Inconsistent, ‘overkill’ use of barrier precautions emerging as prime hypothesis in Ebola infection of two Dallas health workers

March 18th, 2015

Protective barrier equipment (PPE) appears to have been used haphazardly in some instances and with overkill in others in recently caring for an Ebola patient at Texas Health Presbyterian Hospital in Dallas, suggesting how two health care workers may have acquired the virus during treatment of the index case.

The Centers for Disease Control and Prevention has reviewed the records for the first several days of the late Thomas Duncan’s hospital stay – when he was a suspect Ebola case prior to formal diagnosis – and found a lot of variability in the use of PPE. Duncan died Oct. 8 and two health care workers involved in his treatment have tested positive for Ebola -- the first on Oct. 10 and the second on Oct. 14. The first nurse remains under care at Texas Health and the second is being admitted to the biocontainment unit at Emory University Hospital in Atlanta. The hospital successfully treated two health care workers flown in directly from the raging epidemic in West Africa earlier this year.

Though specific incidents or exposures that could have led to occupational transmission at Texas Health Hospital have not been identified, the CDC has repeatedly returned to the issue of PPE use – suggesting it is a prime hypothesis in the ongoing investigation.

“When our people arrived the same day that the patient was diagnosed, we noted, for example, that some health care workers were putting on three or four layers of protective equipment in the belief that this would be more protective,” CDC Director Tom Frieden said at an Oct. 15 press conference. “Other things were done such as taping parts of the protective gear in the belief that this would be more protective. ... By putting on more layers of gloves or other protective clothing, it becomes harder to put them on and take them off. The risk of contamination in the process of taking these gloves off gets much higher.”

In the nurses’ defense, a nursing union official told the New York Times, “Were the protocols breached? The nurses say there were no protocols.” The hospital defended efforts to “provide a safe working environment,” but said they would review any concerns raised by nurses, the newspaper reported.

CDC pinpoints three-day exposure risk period

”Our investigations increasingly suggest that the first several days before the [index case] was diagnosed appear to be the highest risk period – [Sept.] 28th, 29th and 30^th ,” Frieden said. “These two health care workers both worked on those days and both had extensive contact with the patient when [he] had extensive production of body fluids because of vomiting and diarrhea. We are continuing to assess the exposures of all other health care workers at that facility to identify how many may have had that level of intensive contact.”

The CDC is following about 50 other workers who entered Duncan’s room during his hospitalization. In addition, 48 possible Duncan contacts in the community are being followed, but as they near the outer ranges of the 21-day incubation period it is becoming less likely they will develop infection.

The second infected health care worker is ill but clinically stable. When she developed and reported symptoms, she was rapidly isolated, Frieden said. She flew back from Ohio to Texas on October 13^th, the day before she reported for care. Because of the proximity of time of that evening flight and her first report of illness the following morning, the CDC contacted the airline and is identifying and notifying all passengers. Though it is not clear specifically what instructions were given, Frieden made it clear the worker should not have boarded a commercial airplane while she was self-assessing for Ebola onset.

CDC guidance in this situation calls for “controlled movement,” which could include a charter plane or a car -- but not public transport. Going forward, the CDC will see that no other individual who is being monitored for exposure travels beyond the controlled movement limitations, he said.

”Although she did not report any symptoms, and she did not meet the fever threshold of 100.4, she did report at that time she took her temperature and found it to be 99.5,” he said. ”So by both of those criteria, she should not have been on that plane. I don't think that changes the level of risk to the people on board. She did not vomit, she was not bleeding. The level of risk of people around her would be extremely low. [But] because of that extra margin of safety, we will be contacting them all.”