By Will Dunham
WASHINGTON, Aug 10 (Reuters) - Health officials in North Carolina said on Sunday they will require missionaries and others coming home after working with people infected with Ebola in Africa to be placed in quarantine as a precaution against the spread of the deadly viral disease.
The quarantine is set to last for three weeks from the last exposure to someone infected in the West African Ebola outbreak, which is centered in Guinea, Sierra Leone and Liberia, the officials said.
Missionaries from the North Carolina-based Christian aid groups SIM USA and Samaritan's Purse have been working to help combat the world's worst outbreak of the disease. Two of the relief workers contracted the disease and were being cared for at Emory University in Georgia.
"This measure is being taken out of an abundance of caution, and it is important to remember that there are no confirmed or suspected cases of Ebola in North Carolina," Dr Stephen Keener, medical director in North Carolina's Mecklenburg County, said in a statement.
"Quarantine is a public health measure to protect the public that requires healthy people who were exposed to a disease to be prevented from contact with others until it is certain that they are not infected," Keener added.
The statement said the 21-day period is based on the longest duration of Ebola incubation - the delay between exposure and onset of illness. Officials said the average incubation period is eight to 10 days.
SIM USA said on Sunday some of its missionary staff based in Liberia will be returning to Charlotte, where the group is headquartered. se
"We will continue to cooperate and collaborate with them and adhere strictly to their guidelines in the return of our missionaries to the United States," Johnson added.
Ebola is spread through direct contact with bodily fluids including blood, urine, feces and saliva of an infected person, or with objects such as needles that have been contaminated. Nearly 1,000 people in West Africa have now died in the outbreak of one of the deadliest known diseases.
An official with the U.N. World Health Organization said on Sunday there have been 1,825 cases reported, with the mortality rate running at about 55 to 60 percent.
Speaking on the CBS program "Face the Nation", Dr. Keiji Fukuda, WHO's assistant director-general for health security, said he expects the number of infections to increase.
"What is difficult in this situation is that we are dealing with countries with weak health systems. And we are dealing with areas in which practices like good infection prevention and control practices are not the norm in some of the hospitals and in families and communities," Fukuda said.
(Reporting by Will Dunham; Additional reporting by Patrick Rucker; Editing by Stephen Powell)