Volunteers from the Red Cross deliver supplies to the confirmed Ebola patient on Thursday. Photograph by Tom Pennington/Getty

“This case is serious,” Rick Perry, the Governor of Texas, said on Wednesday at a press conference at Texas Health Presbyterian hospital in Dallas, where the first patient diagnosed with the Ebola virus disease in the United States was being treated. “Rest assured that our system is working as it should. Professionals on every level of the chain of command know what to do to minimize this potential risk to the people of Texas and this country.”

Then, a few minutes later, hospital leaders confessed that, in fact, the professionals hadn’t done what they had to do. The hospital had prepared for the possibility that Ebola would arrive in its emergency room. It had adopted a Centers for Disease Control screening checklist to identify patients with fever who had travelled from the region of West Africa beset by Ebola. (Full disclosure: my research center and I advised the C.D.C. on the design of its checklists.) The staff had rehearsed the event. And, on September 24th, when just such a traveller arrived, the triage nurse who saw him actually asked the proper questions and flagged in the medical chart that he was a potential concern for Ebola.

But: “Regretfully, that information was not fully communicated throughout the care team,” the hospital’s chief quality officer said.

As a result, the physician seeing the patient did not realize that the man had travelled from Liberia. He therefore seemed like just another of the thousands of patients who come in with a fever and moderate abdominal pain—he did not yet have the severe diarrhea and vomiting that are commonly associated with Ebola—and was discharged with a diagnosis of a low-grade viral gastroenteritis. He went home for two days and potentially exposed a number of people to Ebola, including five schoolchildren, others in his family, and two emergency medical workers.

Public-health officials have put the patient’s contacts under twenty-one days of surveillance and tried to reassure the public that the disease will be contained. Even though it remains possible that someone he exposed will contract Ebola, this particular case will be contained. What is disturbing, though, is that the hospital’s initial mistake is hardly unusual in our health system. Other hospitals might not have been any better prepared to avoid it.

For one, many likely had not even put the checklists in place, let alone actually rehearsed using them like the Dallas hospital had. For another, failures to communicate critical information—whether it’s a patient’s unusual travel history or dangerous test results or any number of other concerns— remain among the most common causes of major medical error everywhere. For instance, staff routinely put flags about concerns in medical charts and computer systems and then are surprised when doctors fail to notice them buried among all the other information.

It is worth repeating what experience with twenty Ebola outbreaks over the past four decades has established. The disease has many features in our favor. Unusually, it does not make people contagious until they are actually noticeably sick, which makes screening far more effective than for other diseases. It cannot spread through the air or just by being near someone. It is spread through contact with a symptomatic person’s bodily fluids—saliva, vomit, stool, urine, even sweat. It is much harder to spread than a cold. That’s why it is primarily those who take care of the sick—health-care workers and family members—who contract the disease. Even then, it is relatively difficult to pick up.

In a 1996 case in South Africa, a patient spent twelve days in a high-level hospital sick with an illness that wasn’t recognized as Ebola until after he was discharged. Some three hundred health-care workers took care of him. None contracted the disease. A 1995 study of a Congo outbreak looked at seventy-eight household members who lived with patients with Ebola who did not directly touch them or their fluids after they became sick. Again, none contracted the disease.

This relatively weak transmissibility makes the standard public-health technique of contact-tracing effective in halting the disease. Track down the people who’ve been in contact with a sick patient; measure their temperatures and check on them daily for twenty-one days; if any turn up with a fever or looking sick, put them into isolation. Once you get anywhere upward of seventy per cent of the contacts under such surveillance, the disease stops spreading.

For patients who need to be isolated, the requirements are not terribly fancy. You need a room with a door that can close. There’s no need for special ventilation. The door is not to keep germs from coming out but to keep people from inadvertently going in and touching the person. Medical equipment should be dedicated to just the patient. Family members or workers can enter the room if they wear a standard fluid-resistant gown, gloves, eye protection, and a face mask. If they might be exposed to the patient’s bodily fluids, they should wear double gloves, shoe covers, and leg coverings.

Experience suggests that workers should use a buddy system to make sure that protection is used safely. The main challenge is taking off the protective personal equipment—that’s when it is easiest to contaminate yourself. Hazmat suits and respirators are likely overkill, and there is concern that they are even more difficult to remove; still, many hospitals are planning to use them anyway. CNN reported on a Liberian woman who successfully protected herself through two weeks with four infected family members by carefully donning and removing a rain coat, plastic garbage bags over her legs, plastic gloves, and a mask when providing care.

Dealing with the medical waste can be difficult. Many medical-disposal companies have refused to accept such waste from hospitals that register a suspicious patient, because of the procedures required to handle the materials. But the steps are known and agreements are being negotiated.

Ultimately, minimizing this risk is going to require dealing with the reservoir of disease multiplying in West Africa. Voices—so far on the fringe, but they likely won’t be for long—are calling for quarantining travelers who’ve been to endemic countries, or even banning them. Critics charge those arguing for screened but open borders with being afraid to be politically incorrect. But it’s nothing of the sort. The concern is that closing borders doesn’t work.

No travel ban or quarantine will seal a country completely. Even if travel could be reduced by eighty per cent—itself a feat—models predict that new transmissions would be delayed only a few weeks. Worse, it would only drive an increase in the number of cases at the source. Health-care workers who have fallen ill would not be able to get out for treatment, and the international health personnel needed to quell the outbreak would no longer be able to go in. The local economy and health infrastructure would further collapse, causing a far wider spread of the disease. For months, Doctors Without Borders—almost the lone group providing treatment services—has been crying out for help. The international response was contemptible.

We know what needs to be done. Last week, finally, the United States government organized the deployment of three thousand aid workers and began marshalling a wider international response. Inside our borders, the C.D.C. has fostered a cadre of thousands of public-health professionals at the local, state, and federal levels who are ready to respond and who have proved to be reliable and effective at getting this kind of work done. And, with the announcement of the Dallas case, hospitals across the country are now scrambling to get their procedures in place. Doctors' offices should do so, too. They need to download the C.D.C.’s checklists. And they need to do what other high-risk professions have done for years and train people immediately in “closed-loop communication”—confirming verbally that critical information has been received and understood.

The diagnosis of the first U.S. case is not the sign that we need to shut patients out. It’s the sign that we need to bring more help in. The Ebola epidemic is stoppable.