The current strain hasn’t shown up in surveillance of U.S. pigs, and it can’t be caught by eating pork.

The finding about its genetic background illustrates how viruses mutate over time and in some cases jump among species.

“Until you look at that, you can’t understand the epidemiology of it,” said Peter Cowen, the animal disease moderator for ProMed, an online emerging disease early-warning system. “It’s key to understanding what our challenges may be in the future and how the virus is acting in the population.”

The current strain’s eight genetic segments are all associated with swine flu, said Raul Rabadan, a Columbia University scientist studying the new H1N1 genetic sequence that was made public this past week by the Centers for Disease Control and Prevention.

Two of the segments, Rabadan said, appear to come from Eurasia and are somewhat mysterious in origin. The other six can be traced to the North American pig outbreak, which turned out to include a combination of avian, swine and human flu.

“This virus was found in pigs here in the United States,” Rabadan said in an interview.  ”They were getting sick in 1998. It became a swine virus.”

It spread among pregnant sows in Newton Grove, N.C., causing them to abort their litters, and then to swine in Texas, Iowa and Minnesota– putting epidemiologists on alert about the new viral strain and the potential for a human outbreak.

That didn’t happen, but public health officials became more aware of the farm-by-farm monitoring system and its importance to public health.

“We cannot protect human health unless we’re working with what’s going on in the environment and animal species,” said Barrett Slenning, who leads the Animal Health Biosecurity Risk Management Population Health and Pathobiology Department at North Carolina State University.

Scientists don’t yet know when or where the current H1N1 strain first developed. They know only that it was first identified after people in Mexico began falling ill with the fevers and aches associated with flu.

The current virus hasn’t been found in swine, and the country’s pork industry is scrambling to reassure consumers about the safety both of pork and the U.S. farm system.

Still, the findings about the new H1N1 virus’ ancestry also has reignited concerns about the health impacts of factory farms, where thousands of hogs are housed closely together and shipped among sites as they grow.

“Pigs are amazing mixing bowls for creating new viruses,” said Bob Martin, senior officer at the Pew Environmental Group. Martin was executive director of the study.

“It’s a matter of when, not if,” Martin said of the creation of new viruses on factory hog farms. “The structure of the system is the problem.”

Cowen, who also is an epidemiologist at North Carolina State University’s College of Veterinary Medicine, said factory farms have shown their ability to contain disease in their animals.

However, he said the current H1N1 outbreak shows the need to improve surveillance of healthy swine as well as pigs that show signs of illness.

“The key to being prepared in terms of responding to this threat from influenza, wherever its coming from–humans, swine or birds–is to know as much as we can about the viruses that are circulating,” Cowen said.

This week’s discovery is, in part, just another piece of the scientific puzzle in trying to understand the new H1N1 flu’s history.

Scientists working around the world this week began tracing the virus’ origins days after the CDC published its eight-chromosome genetic sequence.

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© 2009, McClatchy-Tribune Information Services.
Visit the McClatchy Washington Bureau at: www.mcclatchydc.com
Distributed by McClatchy-Tribune Information Services.

by Barbara Barrett
McClatchy Newspapers / (MCT)

MCT is a joint venture of McClatchy and the Tribune Co.

Q: What exactly is a virus?
A: It’s a tiny packet of only eight genes wrapped in a cloak of proteins, much smaller than a bacterium. Unlike bacteria, a virus is only half alive. It can’t eat or reproduce on its own, but must take over the genetic machinery of a living cell. Most viruses are harmless; some are useful, but others, such as the flu virus, can be deadly.

Q: What makes this swine flu virus special?
A: It’s a novel combination of bird, pig and human viral genes never before found in the U.S. or elsewhere, so people have no immunity to it. It’s a descendant of the H1N1 virus that killed tens of millions of people worldwide in the pandemic of 1918-1919, mixed in with recent strains of swine and bird flu viruses. The 1918 virus originated in birds and then jumped to humans. This year’s virus apparently jumped from a pig to a 5-year-old boy in Veracruz, Mexico, who passed it on to other humans.

Q: What does H1N1 stand for?
A: It’s the initials of two sugar proteins (their scientific names are hemagglutinin and neuramidinase) that sit on the surface of the virus and do its dirty work. There are 16 types of the H protein, numbered H1 through H16, and 9 types of the N protein, numbered N1 through N9. That makes 144 possible combinations of the virus, a constantly changing challenge for prevention or treatment. A new combination, H2N2, cause a brief swine flu epidemic in 1957. An H3N2 strain was the source of another epidemic in 1968. The bird flu virus that began in Southeast Asia a decade ago and has spread throughout the Old World is an H5N1 combination.

Q: How does the H protein work?
A: The H protein looks like a little spike that fits into a notch, called a receptor, on the outside of an animal or human cell and lets the virus enter. Once inside, the virus hijacks the DNA in the cell’s nucleus and uses it to make copies of itself.

Q: What does the N protein do?
A: After infection, it opens a passage in the cell wall and releases the new baby viruses, which can now invade other cells. Without the N protein, infection would be limited to the first cell, rarely enough to cause disease.

Q: How do medicines such as Tamiflu and Relenza work?
A: They block the action of the N protein so the virus can’t spread. They’re not vaccines to prevent an infection, but drugs to limit its impact. They should be taken as soon as possible since the virus reproduces most rapidly between 24 and 72 hours after illness begins.

Q: How does a new virus develop?
A: When the genes that govern the H and N proteins reproduce, random changes _ mutations _ can occur in their DNA. The changes gradually accumulate, ultimately producing a virus that may be more lethal or may penetrate a target cell more easily. Another possibility is gene-swapping. This can happen when a cell is infected by viruses from different creatures, say a chicken and a pig. The cell becomes a “mixing bowl,” whipping up a new virus containing some chicken genes and some pig genes. In the new strain of H1N1 virus, pieces of human, bird and pig genes are all scrambled up.

Q: How does this H1N1 virus differ from the H1N1 that caused the Spanish flu pandemic in 1918-1919?
A: That virus developed various changes over the years, so it’s similar but not identical to its ancestor _ like a grandson who resembles but also differs from his grandfather. So far, H1N1 is not as virulent as the previous strain, but that could change. The earlier pandemic began mildly in 1918, but returned in a devastating second wave six months later. Experts fear that could happen again. Hence they are rushing to develop a vaccine by this fall.

Q: How does H1N1 virus jump from animals to humans?
A: Usually the H protein on a pig or bird virus doesn’t fit easily into the receptor of a human cell. So a person exposed to such a virus is unlikely to get infected. However, random changes may occur in the genes that control the shape of the H protein and allow the virus to pass through the cell wall. This gives rise to a new strain of H1N1 that’s adapted to humans. Now the virus can pass from person to person, as is happening now. Contact with infected pigs or birds no longer is necessary.

Q: How does one person catch H1N1 from others?
A: The virus can be transmitted through the air _ by a cough or a sneeze _ or by a handshake or by touching an infected surface, such as a doorknob. The virus can live for up to two hours outside a cell. It can’t be passed by eating pork.

Q: Why does this disease seem to be more deadly in Mexico than in the U.S. or other countries?
A: That may be an illusion. The first U.S. death has now occurred in Texas and more fatalities are expected. It’s possible that many cases of mild disease in Mexico went undetected, making the mortality rate appear to be higher there than it does here. It’s also possible that the virus strain in the U.S. differs slightly from the one in Mexico, making it less virulent.

Q: Why does H1N1 seem to attack healthy young adults more than sick and elderly people, who are most affected by the ordinary seasonal flu?
A: Young adults have a healthy immune system that launches a massive counterattack of antibodies against the flu virus. Unfortunately, the counterattack can cause an overwhelming inflammation that damages other organs, such as the lungs. Elderly people with weaker immune systems are less likely to suffer from such harmful inflammation. Older people who were exposed to earlier flu epidemics might also have some residual immunity in their systems.

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© 2009, McClatchy-Tribune Information Services.
Visit the McClatchy Washington Bureau at: www.mcclatchydc.com
Distributed by McClatchy-Tribune Information Services.

by Robert S. Boyd
McClatchy Newspapers / (MCT)

[this story and photo is made available to you from our partnership with the American Society of Newspaper Editors (ASNE) and McClatchy-Tribune Information Services, using their "MCT Campus" newswire service for school newspapers]

MCT is a joint venture of McClatchy and the Tribune Co.

The move comes as state and local authorities, the Centers for Disease Control and Prevention and the international health community step up public awareness, testing and surveillance in an effort to stop the disease before it becomes a global epidemic.

On Sunday, four more cases were confirmed in the Canadian province of Nova Scotia. In Mexico, where the outbreak originated, nearly 90 people have died and thousands of others have become ill from swine flu in the last several weeks.

The World Health Organization said the new swine flu strain has “pandemic potential.”

A flu pandemic occurs when a new influenza virus emerges, people have little or no immunity to it and there’s no vaccine for it.

No deaths have been reported in the United States, but officials confirmed Sunday that eight students at a New York City high school tested positive for the disease after dozens had complained of flu-like symptoms. Some of the students had recently returned from a spring break trip to Cancun, Mexico. The school has been closed as a precaution.

Authorities have confirmed seven more cases in California, two in Kansas and Texas and one in Ohio. More cases are expected in the coming days

“As we continue to look for cases, I expect that we’re going to find them. We’ve ramped up our surveillance around the country to try and understand better what is the scope, what is the magnitude of this outbreak,” said Dr. Richard Besser, the acting director of the CDC.

President Barack Obama is getting regular briefings and updates on the outbreak and the steps being taken to address the problem. Homeland Security Secretary Janet Napolitano is heading the federal effort to deal with the outbreak, but numerous other departments, including Health and Human Services and Agriculture, are also involved.

The virus spreading throughout the U.S. appears to be the same strain that has infected Mexico, but health officials are unsure why the U.S. outbreaks haven’t been as severe. To date, all U.S. flu victims have recovered, and only one has been hospitalized.

That could change, however, since infectious diseases, and the flu virus in particular, are unpredictable, Besser said.

“Given the reports out of Mexico, I would expect that over time, we’re going to see more severe disease in this country,” Besser warned. . . . “We do think that this will continue to spread, but we are taking aggressive actions to minimize the impact on people’s health.”

Sunday’s health emergency declaration frees up federal, state, and local resources for disease prevention. The move allows agencies to conduct diagnostic tests, if necessary, on young children. It also OK’s the release of 12.5 million courses of antiviral medications Tamiflu and Relenza from the nation’s strategic stockpiles. The drugs will go to states in need, with priority given to those with confirmed cases.

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© 2009, McClatchy-Tribune Information Services.
Visit the McClatchy Washington Bureau at: www.mcclatchydc.com
Distributed by McClatchy-Tribune Information Services.

by Tony Pugh
McClatchy Newspapers / MCT CAMPUS

[this story is made available to you from our partnership with the American Society of Newspaper Editors (ASNE) and McClatchy-Tribune Information Services, using their "MCT Campus" newswire service for school newspapers]

MCT is a joint venture of McClatchy and the Tribune Co.

About Swine Flu:
A respiratory disease of pigs, swine influenza infections occur most commonly among humans who are in close proximity to pigs. However, the disease also can spread from person to person. Highly contagious, swine flu has the same symptoms as regular human flu, including fever, cough, sore throat, headache, chills and fatigue.

What You Should Do:
Health officials … say all people also should cover their noses and mouths with a tissue when coughing or sneezing; wash hands often with soap and water, especially after a cough or sneeze and use alcohol-based hand cleaners when possible. Avoid touching your eyes, nose and mouth since germs cans easily spread that way. The CDC also advises avoiding contact with sick people.
Homeland Security Secretary Janet Napolitano urged all citizens to help curb the spread of the disease. She said Sunday, “… If you are sick, stay home. Wash your hands, take all of those reasonable measures; that will help us mitigate, contain how many people actually get sick in our country.”
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© 2009, McClatchy-Tribune Information Services.
Visit the McClatchy Washington Bureau at: www.mcclatchydc.com
Distributed by McClatchy-Tribune Information Services.

by Tony Pugh
McClatchy Newspapers / MCT CAMPUS

[this story and graphic is made available to you from our partnership with the American Society of Newspaper Editors (ASNE) and McClatchy-Tribune Information Services, using their "MCT Campus" newswire service for school newspapers]

MCT is a joint venture of McClatchy and the Tribune Co.