In March 1957, forest officials in Shimoga district, Karnataka noticed something wrong in the trees. Monkeys were dying — not one or two, but dozens, scattered through the Kyasanur forest. Then villagers who had gone in to cut wood or graze cattle started dying too, of a fever with no name. Locals called it “monkey disease.” A long-standing theory holds that forest clearing for new villages and grazing land pushed monkeys to spend more time on the forest floor, in the undergrowth, where infected ticks lived - though scientists still don't fully understand the disease's ecology, and gaps in that picture remain even today. What is clear is that Kyasanur Forest Disease emerged at exactly the point where human, animal and environmental life overlapped.

That is the pattern behind almost every zoonotic disease: not a single cause, but a shift in the relationship between people, animals and the land they share. It is happening again right now — the ongoing Ebola outbreak in Central Africa is only the latest reminder that outbreaks rarely emerge in isolation. Whether it is Ebola, COVID-19, Nipah, Avian Influenza, Rabies or Kyasanur Forest Disease itself, preventing the next public health emergency means paying close attention to the places where human, animal and environment collide.

This is what we now call a “One Health” approach – the theme behind World Zoonoses Day, observed every year on 6 July - which treats the health of people, animals and the environment as one interconnected system rather than three separate ones. This brings together public health, veterinary and environmental sectors to prevent, detect and respond to threats at the point where they actually emerge, from zoonotic disease to food and water safety risks to antimicrobial resistance.

This is critical because often these sectors operate as islands. A hospital records human illness. A veterinary department records animal illness. A forest department tracks wildlife and land use. Each may independently be logging the early signs of an outbreak - a spike in unexplained fevers here, a die-off of livestock there - without any of them realising the other two exist. Fragmented data, limited coordination and weak joint planning are the specific, mundane reasons outbreaks get discovered late – across the world. 

One instance of this makes the pattern concrete.

In May 2018, a man was admitted to a hospital in Kozhikode, Kerala with a fever no one could explain. It was identified as Nipah virus. Within weeks, nineteen cases were confirmed across Kozhikode and Malappuram districts; seventeen people died — a fatality rate of nearly 90 percent. There was no playbook, because Nipah had never before appeared in South India. Kerala has faced Nipah several times since, and each time the response has been faster. In a recent case involving a single Nipah patient in Kozhikode, the state's response was activated and contained as soon as the infection was suspected. 

What changed between 2018 and now was not the virus. It was the preparation: pre-built protocols, trained hospital staff, faster laboratory pipelines, and - critically - public health, veterinary and wildlife officials who already knew how to work together before the next outbreak forced them to.

That is the argument for One Health: the difference between an improvised response and a practiced one is measured in lives.

A burden India already carries

India carries a heavy burden of zoonotic disease - rabies, brucellosis, leptospirosis, avian influenza and KFD among them - in a country where hundreds of millions of people live in close daily contact with livestock. The underlying pressures are intensifying. Rising temperatures and shifting rainfall are expanding the range of disease-carrying mosquitoes and ticks; shrinking natural habitats are pushing wildlife, livestock and people into closer contact more often. Globally, six in ten emerging infectious diseases in humans originate in animals; scientists estimate that of roughly 1.7 million undiscovered viruses circulating in wildlife, nearly half could infect people. 

Towards an Integrated One Health System: India’s leadership

India's One Health journey has evolved steadily over the past two decades — from strengthening coordination across sectors on zoonotic diseases, to building an integrated national system that brings human, animal and environmental health together. Recent milestones include setting up dedicated One Health centres, launching the National One Health Mission (NOHM), expanding zoonotic surveillance networks, strengthening national governance, and adopting new technologies such as AI-enabled early warning systems. Increasingly, the focus is shifting from responding to outbreaks to predicting and preventing them — through digital surveillance, integrated data platforms, disease intelligence systems, climate-informed risk models and community-based reporting.