Rising temperatures and shifting rainfall are driving malaria, dengue and chikungunya into once-protected mountain regions, exposing millions of unprepared communities across the Hindu Kush Himalaya.

A quiet public health crisis is unfolding in India’s highlands – from the alpine valleys of Kashmir to the forested slopes of Himachal Pradesh and beyond. Diseases long associated with the hot, humid plains are moving uphill. Warmer winters, shrinking day-night temperature gaps and changing rainfall patterns are creating new habitats for mosquitoes that transmit malaria, dengue and chikungunya. Communities that once relied on frost to keep these vectors at bay now face rising infections, stretched health systems and the need for surveillance systems that have not kept pace with a rapidly changing climate.

The trend is not limited to India. Across the broader Hindu Kush Himalayan region – spanning parts of Afghanistan, Pakistan, India, Nepal, Bhutan, Bangladesh, Myanmar and China – scientists document the same expansion of vector-borne diseases into higher altitudes once considered non-endemic. The story illustrates how climate change is rewriting the geography of infectious disease far beyond the tropics.

Warmer Winters Open the Door for Mosquitoes

Kashmir’s climate has long been defined by cold winters and heavy snowfall that historically limited mosquito survival. Residents recall winters that began in November and stretched into April. That pattern is breaking. In recent years, February temperatures in parts of the valley have risen nearly 10°C above normal, occasionally touching 21°C. Winter precipitation has shown deficits of nearly 50 per cent for consecutive years. In 2024, Srinagar recorded a July maximum of 35.7°C – six degrees above normal and the highest in nearly 25 years – hotter than several major Indian cities including Delhi and Kolkata.

Neighbouring Himachal Pradesh experienced 28 heatwave days between April and June 2024 and recorded nearly 2,700 forest fires in the same period, the highest since 2007. These conditions reduce the natural winter die-off of mosquito populations. Environmental scientist Raghu Murtugudde notes that frost once interrupted transmission cycles of malaria and chikungunya in the hills. Warmer winters, rising humidity and shifting vegetation now allow these cycles to persist.

Pallavi Joshi of the Institute for Global Environmental Strategies points to another critical change: the shrinking difference between daytime and nighttime temperatures. Stable warmer conditions over 24-hour cycles create more favourable environments for vectors to survive and breed, especially in hilly terrain.

Case Numbers Climb in the Hills

Official data from India’s National Center for Vector-Borne Disease Control show clear upward trends. Jammu and Kashmir recorded 3,381 dengue cases in 2025, nearly double the 1,709 cases reported in 2021. Suspected chikungunya cases in the same territory jumped from just seven in 2021 to 773 in 2025. Himachal Pradesh, which reported zero chikungunya cases in 2021, logged more than 200 in 2025. Similar increases appear in Meghalaya and Uttarakhand.

Malaria continues to exact a toll, particularly among agricultural workers in forested and hilly districts. Although India has reduced overall malaria transmission and deaths over recent decades, the disease still claimed more than 10,000 lives across the country in the past 20 years. The economic burden is substantial: Aedes-borne diseases alone impose an estimated average annual global cost of nearly $1.2 billion through healthcare spending, lost productivity and social disruption.

Scientific modelling reinforces the observational data. Studies project that under future climate scenarios, the dengue vector Aedes albopictus will expand into upper and trans-Himalayan regions, while malaria transmission seasons lengthen in highland areas previously unsuitable for sustained transmission. Populations in these zones often lack acquired immunity, raising the risk of more severe outbreaks when the diseases arrive.

Surveillance Systems Lag Behind the New Geography

Public health experts warn that India’s disease surveillance remains largely reactive. Urvashi Prasad, formerly of the government think tank NITI Aayog, observes that outbreaks once tied tightly to the monsoon now occur across longer and less predictable periods because of unseasonal rainfall and prolonged heat. When cases emerge in remote or hilly areas, detection is often delayed. By the time official reports trigger a response, transmission has already widened.

Prasad and others call for closer integration of climate data – satellite rainfall records, temperature trends and environmental indicators – into early-warning systems. Coordination between climate agencies, health departments and disaster-management authorities remains weak in practice, even where institutional mechanisms exist on paper. Without predictive tools that flag emerging hotspots before cases surge, responses will continue to trail the disease.

Similar gaps appear across the Hindu Kush Himalaya. Systematic reviews of the region find positive associations between rising temperatures, precipitation changes and the expansion of malaria, dengue, chikungunya, Japanese encephalitis and other vector-borne diseases into higher elevations. Experts recommend expanding vector control and surveillance into previously non-endemic highland zones.

A Wider Climate-Health Crisis in the Mountains

The rise of mosquito-borne disease is only one dimension of a broader climate-health challenge in India’s mountains. Extreme weather has become more frequent and destructive. Heat exposure alone cost India an estimated 160 billion labour hours in 2021, equivalent to roughly 5.4 per cent of GDP. Air pollution, already a major health burden in the plains, is worsening in enclosed valleys such as Kashmir, where vehicle emissions become trapped. Residents report a sharp decline in air quality in recent years.

Glacier retreat in the Himalayas – now occurring 65 per cent faster than a decade ago in parts of the Indian Himalaya – threatens water security for hundreds of millions downstream and raises the risk of glacial lake outburst floods. These cascading hazards compound health vulnerabilities. The Himalayas function as a critical water tower and climate barometer for Asia; changes here ripple across borders.

Preparing Communities for a New Disease Landscape

Responses will need to operate on several fronts simultaneously. Strengthened entomological surveillance at higher altitudes, community education on mosquito breeding sites, improved diagnostic capacity in rural and hill health centres, and climate-informed forecasting models are all essential. Vector control programmes designed for the plains will require adaptation to mountainous terrain and seasonal patterns that are themselves shifting.

International cooperation matters. The Hindu Kush Himalayan region shares ecosystems, river basins and disease pathways. Regional bodies and global health organisations have a role in supporting data sharing, joint early-warning systems and research into how climate change is altering disease ecology at altitude. Lessons from India’s experience can inform preparedness in other highland regions worldwide facing similar warming trends.

The human stories are already visible. Indigenous residents in forested central Indian districts report more frequent malaria episodes. Young people in Srinagar describe sleepless nights under unprecedented heat and the need for air conditioning that was rarely required a decade ago. These individual experiences map onto a larger ecological shift: the climate is no longer confining tropical and subtropical diseases to the lowlands.

The Map is Still Being Rewritten

Climate change is not merely intensifying existing disease burdens; it is expanding their geographic reach into populations with limited prior exposure and limited institutional readiness. In India’s mountains, the process is already underway. Dengue and chikungunya case counts in hill states, warmer winters in Kashmir, and scientific projections of further vector expansion together form a coherent and concerning picture.

For global health observers, the lesson is clear. Disease maps drawn under twentieth-century climate assumptions are becoming obsolete. Effective public health in the twenty-first century will require systems that treat climate variables as core inputs rather than external factors. India and its Himalayan neighbours have an opportunity – and an urgent need – to build those systems before the new disease geography becomes the new normal.