Updated 35 minutes ago

When health officials develop a vaccine every flu season running in the United States from October to May, they select virus strains based on versions recently released around the world.

The United States Centers for Disease Control and Prevention and Agencies may use a global flu surveiling system with more than 100 member states – an instrument that was not available in 1918, when an influenza pandemic made more than a third of the world's population sick and at least killed 50 million people, possibly up to 100 million.

It is estimated that approximately 5,000 people have died in Pittsburgh, with another 2,000 deaths in Westmoreland County.

The intervening century has led to more knowledge about the flu virus – first isolated in the 1930s – and vaccines that provide immunity to many known strains. There has also been progress in the preparation and response to influenza infections, including the development of antiviral drugs to treat the disease.

Modern researchers are exploring other approaches for better protection against influenza strains.

"We have better hospital facilities that can support people who get flu," Dr. David Wyszomierski, a doctor of Excela Latrobe Pediatrics, who last year attended a lecture series on past and present influenza problems at Westmoreland County Community College. "We have faster diagnostics that tell us which tribes are hanging around, the CDC keeps track of what's circulating."

However, the predictions of seasonal flu varieties are imperfect as the strains evolve and sometimes skip the species barrier between animals and humans.

The CDC also warns of when the next pandemic will occur.

Wyszomierski pointed out that in recent years health officials have been monitoring so-called bird flu viruses transmitted from wild birds to domestic birds and then to humans, mainly in Asia. Migratory birds naturally harbor and spread a variety of influenza viruses.

"They've only infected a few people, and they're not human-to-human," Wyszomierski said. "If such an influenza virus has the ability to become transmissible from person to person, it could trigger a worldwide epidemic."

Although rare and rare, influenza epidemics are turning into pandemics that spread and infect and kill on a large scale all over the world. Researchers believe that such flu epidemics come from the Middle Ages, if not earlier.

Apart from the deadliest outbreak of 1918, other known flu pandemics died in 1889, 1957, 1968 and 1977 – the last one presumably due to a flu virus that has not been seen since the 1950s and escaped a Chinese lab that was probably working on a vaccine.

The most recent influenza pandemic that affected the US was a new H1N1 virus that was discovered in California in April 2009, a month after its first appearance in Mexico. The letters refer to types of proteins in the virus that are key to creating effective vaccines.

The H1N1 strain has hit the world in 1918 and has since spawned viral offspring. The 2009 virus is "another genetic product in the growing family tree of this remarkable 1918 virus," says an article in the New England Journal of Medicine.

The 2009 virus did not have such a severe impact as the one in 1918, which claimed nearly 700,000 lives in the US. According to the CDC, the global outbreak in 2009 led to 2,125 confirmed deaths in the US, including 344 children.

Health officials quickly found anti-viral drugs – which did not exist a century ago when scientists were not aware of any viruses or their treatment – that could be used to treat the disease in 2009 until a vaccine was ready for distribution in October.

The researchers found that the virus in 2009 contained genetic material derived from human, avian and porcine viruses from different continents. This virus has now become one of the regular seasonal varieties that can be treated with a vaccine.

According to Seema Lakdawala, an assistant professor of microbiology and molecular genetics who runs a flu laboratory at the University of Pittsburgh, the 1918 flu may have reduced the 2009 pandemic impact.

"The H1 H1 protein is very similar to H1 for 1918," Lakdawala said. "People born before 1957 who had seen similar H1 were protected from the 2009 pandemic" had established immunity to the similar virus component.

Search for answers

The extreme virulence of the 1918 flu puzzles officials, but researchers have found some clues.

In 2005, microcologist Terrence Tumpey of CDC became the first researcher to reconstruct and investigate the 1918 flu virus by applying reverse genetics to preserved lung tissue from pandemic victims.

His work revealed that two types of genes in the 1918 virus were "essential for maximum replication and virulence," Tumpey said in an interview published on the CDC website. "Based on this data, some scientists believed that these viral genes could be a potential target for a new generation of anti-influenza A drug development."

Of the four basic types of influenza viruses, the A-type is most commonly associated with cross-species infections and pandemics.

Lakdawala has also worked on methods that affect the ability of an influenza virus to spread among humans.

"We focus on human seasonal viruses," she said. "We mutate it and try to lose its ability to transmit through the air."

Earlier, in conjunction with the National Institutes of Health, Lakdawala operated their Pittsburgh lab for three years. Since 2009 she is researching the transmission of influenza.

"We've learned so much in the last 10 years," she said. "Previously, we only had one lab at the CDC to see how flu is transmitted through the air, and now several labs around the world are investigating it."

Lakdawala emphasized the importance of ventilation to exchange air in a building and help spread airborne flu viruses that were expelled from an infected person with the disease. Equally important is the wiping off of touched surfaces such as doorknobs and elevator buttons in which viruses may be present, she said.

Research has revealed that flu viruses can remain in the air for at least an hour and for up to 16 hours on certain surfaces, according to an article by Lakdawala and colleague Linsey Marr, a professor at Virginia Tech.

According to Wyszomierski, medical centers in the United States and the United Kingdom are working to develop a longer-lasting, universal vaccine against seasonal influenza strains that could be effective between doses for five years or more.

By the time this breakthrough came, he said, "It's always best to follow the direction of the CDC and get the flu vaccine every year."

Jeff Himler is an editor of the Tribune Review. You can contact Jeff at 724-836-6622, jhimler@tribweb.com or Twitter @jhimler_news.

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