Severe chikungunya infection requiring intensive care unit admission during the 2024– 2025 outbreak on Réunion Island: a multicentre observational study
This multicentre observational study of the 2024–2025 Réunion Island outbreak reveals that severe chikungunya infection requiring ICU admission predominantly affects older patients with comorbidities, carries a 29% in-hospital mortality rate driven primarily by pre-existing diabetes, and is characterized by frequent multiorgan failure, particularly hepatorenal involvement.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Mosquitoes are more than just a summer nuisance; they are efficient couriers for a family of viruses that can turn a simple fever into a life-threatening emergency. One such virus, chikungunya, is carried by the Aedes mosquito, a species that thrives in tropical and subtropical climates and is known for its aggressive daytime biting habits. When a person is infected, the virus typically triggers a sudden onset of high fever and severe joint pain, symptoms so intense that the name "chikungunya" comes from a local word meaning "to become contorted." While most people recover, the virus can occasionally strike with a ferocity that overwhelms the body's organs, particularly in older adults or those with pre-existing health conditions. Understanding how this virus behaves when it causes its most severe damage is critical, not just for treating the sick, but for preparing communities for the next time the virus strikes.
In 2024 and 2025, the island of Réunion in the Indian Ocean faced a massive resurgence of this virus. Following a major outbreak two decades earlier, the island had seen the virus fade, only for it to return with a new wave of infections that would eventually be confirmed in more than 54,000 people. To understand the true danger of this second outbreak, a team of researchers from hospitals across the island set out to examine the most critical cases. They focused their attention on the 44 adults who were so severely ill that they had to be admitted to an intensive care unit. These were not just patients with a bad fever; these were individuals whose bodies were failing in multiple ways, requiring machines to breathe for them, drugs to keep their blood pressure up, and dialysis to clean their blood.
The researchers gathered detailed records on every one of these patients, looking at their age, their medical history, and the specific ways their bodies reacted to the virus. They found that the patients were, on average, nearly 70 years old, and almost everyone had at least one chronic health issue before they got sick. High blood pressure was common, but a specific condition stood out: diabetes. The virus seemed to hit these patients with a particular brutality, causing their kidneys to shut down, their hearts to struggle, and their lungs to fill with fluid. In many cases, the virus triggered a cascade of failures where the liver, kidneys, and circulatory system all began to falter at once.
Among the 44 patients studied, the outcome was stark. Thirteen of them, or about 29 percent, did not survive their hospital stay. When the researchers looked closely at what separated those who lived from those who died, a clear pattern emerged. While many factors were associated with a worse outcome, such as older age or heart failure, only one factor independently predicted death: a history of diabetes. Patients with diabetes were nearly five times more likely to die than those without it. This suggests that for these patients, the virus did not just cause a fever; it destabilized their entire system in a way that their bodies could not recover from. The study also noted that many patients had other infections, like pneumonia, complicating their recovery, and that the virus often caused severe abdominal pain, a symptom that surprisingly appeared more often in those who survived.
The virus responsible for this outbreak was not exactly the same as the one that caused the 2005–2006 epidemic. Genetic analysis showed it belonged to a slightly different branch of the virus family, carrying specific mutations that allowed it to spread more easily through the local mosquito population. This genetic shift, combined with a population that had not been exposed to the virus in nearly two decades, created the perfect conditions for a large-scale outbreak. The researchers observed that the virus could cause a wide range of severe problems, including brain inflammation and bleeding disorders, but the most common and deadly pattern involved the kidneys and liver failing together.
This study provides a clear picture of what happens when chikungunya reaches its most dangerous form. It confirms that while the virus can affect anyone, it poses a specific, life-threatening risk to older adults with diabetes. The findings highlight that when the virus strikes, it does not just cause pain; it can trigger a systemic collapse that requires the most advanced medical care available. For doctors and public health officials, the message is clear: monitoring patients with diabetes closely during an outbreak is essential, and the world must remain vigilant, as the virus continues to evolve and find new ways to spread through populations that have not seen it in years.
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