ATLANTA — The first Ebola patient to be brought to the United States from Africa was safely escorted into a specialized isolation unit Saturday at one of the nation’s best hospitals, where doctors said they are confident that the deadly virus won’t escape.Fear that the outbreak killing more than 700 people in Africa could spread in the U.S. has generated considerable anxiety among some Americans. But infectious disease experts said the public faces zero risk as Emory University Hospital treats a critically ill missionary doctor and a charity worker who were infected in Liberia. With news helicopters flying overhead, a police-escorted ambulance carrying Dr. Kent Brantly, a former resident at John Peter Smith Hospital in Fort Worth, arrived at Emory University Hospital, which has a containment unit for patients with dangerous infectious diseases. The unit was built more than a decade ago with consultation from the federal Centers for Disease Control and Prevention, which has its headquarters nearby.Not long after the ambulance pulled into a service entrance at Emory, television footage recorded from helicopters showed Brantly, dressed in protective gear, walking into the hospital with assistance. The ambulance left the hospital, its driver wearing a white hazardous material suit. Security was tight at the hospital: Ahead of Brantly’s admission, law officers were posted around the building, and a police canine unit performed an inspection.The Centers for Disease Control and Prevention has received “nasty emails” and at least 100 calls from people saying, “How dare you bring Ebola into the country!?” Director Tom Frieden told The Associated Press on Saturday.“I hope that our understandable fear of the unfamiliar does not trump our compassion when ill Americans return to the U.S. for care,” Frieden said. Brantly and Nancy Writebol, who will arrive in several days, will be treated in Emory’s isolation unit. . It is one of about four in the country, equipped with everything necessary to test and treat people exposed to very dangerous viruses.In 2005, it handled patients with SARS, which unlike Ebola can spread when an infected person coughs or sneezes. In fact, the nature of Ebola – which is spread by close contact with body fluids including blood – means that any modern hospital using standard, rigorous, infection-control measures should be able to handle it. Still, Emory won’t be taking any chances. “Nothing comes out of this unit until it is noninfectious,” said Dr. Bruce Ribner, who will be treating the patients. “The bottom line is: We have an inordinate amount of safety associated with the care of this patient. And we do not believe that any healthcare worker, any other patient or any visitor to our facility is in any way at risk of acquiring this infection.” Brantly was flown from Africa to Dobbins Air Reserve base outside Atlanta in a small plane equipped to contain infectious diseases, and a small police escort followed his ambulance to the hospital. He climbed out dressed head to toe in white protective clothing, and another person in an identical hazardous material suit held both of his gloved hands as they walked gingerly inside.‘Thankful to God’“It was a relief to welcome Kent home today. I spoke with him, and he is glad to be back in the U.S.,” said his wife, Amber Brantly, who left Africa with their two young children for a wedding in the U.S. days before he fell ill. “I am thankful to God for his safe transport and for giving him the strength to walk into the hospital,” her statement said. In another statement, JPS Health Network CEO Robert Earley and Dr. David McRay, director of maternal and child health for JPS, said: “The JPS Health Network family is delighted and relieved that Kent is back home in the U.S. We are very grateful for the courage and stamina of the team who went to get him. We are grateful to the staff at Emory who will care for him. We remain deeply concerned for his health, the health of his colleague Nancy Writebol as she awaits her turn to come home, and for all those who do not have the option of leaving Africa to receive the most advanced care.”Inside the unit, patients are sealed off from anyone who doesn’t wear protective gear. “Negative air pressure” means that air flows in but can’t escape until filters scrub any germs from patients. All laboratory testing is conducted within the unit, and workers are highly trained in infection control. Glass walls enable staff members outside to observe patients safely, and there’s a vestibule where workers suit up before entering. Any gear is safely disposed of or decontaminated. Family members will be kept outside for now. The unit “has a plate glass window and communication system, so they'll be as close as 1-2 inches from each other,” Ribner said.Dr. Jay Varkey, an infectious disease specialist who will be treating Brantly and Writebol, gave no word Saturday about their condition. Both were described as critically ill after treating Ebola patients at a missionary hospital in Liberia, one of four West African countries hit by the largest outbreak of the virus in history. There is no proven cure for the virus. It kills an estimated 60 to 80 percent of the people it infects, but American doctors in Africa say the mortality rate would be much lower in a functioning healthcare system.The virus causes hemorrhagic fever, headaches and weakness that can escalate to vomiting, diarrhea and kidney and liver problems. Some patients bleed internally and externally.There are experimental treatments, but Brantly had only enough for one person and insisted that his colleague receive it. His best hope in Africa was the transfusion of blood including antibodies he received from one of his patients, a 14-year-old boy who survived thanks to the doctor.‘Best … in the world’Just down the street from the hospital, people dined, shopped and carried on with their lives Saturday. Several interviewed by the AP said the patients are coming to the right place. “We’ve got the best facilities in the world to deal with this stuff,” said Kevin Whalen, who lives in Decatur, Ga., and has no connection to Emory or the CDC. “With the resources we can throw at it, it’s the best chance this guy has for survival. And it’s probably also the best chance to develop treatments and cures and stuff that we can take back overseas so that it doesn’t come back here.” Staff writer Patrick M. Walker contributed to this report, which includes material from The Associated Press and The New York Times.