Though the swine flu scare of 2009 may have bumped the avian variety of flu from of the popular imagination, biomedical researchers certainly haven’t forgotten the potential danger it poses. But researchers are constantly forced to play catch-up by following bird flu’s path through the avian population and trying to track its shifting genetics.
The way to finally get the jump on bird flu would be to create a weapon that works against the whole family of avian flu viruses, whatever their slight genetic quirks. And researchers led by Laurence Tiley say in Science this week that they might have found that kind of comprehensive trick: a genetic modification that seems to prevent flu from spreading in chickens.
It’s a decoy.
The birds carry a genetic tweak that diverts an enzyme crucial for transmitting the H5N1 strain. Although they die of the disease within days, the molecular decoy somehow impedes the virus from infecting others. [Nature]
Specifically, this genetic tweak allows the birds to create an RNA impostor. It matches up to the polymerase enzyme the flu virus would use to replicate its genetic material, so that enzyme is attracted to the decoy, which throws off viral replication. Though the modified chickens that were infected with avian flu died, the fact that they didn’t spread the virus is a potentially huge find—once avian flu enters a chicken population it typically spreads like wildfire.
A new study is providing insights into the 2009 swine flu epidemic, and why more serious complications arose in healthy middle-aged people than expected. The researchers say the culprit may be antibodies to seasonal flu found in the seriously ill patients, which might have caused an immune system overreaction in the lungs.
“Nobody really had a good explanation for why middle-aged people seemed to have more severe disease than would have been expected,” says Richard Scheuermann, an immunologist at the University of Texas Southwestern Medical Center in Dallas. “This explanation is the first one that I’ve seen that actually makes sense.” [Nature News]
Normally, severe flu illness happens in the very young (who haven’t been previously exposed to the flu and don’t have protective immunity) and the elderly (who have weakened immune systems). Instead of affecting these groups, the 2009 pandemic H1N1 “swine flu” primarily caused severe reactions in middle-aged adults.
It’s still out there, you know.
A study out today in the journal Science tracks the path of swine flu, which may have receded from the forefront of humanity’s attention but hasn’t quit mixing and moving and making ready. The scientists led by virologist Malik Peiris say the flu virus that the world feared last year has gone back into pigs in China, where it’s laying down and recombining its genetics with other flu strains. And, they say, we’re not sufficiently monitoring the danger of a new strain jumping back to people.
“Just because we’ve just had a pandemic does not mean we’ve decreased our chances of having another,” said Dr. Carolyn B. Bridges, an epidemiologist in the flu division of the Centers for Disease Control and Prevention. “We have to stay vigilant” [The New York Times].
News that an Iowa cat has been diagnosed with swine flu has sparked a new round of concerns, as pet-owners worry both that their furry companions could get sick, and that their pets could pass the virus on to other humans. The 13-year-old, mixed-breed cat showed the symptoms of lethargy, sneezing and coughing typical to sick cats [ABC News]. The veterinarians who treated him say that several people in the cat’s home had been experiencing flu-like symptoms, and lab work confirmed that the feline had the H1N1 virus.
Happily, the cat is expected to make a full recovery. But both vets and public health officials are rushing to reassure the public that one sick cat probably does not indicate a coming crisis. While it’s possible that more cats will be diagnosed with the swine flu, vets point out that the virus was circulating for more than six months before the first cat case was discovered, indicating that the virus probably doesn’t jump from species to species very easily. Doctors also note that there’s very little chance that a cat will spread the virus to humans: Even when inter-species transmissions do occur, the H1N1 virus seems more likely to move from humans to animals, rather than the other way around [HealthDay News].
There have been no reported cases of dogs catching the virus, but there is one type of pet that is known to be vulnerable. Ferrets are generally susceptible to the seasonal flu, and the AP reported Wednesday that H1N1 infection has been confirmed in two ferrets, one in Nebraska and the other in Oregon. “Not only can they be infected with the flu but they are clearly able to transmit the flu back to people,” Treanor said [HealthDay News]. But the bottom line appears to be: Unless you’re a ferret-owner, you probably have nothing to worry about.
80beats: This Week in Swine Flu: How It Kills, Lawsuits, and a Pregnant Woman’s Story
80beats: This Week in Swine Flu: Vaccines Arrive, and Doctors Combat Myths
80beats: This Week in Swine Flu: Pregnant Women’s Concerns & Hospital Woes
Image: flickr / theogeo
As swine flu is now prevalent in 41 states, doctors are getting plenty of chances to study the workings of the disease. They now know that in severely ill patients, intense inflammation in the lungs prevents oxygen from being tranfered to the blood stream. Says physician Robert Fowler: “Most patients are still able to take breaths, but these breaths are ineffective” [Science News]. That oxygen deprivation can cause widespread organ damage.
The speed with which swine flu patients can go downhill marks the H1N1 virus as strikingly different from the seasonal flu virus, doctors say. “In severe cases, patients generally begin to deteriorate around three to five days after symptom onset. Deterioration is rapid, with many patients progressing to respiratory failure within 24 hours, requiring immediate admission to an intensive care unit” [Reuters], says World Health Organization doctor Nikki Shindo.
Doctors say that severely ill patients should promptly be put on breathing machines and given antiviral drugs like Tamiflu. In cases where patients’ respiratory systems have already crashed, some doctors are trying a treatment called extracorporeal membrane oxygenation, in which blood is extracted from each patient and passed through a machine that adds oxygen [Science News].
Swine flu vaccines have arrived! Or more accurately, limited amounts of the first available vaccine, a nasal spray, have been delivered to distribution points around the country, and several states began vaccinating health care workers and young children on Monday. It’s not a moment too soon: The Centers for Disease Control and Prevention have announced that flu is now widespread in most of the United States. The infections are “overwhelmingly” pandemic H1N1 influenza, commonly known as swine flu. The flu season generally lasts well into May, so many months of uncertainties lie ahead [Los Angeles Times].
CDC director Thomas Frieden says that so far, vaccine “demand is outstripping supply, but we expect that fairly soon supply will be outstripping demand.” … Over the next two to three weeks, tens of millions of additional doses will become available [Los Angeles Times]. The injectable form of the vaccine will be ready for distribution next week.
Now that the vaccines have been successfully hustled off the assembly lines, the next daunting challenge for public health officials is convincing people to go get vaccinated. Myths and worries about the vaccine have spread on talk radio and anti-vaccine Web sites [The New York Times], with even celebrities like Bill Maher unhelpfully chiming in via Twitter. At a Tuesday press conference, Frieden strongly refuted one of the most commonly voiced concerns: that in rushing the vaccine through production, it wasn’t properly tested for safety.
A team of researchers recently discovered that Tamiflu, the leading flu-fighting drug, is accumulating in rivers downstream from sewage-treatment plants in Kyoto. How is this possible? Tamiflu’s active ingredient, oseltamivir phosphate, is excreted in the urine of people taking the medication. Concerns are now building that birds, which are natural influenza carriers, are being exposed to waterborne residues of Tamiflu’s active form and might develop and spread drug-resistant strains of seasonal and avian flu [Science News]. The resistant virus strains would be of the conventional seasonal or avian flu variety, not the H1N1 swine flu strain that is currently pandemic in humans. Seasonal flu, however, kills thousands of people each year.
Study coauthor Gopal Ghosh explains that the team took measurements during normal flu season, and found concentrations that seem “high enough to lead to antiviral resistance in waterfowl” [Science News]. Computer models show that oseltamivir phosphate will survive sewage treatment, but it should break down when exposed to sunlight and its concentrations should decrease by half every three weeks. The high concentrations were found during a period where 1,738 flu cases were reported in Kyoto, according to the study, published in the journal Environmental Health Perspectives. In the United States, Tamiflu is only recommended for the very sick or those with compromised immune system, while Japan has a more liberal policy.
80beats: Fish Are on Antidepressants, Allergy Meds, and a Host of Other Pharmaceuticals
Discoblog: Prozac Ocean: Fish Absorb Our Drugs, and Suffer for It
Discoblog: What You Need to Know About Drug Water
DISCOVER: Drugs, From Development to Testing to Marketing to Drinking Water
DISCOVER: Italians Find Drugs in River Sewage
Image: flickr / law_keven
As the nation prepares for a massive vaccination campaign to protect the most vulnerable people from the swine flu virus, scientists are preparing to combat public fears over the vaccine. Scientists worry that the public (or at least the activists who are convinced, against all scientific evidence, that vaccines cause autism and other diseases) will misinterpret coincidental deaths as side effects of the vaccine.
As soon as swine flu vaccinations start next month, some people getting them will drop dead of heart attacks or strokes, some children will have seizures and some pregnant women will miscarry…. “There are about 2,400 miscarriages a day in the U.S…. You’ll see things that would have happened anyway. But the vaccine doesn’t cause miscarriages. It also doesn’t cause auto accidents, but they happen” [The New York Times], says Jay Butler of the Centers for Disease Control and Prevention.
The CDC is particularly focused on convincing pregnant women of the vaccine’s safety. A recent study in The Lancet reported strikingly high rates of death and of complications like pneumonia in pregnant women with H1N1 influenza. Pregnancy meant a fourfold risk of hospitalization, sometimes with a tragic outcome [The New York Times]. Experts note that pregnant women often avoid medications out of fear of harming the fetus, but say that these women should be among the first to get vaccinated for swine flu, and should swiftly start antiviral medications if they come down with the virus. To date, the virus has killed 28 pregnant women in the United States.
Now that the first vaccines against swine flu are about to become available, scientists are busy working out the details of how the vaccines can best be administered. Researchers already knew that a single dose was sufficient to protect adults, and they’ve now found that one shot works for teenagers and children over the age of 10. But young children who have never had the flu or a flu shot, however, need two doses, they said…. Children 6 months to 9 years old received some protection from one shot, but not enough, so health officials will recommend that they get two shots 21 days apart [The New York Times].
At least 6 million doses of vaccine will be available the first week of October, federal health officials announced today, and this first batch is in the form of a nasal spray called FluMist. The intranasal vaccine has not been approved for children younger than 2, adults older than 49 or pregnant women, so it may go primarily to healthcare providers [Los Angeles Times]. Injectable vaccines should make it to doctors’ offices a week or two later.
New York State has taken the drastic step of requiring that all hospital, home health and hospice workers get the swine flu vaccine. Experts say the mandatory vaccination will protect not just the workers, but also their patients. But some workers are upset by the edict. Health workers’ union official Joel Shufro says the unions do not oppose vaccination “but we oppose a mandatory program,” he said. “This is: ‘You don’t get the shot, you’re fired’” [The New York Times].
The big news in swine flu this week: Vaccines from four drugmakers have been approved for use in the United States, and with the companies’ production lines cranking there will be plenty to go around. Clinical trials have also shown that a single shot is enough to create a strong immune response, which means stockpiles will go twice as far as they would have if two shots were necessary. Said U.S. Health Secretary Kathleen Sebelius: “There will be vaccines for everyone.” … The first doses should be available within the next four weeks, according to the FDA [Reuters].
But as flu season is already ramping up, some people are wondering what they can do to protect themselves until the vaccine is available. One enterprising reporter decided to find out what her daily routine would be like if she wore a paper jumpsuit, mask, goggles, and gloves provided by a company called Flu Armor. But experts are reminding the public that face masks, which became a symbol of the initial outbreak in Mexico last spring, are really designed to stop the spread of droplets from the person wearing the mask, not to protect the wearer from viruses [Los Angeles Times].
The most effective preventive measure is also a simple one: wash your hands with soap often, or use an alcohol-based hand sanitizer. Experts note that hand-to-face contact has a surprising impact on health. Germs can enter the body through breaks in the skin or through the membranes of the eyes, mouth and nose [The New York Times].