Guwahati: A major new analysis published in The Lancet Regional Health – Southeast Asia has revealed that the Northeast accounts for more than one-third of all zoonotic disease outbreaks in India between 2018 and 2023, underscoring the region’s vulnerability at the interface of people, livestock, and wildlife.
The study, led by researchers from the Indian Council of Medical Research–National Institute of Epidemiology and the South Asia Field Epidemiology and Technology Network, examined six years of data from India’s Integrated Disease Surveillance Programme (IDSP).
It found that out of 6,948 total outbreaks reported nationwide, 583—or 8.3 per cent—were zoonotic in nature. The Northeast alone contributed 35.8 percent, followed by the southern region at 31 percent.
“Three-fourths of the zoonotic outbreaks were reported in the northeast region. In the northeastern region, JE, rabies, and scrub typhus were the commonly reported outbreaks, the study revealed.
Human activities, alongside environmental changes, intensify the likelihood of zoonotic diseases as they increase close contact between animals and humans. Zoonotic diseases present a global concern, yet they hold particular significance in low and low-middle-income countries (LMICs).
Assam emerged as the epicentre of zoonotic reporting, with districts such as Barpeta, Biswanath, Dibrugarh, Kamrup Metro, Lakhimpur, and Majuli identified as “high-cluster” zones.
Meghalaya’s Ri-Bhoi district also figured among the national hotspots. The study attributes these trends to ecological and human-driven factors that heighten animal–human contact, including deforestation, flooding, and agricultural practices involving livestock.
Japanese Encephalitis (JE), leptospirosis, and scrub typhus together accounted for over 60 per cent of all zoonotic outbreaks. The monsoon months—June through August—consistently saw spikes in cases. JE alone made up nearly 30 per cent of all zoonotic outbreaks, with two-thirds reported from the Northeast.
In Assam, where JE has long been endemic, pigs and mosquitoes act as amplifying hosts during the pre-monsoon and monsoon seasons. “The seasonal surge corresponds with high mosquito density and pig seroconversion rates,” the study noted.
Meanwhile, scrub typhus—a mite-borne infection often linked to rural and forested areas—was most frequent in Assam and Mizoram, where rodent and chigger mite infestation indices exceeded critical thresholds.
Interestingly, the study observed a decline in zoonotic outbreak reports during the COVID-19 years (2020–21), likely due to diverted health resources and reduced field surveillance. But the post-pandemic rebound was sharp—a 58.8 per cent rise in outbreaks was recorded in 2023 compared to the previous year.
“The pandemic may have temporarily masked the true burden of zoonotic diseases,” the authors wrote. “Once routine surveillance resumed, the backlog of undetected outbreaks became visible.”
While the region remains a hotspot, the study also highlights improvements. Assam, which once accounted for nearly 70 per cent of delayed outbreak reports in 2019, achieved near-complete timely reporting by 2023.
This improvement coincides with the rollout of the Integrated Health Information Platform (IHIP) in 2021, which allows real-time outbreak alerts and inter-departmental visibility.
Still, the researchers warned that follow-up reports were missing for 97 per cent of zoonotic outbreaks nationwide, limiting the ability to track containment and recovery.
The authors advocate for a One Health approach—integrating human, animal, and environmental health systems—to strengthen early warning and response mechanisms.
The study recommends targeted surveillance in hotspot states, such as Assam, Mizoram, Karnataka, and Kerala, as well as improved data sharing between veterinary and human health departments.
Experts note that the Northeast’s ecological richness makes it both a biodiversity haven and a zoonotic frontier. Expanding agricultural frontiers, urbanisation, and wildlife–human interactions in tea garden and forest-edge communities add layers of risk.
As the region continues to balance economic development with conservation, the findings underscore the need for renewed investment in disease surveillance, vector control, and community awareness—before the next spillover occurs.
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