– The deadliest outbreak of Ebola on record is forcing farmers and their families to flee cocoa, rice and peanut plantations in northeastern Sierra Leone, where agriculture makes up more than half of the nation's economy.

Output of the chocolate-making ingredient will drop this year and peanuts and rice, both staples, will be left unharvested, Edmond Saidu, district agriculture officer in Kailahun District, said.

The area borders Guinea, where the disease was first reported in March, and Liberia, which has confirmed cases of the hemorrhagic fever that has no cure or treatment.

"Ebola has left us with a high number of orphans who cannot take care of themselves and family plantations," said Brima Kendor, a plantation owner and spokesman for the local chief in Kissi Tongi, Kailahun District. "This is the time to rehabilitate the cocoa farms, but we can't do that now."

Abandoned farms threaten to curb economic growth in a country struggling to rebuild after a 10-year civil war that ended in 2002 and left the nation's infrastructure in ruins. Agriculture makes up about 57 percent of the $4.9 billion economy, according 2011 World Bank data, the most recent figures available.

The virus will probably spread for four more months in West Africa, where more than 600 people have died since the fever was reported in March in Guinea, according to the World Health Organization.

Before the outbreak, the central bank had cut borrowing costs in half since 2012, inflation had slowed to below 10 percent and the economy was poised to expand 14 percent this year. Sierra Leone started exporting iron ore, the raw material for steel, in 2011.

Ritual burial practices, poor hygiene and insufficient medical care have made controlling the disease difficult in the border region of dense forest between Guinea, Sierra Leone and Liberia, according to WHO. Sierra Leone has recorded 146 deaths from Ebola and 435 confirmed cases, the Ministry of Health said.

A Nigerian spokesman said Friday that a Liberian man died of the virus, the first case in Africa's largest economy. The fact that the traveler from Liberia could board an international flight also raised new fears that other passengers could take the disease beyond Africa due to weak inspection of passengers and the fact Ebola's symptoms are similar to other diseases. On Saturday, the aid organization Samaritan's Purse said a U.S. doctor working with Ebola patients in Liberia had tested positive for the virus. A news release said Dr. Kent Brantly was being treated at a hospital in Monrovia.