More than 50 million sheep and goats in 15 countries across southern Africa are at risk from a virus with a death rate that can approach 100 percent, the United Nations Food and Agricultural Organization said Tuesday.

While the Small Ruminants' Plague does not infect humans, the U.N. agency said it could have a devastating economic and social impact across the region.

"Sheep and goats are critical to food and income security for pastoral communities. The presence of the disease directly affects a family's wealth," the FAO's chief veterinary officer, Juan Lubroth, said in a statement.

The disease broke out in Tanzania early this year, the FAO said. It is easily spread as animals make contact in pastures and in markets, according to Adama Diallo, who led a recent FAO-sponsored emergency mission to Tanzania.

Diallo recommend an emergency vaccination program around outbreak sites and herding routes, especially along borders with Malawi, Mozambique and Zambia, and that authorities not allow herders to move their flocks.

The disease has previously infected western, eastern and central Africa. It is also found in the Mideast and parts of central Asia, the FAO said.