What the Latest Ebola Infection Says About Odds of Widespread US Outbreak

What the Dallas cases can teach us about whether the virus will spread further.

And as troubling as this second case may be, especially in terms of possible lapses in protocol, it also could serve as a much-needed wake-up call to public health officials nationwide about how vigilant they must be, experts said.

The difficulties at the Dallas hospital aside, the overall public health response has been swift and efficient, Schaffner said. As soon as the two individuals with infection were identified, health officials acted immediately to isolate them from the general public, he pointed out. Their contacts were quickly found and put under surveillance, he said, and their homes and belongings were disinfected.

"Patients become more and more contagious as the disease progresses because viral load increases and more organ systems involved," said Hotez, who is also the dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.

Schaffner said he is actually encouraged by how immediate the public health response has been in Dallas. It is also a good sign that so far none of the family or friends of Thomas Eric Duncan –- the first patient to die of Ebola in the U.S. –- have become ill. With their 21-day quarantine period almost at an end, it doesn't appear the virus had a chance to spread, he said.

"This is a terribly important lesson that virus is not going to run rampant in Dallas or anywhere else in the U.S.," Schaffner said. "Let's not forget that we've done some things right."