RENEE MONTAGNE, host:
The virus responsible for the historic flu pandemic of 1918 probably didn't kill tens of millions of people around the world all by itself. Turns out in most cases it took a second infection, a bacterial infection, to deal the fatal blow. The finding adds to the body of knowledge about one of the most catastrophic health events ever. It also has implications for getting ready for the next pandemic. NPR's Joanne Silberner has more.
JOANNE SILBERNER: Researchers from the National Institute of Allergy and Infectious Diseases studied preserved lung tissue collected from 58 soldiers who died of the flu in 1918 and 1919. And they looked at what doctors back then had to say about what was killing their patients. Both led to the same conclusion.
Dr. ANTHONY FAUCI (National Institute of Allergy and Infectious Diseases): Those data strongly pointed to the fact that these people died of pneumonia - a bacterial pneumonia.
SILBERNER: Not a pneumonia caused by the flu virus, says Anthony Fauci, one of the researchers.
Dr. FAUCI: There's no doubt that the virus caused damage of the lung tissue, which likely set the person up to be much more highly susceptible to the overwhelming effect of the bacterial pneumonia.
SILBERNER: The researchers report in the current online version of the Journal of Infectious Diseases that all the preserved tissue showed changes that happen when a lung is infected by bacteria. For example, inflamed cells gathered around some of the tubes that carry air in and out of the lungs. And they found that in the 8,400 autopsy reports made at the time, doctors knew that they were dealing with something more than just the influenza virus.
Dr. FAUCI: They saw bacteria in the autopsy tissue. They cultured it. They had antibodies that identify them.
SILBERNER: That understanding of the pandemic came to be unappreciated and was lost over time. Fauci's colleague, David Morens, rediscovered the astuteness of those doctors when he pored through the initial medical reports. One French physician said it this way in 1918: The flu condemns a person, but a secondary infection is what actually kills.
Dr. Fauci said there was nothing doctors back then could do about it.
Dr. FAUCI: If we had the antibiotics then that we have now we could've saved a lot of people, particularly the younger people who were otherwise healthy.
SILBERNER: And in fact, flu pandemics in 1957 and 1968 didn't kill nearly so many people. The bacterial connection is an important one, says James McCullers, an infectious diseases expert at St. Jude Children's Research Hospital.
Dr. JAMES MCCULLERS (St. Jude Children's Research Hospital): I think really the biggest thing they're doing is just reminding us of something that we had forgotten that is very important in the context of current pandemic planning, which is that bacteria are the biggest problem we may have to deal with.
SILBERNER: Emergency planners focusing on being ready for the next pandemic have been working on developing a vaccine against whatever new virus comes along and being ready with stockpiles of the few flu drugs that are available.
Fauci, who's involved with the government effort, says one of the reasons for digging up the old case reports and doing the tissue studies is to bring bacteria into the mix in case of a repeat of 1918-style epidemic. He says the government has stockpiles of many antibacterial drugs, but they could use more. And he says there needs to be a greater effort to vaccinate people, especially older people, against bacterial pneumonia as well as the flu.
Joanne Silberner, NPR News.