirus) transmitted mainly by Aedes mosquitoes bites (Aedes aegypit and Aedes albopictus) but also via sexual intercourse, perinatal or in utero to the newborn, and likely by blood transfusion.6 The virus was first identified in 1947 on rhesus monkeys in the Zika forest in Uganda. From the first case in humans in 1952 until the present day, outbreaks of Zika occurred in 2007 in Micronesia, 2010 in Cambodia and 2013-2014 in French Polynesia.24 The latter affected 11% of the population (28,000 infected) and was marked an excessive number of Guillain-Barré syndrome cases.6 The virus might have been brought to Brazil during the 2014 World Cup or later that same year during the Va’a World Sprint Championship canoe race, in which teams from the Pacific Island competed.43

One in five infected people will develop symptoms after two to 14 days of incubation. The disease often presents with a pruritic, descending and maculopapular rash, arthralgias, conjunctival injection, fatigue, malaise, retro-orbital pain, paresthesia, headache, myalgia, and lymphadenopathy. Most cases are mild and can last up to seven days.24,37

There is an increased incidence of Guillain-Barré Syndrome among Zika patients, although most patients fully recover. This neurological condition presents as ascending motor weakness and paralysis (sometimes requiring ventilatory support) lasting for days or weeks.37 Another potential complication of Zika is the development of microcephaly and other neurological abnormality in newborns when the infection occurs during pregnancy.

There is not a specific therapy. Because Zika is usually self-limited with mild symptoms, rest, hydration and acetaminophen are recommended. Nonsteroidal anti-inflammatories and aspirin should be avoided because they increase the risk of hemorrhage in dengue cases (differential diagnosis).

Prevention of Zika and Dengue

The key way to prevent Zika and dengue is to avoid mosquito bites.8 So, the Centers for Disease Control and Prevention recommends the following actions to athletes, visitors and the general population:

  • Personal protection: Wear long-sleeved shirts and long pants, use insect repellents, and treat clothing and gear with permethrin.23,37
  • Safe sex: Because the Zika virus can be spread through semen during all stages of the disease, the use of condoms should be considered for male athletes who have been diagnosed or had symptoms (for at least six months), those who traveled to an endemic area but did not have symptoms (at least eight weeks after returning), and those who live in such an area. 23,37
  • Environmental precautions: Stay in places with air conditioning or that use window and door screens to keep mosquitoes outside, sleep under a mosquito net, and avoid places with stagnant water (tires, flower pots, containers, etc.) because these are breeding grounds for larvae and mosquitoes.23,37


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