The worst-ever Ebola outbreak has governments scrambling to contain the disease. At the heart of the issue, however, is the difficulty in identifying who will likely come down with Ebola.

One of the biggest challenges facing authorities and health officials is determining how best to screen travelers who could have come into contact with the disease. Ebola’s incubation period is two to 21 days, which means a traveler could go three weeks before showing any symptoms — during which they could travel anywhere in the world.

Concern over the outbreak, which has killed more than 3,400 people in West Africa, is now global. Tactics to combat Ebola vary widely, but as recent scares at U.S. airports in New Jersey and in Orlando show, efforts to stop the disease in its tracks are now underway.

Ebola spreads relatively slowly; the average victim told Science Magazine that passing through the Monrovia airport in Liberia was where he felt the highest risk of contracting the disease.

“They are bringing hundreds of people into a very confined space with a lot of direct contact, so if you get a patient into that environment, you are going to have exposures,” he said. “It is a ridiculous situation.”

Feldmann added that when he went through the airport last month, the checks in place were useless because the workers checking temperatures did not appear to be trained well enough, and that the number of passengers was overwhelming for them.

Liberia is also requiring travelers to indicate if they have come into contact with anyone sick with Ebola. Thomas Eric Duncan, the first U.S. Ebola patient, allegedly lied about his condition, and Liberian officials say they will prosecute him when he returns to the country.

What’s more, the hospitals treating Ebola patients are so overwhelmed that they are turning people away, according to Feldmann.

In Sierra Leone, BBC health reporter Tulip Mazumdar described a harrowing scene at clinics treating patients with Ebola.

West African countries hit hardest by the disease are feeling pressure to contain it, as evident in a declaration from Sierra Leone’s transportation minister that “not a single case of Ebola has gone past screening measures at Lungi International Airport.”

Travelers at Lungi are required to wash their hands in chlorine, and submit to having their temperature taken, according to The Telegraph.

In Guinea, where international flights to the airport have gone down from the usual 57 to about 17, travelers must complete a questionnaire and have their temperatures taken. The World Health Organization originally conducted the approximately 3,000 screenings at Conakry International Airport each week, but since August, has been training local workers.

The United Nations Economic Commission for Africa in September called for an end to travel restrictions to Ebola-affected countries.

In Europe

A nurse in Spain is the first person to contract the disease outside of West Africa. The case is an example of how healthcare providers can be most vulnerable to Ebola: She was part of a medical team that treated a Spanish priest who died in a hospital in Madrid in September, according to Spain’s health minister. The priest was previously in Sierra Leone, according to the BBC.

Ebola’s now in Europe: http://t.co/1TNEEknbwP pic.twitter.com/RWtCBhNlfB

— RYOT NEWS (@RYOTnews) October 7, 2014

Some European airlines have canceled flights to and from Ebola-affected countries, but travel is still possible.

Airport and airline responses in Europe and the United States are primarily focused on identifying travelers who are sick, as opposed to screening passengers’ temperatures or guessing who may become sick.

In the United States

In the U.S., the Centers for Disease Control and Prevention (CDC) have warned residents to avoid all non-essential travel to Guinea, Sierra Leone and Liberia. For those who must travel there, the CDC recommends avoiding contact with any bodily fluids of the sick. Travelers returning to the U.S. from West African countries are provided a fact sheet about the disease.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN that “all options are being looked at” for screening as people enter the U.S. While the procedures for screening passengers leaving Ebola-affected countries are obvious, Fauci said the U.S. is still trying to figure out “what kind of screening you do on the entry end. That’s something that’s on the table now.”

The White House has resisted calls for a travel ban by members of U.S. Congress. There are no direct flights to the U.S. from the West African countries affected by Ebola, making a travel ban both difficult and of questionable effectiveness.

The effort to combat Ebola’s spread must be global, President Barack Obama said, even though the U.S. is assisting. “We have not seen other countries step up as aggressively as we need them to,” Obama said Monday. “Countries that think that they can sit on the sidelines and just let the United States do it; that will result in a less effective response, a less speedy response, and that means that people die.”

Duncan, the first U.S. Ebola patient, had gone to Texas Health Presbyterian Hospital Dallas, but was sent home with antibiotics on Sept. 25. Three days later, on Sept. 28, he returned to the hospital where he was put in isolation. Duncan was eventually diagnosed with Ebola on Sept. 30. At a Dallas-area clinic, a doctor posted the following notice to patients, asking them to say if they had recently traveled internationally.

In Asia

In August, Vietnam isolated two Nigerian travelers who arrived to the airport with a fever. Neither of the travelers was found to have Ebola. Vietnam’s two major airports, Hanoi and Ho Chi Minh City, have been taking travelers’ temperatures, according to South China Morning Post.

Myanmar also identified one traveler who had a fever and had recently been in Guinea and Liberia. Myanmar’s health officials determined that the man was suffering from malaria.

There have been no confirmed cases of Ebola in Asia, according to WHO.

In the Middle East

Emirates has halted flights to Conakry, Guinea, until further notice, according to the airline.

Airlines and airports in the region have been monitoring the Ebola situation without yet imposing additional measures, Travel Daily Media reported.

There have been no confirmed cases of Ebola in Middle Eastern countries.

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