India Could Bear The Heaviest Long-Term Burden Of Chikungunya: Global Study

Mosquito-borne diseases have long been a public health menace in tropical and subtropical regions. But a new study suggests chikungunya may pose a far heavier and more widespread risk than commonly appreciated. Chikungunya, transmitted by the Aedes mosquito (the same genus responsible for dengue), causes acute fever and severe joint pain. While many recover in weeks, a sizeable fraction go on to suffer persistent pain, arthritis, and functional disability for years.

In a pioneering global mapping effort, a team led by researchers at the London School of Hygiene & Tropical Medicine and collaborating institutions estimated both the current and potential future burden of chikungunya at high spatial resolution, taking into account climatic, ecological, and socioeconomic factors. Their aim was to predict how many people actually get infected each year and how many live with long-term consequences.

The results are alarming. Even under conservative assumptions, they estimate 14.4 million infections per year across areas already reporting chikungunya. In more expansive scenarios, that could reach 34.9 million globally. Of particular concern: India emerges as the country likely to bear the greatest long-term burden, both because of its population size and favourable conditions for transmission.

This study offers a wake-up call. If true, chikungunya is not just an episodic tropical fever but a chronic disability burden on par with some noncommunicable diseases. The implications for health systems, economies, and individual lives could be profound.

Demystifying The Study: What Was Done And What It Reveals

What the researchers behind this new study sought to do was estimate how many people get infected with chikungunya each year (force of infection) across both known and potentially susceptible regions. Their idea was to map that risk at fine spatial resolution (5 x 5 km) globally, considering environmental, socioeconomic, and ecological variables, and then translate those infection numbers into health impact, including chronic disability.

The researchers then fed in known chikungunya incidence data plus predictors like temperature, rainfall, mosquito presence, socioeconomic metrics, and ecology to train a model that estimates how strongly the virus transmits (force of infection) in each region. Each 5 x 5 km cell across 103 countries was scored for its risk. They converted estimated infections into DALYs, factoring in acute illness, chronic sequelae (long-term joint pain, disability), and age distributions of risk.

Here are the key findings of this study:

• Global burden (focal scenario): Around 14.4 million chikungunya infections were observed annually. And up to 34.9 million infections are likely to occur in future.
• Chronic burden dominates: About 54% of total burden is from chronic disease (long-term disability) rather than acute illness due to chikungunya.
• Age risk: Persons aged 40-60 bear a disproportionate share of chronic burden. Children under 10 and elderly over 80 face higher mortality relative to other ages.
• Geographic risk not limited to tropics: The model suggests that transmission risk exists beyond classical tropical zones, like parts of Africa, Latin America, Asia, and even non-tropical regions may see outbreaks.
• India and Brazil major burden bearers: India alone might see over 5 million infections annually (more under expansion scenario) and be among the top contributors to global burden. The study flags India and Brazil as likely to shoulder nearly half the global chikungunya disability burden.

Implications For India And Beyond: The Chikungunya Threat Explained

Based on the study and its findings, here are some things that India and other nations, specifically Brazil and other tropical regions, have to grapple with.

Health systems under pressure

Millions of affected individuals may develop chronic joint disability, which requires ongoing medical care, physiotherapy, pain management, and possibly rehabilitation services. This imposes both direct costs (treatment) and indirect costs (lost productivity, absenteeism).

Need for better surveillance

The study suggests that many regions currently not reporting chikungunya may actually be vulnerable. Strengthening active surveillance, laboratory diagnostics, and geo-referenced reporting is essential to close the gap between modelled risk and observed cases.

Vector control remains critical

Reducing Aedes mosquito populations via eliminating breeding sites, insecticide strategies, community engagement, and environmental management becomes more urgent, especially in areas flagged by the model as high-risk.

Vaccine prioritisation

Two chikungunya vaccines (Ixchiq and Vimkunya) are approved in some countries, though not yet widely in India. The model's age- and location-specific risk estimates can help policymakers prioritize which age groups or regions should receive vaccines first once available.

Public awareness and prevention

People living in or traveling to high-risk areas should be better informed about mosquito bite prevention (nets, repellents, clothing, screens). Public health messaging must reflect the chronic risk, not just the acute "fever phase."

Climate change and expansion vigilance

As the model suggests, changing climate, increasing temperature ranges, and expanded mosquito habitats could bring chikungunya into regions previously considered safe. Preparedness planning must include those marginal zones.

This landmark mapping and modelling study in BMJ Global Health signals that chikungunya may no longer be a localized, episodic tropical fever. It may be quietly evolving into a major contributor to chronic disease burden, especially in populous nations like India. The estimates, though imperfect, provide a sobering lens: millions infected annually, and over half of the health burden coming from long-term disability.

For India, the message is stark. Without proactive surveillance, aggressive vector control, and fast-tracked vaccine strategies, the country risks carrying the heaviest global burden of chikungunya for decades. Policymakers, public health bodies, and medical institutions must heed these findings, not as distant forecasts, but as signals demanding immediate, sustained action.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.