Scientists at the National Institutes of Health say they've found the influenza virus in lung tissue and other autopsy material from 68 American soldiers who died at least four months before the disease reached pandemic levels in the fall of 1918.
Four of the soldiers, who died between May and August of 1918, are the earliest 1918 pandemic influenza cases known to be documented anywhere in the world, a release from the NIH's National Institute of Allergy and Infectious Diseases said Monday.
The clinical damage seen in the pre-pandemic cases were indistinguishable from what was seen in cases that occurred during the height of the pandemic, suggesting the virus did not undergo any dramatic change that could explain the unusually high mortality that resulted, NIAID researcher Jeffery K. Taubenberger said.
However, bacterial co-infections such as pneumonia were found in all of the 68 cases studied, highlighting the deadly role such infections can play in conjunction with any influenza virus.
That shows the need for public health officials to prepare to prevent, detect and treat bacterial co-infections during future influenza outbreaks, the researchers said.