Could there be a dengue outbreak during the 2024 Paris Olympics?

The Concern

Dengue cases in France have been reaching unprecedented levels in recent years.¹ In 2022, locally acquired cases of dengue (contracted within France itself rather than "imported" from abroad) hit a record high, with at least 65 detected.¹

Through the first quarter of 2024, France registered a record number (1,679) of imported dengue cases compared to 131 cases during the same period in 2023.^3,4 The recent surge in imported dengue cases is concerning given its timing – the same year as the Paris 2024 Olympic Games.² The concern is that a person infected with dengue can transmit it to a mosquito, which in turn, can transmit the virus to another person.⁵

Therefore, the French health authority, Santé Publique France, will carry out reinforced surveillance of arboviruses between May and November, including dengue.⁶ Arboviruses have been identified as one of the main infectious risks over the summer period.⁶

With over 10 million athletes, spectators, officials and tourists expected to gather in the city for the event, could the Paris Olympics cause a dengue ‘super-spreader’ event ?² The term ‘super-spreader’ can refer to people who have a higher than average capacity to help infect others, possibly due to their physiology, biology, social position or behavior, and who are responsible for the majority of infections.⁷

Where

• Metropolitan France (Paris Olympics)

The numbers

• 1,679 imported cases (in all of France) were reported to Santé publique France since January to April 2024 – compared to 131 cases during the same period in 2023⁴

The contributing cause

• According to the European Centre for Disease Prevention and Control (ECDC), most of the imported cases in France originate from Guadeloupe and Martinique, where an ongoing "epidemic" is being observed⁸

• In many countries during 2024 dengue cases have reached record levels and travelers from these areas could bring dengue with them⁹

The impact

• The true impact remains to be seen as Paris braces itself for the event:

The response

• A French health ministry official stated the authorities were "fully mobilised" and preparing for any possible infectious disease threats during the Olympics⁵

• “Dengue detectives” were recruited to actively search for possible breeding grounds for Aedes albopictus mosquitos to prevent an outbreak. Their remit included identifying disease hotspots and seeking out mosquito sites¹¹

• On May 1, the Greater Paris Regional Health Agency (ARS) launched a surveillance campaign of mosquitos in the city and its suburbs. This included placing over 500 nesting traps, in various locations around the city and its suburbs. These traps, which emit human-like scents to capture mosquitoes, would be sent for testing once a month to help survey the spread of the Aedes albopictus ahead of the games^10,11

• Also, to further monitor the situation, health authorities set up a website and were calling for hotels, schools, and other locations to report possible outbreaks early¹¹

Looking ahead: managing the risk

• For the Olympics gathering to cause a significant number of dengue cases, there would need to be enough mosquitoes, and enough susceptible and already infected people present, as well as enough time for mosquitoes to transmit dengue¹²

• An added consideration is that infected visitors could unknowingly carry the dengue virus back to their home country and help spread it among the local population, in areas where Aedes mosquitoes are present²

• Conversely, successful prevention of the spread of dengue during the Olympics in Paris could not only protect people but also hold precious lessons for other future major sporting events held in locations that are vulnerable to the spread of dengue