Medical workers wearing protective clothing transport a man suffering from Ebola to the isolation ward at the University Clinic in Frankfurt am Main, central Germany. (Boris Roessler/AFP/Getty Images)

The United States’ first Ebola patient was identified this week in Texas. He probably won’t be the last.

Ebola is contagious and highly lethal. With no demonstrably effective vaccine available, isolation and quarantine are invaluable tools. Is it enough to stop Ebola here?

Although used interchangeably, isolation differs from quarantine in a couple of key ways. Isolation refers to placing an ill and contagious person in a controlled environment to prevent transmission. Quarantine, on the other hand, means restricting the movements and contacts of healthy people exposed or potentially exposed who may become contagious.

Isolation is commonly used in hospitals for many diseases. Quarantine is rarely employed because it may unnecessarily restrict liberty and may spread disease to quarantined persons who were not actually exposed. Calls for quarantine to control AIDS in the 1980s were counterproductive. Quarantine of passengers arriving from Ireland in the 1800s on typhus ships condemned many to death. Quarantining crowded slums in Liberia may have increased the spread of Ebola as people fled.

Mass quarantine efforts in the United States would likely be similarly ineffective as people seek to escape perceived death traps. Closing borders to healthy travelers from Africa would be ineffective. People would simply lie, forge documents or carry more than one passport. An inability to return if exposed would deter skilled health workers from supporting control efforts in Africa.

Except for extremely high risk or uncooperative persons, quarantine has been replaced by identification and monitoring of at-risk people.

In prior Ebola outbreaks, cases were not infectious until they developed fever. Family members, home care providers, medical personnel and persons handling corpses were at highest risk, demonstrating that Ebola virus was spread through direct contact with blood and bodily fluids.

To control the outbreak, all exposed people must be rapidly traced and monitored for 21 days. Those developing fever are isolated in hospital, where they can receive supportive care to increase their chances of survival. Such containment efforts are labor intensive, but have been demonstrably effective in controlling prior Ebola outbreaks in the Congo and Uganda. Monitoring and isolation have halted Ebola in Nigeria and Senegal during the current outbreak. Isolation and quarantine alone terminated the much more infectious global SARS outbreak in 2003.

The key to success here is emphasizing early identification and isolation of Ebola cases plus rapid tracing and monitoring of all contacts. Despite efforts by public health agencies to prepare hospitals for Ebola, the system failed in Dallas. A nurse initially noted that the patient had been in West Africa, but that vital fact was not communicated onwards and the patient was discharged. This error caused additional medical personnel and, possibly, other family and friends to be unnecessarily exposed. Some 100 persons are now being monitored, and family members are quarantined at home. Those people will be lucky if none of them develop Ebola.

Success in controlling the spread of Ebola in the U.S. requires medical personnel to be hyper-vigilant concerning ill people who’ve recently traveled from West Africa. It means that hospitals will need to aggressively observe isolation precautions. Not just to protect the public, but also themselves.

The global failure to support containment efforts in Africa has brought Ebola to our doorstep. Ultimately, control of Ebola in the U.S. will require terminating the West African outbreak, thereby eliminating all importations.

Harry F. Hull, MD, was trained in epidemiology at the U.S. Centers for Disease Control and Prevention and is an adjunct professor of pediatric infectious diseases at the University of Minnesota School of Medicine, and was an adjunct professor of infectious disease epidemiology at the School of Public Health.