Spanish flu: Skeletons reveal clues about victims – 10/13/2023 – Science

The flu usually kills the very young, the elderly and the sick. This made the 1918 virus unusual, or so the story goes: It killed young, healthy people as readily as those who were frail or had chronic conditions.

Doctors at the time reported that among those in the prime of their lives, good health and youth were no protection: the virus was indiscriminate, killing at least 50 million people, or between 1.3% and 3% of the world’s population. In contrast, Covid-19 killed 0.09% of the population.

But an article published on Monday (9) in the journal Proceedings of the National Academy of Sciences challenges this persistent narrative. Using evidence from skeletons of people who died in the 1918 outbreak, researchers reported that people who suffered from chronic illnesses or nutritional deficiencies were more than twice as likely to die than those who did not have such conditions, regardless of age.

The 1918 virus did kill young people, but, the article suggests, it was no exception to the fact that infectious diseases more readily kill frail and sick people.

Sharon DeWitte, an anthropologist at the University of Colorado, Boulder, and author of the paper, said the finding had a clear message: “We should never expect any non-accidental cause of death to be indiscriminate.”

The analysis of the skeletons, said J. Alex Navarro, a historian of the influenza pandemic at the University of Michigan, is “a fascinating paper and a very interesting approach to studying this question.”

The paper’s lead author, Amanda Wissler, an anthropologist at McMaster University in Ontario, Canada, said she was intrigued by claims that the 1918 virus killed young, healthy people as readily as those with pre-existing conditions. At that time, there were no antibiotics or vaccines against childhood diseases, and tuberculosis was widespread among young adults.

There was, however, a mystery about who died from that flu, which helped fuel speculation that good health was not synonymous with protection. The mortality curve was unusually W-shaped. Typically, mortality curves are U-shaped, indicating that babies with immature immune systems and older people have the highest mortality rates.

OW emerged in 1918 because death rates soared in people ages 20 to 40, as well as in infants and older people. This seemed to indicate that young adults were extremely vulnerable and, according to numerous contemporary accounts, it did not matter whether they were healthy or chronically ill. The flu was an equal opportunity killer.

In a report, Colonel Victor Vaughn, an eminent pathologist, described a scene at Fort Devens in Massachusetts, USA. He wrote that he had seen “hundreds of young men in their country’s uniforms, entering the wards in groups of ten or more.” The next morning, he added, “dead bodies are piled around the ward like firewood.”

The influenza pandemic, he wrote, “was taking its toll on the stoutest, sparing neither soldiers nor civilians, and flying its red flag in the face of science.”

Wissler and DeWitte, who had previously done similar research on the Black Death, saw a way to test the hypothesis about young people. When people have persistent illnesses like tuberculosis or cancer, or other stressors like nutritional deficiencies, their shin bones develop small bumps.

Assessing frailty by looking for these bumps “is quite legitimate” as a method, said Peter Palese, an influenza expert at the Icahn School of Medicine at Mount Sinai in New York.

The researchers used skeletons from the Cleveland Museum of Natural History. Its collection of the remains of 3,000 people, kept in large drawers in a huge room, includes each person’s name, age at death and date of death.

Wissler said he treated the remains “with great respect” as he examined the shin bones of 81 people ages 18 to 80 who died in the pandemic. Twenty-six of them were between 20 and 40 years old.

For comparison, researchers examined the bones of 288 people who died before the pandemic.

The results were clear: Those whose bones indicated they were fragile when they became infected — whether young adults or older people — were by far the most vulnerable. Many healthy people were also killed, but those who were already chronically ill were much more likely to die.

That makes sense, said Arnold Monto, a public health researcher and professor emeritus at the University of Michigan School of Public Health. But, he said, while the new study makes “an interesting observation,” the skeletons were not a random sample of the population, so it can be difficult to be specific about the risk that came with fragility.

“We’re not used to the fact that young, healthy adults are going to die,” which occurred frequently in the 1918 pandemic, Monto said.

Palese said there was a reasonable explanation for the W-shaped mortality curve of the 1918 flu. This meant, he said, that people over the age of 30 or 40 had probably been exposed to a similar virus that gave them some protection. Younger adults had not been exposed.