Each time the Olympic Games approach, a different illness appears to loom over the competition. During Rio 2016, it was Zika. At the delayed Tokyo games, it was Covid. And for the upcoming 2024 Paris Olympics? The options are plenty. Authorities have been striving to contain both dengue and measles, diseases that have been increasing in prevalence in France and numerous other nations.
When the Olympics and Paralympics take place this summer, millions of individuals from various corners of the globe will converge in the host city: French officials are gearing up to receive over 15 million tourists in the country. Even for a bustling capital accustomed to heavy tourism—nearly 40 million individuals visit Paris annually—this surge in numbers is significant. Some travelers may carry infectious illnesses with them. Others, lacking adequate immunity, face the risk of contracting something during their visit. With dengue and measles already posing challenges in Paris, authorities have been strategizing on how to minimize the chances of the Games turning into a superspreader event.
“Controlling the epidemic risk related to dengue is immensely challenging,” elucidates Anna-Bella Failloux, a medical scientist specializing in insects at the Pasteur Institute in Paris. The virus spreads from person to person through mosquitoes, particularly the invasive tiger mosquito, Aedes albopictus, in France. The insect becomes a growing issue as temperatures rise, and the hot European summer is favorable for the species to flourish. “The mosquito eggs are highly resilient, and with the warmer weather, the mosquito’s metabolism accelerates. This results in the insect reaching maturity earlier, and subsequently, it starts biting earlier as well.”
Tiger mosquitoes are not a recent introduction to France: They made their appearance as early as 2004 in the southern regions, and have been present in Paris since 2015. Originating from Asia, they lay eggs in stagnant water sources, which can hatch weeks later, even after the water source has dried up. This explains the migration of the insect to Europe, initially reaching Genoa, Italy, before entering France.
On the other hand, dengue is a more recent concern. With dengue outbreaks rampant in tropical regions worldwide—this year has seen an estimated 10 million cases globally, with South America and Southeast Asia severely affected—France has witnessed a surge in cases. From January 1 to April 30, 2024, health authorities documented 2,166 cases, compared to a yearly average of merely 128 for the same period over the past five years. The majority of cases this year were imported from the overseas French territories of Guadeloupe, Martinique, and French Guiana, where outbreaks are ongoing. However, the European Centre for Disease Control and Prevention has registered instances of local transmission within Europe this year, including in France.
This underlines the risk involved in a gathering of people from all corners of the world at a time when cases are escalating worldwide. Should this lead to a rise in imported cases in Paris, an abundance of tiger mosquitoes could potentially facilitate domestic virus spread.
For most individuals, an infection remains asymptomatic or results in mild feverish symptoms, but in some cases, the illness can become severe, even fatal. There is no targeted treatment for the virus, and only a few Europeans possess immunity from prior exposure. Vaccines have only recently become accessible, and are currently provided in a limited number of countries with high transmission rates.
