Cassava, an edible tuber that tolerates drought and poor soil, is widely grown in tropical countries from Africa to South America to Asia. According to a New York Times article, it is the third-largest source of calories in the world. But a virus, known as brown streak, has struck the crop.

That newcomer, brown streak, is now ravaging cassava crops in a great swath around Lake Victoria, threatening millions of East Africans who grow the tuber as their staple food.

Although it has been seen on coastal farms for 70 years, a mutant version emerged in Africa’s interior in 2004, “and there has been explosive, pandemic-style spread since then,” said Claude M. Fauquet, director of cassava research at the Donald Danforth Plant Science Center in St. Louis. “The speed is just unprecedented, and the farmers are really desperate.”

It is already being compared to the potato blight and resulting famine that struck Europe in the 1840s. According to the article, even livestock will not eat the infected cassava.