The risk of the virus moving to other continents is low, disease specialists say. But tracing every person who may have had contact with an infected case is vital to getting on top of the outbreak within West Africa, and doing so often means teasing out seemingly routine information about victims' lives.
What is Ebola?
Ebola virus disease (also known as Ebola hemorrhagic fever), along with being one of mankind's deadliest diseases, is also one of its most brutal. It causes extreme body aches, high fever, profuse vomiting, diarrhea and heavy internal and external bleeding, sometimes through body orifices and the pores of the skin.
Doctors and journalists who have observed those dying of Ebola have described the process, horrifically, as watching human beings "dissolve."
Symptoms can manifest themselves between two and 21 days after exposure and usually begin with headaches and fever. There is no cure for the disease, which has been fatal in up to 90 percent of patients during some outbreaks, though the current outbreak has killed about 60 percent of those so far infected.
According the the World Health Organization, treatments include managing the patient's fluids and electrolytes, as well as blood pressure and kidney function, all of which are in jeopardy as the infected bleed out of organs and even blood vessels.
Transmission of the virus occurs when a person comes into contact with the bodily fluids - blood, vomit, feces - of one who is infected. This puts health workers tending to Ebola patients in an extremely dangerous position as patients can throw off huge amounts of their fluids during uncontrollable fits of pain and vomiting. Walls, sheets and medical equipment can become soaked in the highly infectious substances. Patients are kept in isolation to avoid infecting others in a clinical setting.
Even with the full body suits health workers wear - the iconic image of the disease - transmissions still occur. Several American missionaries working to disinfect doctors and nurses operating in suits have contracted Ebola and the chief doctor fighting the outbreak in Sierra Leone, Dr. Sheik Umar Khan, recently caught the virus while treating others and died.
The first diagnosed case of the Ebola Zaire strain was a nurse who perished after treating a nun who broke with Ebola after helping treat the sick in then Zaire, now the Democratic Republic of Congo.
There are five known strains of Ebola, which first manifested itself in humans in the 1976 in Sudan and in a village in Zaire near the Ebola River, from which the disease draws its name. Four of the five have caused disease in humans, while the fifth, Ebola Reston, caused disease only in primates. The Reston strain is named for Reston, Virginia where the strain was discovered in a commercial monkey house in 1989. It killed hundreds of monkeys, and many more were euthanized, but never made the jump to human beings.
The outbreak spreads
In Nigeria, which had an imported case of the virus in a Liberian-American who flew to Lagos this week, authorities will have to trace all passengers and anyone else he may have crossed paths with to avoid the kind of spread other countries in the region have suffered.
The West Africa outbreak, which began in Guinea in February, has already spread to Liberia and Sierra Leone. It is the largest since the Ebola virus was discovered almost 40 years ago.
Sierra Leone has declared a state of public emergency to tackle the outbreak, while Liberia is closing schools and considering quarantining some communities.