Last week, a former Minnesota resident died of Ebola in Nigeria. This week, the what-ifs are rampant.

The victim's wife said her husband had been scheduled to fly to Minneapolis in mid-August to attend a birthday party for two of their children. "He could have brought Ebola here," she told The Daily Beast.

Watch "Ebola: Are We Next?" on Thursday, Sep. 18, starting at 9/8c on both Discovery Channel and Discovery Fit & Health.

Two other Americans in Africa have been diagnosed with the disease, and Sierra Leone's leading Ebola doctor died of it yesterday. Among the volunteers the Peace Corps is removing from three affected countries in Africa, two have had confirmed exposure to an Ebola victim. They're being isolated outside the United States until they get medical clearance.

Ebola's Deadly Jump From Animal to Animal

While the Centers for Disease Control and Prevention on Monday issued both a Level 2 travel alert, recommending those traveling to Africa "avoid contact with blood and bodily fluids," and a Health Alert Notice to U.S. health care workers, experts and officials believe there's no need for panic. Far from it, in fact: "It's extremely unlikely," said Thomas Geisbert, a virologist with the University of Texas in Galveston, Texas, who studies Ebola and other hemorrhagic fevers.

And, if someone were diagnosed anywhere in the United States, "every infectious disease doctor in any hospital would be on full alert for signs and symptoms," Geisbert said. "For containing outbreaks, with quarantine and prevention we're 90 percent of the way there."

How Can Ebola Be Stopped?

Even if someone with Ebola got on an airplane to the United States, "it's very unlikely that they would be able to spread the disease to fellow passengers," said Dr. Stephan Monroe, deputy director of CDC National Center for Emerging & Zoonotic Diseases in a press conference call.

"The Ebola virus spreads through direct contact with the blood, secretions, or other body fluids of ill people, and indirect contact -- for example with needles and other things that may be contaminated with these fluids. Most people who become infected with Ebola are those who live with and care for people who have already caught the disease and are showing symptoms."

Health specialists prepare for work in an isolation ward for patients at the Doctors Without Borders facility in Guékedou, southern Guinea.AFP/Getty Images

On the off-chance that the situation did occur, here's what would happen: The patient would be transferred to an isolation ward, and all health care workers coming in contact with the person would wear full personal protective equipment. Ebola is classified as a biosafety level 4 virus, so testing for the virus would happen in one of a few labs in the nation qualified to safely handle the virus in air-controlled rooms.

Once a diagnosis was confirmed, contact tracing would begin: Anyone the person had contact with -- on an airplane, at a market, at a family gathering -- would be informed of the situation and monitored. That's a much easier task in a developed country that has ready access to communication than it's been in Africa, where cultural, language, communication and transportation hurdles must be overcome to relay information.

This spring, for example, a man with Middle East Respiratory Syndrome (MERS) landed in Indiana, and a man checked into a hospital in Minnesota with Lassa fever. In both cases, health workers followed contact tracing protocol (requiring getting in touch with 140 people), and the viruses were contained.

What Is Ebola?

In the Indiana case, the Indiana Department of Public Health traced everybody on the bus the patient traveled on, on his flights, in the waiting room, visitors to the hospital, and family. The CDC tested over 50 people and found one with mild MERS. In the Minnesota case, over 140 people were contacted and no one else was diagnosed with the disease.

Because the incubation period of Ebola is relatively long -- up to 21 days, the list of contacts gets extensive quickly.

"The CDC and state public health departments are able to do it, but that's not always the case where the outbreaks are," said Dan Epstein, a World Health Organization spokesman.

Until a vaccine is approved -- and although Geisbert's lab has developed three leading candidates that work in animal models, it could take up to six years before an inoculation is ready for humans -- Americans at the greatest risk are health care workers in the outbreak areas.