Health workers bury the body of a woman who is suspected of having died of the Ebola virus on the outskirts of Monrovia, Liberia, on Monday, October 20. Health officials say the Ebola outbreak in West Africa is the deadliest ever. More than 4,000 people have died there, according to the World Health Organization. Christine Wade, a registered nurse at the University of Texas Medical Branch, greets Carnival Magic passengers disembarking in Galveston, Texas, on Sunday, October 19. Nurses met passengers with Ebola virus fact sheets and to answer any questions. A Dallas health care worker was in voluntary isolation, although she had shown no signs of the disease, in her cabin aboard the cruise ship because of her potential contact with the Ebola virus. Garteh Korkoryah, center, is comforted during a memorial service for her son, Thomas Eric Duncan, on Saturday, October 18, in Salisbury, North Carolina. Duncan, a 42-year-old Liberian citizen, died October 8 in a Dallas hospital. He was in the country to visit his son and his son's mother. An airplane carrying Nina Pham arrives at an airport in Frederick, Maryland, on Thursday, October 16. Pham is one of the two nurses who were diagnosed with Ebola after treating Thomas Eric Duncan, a Liberian national visiting Dallas. Pham is going to be treated at a National Institutes of Health hospital in Maryland. Boys run from blowing dust as a U.S. military aircraft leaves the construction site of an Ebola treatment center in Tubmanburg, Liberia, on Wednesday, October 15. Aid workers from the Liberian Medical Renaissance League stage an Ebola awareness event October 15 in Monrovia, Liberia. The group performs street dramas throughout Monrovia to educate the public on Ebola symptoms and how to handle people who are infected with the virus. U.S. President Barack Obama speaks to the media about Ebola during a meeting in the Cabinet Room of the White House on October 15. Obama said his administration will respond to new Ebola cases taking charge of the issue after the second Texas nurse was diagnosed with the disease. A U.S. Marine looks out from an MV-22 Osprey aircraft before landing at the site of an Ebola treatment center under construction in Tubmanburg on October 15. It is the first of 17 Ebola treatment centers to be built by Liberian army soldiers and American troops as part of the U.S. response to the epidemic. A man dressed in protective clothing treats the front porch of a Dallas apartment where one of the infected nurses resides on Sunday, October 12. Ebola survivors prepare to leave a Doctors Without Borders treatment center after recovering from the virus in Paynesville, Liberia, on October 12. A member of the Liberian army stands near a U.S. aircraft Saturday, October 11, in Tubmanburg. A woman crawls toward the body of her sister as a burial team takes her away for cremation Friday, October 10, in Monrovia. The sister had died from Ebola earlier in the morning while trying to walk to a treatment center, according to her relatives. Ebola survivor Joseph Yensy prepares to be discharged from the Doctors Without Borders treatment center in Paynesville, Liberia, on Sunday, October 5. Sanitized boots dry at the Doctors Without Borders treatment center in Paynesville on October 5. Residents of an Ebola-affected township take home kits distributed by Doctors Without Borders on Saturday, October 4, in New Kru Town, Liberia. The kits, which include buckets, soap, gloves, anti-contamination gowns, plastic bags, a spray bottle and masks, are meant to give people some level of protection if a family member becomes sick. A person peeks out from the Dallas apartment where Thomas Eric Duncan, the first person diagnosed with the Ebola virus in the United States, was staying on Friday, October 3. A girl cries as community activists approach her outside her Monrovia home on Thursday, October 2, a day after her mother was taken to an Ebola ward. Marie Nyan, whose mother died of Ebola, carries her 2-year-old son, Nathaniel Edward, to an ambulance in the Liberian village of Freeman Reserve on Tuesday, September 30. A health official uses a thermometer Monday, September 29, to screen a Ukrainian crew member on the deck of a cargo ship at the Apapa port in Lagos, Nigeria. Children pray during Sunday service at the Bridgeway Baptist Church in Monrovia on Sunday, September 28. Residents of the St. Paul Bridge neighborhood in Monrovia take a man suspected of having Ebola to a clinic on September 28. Workers move a building into place as part of a new Ebola treatment center in Monrovia on September 28. Medical staff members at the Doctors Without Borders facility in Monrovia burn clothes belonging to Ebola patients on Saturday, September 27. A health worker in Freetown, Sierra Leone, sprays disinfectant around the area where a man sits before loading him into an ambulance on Wednesday, September 24. Medics load an Ebola patient onto a plane at Sierra Leone's Freetown-Lungi International Airport on Monday, September 22. A few people are seen in Freetown during a three-day nationwide lockdown on Sunday, September 21. In an attempt to curb the spread of the Ebola virus, people in Sierra Leone were told to stay in their homes. Supplies wait to be loaded onto an aircraft at New York's John F. Kennedy International Airport on Saturday, September 20. It was the largest single shipment of aid to the Ebola zone to date, and it was coordinated by the Clinton Global Initiative and other U.S. aid organizations. A child stops on a Monrovia street Friday, September 12, to look at a man who is suspected of suffering from Ebola. Health workers on Wednesday, September 10, carry the body of a woman who they suspect died from the Ebola virus in Monrovia. A woman in Monrovia carries the belongings of her husband, who died after he was infected by the Ebola virus. Health workers in Monrovia place a corpse into a body bag on Thursday, September 4. After an Ebola case was confirmed in Senegal, people load cars with household items as they prepare to cross into Guinea from the border town of Diaobe, Senegal, on Wednesday, September 3. Crowds cheer and celebrate in the streets Saturday, August 30, after Liberian authorities reopened the West Point slum in Monrovia. The military had been enforcing a quarantine on West Point, fearing a spread of the Ebola virus. A health worker wearing a protective suit conducts an Ebola prevention drill at the port in Monrovia on Friday, August 29. Volunteers working with the bodies of Ebola victims in Kenema, Sierra Leone, sterilize their uniforms on Sunday, August 24. A guard stands at a checkpoint Saturday, August 23, between the quarantined cities of Kenema and Kailahun in Sierra Leone. A burial team from the Liberian Ministry of Health unloads bodies of Ebola victims onto a funeral pyre at a crematorium in Marshall, Liberia, on Friday, August 22. Dr. Kent Brantly leaves Emory University Hospital on Thursday, August 21, after being declared no longer infectious from the Ebola virus. Brantly was one of two American missionaries brought to Emory for treatment of the deadly virus. Family members of West Point district commissioner Miata Flowers flee the slum in Monrovia while being escorted by the Ebola Task Force on Wednesday, August 20. An Ebola Task Force soldier beats a local resident while enforcing a quarantine on the West Point slum on August 20. Local residents gather around a very sick Saah Exco, 10, in a back alley of the West Point slum on Tuesday, August 19. The boy was one of the patients that was pulled out of a holding center for suspected Ebola patients after the facility was overrun and closed by a mob on August 16. A local clinic then refused to treat Saah, according to residents, because of the danger of infection. Although he was never tested for Ebola, Saah's mother and brother died in the holding center. A burial team wearing protective clothing retrieves the body of a 60-year-old Ebola victim from his home near Monrovia on Sunday, August 17. lija Siafa, 6, stands in the rain with his 10-year-old sister, Josephine, while waiting outside Doctors Without Borders' Ebola treatment center in Monrovia on August 17. The newly built facility will initially have 120 beds, making it the largest-ever facility for Ebola treatment and isolation. Brett Adamson, a staff member from Doctors Without Borders, hands out water to sick Liberians hoping to enter the new Ebola treatment center on August 17. Workers prepare the new Ebola treatment center on August 17. A body, reportedly a victim of Ebola, lies on a street corner in Monrovia on Saturday, August 16. Liberian police depart after firing shots in the air while trying to protect an Ebola burial team in the West Point slum of Monrovia on August 16. A crowd of several hundred local residents reportedly drove away the burial team and their police escort. The mob then forced open an Ebola isolation ward and took patients out, saying the Ebola epidemic is a hoax. A crowd enters the grounds of an Ebola isolation center in the West Point slum on August 16. The mob was reportedly shouting, "No Ebola in West Point." A health worker disinfects a corpse after a man died in a classroom being used as an Ebola isolation ward Friday, August 15, in Monrovia. A boy tries to prepare his father before they are taken to an Ebola isolation ward August 15 in Monrovia. Kenyan health officials take passengers' temperature as they arrive at the Jomo Kenyatta International Airport on Thursday, August 14, in Nairobi, Kenya. A hearse carries the coffin of Spanish priest Miguel Pajares after he died at a Madrid hospital on Tuesday, August 12. Pajares, 75, contracted Ebola while he was working as a missionary in Liberia. Health workers in Kenema screen people for the Ebola virus on Saturday, August 9, before they enter the Kenema Government Hospital. Paramedics in protective suits move Pajares, the infected Spanish priest, at Carlos III Hospital in Madrid on Thursday, August 7. He died five days later. Nurses carry the body of an Ebola victim from a house outside Monrovia on Wednesday, August 6. A Nigerian health official wears protective gear August 6 at Murtala Muhammed International Airport in Lagos. Officials with the Centers for Disease Control and Prevention in Atlanta sit in on a conference call about Ebola with CDC team members deployed in West Africa on Tuesday, August 5. Aid worker Nancy Writebol, wearing a protective suit, gets wheeled on a gurney into Emory University Hospital in Atlanta on August 5. A medical plane flew Writebol from Liberia to the United States after she and her colleague Dr. Kent Brantly were infected with the Ebola virus in the West African country. Nigerian health officials are on hand to screen passengers at Murtala Muhammed International Airport on Monday, August 4. Nurses wearing protective clothing are sprayed with disinfectant Friday, August 1, in Monrovia after they prepared the bodies of Ebola victims for burial. A nurse disinfects the waiting area at the ELWA Hospital in Monrovia on Monday, July 28. In this photo provided by Samaritan's Purse, Dr. Kent Brantly, left, treats an Ebola patient in Monrovia. On July 26, the North Carolina-based group said Brantly tested positive for the disease. Days later, Brantly arrived in Georgia to be treated at an Atlanta hospital, becoming the first Ebola patient to knowingly be treated in the United States. A doctor puts on protective gear at the treatment center in Kailahun on Sunday, July 20. Members of Doctors Without Borders adjust tents in the isolation area in Kailahun on July 20. Boots dry in the Ebola treatment center in Kailahun on July 20. Dr. Jose Rovira of the World Health Organization takes a swab from a suspected Ebola victim in Pendembu, Sierra Leone, on Friday, July 18. Red Cross volunteers disinfect each other with chlorine after removing the body of an Ebola victim from a house in Pendembu on July 18. A doctor works in the field laboratory at the Ebola treatment center in Kailahun on Thursday, July 17. Doctors Without Borders staff prepare to enter the isolation ward at an Ebola treatment center in Kailahun on July 17. Dr. Mohamed Vandi of the Kenema Government Hospital trains community volunteers who will aim to educate people about Ebola in Sierra Leone. A woman has her temperature taken at a screening checkpoint on the road out of Kenema on Wednesday, July 9. A member of Doctors Without Borders puts on protective gear at the isolation ward of the Donka Hospital in Conakry on Saturday, June 28. Airport employees check passengers in Conakry before they leave the country on Thursday, April 10. A Guinea-Bissau customs official watches arrivals from Conakry on Tuesday, April 8. Egidia Almeida, a nurse in Guinea-Bissau, scans a Guinean citizen coming from Conakry on April 8. A scientist separates blood cells from plasma cells to isolate any Ebola RNA and test for the virus Thursday, April 3, at the European Mobile Laboratory in Gueckedou, Guinea. Health specialists work Monday, March 31, at an isolation ward for patients at the facility in southern Guinea.
- Scientists use model to predict number of Ebola-infected travelers leaving West Africa
- Up to three people with the deadly virus might travel internationally each month
- Majority of people flying out of affected countries are going to low- or middle-income nations
(CNN) -- Up to three Ebola-infected travelers might board an international flight each month in West Africa, according to a new study, and potentially spread the deadly virus to other countries.
Scientists used a model to predict that, on average, three people who are infected with Ebola will leave Guinea, Liberia or Sierra Leone in each of the coming months to fly to another country. They based their model on scheduled flights for September 1 to December 31, 2014, historic flight itineraries from 2013, and Ebola surveillance numbers from the current outbreak. The results were published in The Lancet this week.
Ebola fears lead to conspiracy theories Couple: Quarantine is "nerve-wracking" Fauci: A travel ban isn't a good idea "We understand there could be global risks associated with the current outbreak," said study author Dr. Isaac Bogoch, a specialist in infectious diseases and tropical medicine at the University of Toronto. "We wanted to understand what those risks were."
Three passengers per month, or 2.8 to be exact, was around what Bogoch was expecting. Considering the number of people living in these West African countries, he says, the prevalence of the disease is still relatively low. Guinea, for example, has around 11.4 million people, and just over 1,500 recorded cases of Ebola.
Nonessential travel to and from these countries has also been reduced significantly over the past six months.
Of the approximately 500,000 travelers who flew out of Guinea, Liberia and Sierra Leone in 2013, more than half flew to one of five countries: Ghana, Senegal, the United Kingdom, France and Gambia. In fact, the study authors say the likelihood of someone traveling to the United Kingdom or France with Ebola is about eight times higher than the likelihood of someone traveling to the United States with the disease.
Of course, Ebola has already come to the United States.
The study authors note that the majority of people flying out of Guinea, Liberia and Sierra Leone are traveling to other low- or middle-income countries. As one hospital in the United States has had some trouble preventing transmission, experts question whether less-equipped nations will be able to stop the virus.
"If you look at how challenged the U.S. has been in dealing with this one imported case, I think it's really important for WHO and other countries to up the preparedness in areas where they might have less resources," said Dr. Jesse Goodman, professor of medicine and infectious diseases at Georgetown University, who was not involved with the study.
The researchers also looked at the effectiveness of airport screenings in stopping the spread of the Ebola virus. Overall, they concluded that exit screening is more effective than screening passengers for Ebola when they arrive in another country. Exit screening at three airports is easier, Bogoch says, and requires fewer resources than doing entry screening at hundreds of airports around the globe.
But even exit screening, he says, is unlikely to have much effect because of the virus' long incubation period.
New calls for Ebola hot zone travel ban Hospital worker quarantined on cruise ship CDC: Ebola patient shouldn't have flown Someone can be infected with Ebola for up to 21 days before becoming symptomatic. That's how Thomas Eric Duncan made it to the United States with the virus; his temperature was taken before he boarded, but his symptoms didn't start until several days after his flight landed.
Airport screenings are "a control measure, but an imperfect control measure," says Dr. William Schaffner, an expert on infectious diseases at Vanderbilt University.
Schaffner compares it to making fresh-squeezed juice: Airport screenings, from a fundamental public health point of view, he says, are "very much squeeze with very little juice."
The bottom line is that the vast majority of our resources, Bogoch said, should be focused on preventing the spread of infection in Guinea, Liberia and Sierra Leone.
"If there are fewer cases in West Africa, fewer (infected) people will be boarding planes to other parts of the world," he says. "That said, we still have to be prepared elsewhere. Because we know from experience that it can land on our doorstep."