When a new, highly infectious disease lands on U.S. shores, four unique treatment centers stand ready to contain and treat it. Sprinkled across the east coast, Midwest and Rocky Mountain west, these "biocontainment units" inside larger facilities have been funded and tapped by the federal government to take patients who could otherwise fuel a devastating epidemic.

These centers made the news in August as Ebola patients began to arrive in the U.S. Of these, three patients have been treated at Emory University Hospital (Kent Brantly, Nancy Writebol and a doctor who remains unidentified) and two at Nebraska Medical Center (Rick Sacra and Ashoka Mukpo)—and all have survived. But these units weren't designed with Ebola in mind.

Containing Ebola, a hemorrhagic fever virus that is spread via contact with bodily fluids, should be a relatively simple undertaking for these specialized units. The centers were made to contain and treat highly infectious as well as contagious deadly diseases, such as those that can easily spread through the air. (Ebola is highly infectious in that patients displaying symptoms shed many virus particles but it is not considered highly contagious, given that it can only be spread through bodily fluids of symptomatic patients.) Among the scary diseases these highly specialized facilities can handle are bird flu (avian influenza), drug-resistant tuberculosis, monkeypox, plague, SARS, smallpox and tularemia. "Right now they're the best we have," says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. "They serve as the very foundation in the U.S." for fighting highly infectious diseases. They have, he notes, the best equipment, the right protocols and the properly trained personnel to confront diseases for which most other hospitals would be unprepared.

"Highly infectious patients are really their forte," says Amy Ray, an assistant professor focusing on infectious disease at the Case Western Reserve University School of Medicine and chair of the University Hospitals System Infection Control Committee. "This is really what these centers were built for."

So how do these centers deal with patients who show signs of rare, highly virulent or unknown pathogens? Here are the vitals on each facility.

National Institutes of Health
Embedded in the sprawling campus of the National Institutes of Health (NIH) in Bethesda, Md., is a small but mighty high-level containment facility known as the Special Clinical Studies Unit. The unit aims to mesh treatment with front-line research. Its ward is "specifically designed to provide high-level isolation capabilities and is staffed by infectious disease and critical care specialists," a spokesperson said in a prepared statement. "The unit staff is trained in strict infection-control practices optimized to prevent spread of potentially transmissible agents."

The unit has just four rooms and seven beds; three of the rooms are built for two patients and one is single-occupancy. Each room is equipped with negative airflow, which sends cleaned, filtered air at all times into the patient room while preventing air—along with potentially infectious particles—from escaping out into the rest of the hospital. Closed-circuit video cameras monitor safety throughout the patient areas. A glass window—and intercom connection—links the patient care area to the room where unprotected health care providers are stationed, to let workers observe and communicate with the patient without having to don specialized garb.

The facility, in keeping with the NIH's research-focused mission, is also designed for implementing best practices for research into infectious diseases. The unit "allows for the study of patients harboring potentially infectious pathogens," explains Molly Hooven, a spokesperson for the NIH's Clinical Center—as well as for trials that use potentially infectious vectors, such as vaccine studies that include attenuated live viruses. Many of the individuals who end up staying here are otherwise healthy participants in vaccine trials.

Emory University Hospital
Located outside of Atlanta and near the U.S. Centers for Disease Control and Prevention (CDC), Emory University Hospital's Isolation Unit was built in cooperation with that agency.

It houses just two patient rooms—designed to be identical to intensive care unit (ICU) rooms, and each with contained bathrooms with toilets and showers. Each room also has a window and intercom connecting it to an area where health care workers can be without putting on protective equipment. The design dedicates a substantial amount of space to staff work areas. Between the two rooms is an anteroom with hands-free sink as well as a staff prep room with lockers and a shower for emergency decontamination. The work space includes its own biosafety hood, where staff can prepare samples in a contained space and an adjacent dedicated lab that can be used to test for pathogens, do blood tests and other essential procedures.

Negative air pressure—continuously tracked by multiple digital pressure monitors—keeps clean air flowing in from the hallways into the anteroom, from the anteroom into the patient rooms and then out through high-efficiency particulate air (HEPA) filters. That gives "two levels of protection to make sure that no airborne particles in the patient room go into the general hallway," Bruce Ribner, a professor of infectious diseases at Emory University School of Medicine, explains in a video demonstration of the unit. Even in the patient rooms the airflow has been specially designed, coming from vents in the ceiling and exiting through a vent near the floor to avoid any turbulence and redirected flow. Each room has full air exchange on average every three minutes.

The hospital has taken a serious approach to ensuring waste is safe. Items that are disposable, such as protective suits and food trays, are first sanitized with pressurized steam and then incinerated. Any liquid waste—such as the patient's bodily fluids coming from the bathroom or receptacles—is treated with bleach or detergent for more than five minutes, preventing live pathogens from entering the local wastewater system.

University of Nebraska Medical Center
Also commissioned in partnership with the CDC, the University of Nebraska Medical Center's Biocontainment Patient Care Unit opened in 2005 and is "designed to provide the first line of treatment for people affected by bioterrorism or extremely infectious naturally occurring diseases," according to a statement from the university. The 10 beds make this unit the largest of the four U.S. biocontainment facilities.

To get patients safely from outside into the isolation ward, the hospital has "biopods" or "isopods"—mobile, contained, person-length bubbles that can strap over hospital gurneys. They stay inflated with negative-pressure air that is then HEPA filtered before being pushed out. A series of rubberized gloves dot each clear side so that health care workers can care for the patient inside with a clear view without having to open the pod (watch this detailed video on its features).

The unit is on its own ventilation system, separate from the rest of the hospital. In addition to negative-pressure air in patient rooms (which cycles through 15 complete air exchanges per hour) and HEPA filtration systems, it also has a double-door air lock to the unit's main entrance. The unit uses ultraviolet light to disinfect contaminated items—as well as a disinfecting "dunk tank" where workers can place containers of samples (such as blood) into the solution before taking them out of the unit. It also has a "pass-through" autoclave that can sterilize equipment leaving the unit with high-pressure steam. A different sterilizer processes laundry from patient rooms as well.

Staff at the unit go through special training as well as multiple drills each year. A public running leaderboard ranks nursing staff as they complete levels of training. The unit is located close to Nebraska Public Health Laboratory's Biosafety Level 3 Laboratory, which can expedite diagnosis and analysis of a pathogen from an infected patient.

Saint Patrick Hospital
The containment facility farthest west is in Missoula, Mont. The Care and Isolation Unit at St. Patrick Hospital was born from a 2005 NIH request for a local patient isolation facility—specifically to serve staff and visitors who might accidentally become infected at the nearby Rocky Mountain Laboratories, an NIH research facility that works with dangerous pathogens in biosafety level 2, 3 and 4 labs.

Grant money to bring the facility up to speed for the NIH labs allowed the hospital to prepare for infectious patients coming from the broader community and country. The unit has three rooms designed to hold a single patient but they can each serve two patients if necessary. All of the rooms are equipped with standard ICU fittings and each also has a separate bathroom. Security cameras installed on the ceiling monitor safety. A large, dedicated nurses station and lab service the small unit, which also has portable radiology machines as well as its own autoclave for sanitizing equipment. An anteroom for each patient room has areas for health care workers to suit up, along with a touchless sink.

Negative air pressure keeps airborne pathogens from escaping patient rooms, which have separate air-handling systems to avoid cross-contamination. Each room has full air exchange roughly every five minutes, with the air flowing diagonally from ceiling vents, past the patient, into two large ducts along the headboard wall. Exhaust air is processed through HEPA filters before being released—2.5 meters above the hospital's roofline.

Lessons from the best
Beyond all of the air filters and autoclaves these highly specialized units have one key, intangible asset. And that, Osterholm says, is: "training, training and training." To be more specific, he adds, employees at these biocontainment centers “have worked through very specific protocols and they have practiced those—and practiced those and practiced those."

Which is an important lesson for community hospitals throughout the U.S. and the globe. Training, protocols and drills are an important part of readiness for a hospital at any level. Larger hospitals might also begin replicating other features of these biocontainment units, Osterholm says. "In the end I think we may very well see more of these treatment centers showing up around the country—particularly on a regional basis."

Having local and regional hospitals prepared for handling infectious disease patients is important for long-term epidemic preparedness because these few, specialized containment units are not exactly sprawling wards. If general hospital ICUs are the battalions in a large-scale war against an infection, these units are the special forces. With an extremely limited number of beds—25 max at current capacity—these units are not going to be the nation's answer to a larger, widespread outbreak.