Senior author Katherine Kedzierska, an associate professor of the University of Melbourne, said some groups have a specific genetic make-up that prevents them from fighting off influenza.
The new influenza virus H7N9 originated in birds -- also known as bird flu -- and caused an outbreak in China last March, which infected more than 140 people. The flu strain resulted in a very high mortality rate of 30 percent due to severe pneumonia and acute respiratory distress syndrome.
The study, published in the Proceedings of the National Academy of Sciences, found indigenous people such as in Alaska and Australia displayed limited immunity response to the effects of influenza.
Lead author Peter Doherty, a laureate professor from the University of Melbourne, said the study shed light on what had happened during the catastrophic 1918 to 1919 influenza pandemic during which high adult mortalities -- up to 100 percent -- were reported in some isolated Alaskan villages.
"The findings suggested that there may be ethnic differences in the ability to mount an immune response to the H7N9 virus," Kedzierska said in a statement. "Due to genetic differences in a protein complex involved in cell-mediated immune responses, people may vary in their ability to mount this kind of immune response against the H7N9 influenza virus that emerged unexpectedly in 2013."
Similarly, as many as 10 percent to 20 percent of indigenous Australians died of influenza in 1919, compared to fewer than 1 percent mortality rate in non-indigenous Australians, Doherty said.
"Hospitalization and morbidity rates were also higher for indigenous Australians," Doherty said. "This was also the case during the recent 2009 H1N1 pandemic influenza, with 16 percent of hospitalized Australians indigenous."
The genetic susceptibility of indigenous Australian and Alaskans would have resulted from isolation of indigenous populations from the viruses like influenza. The indigenous populations were not subjected to evolutionary pressures caused by the viruses over the centuries, Kedzierska said.
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