An electron microscope image of the CDC’s recreated 1918 Influenza virus, seen here, 18 hours after infection. Courtesy: CDC/Dr. Terrence Tumpey Despite recent advances in microbiology ...

One of those cases still contained genetic fragments of the 1918 virus, and that was a case that had really good histologic evidence, that is under the microscope, of primary influenza pneumonia.

Bird flu is also now killing wild birds ... it’s only when we then send those tissues in that they can look under a microscope and see some subtle changes,” Dr. LaHue explained.