San Diego woman's death from swine flu baffles experts: 180 people go to ER at medical center with-in 24 hours after news of death

Source: San Diego Union-Tribune
Date: 19 June 2009

Adela Chevalier didn't fit the profile of someone who might die of swine flu. The Escondido woman was young, having turned 20 in January. She was active and worked two jobs. And she was healthy — family members said she never had a serious illness before last weekend.

Statistics on swine-flu patients also were in her favor.

About 70 percent of people in the United States who have been hospitalized for the virus, also called H1N1 influenza A, suffered from some underlying health problem, such as asthma, diabetes, chronic heart disease or a weakened immune system, according to the federal Centers for Disease Control and Prevention.

But those factors weren't enough to save Chevalier on Monday, when she arrived at the emergency room of Palomar Medical Center in Escondido. Within a few hours, she had become San Diego County's first swine-flu fatality.

Chevalier's death has perplexed public-health officials and medical researchers. It also has panicked some county residents, especially in Escondido and San Marcos — where the victim lived and worked.

“It's clearly very shocking,” biomedical researcher David Woodland, who directs the Trudeau Institute in Saranac Lake, N.Y., said yesterday.

“One of the things that we've all been very concerned about with the outbreak of a new flu is that the severity of the infection could be much worse than the normal seasonal flu,” Woodland said.

An excessive immune-system response that triggers a lethal molecular battle within the body could explain the deaths of Chevalier and the handful of other young, healthy swine-flu patients, some scientists and epidemiologists said.

“It may be that the severity of the disease is due to the robust immune response of younger individuals,” Dr. Daniel Jernigan, deputy director of the CDC's Influenza Division, said during the agency's swine-flu briefing yesterday.

In North County, Chevalier's death reignited fears that had largely subsided in the weeks since swine flu first surfaced locally and quickly morphed into an international pandemic.

About 80 people showed up at the Palomar emergency room Wednesday night — hours after county officials and news media released information about Chevalier. An additional 100 had arrived by yesterday afternoon, said nurse Cathy Prante, the hospital's director of emergency services.

The deluge prompted Palomar officials to set up a pair of canopies outside the emergency room where potential flu patients were directed for initial evaluation.

Many of the visitors weren't sick. They were worried about having been exposed to the swine-flu virus, Prante said.

“We've seen people who worked at the places where (Chevalier) did, or they socialized with her family members,” the nurse said.

San Diego County's public-health officials yesterday urged people not to panic. They said emergency room visits should be reserved for those with serious flu symptoms such as breathing difficulties, stomach pain, dizziness and severe vomiting.

At Palomar, staffers are using a new system designed to quickly assess the condition of ER patients. A nurse stationed in the emergency room lobby briefly evaluates each incoming patient, looking for dizziness, breathing problems, high fever and other signs that urgent care is needed.

People fitting that description are sent to an ER bed for immediate treatment.

The system, dubbed “Quick View,” was initiated Monday and used hours later with Chevalier.

Her case “tested the system” and immediately proved its value, Prante said.

The county Medical Examiner's Office is still days away from releasing its autopsy report on Chevalier, and the bits of information made public so far aren't enough to explain how she died.

“We just don't know at this point,” said Dr. Glenn Wagner, the county's chief medical examiner. “I know that she was reasonably healthy and a bit overweight.”

He also said Chevalier's lungs weighed more than normal, suggesting they were saturated with fluid.

The liquid might have come from intravenous fluid pumped into Chevalier by hospital workers as they fought to resuscitate her, or it could have come from her own body.

Medical examiners still must analyze tiny slices of Chevalier's lung tissue under a microscope to determine where the fluid originated and whether the volume was large enough to kill her, Wagner said.

If the fluid resulted from a battle spawned by her immune system, it might be evidence of a cytokine storm.

That potentially deadly process begins when an infection invades a person's respiratory tract. As viruses take over cells in the sinuses and lungs, the body releases messenger molecules known as cytokines to trigger an immune-system response.

Larger amounts of viruses cause more cytokines to activate, leading to a greater invasion of white blood cells that attack infected cells along with healthy ones that happen to be in the way.

Such collateral damage can be devastating to the lungs' delicate tissues, which allow oxygen molecules to mix with flowing blood.

“You've got damage caused by the virus itself, and damage caused by the immune response,” said Woodland, whose laboratory team studies how the immune system takes on viral and bacterial infections in the lungs.

When the fight is against a familiar infection, Woodland said, the immune system's barrage is typically measured. But with a novel disease, such as the H1N1 swine flu, the immune response might not occur until the lungs are filled with viruses. By then, a more massive counteroffensive can be disastrous.

“Fluid starts flooding into the lungs,” Woodland said. “You basically drown.”

Scientists have theorized that a similar process was responsible for the deaths of a surprisingly large number of young people during the influenza pandemic of 1918-19, which killed an estimated 50 million worldwide.

Several years ago, researchers triggered a cytokine-storm response in mice by infecting them with a genetically reconstructed version of the 1918-19 flu. The results of their study were published in the October 2006 edition of the journal Nature .

Scientists studying the current strain of swine flu aren't close to determining whether the virus has the genetic structure needed to trigger a cytokine storm, said Dr. Douglas Richman, a professor of infectious diseases at UCSD Medical Center and the San Diego VA Healthcare System in La Jolla.

“The question is whether this flu is more virulent than the garden variety flu,” Richman said. “The answer is that we don't know yet.”