Ebola Experts: Advanced Medical Procedures Could Add Risk

Procedures such as dialysis and intubation could create an aerosol that puts health care workers in the area at risk, experts said

As U.S. health officials take a close look at protocols for treating Ebola after two nurses in a Dallas hospital contracted the disease, some medical experts are questioning whether advanced medical procedures might put health-care workers at greater risk.

Authorities have repeated that Ebola is spread only through direct contact with patients’ bodily fluids.

But two doctors with extensive experience with Ebola are urging caution, warning that the virus could possibly be transmitted through an aerosol spray as a result of medical procedures such as dialysis and intubation. That could be a particular concern for doctors, nurses and other health-care workers in the immediate vicinity of a patient.

"I certainly would be worried about situations where modern medical measures were brought to bear on Ebola-infected patients, because we don’t have any experience with that," said Dr. C.J. Peters, a former U.S. Army colonel who was chief of the special pathogens branch at the Centers for Disease Control and Prevention. Peters has worked to stem Ebola outbreaks, including one among monkeys at a research facility in Reston, Virginia. 

Dallas nurse Nina Pham and a second unidentified health-care worker became ill with Ebola while caring for Thomas Eric Duncan, the 42-year-old Liberian man who was hospitalized at Texas Health Presbyterian Hospital after traveling from West Africa to Dallas. He died last week.

It's not clear how they became infected, and all studies indicate that Ebola does not transmit like the flu or the cold, through coughs and sneezes.

In West Africa — where the Ebola epidemic in Guinea, Sierra Leone and Liberia has killed nearly 4,500 people — patients are not typically put on respirators or kidney dialysis machines, Peters said.

But in Dallas, Duncan was on a ventilator and a dialysis machine immediately before he died, his family said.

Both Peters and Dr. Philip K. Russell, a retired major general who oversaw Ebola research for the Army Medical Research and Development Command, said putting a patient on a respirator, intubating a patient and other procedures create an aerosol.

"So then the question is, 'Is this a mode of transmission?'" Russell said. "Basically we don’t know.”

Health-care workers at hospitals that have treated Ebola patients in the United States have all used what are called positive air pressure respirators, devices to protect them from aerosol exposure, Frieden said on Monday.

“That is clearly not how the individual in Texas became infected so I don’t think we have concerns about the potential route of transmission, but our guidelines already say that if there is any concern for aerosol-generating procedures such as intubation of a patient or suctioning, then absolutely we recommend respiratory protection," he said.

But late Tuesday, the country's largest nurses' union released a statement from nurses at the Dallas hospital saying staff had treated Duncan for days without the correct protective gear. The nurses at first wore only surgical masks with more sophisticated ones optional and they taped closed openings in gowns that did not cover their necks, the union said.

The union declined to identify the nurses who made the complaints. Its officials said they were reading the statement so that the nurses, who are not represented by a union, could speak out anonymously without fear of losing their jobs.

The hospital had said in a statement that there were numerous measures in place to provide a safe working environment, including mandatory annual training and mechanisms to allow for anonymous reporting.

"I don't think we have a systematic institutional problem," Dr. Daniel Varga, chief clinical officer of Texas Health Resources, said during a media briefing Wednesday.

Russell said there was some evidence from recent studies that the strain of virus being seen now might be producing higher levels of virus in the blood, which could make it more transmissible. The virus needs to be watched carefully to see if it is mutating in ways that make it more dangerous, he said.

“There’s a lot of unknowns in this epidemic and some of them have to do with the nature and the virulence of the virus,” he said. “The others have to do with the way it produces an illness and how it’s transmitted.”

Dr. Daniel G. Bausch of the Tulane School of Public Health and Tropical Medicine, who has studied the risk of Ebola transmission from bodily fluids, said he saw no reason to change the medical assumptions about Ebola.

"I can't think of any example of natural mutations of a pathogen that has fundamentally changed its biology so that we have something that mutated that once was spread by contacts with blood and bodily fluids and now has changed its biology to be spread by airborne or aerosol," he said. "I suppose that rare things happen rarely."

Peters stressed that he thought the CDC was doing exactly what it should be doing to control Ebola.

“Aerosol transmission doesn’t mean that it’s going to be influenza,” he said. “It just means that sometimes it may happen that way.”

And Russell acknowledged the tremendous danger of infection through contact.

"But to assume that there isn't any virus in the air is also I think dangerous," he said. "But if everybody's wearing the positive pressure equipment to protect themselves against inhaled aerosol, that's great. That's what I think should be." 

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