The World Health Organization has issued a stark warning: the chikungunya virus is resurging in a pattern strikingly similar to the major outbreak of 2004–2005. With major flare‑ups already underway in Indian Ocean territories such as Réunion, Mayotte, and Mauritius, the agency cautions that more than 5.6 billion people across 119 countries remain vulnerable to the mosquito‑borne disease.
Roaming mosquitoes like Aedes aegypti and Aedes albopictus — the infamous tiger mosquito — remain the primary vectors, spreading a disease characterized by sudden high fever, debilitating joint pain, rash, fatigue and nausea. While fewer than 1% of infections result in death, the sheer scale of infection makes even a low fatality rate potentially deadly—resulting in thousands of deaths if millions fall ill.
Epicentre: Indian Ocean Islands Face Full-Blown Epidemic
In Réunion Island alone, health authorities have documented over 47,500 confirmed cases and 12 associated deaths as of early May 2025, with weekly incidence surging from just 30 cases at the end of 2024 to roughly 4,000 during mid-March.
Of these, more than 340 hospitalisations have occurred, affecting infants, adults with comorbidities, and older individuals; 12 deaths among those aged over 70 have been attributed to chikungunya as of late April.
Nearby Mayotte has also seen a resurgence: 116 total cases reported by early May, including locally acquired infections for the first time since 2006. So far no deaths, though one hospitalization has occurred. These outbreaks have triggered elevated vector-control measures including vaccination pilots, surveillance, and public health campaigns.
Europe on Alert: Local Transmission Emerges in Mainland
Europe is now confronting its own local transmission episodes. As of mid-July 2025, France has confirmed 30 locally acquired cases across 12 administrative units, including new detections in the Grand Est, Gironde, Provence‑Alpes‑Côte d’Azur, Corsica, Occitanie, and Auvergne‑Rhône‑Alpes regions. Meanwhile, Italy has reported its first local case since 2017 in Piacenza.
Between May 1 and mid-July, France logged about 800 chikungunya infections, most being imported, but 12 clusters of local transmission confirmed the virus is now being passed by local mosquitoes.
French experts stress this is an early-season phenomenon—much earlier than previous years—likely reflecting longer, warmer mosquito seasons due to climate change.
Why Now? Climate, Mobility, and Waning Immunity Drive Spread
Conditions resemble the 2005 epidemic patterns: islands with fading population immunity, tropical climate supporting mosquito breeding, and rapid human mobility have fostered transmission. In Réunion, immunity built up in 2005–06 has waned, paving the way for new outbreaks nearly two decades later.
Additionally, climate change is expanding the range and season length of Aedes albopictus, enabling the species to thrive across more temperate parts of Europe. These mosquitoes bite during the day (peaking in early morning and late afternoon), evading many nighttime‑focused anti‑mosquito strategies.
WHO and Health Bodies Respond with Prevention & Guidance
The WHO’s latest epidemiology update underscores that 119 countries now report local chikungunya transmission, with surveillance and diagnostics still lagging in many regions. Under-reporting remains a concern, complicating response efforts worldwide.
In May 2025, WHO published new clinical management guidelines covering dengue, chikungunya, Zika, and yellow fever, aimed at supporting healthcare providers at all levels—from primary care to hospital wards—to improve case recognition and treatment outcomes for arboviral diseases.
The European Centre for Disease Prevention and Control (ECDC) also launched weekly reports and region-specific guidelines for vector control and outbreak response tailored to risk levels, across countries with emerging local transmission.
Vaccine Developments Draw Global Scrutiny
As part of outbreak response, two chikungunya vaccines have received regulatory approval: Ixchiq (live attenuated) authorized by the FDA in November 2023 and by EMA in mid-2024, and Vimkunya (recombinant) approved in early 2025 for individuals aged 12 and above.
However, post-marketing reports of serious neurological and cardiac adverse events, including fatalities in older adults (aged 62–89), have led regulators in the U.S., UK, EU, and UK’s MHRA to suspend the use of Ixchiq in those over 60 or 65 pending further investigation .
What You Can Do: Protection at Every Level
Personal prevention remains vital: use insect repellent, wear long-sleeved clothing, and eliminate stagnant water in containers such as buckets, gutters, and flowerpots to reduce breeding sites.
Travelers returning from affected areas should maintain precautions to avoid introducing the virus into mosquito-endemic regions.
Clinicians are urged to apply updated WHO clinical guidelines to recognise and manage arboviral illnesses early and effectively.
Public health authorities should intensify mosquito surveillance, launch targeted vector-control campaigns, and consider outbreak-specific vaccination strategies.
In summary, the chikungunya virus is poised to become a major global concern in 2025. The escalating outbreaks in the Indian Ocean, the emerging cascade of local cases in Europe, and signs of early seasonal transmission reinforce that this is a critical moment for coordinated, global prevention and response.
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