AI Risk Assessment for Arboviral Epidemics During the Paris 2024 Olympics

 

As the world eagerly anticipates the Paris 2024 Olympics, the Ile-de-France Region (IDFR), the epicenter of this grand event, faces an unexpected and potentially serious health risk. The region has recently seen a concerning rise in imported cases of chikungunya, Zika, and dengue, all arboviral diseases transmitted by the Aedes albopictus mosquito. This vector, known for thriving in temperate climates, has increasingly established itself in parts of the IDFR, raising alarms about the potential for local outbreaks during the Games.

The Growing Threat in Ile-de-France

The IDFR’s first dengue outbreak last fall was a stark reminder of the region’s vulnerability to arboviral diseases. This has fueled growing apprehension, particularly among public health experts and the media, that the influx of visitors during the Olympics could trigger autochthonous (locally transmitted) outbreaks in Paris. Unlike the Rio 2016 Olympics, where the primary concern was the global spread of the Zika virus from Brazil, the Paris 2024 scenario presents a unique risk: the importation of arboviral diseases into a nonendemic area with a nonimmune population and a competent vector capable of transmitting these diseases.

Aedes albopictus: The Competent Vector in Paris

Recent data shows that by late 2023, Aedes albopictus had colonized several western peripheral areas of Paris, including key Olympic sites such as Le Trocadéro, Le Parc des Princes, Le Stade Roland Garros, l'Arena Paris Sud, and l'Arena Bercy. Fortunately, central Paris remains unaffected, and the competition venues outside of Paris, particularly those in Seine-Saint-Denis where the Olympic Village will be located, are not within the colonized zones. However, the risk is mitigated by stringent vector control measures implemented by public health authorities in the IDFR. These efforts aim to minimize the presence of A. albopictus at Olympic venues, thereby reducing the chances of an outbreak.

Global Arboviral Disease Patterns and the Olympics

Arboviral diseases like dengue, Zika, and chikungunya are endemic to various tropical and subtropical regions, with transmission patterns that vary by season. Over the past five years, peak transmission periods for dengue—the most prevalent arboviral disease globally and the leading imported disease in the IDFR—have been observed between June and August in Southeast Asia, the Caribbean, and most African nations. These regions are of particular concern as they align with the timing of the Paris 2024 Olympics.

The French Overseas Territories, notably the French West Indies, have consistently been a primary source of imported dengue cases to the IDFR during the summer months. In 2024, this trend has continued, with a significant increase in imported dengue cases between May and July. However, the current decline in the dengue outbreak in the French West Indies offers a glimmer of hope, suggesting a reduced importation risk during the Olympics.

Visitor Projections and Air Traffic Trends

As the Olympics draw near, projections indicate a significant influx of visitors, with domestic tourism expected to dominate. Approximately 85% of the anticipated 15 million visitors will be French, with the majority hailing from the IDFR itself. Among international visitors, the largest groups are expected from the United Kingdom, the United States, and Germany. Interestingly, flight bookings to the IDFR have decreased among visitors from Southern Europe, reducing the already low risk of importing autochthonous arboviral cases from regions like the south of France, Italy, and Spain, where such outbreaks are relatively common.

Updated data from the Paris tourist office reflects a decline in international arrivals from endemic areas compared to the previous year. This includes regions with sustained dengue, Zika, and chikungunya circulation, further mitigating the risk of an arboviral disease outbreak during the 2024 Olympics.

Conclusion: A Careful Balance

While the Paris 2024 Olympics pose a unique risk due to the convergence of nonimmune populations, a competent vector, and imported arboviral cases, the situation is being closely monitored and managed. The IDFR’s public health agencies have implemented comprehensive vector control measures, and current trends in visitor demographics and air traffic suggest a lower-than-expected risk of large-scale outbreaks.

However, vigilance remains key. The lessons learned from previous large-scale events, coupled with ongoing surveillance and preventive efforts, will be crucial in ensuring that the Olympics remain a celebration of human achievement, not a trigger for an epidemic.