This mystifies infectious disease experts, who consider the viruses that cause Middle East Respiratory Syndrome (MERS) and bird flu much more contagious — and therefore more dangerous to the public. Transmission of Ebola requires direct contact with an infected person's blood, vomit or feces during the period that he or she is contagious, something that is extremely unlikely for anyone but health-care workers. The virus is not spread by coughing or sneezing. Nor do Americans bury their own dead family members or friends, as some residents of Sierra Leone, Liberia and Guinea must do with Ebola victims.
"There is zero danger to the U.S. public from these [two] cases or the Ebola outbreak in general," said Amesh Adalja, a member of the public health committee of the Infectious Disease Society of America and an infectious disease doctor at the University of Pittsburgh.
"People who have Ebola are not walking around on the street. They are very, very sick and pretty much confined to a hospital and to a bed," he added.
But what if you find yourself on an airplane, or in a hospital waiting room, with a symptomatic carrier of Ebola? What if you shake hands with an infected person whose hygiene is not perfect? Couldn't you contract it that way?
Theoretically, yes, Adalja acknowledges, but here he quickly notes something that most Americans don't realize: Lassa fever, another horrifying hemorrhagic disease that kills about 5,000 people in West Africa every year, has been imported into the United States by travelers seven times in recent years, with no known case of transmission.
"Ebola will find the Unites States just as inhospitable as lassa fever," he predicted.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, struck a similar tone in an interview with The Washington Post Thursday. "There is certainly a possibility that someone might get on a plane who is infected in Sierra Leone or Liberia and come to the United States," he said. "But the chance of it being spread here the way you are seeing there is extraordinarily low, to the point that the CDC and me and other officials feel confident that there's not going to be an outbreak here."
Added Tom Frieden, head of the U.S. Centers for Disease Control and Prevention: "Ebola poses little risk to the U.S. general population.
Additionally, President Obama announced Friday that officials would begin screening travelers for signs of Ebola before they leave Africa and again when arrive in the United States.
The CDC is among the medical authorities that acknowledge that hospitals must do a better job of controlling infection. According to this report by the agency, one in 25 patients acquires an infection while under care in a U.S. hospital. Adalja agrees, but notes that the systems in place, even in small community hospitals, are much better than they are in West Africa.
The first line of defense is a doctor or triage nurse asking every patient who shows up with a fever whether he or she has recently traveled to West Africa, which the CDC has reminded them to do. Beyond that are ever tighter barriers -- gowns, gloves and equipment used only on a patient when "contact precautions" are called for; droplet precautions such as surgical masks for flu cases; better masks for infections that can be transmitted through the air, such as tuberculosis, and negative pressure rooms for cases that require even better control, such as MERS.
Here's how one Indiana hospital got it right when a MERS case unexpectedly showed up at the door.
If, in the end, you still want to worry about something, Adalja said, worry about the H5N1 bird flu that continues to infect poultry, and occasionally people, in Asia and the Middle East. It is currently fatal to humans about 60 to 65 percent of the time and is much more contagious than Ebola. Ebola's fatality rate is also about 60 percent.