From heat to dengue: Arunachal is warming, is its health system ready?

Itanagar: In parts of Arunachal Pradesh, collecting data can become difficult when the monsoon cuts off roads and disrupts mobile networks.

A District Vector Borne Disease Consultant in Upper Siang said timely reporting is not always possible from Tuting block and its peripheral health centres, where poor network connectivity and difficult access during the rainy season make data collection and performance reporting challenging, leading to delays.

And as per reports, the state is experiencing a changing climate, with rising temperatures, shifting rainfall patterns and increasing the need for the health system to prepare for climate-sensitive diseases and extreme weather.

The India Meteorological Department’s assessment of Arunachal Pradesh’s climate in 2025 found that the state’s annual mean land-surface air temperature was 20.72°C, or 0.85°C above the 1991–2020 long-period average.

It was the second-warmest year on record for the state since 1901, based on annual mean temperature. The monsoon was the warmest on record, with an annual maximum-temperature anomaly of 1.6°C. Winter minimum temperatures were also 1.5°C above normal, the highest such anomaly recorded since 1901.

The same IMD assessment shows that the warming signal is not uniform across every measure: 2025 ranked fourth in terms of annual maximum temperature and third for annual minimum temperature.

According to the state’s Heat Wave Action Plan, heat is identified as a health concern and sets out measures including early warning, heat alerts, hospital preparedness, surveillance and treatment protocols.

Under the National Programme on Climate Change and Human Health, Arunachal Pradesh has also introduced surveillance for heat-related illness through the Integrated Health Information Platform.

The data supplied by the state health department, 43 heatstroke cases were reported in 2023 and 46 in 2024, when two suspected heatstroke deaths were also recorded. Reported cases fell to one in 2025 and none in 2026 so far.

The 2026 figures are provisional. The decline does not necessarily mean that heat-related health risks have diminished.

The department says the lower number of reported cases in 2025 and 2026 could reflect a combination of climatic conditions, preparedness and public awareness, as well as continuing gaps in case detection and reporting.

That reporting gap is significant. Health facilities from the primary health centre level upwards have been instructed to report heat-related illnesses, but “the reporting mechanism needs further push, as the current reporting status is at 38% of reporting facilities,” said Dr Dukam Taipodia, State Nodal Officer, NPHCE, and Assistant Nodal Officer for Climate Change and Human Health.

Dr Taipodia informed, “the greatest heat risk is considered to be in the foothill districts bordering Assam, where temperatures are generally higher than in the state’s high-altitude areas. Heat Stroke Rooms have already been established at Nari, Ruksin and Chowkham, with additional facilities proposed under the 2026–27 programme.”

For a state better known for its cool mountain climate, the emerging concern is therefore not simply whether temperatures are rising, but whether the health system can detect and respond to the resulting health risks consistently.

Heat, however, is only one part of the emerging climate-health picture. Vector-borne diseases are another concern.

The state health department says changing temperature and rainfall can influence transmission patterns of vector-borne diseases and has identified them as one of the major climate-sensitive health concerns in Arunachal Pradesh.

The state’s climate-and-health action plan also includes a specific adaptation plan for vector-borne disease.

Dengue has been among the diseases under surveillance in recent years. Data available through the health system’s surveillance platform show that positive dengue test results increased substantially between 2021 and 2025.

In 2025, the surveillance system recorded 337 positive NS1 ELISA results, 199 positive rapid NS1 tests, 78 positive rapid IgM tests and 23 positive IgM ELISA results, for 637 positive test results across the different testing categories.

Those figures, however, are test-wise results and not numbers of unique patients. A person can undergo more than one diagnostic test, so the figures cannot be added together to estimate the number of people who had dengue.

The available 2026 surveillance data show that dengue continues to be detected across the state. Between January 1 and July 29, 2,805 samples were tested, with 71 positive results.

Papum Pare recorded 51 positive results among 518 tests during the period, while smaller numbers were recorded in several other districts.

The data show that dengue is being detected, but they do not by themselves establish that climate change caused the increase in positive tests, because dengue transmission is influenced by multiple factors, including mosquito ecology, rainfall, temperature, human movement, urbanisation, water storage and patterns of testing and healthcare-seeking.

The current IMD climate-health bulletin also illustrates why the relationship needs to be examined carefully. Its two-week ERFS-based forecast issued on August 13, 2026, found no districts in Arunachal Pradesh in the higher temperature-based transmission-window categories for dengue for either August 14–20 or August 21–27.

All districts were placed in the less-than-35% probability category. The bulletin lists 11.9°C as the threshold minimum temperature for dengue, while its threshold maximum temperature is listed as not known.

In other words, the presence of dengue in surveillance data does not mean that every period of warmer weather will produce a corresponding increase in transmission.

While malaria offers another picture, malaria surveillance also shows why disease patterns need to be examined alongside, rather than simply attributed to, climate. Through July 29, 2026, Arunachal’s surveillance system recorded 75,514 malaria samples tested and 11 positive results.

At the same time, the IMD’s August climate-health bulletin identifies temperature conditions that fall within modelled transmission windows for malaria in parts of Arunachal Pradesh.

In its first-week forecast, parts of the state appear in the 35–55% probability category for Plasmodium falciparum transmission, while parts of Arunachal are also included in higher probability categories in the second-week forecast. Similar patterns appear in the Plasmodium vivax assessment.

These forecasts do not predict that people will develop malaria. They indicate that predicted temperatures fall within a modelled range considered favourable to transmission.

For Arunachal, where altitude, geography, mosquito ecology, rainfall and access to healthcare vary sharply between districts, understanding how those factors interact will require more detailed surveillance.

Moreover, the state health department identifies floods, flash floods and landslides as major health concerns because they can cause injuries, contaminate water supplies and interrupt access to health facilities and essential services.

It also identifies air-pollution-related illness, WASH-related problems and the health effects of forest fires among its climate-sensitive concerns.

The state’s geography makes these disruptions particularly difficult to manage. The health department lists difficult mountainous terrain, remote habitations, scattered populations and limited accessibility during the monsoon among the principal challenges to climate-resilient healthcare.

Extreme weather can damage infrastructure and disrupt health services at the same time that communities may need them most, and therefore the department has recommended Upper Siang, Upper Subansiri, Lower Siang, Papum Pare and Keyi Panyor for field assessment following recent monsoon events, as these districts have experienced recurrent floods, flash floods and landslides that have damaged infrastructure, disrupted transportation and healthcare access.

Arunachal Pradesh has begun putting in place measures intended to respond to these risks. The state is implementing heat- and air-pollution-related illness surveillance, assessing district hospitals for climate resilience, establishing Heat Stroke Rooms, training healthcare workers and disseminating heat advisories.

It is also considering measures such as solarisation, rainwater harvesting, energy audits and cool-roof interventions at health facilities.

The State Action Plan for Climate Change and Human Health, prepared under the National Programme on Climate Change and Human Health, covers heat-related illness, vector-borne diseases, air-pollution-related illness, disaster management and climate-resilient healthcare facilities. But implementation remains uneven.

The health department points to limited financial resources, difficult terrain, scattered settlements, monsoon-related inaccessibility and damage to health infrastructure as continuing constraints.

For Arunachal Pradesh, the bigger challenge is whether its health system can spot changing health risks early, reach vulnerable communities during extreme weather and keep essential services running when roads, communications and health facilities are disrupted, and the gaps in reporting and access suggest that understanding the full health impact of climate change will require not only more data, but better and more reliable data from the places that are hardest to reach.

The author is a mentee of the Climate Change Media Hub at the Asian College of Journalism, Chennai. The programme is supported by Interlink Academy, Germany.

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