NY autopsies show H1N1 virus damages entire lung in fatal cases
Researchers from the National Institutes of Health (NIH) and the New York City Office of Chief Medical Examiner report that the H1N1 influenza virus damages the entire lung in fatal cases. The findings are similar to the viruses that caused the 1918 and 1957 influenza pandemics. Autopsies revealed that the H1N1 virus cause damage to the tissue deep in the lungs, as well as the upper respiratory tract.
The researchers looked at 34 people who died of 2009 H1N1 influenza between May 15 and July 9, 2009, most of which occurred in New York City. The virus caused inflammation primarily in the upper airway. According to Jeffery K. Taubenberger, M.D., Ph.D., of the National Institute of Allergy and Infectious Diseases (NIAID) at NIH, "We saw a spectrum of damage to tissue in both the upper and lower respiratory tracts," the same findings seen among victims of the influenza pandemics of 1918 and 1957.
Ninety one percent of H1N1 victims autopsied in New York had heart disease, asthma or other respiratory disease. Seventy two percent were obese – a known risk factor associated with increased risk of death from H1N1 influenza.
Eighteen of thirty-four cases autopsied revealed bacterial infection of the lungs in addition to H1N1 flu, though not all of the patients had been hospitalized. The implication, according to the authors, is that bacterial pneumonia is community acquired risk that can increase severity of H1N1 flu deaths.
CT scans showed an abnormality known as ground-glass opacity in four cases, meaning there was a round hazy appearance to the lung tissue, that may be associated with milder flu cases. The researchers hope CT scans could better help clinicians identify and treat cases of H1N1 flu that are severe.
The authors say more research is needed to understand the damage that occurs to the lungs with H1N1 flu. The autopsies performed in New York show that H1N1 flu causes upper airway inflammation that in some cases is severe. In twenty five cases of H1N1 flu, the alveoli in the lower lungs were also damaged.