Every time he As the Olympics approach, it seems there’s a different disease stalking the event. At Rio 2016 it was Zika. At the postponed Tokyo Games it was Covid. And at the Paris 2024 Olympics this summer? Take your pick. Authorities have been working to contain both dengue and measles, which have been on the rise in France and many other countries.
During this summer’s Olympic and Paralympic Games, millions of people from around the world will flock to the host city: French authorities are preparing to welcome more than 15 million visitors to the country. Even for a capital accustomed to mass tourism (nearly 40 million people visit Paris each year), this is a huge influx of people. Some will bring infectious diseases with them. Others, without sufficient immunity, risk catching something during their stay. With dengue and measles already a problem in Paris, authorities have been planning how to limit the potential for the Games to become a superspreader event.
“It is very difficult to limit the risk of an epidemic when it comes to dengue,” explains Anna-Bella Failloux, an entomologist at the Pasteur Institute in Paris. The virus is transmitted from person to person via mosquitoes, with the tiger mosquito being the cause in France, an invasive mosquito. Aedes albopictusThe problem with the insect increases with the rise in temperature and the heat of the European summer creates the conditions for the species to thrive. “The eggs are very resistant and the metabolism of the mosquito is accelerated by the heat. The insect becomes an adult earlier and therefore bites earlier too.”
Tiger mosquitoes are not new to France: they arrived in the south in 2004 and have been in Paris since 2015. Originally from Asia, they lay eggs in pockets of stagnant water, which can hatch weeks later, even after the water has evaporated. This explains how the insect spread to Europe, first reaching Genoa, Italy, before arriving in France.
However, dengue is a more recent problem. With outbreaks of the virus sweeping through tropical parts of the world (an estimated 10 million cases worldwide this year, with South America and Southeast Asia severely affected), France has seen cases rise. Between January 1 and April 30, 2024, health authorities recorded 2,166 casescompared with an average of just 128 for the same period in each of the previous five years. Most of this year’s cases were imported from the French overseas departments of Guadeloupe, Martinique and French Guiana, where epidemics are ongoing, but the European Centre for Disease Control and Prevention has recorded some cases of transmission within Europe this year, including in France.
This indicates the risk of an event that brings together people from all over the world at a time when cases are soaring worldwide. If this increases the number of imported cases in Paris, the abundance of tiger mosquitoes has the potential to spread the virus nationally.
For most, an infection is asymptomatic or produces mild febrile symptomsBut in some cases the disease becomes more severe and can be fatal. There is no specific treatment for the virus and few Europeans have immunity from previous exposure. Vaccines have only become available in recent years and are offered only in a small number of countries with high transmission.