From CK Nayak
NEW DELHI, Oct 25: The Northeast has emerged as one of the country’s hotspots for zoonotic diseases, accounting for more than one/third of all reported outbreaks between 2018 and 2023, two new studies have found.
The region’s hilly, forested terrain – abundant with wildlife and dotted with mixed farming where people raise livestock alongside crops — creates the perfect setting for pathogens to jump from animals to humans.
Experts note that the Northeast’s ecological richness makes it both a biodiversity haven and a zoonotic frontier. Expanding agricultural frontiers, urbanisation and wildlife 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. It suggests community awareness before the next spillover occurs.
The studies have been done by the Zoonotic and Vector-borne Disease Centre at the Indian Institute of Public Health, Shillong, and the Indian Council of Medical Research (ICMR)–National Institute of Epidemiology and the South Asia Field Epidemiology and Technology Network. Both the studies examined six years of data from India’s Integrated Disease Surveillance Programme.
They found that out of the total 6,948 outbreaks reported nationwide, 583 were zoonotic in nature. The Northeast alone contributed 35.8 per cent, followed by the southern region at 31 per cent.
According to the studies, three-fourths of the zoonotic outbreaks were reported in the Northeast region. In the vulnerable region, Japanese Encephalitis (JE), rabies, and scrub typhus were the commonly reported outbreaks.
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.
ICMR carried out the study at Ichamati village in East Khasi Hills district which has a mixed tribal and non-tribal population close to Bangladesh. This village is one of three sites in the Eastern Himalayan state chosen to track six diseases: leptospirosis, brucellosis, scrub typhus, cryptosporidiosis, influenza H1N1, and JE.
Assam and Meghalaya emerged as the epicentre of zoonotic reporting, with Barpeta, Biswanath, Dibrugarh, Kamrup (Metro), Lakhimpur, Majuli and Ri-Bhoi districts identified as “high-cluster” zones. Ri-Bhoi also figured among the national hotspots. The studies attribute these trends to ecological and human-driven factors that heighten animal-human contact, including deforestation, flooding and agricultural practices involving livestock.
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, according to the studies.
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 studies 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 studies also highlight improvements. Assam, which accounted for nearly 70 percent 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 in 2021, which allows real-time outbreak alerts and inter-departmental visibility.
Still, the researchers warned that follow-up reports were missing for 97 percent of zoonotic outbreaks nationwide, thus 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.
