Sterile laboratory mice mount a massive immune defense against worms that actually doesn't exist in any animal living in the wild.

Clean mice raised in ultra-sterile facilities are the standard tool used to understand how the body fights off infections. These lab-bred animals trigger a violent weep and sweep reaction that flushes parasites out of the gut with mucus and muscle contractions. Wild mice living in natural environments fail to produce this response even when they are heavily infected. Natural microbial exposure creates a layer of immune suppression that makes the gut much less reactive than what is seen in a sterile cage. The layered immune suppression found in wildlings suggests that decades of medical data on allergies and asthma might be based on an artificial hyper-sensitivity. Pharmaceuticals developed in these perfect environments may be trying to fix a biological glitch that only exists in a lab.