The first Ebola patient has been diagnosed in the U.S. This news is likely making many of my regular readers wonder, “Should I freak out?” This is a reasonable question, and I will attempt to answer it. But first, let’s go over how this nasty microbe spreads.

Ebola is caused by a virus that is transmitted through contact with the bodily fluids of someone who is sick. It is not airborne; that is, it is not spread by respiratory droplets (coughing, sneezing). After being infected with the Ebola virus, a patient develops symptoms 2 to 21 days later. The patient is only contagious once symptoms appear, not before. Symptoms of Ebola include fever, headache, muscle aches, diarrhea and vomiting.

On September 15, Thomas Eric Duncan, a man living in Liberia, was helping a neighbor who had become ill. (The neighbor later died.) On September 19, while Mr. Duncan was feeling well, he boarded a plane and flew from Liberia through Brussels and Washington. He landed in Texas on September 20 and visited family in Dallas. As is now standard practice for all passengers leaving Liberia, his temperature was checked before boarding his flight and was normal.

On Wednesday, September 24, Mr. Duncan began feeling ill. On September 26 he presented to the emergency department at Texas Health Presbyterian Hospital. He told a nurse he had been in Liberia. The nurse used a checklist to screen for possible Ebola patients. Embarrassingly, that information didn’t get transmitted to the rest of the team caring for Mr. Duncan. He was evaluated and discharged with a prescription for antibiotics. Oops. Major, potentially consequential oops.

On September 28 Mr. Duncan became more ill and was taken by ambulance to the same hospital. At that point, things unfolded as they should. He was quickly identified as a potential Ebola patient and isolated. On September 30, tests confirmed that Thomas Eric Duncan is the first patient to be diagnosed with Ebola in the U.S. He remains hospitalized under isolation and is in serious condition.

Since then Centers for Disease Control (CDC) and state health officials have carefully tracked Mr. Duncan’s movements since he became ill. Remember, the disease is not transmissible until symptoms develop. So, as a CDC official said, there is “zero risk of transmission on the flight.” Four people at the Dallas apartment where he stayed are under quarantine and are being evaluated daily for symptoms. So far, all of them are still well. 12 to 18 people had direct contact with the patient and are also being followed by health officials but are not quarantined. A broader list of about 100 people who may have had very brief contact with Mr. Duncan was also interviewed by health officials to narrow the list to those who might have been exposed to Ebola and require monitoring.

So, dear reader, this is why you shouldn’t freak out. The conditions that have permitted Ebola to spread like wildfire in Africa simply don’t exist here.

What’s the worst that could (likely) happen? A few of the people under quarantine might get sick. That would be terrible. (Some of them are kids.) But the CDC would be on them like, well, health officials on an Ebola patient. They would be immediately hospitalized and isolated. It’s conceivable, but unlikely, that a couple of the 12 to 18 less-close contacts also become ill, but they would get the same treatment. The point is, if Mr. Duncan infected anyone, those patients won’t have a chance to infect anyone else. That’s good workaday epidemic control and it’s one of the many things that African health officials don’t have the resources for.

There are a few other important differences between the conditions here and in Africa that bear on this outbreak. The first is that a very large number of the victims in Africa are health care workers. That’s because of the lack of even the most basic equipment for personnel protection, like latex gloves and disposable gowns. Another difference is that in Africa there is deep mistrust of public health officials and many families hide sick relatives and don’t seek care. In the U.S. the response from the public is likely to be the opposite. If even three or four more patients are identified, the public is likely to overreact. Every fever, runny nose, or pessimistic thought in Dallas is likely to be reported to a physician. The problem will not be in quickly identifying all the Ebola cases. The problem will be that the health care system will be flooded with run of the mill flu symptoms. Don’t have a heart attack that day.

Traditional burial practices in Africa which involve direct contact with the deceased have also contributed to the spread of the disease, and obviously would not be allowed here.

So, spare a kind thought for Mr. Duncan. The Ebola case mortality in Africa is about 50 percent, but I hope with excellent care his chances are much better than that. I also hope that if any of his family fall ill they also recover.

West Africa will continue to require enormous resources to control the current outbreak. And infected people, despite the best screening methods, will continue to travel to the developed world and then learn that they are sick. But a few simple questions, some gloves and gowns, and meticulous tracking of contacts will always prevent a sustained outbreak here.

Albert Fuchs is an internal medicine physician who blogs at his self-titled site, Albert Fuchs, MD.