Every year, hundreds of people suffer with chikungunya, which begins with a rapid fever followed by excruciating joint discomfort that can last months. While the mosquito-borne virus is rarely lethal, it can cause long-term pain and exhaustion, particularly in babies and elderly adults. Scientists now warn that the disease is spreading to other areas, including a recently confirmed case on Long Island, New York. 

Outbreaks have erupted across Asia, Africa, and South America, prompting quarantines and large-scale mosquito control efforts in countries such as Bangladesh, Kenya, Sri Lanka, and China's Guangdong Province. 

In a new publication published in Science Advances, researchers from the University of Notre Dame examined data from 86 chikungunya outbreaks globally, the largest such study to date. Their goal is to figure out why certain epidemics infect only a few people while others spread to tens of thousands. 

"Chikungunya outbreaks are unpredictable in both size and severity," said Dr Alex Perkins, a professor of infectious disease epidemiology and co-author of the research. "That unpredictability makes public health planning—and vaccine development—very difficult." 

By comparing outbreaks from several places, the team discovered patterns that transcend climate and geography. 

Chikungunya-carrying mosquitoes, Aedes aegypti and Aedes albopictus, flourish in warm, humid circumstances. Surprisingly, the study discovered that climate isn't the primary cause. 

"Temperature and rainfall can tell us where outbreaks are possible," said Alexander Meyer, the study's principal researcher. "However, temperature and rainfall do not predict the severity of the outbreaks." Local factors, including housing quality, mosquito density, and community response, all significantly influence the outbreaks. And some variance is purely random." 

According to the experts, the randomness makes it difficult to forecast when and where vaccine trials should begin. 

Only two vaccinations for chikungunya have gotten regulatory approval thus far, and they are still not widely available in the most impacted areas. Scientists hope that by creating a massive global dataset, they would be able to better predict future outbreaks and direct vaccine producers to the right regions at the right time. 

The findings demonstrate how better data and local action, ranging from mosquito control to housing repair, can safeguard communities. Millions of people living in mosquito-prone areas may benefit from less painful infections and faster access to life-saving vaccines.