Nigeria has stepped up surveillance at its ports and borders, following the country's first confirmed death from the Ebola virus.
Health Minister Onyebuchi Chukwu says health officials are monitoring airports, seaports and land borders, for people arriving who may show signs of the virus.
He commented on Friday, after officials confirmed that a man who died after arriving in Lagos on a flight from Liberia had tested positive for Ebola.
Chukwu also said investigators are trying to track down the other passengers who were on the nearly three-hour flight from Monrovia.
Nigeria has become the fourth West African country to confirm the presence of Ebola.
The World Health Organization (WHO) says the disease has killed 672 people in the region.
The majority of deaths are in Guinea. In a report updated on Friday, WHO said 319 people had died from Ebola in Guinea. The health organization reported 224 deaths in Sierra Leone and 129 in Liberia.
Officials in Sierra Leone are searching for a woman with Ebola who was forcibly removed from a Freetown hospital by her family.
On Friday, a doctor at the facility said investigators believe the woman may have been taken to a traditional herbalist for treatment.
There is no cure or vaccine for Ebola, which causes symptoms that include fever, vomiting, diarrhea and bleeding.
