Mapping Technology Presents Clearer Picture of Chikungunya around the World 

After being bitten by a mosquito, you might become ill with fever, headache, and joint and muscle pain. If your first thought is to get tested for malaria, you’re not alone. But chikungunya is another disease spread by mosquitoes—a ghost infection that is often ignored or misdiagnosed as dengue or zika virus, leading to significant underreporting. Climate change is contributing to an increase in these types of diseases, and global health experts seek to better understand chikungunya transmission patterns and improve interventions, including vector control and the use of the recently approved Valneva vaccine.

Chikungunya emerged around 500 years ago and is most prevalent in Central and South America and Southeast Asia. The virus presents a significant global health risk due to its rapid rate of expansion and epidemic potential in densely populated tropical regions, including a recent major outbreak in Paraguay. With no antivirals, treatment is limited to symptom management with anti-inflammatory drugs. A pregnant woman can also pass chikungunya to her unborn baby, so prevention in the late stages of pregnancy is critical. Infections are significantly underestimated due to inaccurate diagnoses, limited health network infrastructure, low availability of diagnostics, and underdeveloped surveillance systems. The fact that chikungunya has the potential to cause significant morbidity worldwide and treatment options are so limited makes it even more important to clearly understand where and when cases are occurring to prevent harm.

I recently presented new research, conducted in collaboration with the London School of Hygiene and Tropical Medicine, at the Annual Meeting of the American Society of Tropical Medicine and Hygiene in New Orleans. Our research used geospatial data to map the global burden of chikungunya from 2017 to 2023. The maps were based on surveillance data extracted from government agencies and international sources, including country databases and weekly epidemiological reports published in English, Spanish, and Portuguese. The aim of this research was to see if we can use national- and regional-level data to get a more detailed look into trends of when and where infections are occurring versus globally reported data (like this very basic map produced by the European CDC). We then used geographic information system technology to visually represent the full scope of outbreaks, identify gaps in knowledge and surveillance data, and provide recommendations to strengthen these areas.

In the study, we estimated that there were more than 425,000 chikungunya cases globally in 2022, an increase of nearly 30% since 2015. Chikungunya causes a significant global burden of disease, with more than 130,000 disability-adjusted life years (DALYs) lost last year—more than from zika and yellow fever combined. Based on this study, the estimates for DALYs caused by chikungunya in India alone are higher than previous estimates for all of the Southeast Asia region combined. We also identified a shift in disease burden over the last decade from the Caribbean to South America. Stakeholders interviewed as part of a broader MSH-led collaboration noted that the limited surveillance data available hampered their ability to fully grasp the scope of the disease. This led to difficulties making informed decisions on key interventions, like planning for vaccine introduction.

Moving forward, increased organization and transparency of chikungunya surveillance data will be important to a cohesive global response to monitoring and responding to outbreaks. Enhanced surveillance systems and better mapping will help inform the use of vector control measures to interrupt transmission. Timely testing, diagnosis, and case management, especially during pregnancy, is essential. Contingency plans for screening patients and diverting health services during outbreaks should be developed. To promote data for decision making, a centralized monitoring platform should be established using published Ministry of Health data for additional WHO regions, similar to the Pan American Health Organization’s PLISA platform for the Americas. In remote areas with no surveillance capacity for chikungunya, proxy data, including climate forecasting, as is being done for dengue in Asia, can be utilized.

With invasive urban mosquito populations set to increase 20% by the end of this century, MSH’s work strengthening integrated vector control measures to prevent malaria and less common diseases like chikungunya and zika remains more important than ever. The epidemic in Paraguay was not the first and is unlikely to be the last. Collecting, using, and sharing accurate temporal and geospatial disease data that inform the implementation of preventive measures will remain critical moving forward.