Large-scale analysis provides insight into the sporadic nature of chikungunya virus outbreaks

Large-scale analysis provides insight into the sporadic nature of chikungunya virus outbreaks

Symptoms come on quickly – acute fever, followed by debilitating joint pain that can last for months. Although chikungunya virus, a mosquito-borne disease, is rarely fatal, it can be particularly serious for high-risk people, including newborns and older adults.

While the virus is widespread in tropical and subtropical regions, including Asia, Africa and South America, health authorities have tracked reported infections in Europe and a confirmed case in Long Island, New York, in September.

Chikungunya outbreaks have prompted the Centers for Disease Control to issue health warnings for travelers heading to Bangladesh; Cuba; Guangdong Province, China; Kenya; Madagascar; Somalia; and Sri Lanka.

In Guangdong province, an "unprecedented" outbreak recently prompted government officials in China to order quarantines for anyone suspected of being infected with the virus, spray individuals with mosquito repellent, and spray affected buildings and other areas with insecticide.

In a new study published inScientific advancesResearchers at the University of Notre Dame analyzed more than 80 chikungunya virus outbreaks to improve prediction of future outbreaks and aid in the development of vaccine trials.

“Chikungunya outbreaks are unpredictable in both their size and severity,” said Alex Perkins, the Ann and Daniel Monahan Professor of Infectious Disease Epidemiology in the Department of Biological Sciences and co-author of the study.

There can be an outbreak that infects just a few people and another in a similar setting that infects tens of thousands. This unpredictability is what makes public health planning – and vaccine development – ​​so difficult.”

Alex Perkins, Ann and Daniel Monahan College Professor, Department of Biological Sciences, University of Notre Dame

For the study, Alexander Meyer, a postdoctoral fellow in Perkins' lab and lead author of the study, and a team of researchers reconstructed and analyzed 86 chikungunya outbreaks, creating the largest comparative data set of its kind.

“Instead of looking at outbreaks in isolation, by looking at many outbreaks, all varying in size and severity, we were able to look for patterns between them,” Meyer said.

Chikungunya was first identified in the 1950s. Outbreaks are becoming increasingly common and widespread, but they are also sporadic and difficult to predict, presenting a challenge for health authorities when it comes to planning and preventing infections.

Changes in outbreaks of chikungunya, which are transmitted through the bites of infected mosquitoes - Aedes aegypti or Aedes albopictus are the main vectors - and other mosquito-borne diseases are often considered in the context of climate change, as warmer, moist conditions can promote mosquito activity.

But Perkins said this study showed that climate is not necessarily the most important factor when trying to predict the severity of a disease outbreak caused by a virus such as chikungunya virus.

"Climate factors like temperature and precipitation can tell us where outbreaks are possible, but this study shows they don't do much to predict how severe they will be," he said. "Local conditions matter - things like housing quality, mosquito density and the way communities respond. Some variations are simply due to chance. That chance is also part of the story."

Currently, only two chikungunya vaccines have received regulatory approval - but they are not widely available in regions where the virus is most common.

That's why having such a large, comprehensive data set is so helpful in vaccine development, Perkins said.

To test effectiveness, vaccine makers need accurate predictions of where an outbreak might occur before it occurs, to conduct trials and monitor whether vaccine candidates are effective.

The study shows how more comprehensive analysis of past outbreaks can help health authorities prepare for future outbreaks, thereby protecting vulnerable populations and supporting vaccine development.

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