Land Use and Zoonotic Spillover: how the Nipah Virus revealed the hidden costs of unchecked development

NOTE: I wrote this in the Summer of 2020 during the height of the COVID-19 pandemic. I didn't have a place to publish it at the time. However, now that Off the Docket is up and running, I might as well share it - no point in keeping it stashed away on iCloud forever.

In the fall of 1998, pig farmers in Peninsular Malaysia began falling ill with a mysterious and often fatal disease. The symptoms were severe. High fever, respiratory distress, and inflammation of the brain. In less than a year, over 100 people died. Entire communities were upended. The source? A fruit bat. Pteropus, commonly known as the flying fox.

The virus was Nipah. And its path from bat to pig to human offers one of the clearest examples of how development decisions can drive disease emergence. This wasn’t just a public health failure. It was a land use story.

Throughout the 1990s, Malaysia’s economy was growing rapidly. A rising middle class fueled demand for pork, and the country responded by shifting from small, scattered pig farms to large-scale, industrial operations. These farms were often built on the outskirts of cities, close to forested areas where land was cheaper and oversight was limited. At the same time, logging and land clearing for palm oil plantations and agriculture pushed deeper into natural forest systems. This deforestation forced wildlife, especially fruit bats, into closer proximity with people and domestic animals.

The flying foxes, natural reservoirs for the Nipah virus, began roosting in mango trees planted near pig enclosures. These trees provided easy access to food for the bats and, inadvertently, a transmission route for disease. Fruit contaminated with bat saliva or droppings would fall into open-air pig pens. The pigs, in turn, became infected. With thousands of animals packed into tight spaces, the virus spread quickly through the herds. Farmers and slaughterhouse workers who had close contact with the pigs soon began to get sick. Really sick.

What happened in Malaysia was not a freak occurrence. It was the outcome of overlapping land use decisions that ignored ecological context. Deforestation created new migration patterns for wildlife. Fruit trees planted alongside livestock pens brought viral hosts and domestic animals into the same space. Poorly regulated high-density farming made rapid disease transmission inevitable. It wasn’t one single misstep. It was a cascade of land use choices that, together, made spillover likely.

Is a spillover event like the Nipah outbreak likely to happen in the United States? Probably not. But that doesn’t mean we’re immune. We’ve had our own close calls (Hantavirus in the American Southwest, for instance, emerged from changes in rodent populations tied to habitat loss and climate variability). But the point here is that reckless development has a cost.

This is not an anti-development post. Far from it! I routinely represent commercial and multi-family developers, and I believe in the importance of thoughtful, well-executed development. But by ignoring natural systems, cutting into habitat, or pushing infrastructure into ecologically sensitive areas, we increase the odds of unintended consequences, whether that’s flooding, pollution, or disease emergence.

The solution is not to stop building, but to build differently. We need to plan with a longer horizon, using ecological and environmental insight to guide growth. That means prioritizing infill over sprawl, preserving natural buffers, and, when possible, building upward rather than outward. Sustainable development isn’t just about energy efficiency or green roofs. It’s about recognizing that the health of the environment depends on the health of the natural systems around it.