How to prevent a factory farmed pandemic

October 21, 2020·25 min·2 clips

Inside crowded factory farms, influenza viruses swap genes like Greek monsters, creating chimeric super viruses that could jump to humans.

Host Sigal Samuel opens the Future Perfect episode recapping the Covid-era focus on Chinese wet markets. She introduces NIH virologist Martha Nelson, who counters that pandemic risk is visible in Americans' own backyard. Producer Bird Pinkerton walks through three systemic risks in US swine production. First is swine ways, the routes pigs take from breeding farms in places like North Carolina to grain-rich Midwestern growing facilities, and the Boeings that fly high-efficiency US sows to China, Thailand, and Vietnam. Second is factory farms themselves, where 5,000 to 10,000 pigs live in close contact with their feces and create an ideal mixing vessel. Nelson explains influenza's eight-segment genome and how coinfection lets viruses swap whole segments into chimeras, usually duds but occasionally fit survivors in dense pig populations. Third is spread out to humans, particularly through county fairs where about 150 million Americans attend each year and kids bond closely with show pigs. Nelson has documented novel flu cases every summer, with one year spiking above 300 children. A chimeric monster could trigger a flu pandemic as severe as the Covid-19 pandemic, especially affecting children. The episode then pivots to Kansas State's Jorgen Richt, a veterinary researcher who used pre-CRISPR gene editing in the 1990s to build a mad cow-resistant herd now supplying fetal calf serum for human vaccines. He is now using CRISPR to knock out two pig genes that enable swine flu infection, with gestation taking three months, three weeks, and three days. His first attempt produced a miscarriage and a lame piglet that was put down, losing a year. Nelson welcomes genetic fixes but also proposes smaller system tweaks like restaging or adding gaps to county fair schedules, while questioning whether the real barrier is economic viability when Covid proved the system can shut down when forced.

As heard by us

A steady, unsettling look at how pandemic risk can move from wet markets to factory farms and county fairs.

An unsettling episode follows coronavirus fear into a harder question: how factory farms and county fairs can turn animal-to-human spillover into the next pandemic.

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Why you'd press play

You want a public-health story about how a virus can move from wet markets to factory farms and back into people.

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