Every time As the Olympics approach, another disease seems to be stalking the event. In Rio 2016, it was Zika. In the postponed Tokyo Games, it was Covid. And at the 2024 Paris Games this summer? Take your pick. Authorities are scrambling to contain both dengue and measles, which are on the rise in France and many other countries.
This year’s Olympics and Paralympics will see millions of people from around the world converging on 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 — Paris sees nearly 40 million visitors a year — that’s a huge influx. 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 are planning how to limit the possibility of the Games becoming a superspreader event.
“It is very difficult to limit the risk of an epidemic when it comes to dengue,” explains Anna-Bella Failloux, a medical entomologist at the Pasteur Institute in Paris. The virus is transmitted from person to person by mosquitoes, and the culprit in France is the invasive tiger mosquito, Common mosquito. The insect is becoming a bigger problem as the weather warms and heated summers in Europe create conditions for the species to thrive. “The eggs are very resistant, and the metabolism of the mosquito speeds up with the heat. The insect becomes an adult earlier, and therefore bites earlier.”
Tiger mosquitoes are not modern 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 standing water that can hatch after several weeks, even after the water has evaporated. This explains how the insect spread across Europe, first arriving in Genoa, Italy, and then in France.
Dengue, however, is a more recent problem. With outbreaks of the virus in tropical parts of the world — there have been about 10 million cases worldwide this year, with South America and Southeast Asia demanding hit — France has seen an enhance in cases. Between January 1 and April 30, 2024, health authorities recorded 2166 casescompared with an average of just 128 cases during the same period in each of the previous five years. Most of this year’s cases have been imported from the French overseas departments of Guadeloupe, Martinique and French Guiana, where outbreaks are ongoing, but the European Centre for Disease Control and Prevention has recorded several cases of intra-European transmission this year, including in France.
This suggests the risk of an event that brings people together from all over the world at a time when cases are rising rapidly around the world. If this increases the number of cases imported to Paris, then a vast number of tiger mosquitoes will have the potential to spread the virus in the country.
For most people the infection is asymptomatic or with mild febrile symptomsbut in some, the disease becomes more severe and can be fatal. There is no specific treatment for the virus, and few Europeans have any immunity after previous exposure. Vaccines have become available only in the past few years and are only offered in a miniature number of countries with high transmission.