Feeding antibiotics to healthy livestock is leading to an
emerging human health crisis—one scientists and government
officials have seen coming for decades. Stuart Levy once kept a
flock of chickens on a farm in the rolling countryside west of
Boston. No ordinary farmer, Levy is a professor of molecular
biology and microbiology and of medicine at Tufts University
School of Medicine. This was decades ago, and his chickens were
taking part in a never-before-conducted study. Half the birds
received feed laced with a low-dose of antibiotics, which U.S.
farmers routinely administer to healthy livestock — not to cure
illness, but merely to increase the animals’ rates of growth.
The other half of Levy’s flock received drug-free food. Results
started showing up almost instantly. Within two days, the
treated animals began excreting feces containing E. coli
bacteria that were resistant to tetracycline, the antibiotic in
their feed. (E. Coli, most of which are harmless, normally live
in the guts of chickens and other wa