dermo-

At the same time, while saltier waters also can allow diseases such as MSX and Dermo to spread among oysters, that hasn’t happened.

They examined more than 8,000 paper-thin slices of tissue and found striking differences over that period, including a shift in where the Dermo parasite attacked, from connective tissue to the lining of oysters’ digestive tract.

Before the mid-1980s, the Dermo parasite typically caused a chronic disease that killed about 30% of oysters, mostly older animals that had been exposed to the parasite for several years.

“Around 1986, Dermo suddenly became an acute and profoundly destructive disease capable of killing more than 70% of host oysters within months of infection,” Carnegie said.

The increased virulence of the Dermo parasite has persisted since then.