State's only swine flu death still a mystery
Specialists hunting for clues to explain woman's decline
The only person known to have died of swine flu in Massachusetts suffered from none of the underlying medical conditions that can turn a relatively mild viral infection into a life-threatening illness, city disease trackers disclosed yesterday.
The finding deepens the mystery around the June 14 death of a 30-year-old Boston woman who arrived at Boston Medical Center already gravely ill from symptoms associated with the respiratory disease, known by the scientific designation H1N1.
Investigators with the Boston Public Health Commission delved through medical records obtained from the woman’s primary care physician, hunting for clues that might explain her precipitous decline.
But there was no evidence she had ever been diagnosed with asthma, cancer, diabetes, heart disease, or any other chronic malady known to intensify the risk of dying from a flu virus.
In patients with such persistent conditions, the flu virus can exacerbate the underlying disease - causing a lethal asthma attack, for instance - or exploit an already battered immune system.
The city’s review will be shared with disease specialists at state and federal health agencies, providing another piece in the emerging portrait of a germ that has swept the globe in two months.
“H1N1 is a novel virus, and while we work to prevent severe illness and death, we are also gathering information to better understand the patterns associated with this virus,’’ said Barbara Ferrer, executive director of the city health agency.
“It is known to us that otherwise absolutely healthy people have, in fact, unfortunately died from influenza. It is rare, but it does, in fact, happen.’’
City health authorities said the woman’s medical files indicated she had dealt with health issues, although none particularly unusual for a person of her age.
Officials declined to identify the woman or to provide further details of her medical history, citing patient confidentiality laws.
Tom Skinner, a spokesman for the US Centers for Disease Control and Prevention, said the vast majority of the 87 swine flu deaths in the nation have been reported in adults and children with existing medical problems.
But Dr. David Ozonoff, a Boston University School of Public Health professor who presides over an online flu encyclopedia, highlighted World Health Organization estimates that between one-third and one-half of swine flu fatalities were among those otherwise healthy before they were stricken with the virus.
More than 21,000 cases of swine flu have been confirmed in the United States, with nearly 1,300 in Massachusetts. That is regarded as only a small fraction of the total. Most cases are mild and not reported.
Overwhelmingly, the germ has proved most troublesome to younger adults and children, unlike the seasonal flu, which disproportionately harms the aged. That, Ozonoff said, suggests that the immune systems of the young are like blank slates, with no memory of how to respond to viruses from the family that includes swine flu.
"They’re sort of defenseless,’’ Ozonoff said. “And it’s possible it may be more severe in this younger group because there’s not the kind of immune reaction to it’’ that older adults may have. Some disease specialists theorize that older people may have added protection because they were exposed to H1N1 viruses circulating widely from 1918 to 1957; those strains then vanished for two decades.
Disease researchers know that even with the seasonal flu, healthy people can be felled by the virus. An irreversible cascade of illness can be unleashed, with secondary pneumonia infections proving deadly.
“More times than not, people with pneumonia can experience severe respiratory distress,’’ the CDC’s Skinner said. “And it gets to the point that they’re unable to overcome the secondary infections that accompany severe cases of influenza.’’
The health commission’s Ferrer said disease detectives from Boston to Atlanta, home of the CDC, will continue to scour the medical records of the Boston woman, searching for overlooked clues that might explain the behavior of the virus.
Maybe, Ferrer said, there is something in the Boston woman’s medical background that mirrors the health history of other patients killed by swine flu, even though they harbored none of the recognized risk factors.
“We need to make sure we’re not missing any pieces here,’’ Ferrer said.
Stephen Smith can be reached at stsmith@globe.com.
Correction: Because of a reporting error, a story in yesterday’s Metro section about the state’s only swine flu death incorrectly explained one theory about why older people might have stronger immunity against the current H1N1 flu virus. Although other H1N1 strains have been circulating in recent years, older people might have more protection because they were exposed to H1N1 strains from 1918 to 1957, before those strains vanished for two decades.
