Should We Be Worried About Dengue at the 2024 Paris Olympics?

Image by: Image by: Shawn Carpenter; CC BY-SA 2.0 DEED

The 2024 Olympics have begun, and more than 10 million people are expected to be in Paris for this year’s games.1 While the Olympics will undoubtedly be an exciting event highlighting the world’s top athletes, its large crowds have created some worry. The COVID-19 pandemic demonstrated how disease can spread rapidly in big groups of people. So, should we be concerned about the potential public health impacts that may result from the Olympics?

There is a long history of the Olympics sparking worry over the public health impact. For example, there were worries about the Spanish flu in Antwerp (1920), swine flu in Vancouver (2010), and Zika in Rio (2016).2  In recent years, an outbreak of norovirus, a highly contagious virus that causes gastrointestinal symptoms, occurred at the 2018 Pyeongchang Olympics.3 In the wake of the COVID-19 pandemic, there was concern that the 2021 Tokyo Olympics and the 2022 Beijing Olympics would be super spreader events.4 In an attempt to mitigate the public health impact of these viruses, officials implemented both preventive and reactionary measures. In Pyeongchang, once the norovirus outbreak was detected, officials implemented quarantines and tested food and water to try to determine the source of the disease.2 Food handlers were also tested, allowing for the detection of asymptomatic cases.5 These measures helped prevent further spread of norovirus at the Games.5 In Tokyo and Beijing, officials implemented regular testing, social distancing, contact tracing, and more to prevent the spread of COVID-19.4 As a result, there were no instances of severe illness.4 These three Games exemplify the need for the Olympics to invest in the development of public health plans and mitigation strategies, especially when dealing with large groups of people. 

With visitors traveling to Paris from all over the world, there is the potential for imported cases of diseases. Dengue, which is not endemic to Europe, is a concern for the 2024 Paris Olympics.6 Dengue is a virus that spreads to humans through mosquito bites. Dengue can present asymptomatically or with mild symptoms such as fever, rash, pain behind the eyes, swollen glands, severe headache, muscle and joint pains, nausea, and vomiting.7 In rare cases it can result in more severe illness and even death.7 The number of dengue cases has been on the rise globally, especially in the past year. According to the WHO, there have been 7.6 million cases of dengue reported between January and April 2024. This is greater than the total number of cases, about 5 million, reported in all of 2023.6, 8 Climate change has contributed to the increase in dengue cases globally due to hotter and wetter environments.8 The Aedes species of mosquitoes tend to lay eggs in containers with water or stagnant pools.8, 9 Thus an abundance of rain can increase breeding grounds for mosquitos and by extension the mosquito population.9, 10 Hot temperatures are beneficial to the mosquito life cycle because they impact hatching rates, mosquito development time, and their ability to survive.10,11 Moreover, mosquitoes become infectious more quickly at warmer temperatures because the extrinsic incubation period is shortened.10, 11 In 2023, almost all dengue cases in Europe were the result of travel from places where dengue is endemic.12 This fact is noteworthy as Paris prepares for large numbers of visitors from around the globe. Dengue does not spread through human-to-human transmission. However, mosquitos can become infected after biting people with the virus and can go on to infect humans.9 It takes only one mosquito to spread the disease. With the potential of asymptomatic visitors to Paris, there is growing concern that infected individuals will unknowingly spread dengue. This concern is mounting as several dengue cases have already been identified in France this year.13

Thankfully, France is aware of the risk of dengue and has taken precautionary steps in the greater Paris area.14 Traps and testing have been established around the Stade de France, the Olympic village, some “fan zones”, airports, and the Marseille Marina.14 Health officials have also created a website to report sightings of tiger mosquitos.14 Moreover, Paris health officials are hoping to educate the public on the disposing of stagnant water to prevent mosquito breeding.14 Individuals planning on attending this year’s events should also practice prevention strategies such as using bug spray and wearing loose-fitting clothing that covers one’s arms and legs.15 If possible, visitors should also stay in places with window or door screens.15 For more information, you can visit the CDC website to learn more.

Sources:

  1. https://www.cnn.com/2024/06/14/health/dengue-paris-olympics/index.html
  2. https://www.cnn.com/2021/07/23/sport/olympic-pandemics-intl-hnk/index.html
  3. https://www.nytimes.com/2018/02/08/world/asia/norovirus-olympics-korea.html
  4. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)02635-1/abstract?uuid=uuid%3A24704d7e-2ebc-4e19-89a3-d8054d80af6d
  5. https://pubmed.ncbi.nlm.nih.gov/34115864/
  6. https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON518#:~:text=Dengue%20is%20not%20endemic%20in,cases%20are%20mainly%20travel%2Drelated.
  7. https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue
  8. https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON498
  9. https://www.cdc.gov/dengue/transmission/index.html 
  10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381975/ 
  11. https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(23)00147-0/fulltext 
  12. https://www.ecdc.europa.eu/en/news-events/worsening-spread-mosquito-borne-disease-outbreaks-eueea-according-latest-ecdc-figures#:~:text=In%202023%2C%20there%20were%20130,73%20for%20the%20whole%20period.
  13. https://www.santepubliquefrance.fr/maladies-et-traumatismes/maladies-a-transmission-vectorielle/chikungunya/articles/donnees-en-france-metropolitaine/chikungunya-dengue-et-zika-donnees-de-la-surveillance-renforcee-en-france-hexagonale-2024
  14. https://www.telegraph.co.uk/global-health/science-and-disease/paris-olympic-games-2024-dengue-outbreaks-mosquitoes/#:~:text=%E2%80%9CWe%20are%20prioritising%20our%20surveillance,the%20city’s%20airports%2C%20adds%20Somarriba.
  15. https://www.cdc.gov/dengue/prevention/index.html#:~:text=There%20is%20no%20widely%20available,long%2Dsleeved%20shirts%20and%20pants.

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