TUESDAY, Feb. 28 -- A new influenza A virus has been discovered in Guatemalan fruit bats, according to scientists at the U.S. Centers for Disease Control and Prevention.
Although the bat flu does not currently pose a threat to humans, the CDC team cautioned that more research is needed to determine if the virus could be a possible source of human flu.
"This is the first time an influenza virus has been identified in bats, but in its current form the virus is not a human health issue," study lead author Dr. Suxiang Tong, team leader of the Pathogen Discovery Program in the CDC's viral diseases division, said in a CDC news release. "The study is important because the research has identified a new animal species that may act as a source of flu viruses."
For the bat flu to affect humans, the investigators pointed out that it would have to swap genetic information with another flu virus, giving it some genetic properties of a human flu virus. This process, called reassortment, could potentially lead to a new flu capable of infecting humans.
The CDC study, published online Feb. 27 in the Proceedings of the National Academy of Sciences, noted that some initial research revealed that the bat flu genes are compatible with human flu viruses.
"Fortunately, initial laboratory testing suggests the new virus would need to undergo significant changes to become capable of infecting and spreading easily among humans," study co-author Dr. Ruben Donis, chief of the Molecular Virology and Vaccines Branch in the CDC's influenza division, explained in the news release. "A different animal -- such as a pig, horse or dog -- would need to be capable of being infected with both this new bat influenza virus and human influenza viruses for reassortment to occur."
The CDC said it is working with global disease experts to track animal flu viruses that could potentially affect people, such as H1N1, which caused a pandemic in 2009.
-- Mary Elizabeth Dallas
SOURCE: U.S. Centers for Disease Control and Prevention, news release, Feb. 27, 2012
MONDAY, Feb. 27 -- Rapid diagnostic influenza tests provide an accurate diagnosis, and their use during flu season could lead to earlier treatment for patients and help prevent the spread of the illness, two new studies suggest.
The 2012 flu season is just beginning and, despite the late start, is expected to sicken up to 5 million people worldwide, experts say. Most patients will recover, but up to 500,000 will die, with the youngest and oldest patients most vulnerable.
The two studies, published online in the Feb. 28 issue of the journal Annals of Internal Medicine, highlight the importance of prompt diagnosis and treatment.
Viral cultures are accurate in diagnosing flu but can take up to 10 days to provide results. Newer reverse transcriptase-polymerase chain reaction (RT-PCR) tests provide results much sooner but are expensive and require specialized equipment.
Rapid influenza diagnostic tests, which are inexpensive and easy to use in a doctor's office, are another option, but little was known about their accuracy.
In one study, researchers reviewed 159 published articles and found that rapid influenza diagnostic tests accurately diagnose flu, but are less accurate at ruling it out. This means that patients with a negative result would require follow-up testing with a viral culture or RT-PCR, the researchers said in a journal news release.
They said their results suggest that rapid diagnostic tests would be useful in clinical practice, especially when treating children and other patients at risk for flu-related complications. This includes people over 65, pregnant women and those with chronic health conditions such as asthma.
For patients diagnosed with flu, doctors may decide to begin treatment with antiviral drugs.
In the second study, researchers reviewed 74 published studies and found that early treatment with antiviral drugs (within 48 hours) may confer more benefits than later treatment.
The researchers tested four commonly prescribed antivirals, and said oral oseltamivir and inhaled zanamivir appeared to shorten duration of flu symptoms compared to no treatment.
-- Robert Preidt
SOURCE: Annals of Internal Medicine, news release, Feb. 24, 2012
THURSDAY, Feb. 23 -- It took a long time to get started, but this winter's flu season is finally here, say experts at the U.S. Centers for Disease Control and Prevention.
They report that flu activity picked up in the past couple of weeks, making this the latest start to any influenza season since 1987-1988. Lab-confirmed cases of influenza have now been spotted in all 50 states, but the weekly percentage of lab-tested respiratory specimens did not exceed 10 percent -- the threshold for declaring that a flu season has begun -- until Feb. 4, the CDC report found.
Why this year's flu season is starting so late is most likely the result of a complex set of circumstances that remain unclear, said Dr. Joseph Bresee, chief of the CDC's epidemiology and prevention branch in the CDC's influenza division.
"It's probably related to several things and probably other things we don't understand well," Bresee said. "Mostly, it's related probably to the fact that flu is unpredictable. There are a lot of things about flu we don't understand."
The flu update was published in the Feb. 24 issue of Morbidity and Mortality Weekly Report, a CDC publication.
In most flu seasons, there are some 200,000 hospitalizations and 36,000 deaths from flu complications, according to the CDC.
However, so far hospitalizations for flu have remained below epidemic levels -- just one hospitalization per 100,000 people, compared to nearly 22 per 100,000 people in the 2010-2011 season.
There have been reports of three infant deaths in the United States so far from flu complications, much lower than the total of 122 flu-linked infant deaths seen last season and the 348 infant deaths observed during the 2009-2010 H1N1 pandemic.
Only one state, California, is reporting "widespread" influenza cases, the CDC added.
This year, three flu strains are circulating: Influenza A (H3N2) viruses (which has predominated this season), influenza A H1N1 (the "swine flu" strain) and influenza B.
These strains haven't evolved or mutated and are the same strains that have been circulating for the past few years, Bresee said. They also match the strains included in the flu vaccine over the past two years.
Good vaccination coverage may be playing a role in flu's relative inactivity this year. "We have had very high vaccination rates in the last couple of years, and that probably dampens the amount of flu," Bresee said. "The underlying immunity of the population is probably higher than it usually is to the viruses we are seeing."
"But there are a lot of things that play into it, most of which we don't understand but are thankful for," Bresee added.
And does the late arrival of the flu herald its early departure this year? "It's hard to know if the late start to the flu season means that it will go on longer," Bresee said.
"We are getting a late start, but we don't know when the peak will be, if it will be a lower peak or a normal peak," he said. "We always can predict after the year is over, sadly."
"So, the good news is that because of the late start, folks who haven't been vaccinated still have a chance to do so," Bresee said. "Since we are seeing a late start, most communities have the opportunity to get vaccinated ahead of the flu season."
Everyone aged 6 months and older should get a flu shot, according to the CDC.
SOURCES: Joseph Bresee, M.D., chief, epidemiology and prevention branch, influenza division, U.S. Centers for Disease Control and Prevention; Feb. 24, 2012, Morbidity and Mortality Weekly Report
THURSDAY, Feb. 23 -- The avian flu, which killed almost 60 percent of those known to be infected, actually struck many more people worldwide but didn't make them very sick, a new analysis finds.
The actual fatality rate of the H5N1 flu strain, therefore, is probably less than 60 percent considering that millions of people may have been infected over the past eight years, the researchers report.
The analysis results confirm earlier findings, said one expert, Dr. Marc Siegel, an associate professor of medicine at New York University. It's still not clear how fatal the strain actually is, but the research "emphasizes that H5N1 is not as deadly in humans as is being proposed by some people," said Siegel, author of Bird Flu: Everything You Need to Know About the Next Pandemic.
Siegel added that he doesn't think "this particular virus is going to mutate to go easily from human to human. That's extremely unlikely."
Scientists and public health officials have been sounding the alarm for years about the potential that the avian flu strain called H5N1 could become a major threat to humans. As of last December, the World Health Organization (WHO) reported a total of 573 cases since 2003; of those, 59 percent died.
Fears about the strain are so intense that a controversy erupted this year over whether scientists might help bioterrorists by publishing details about their research into bird flu. The WHO agreed last week to allow the research, which examines a mutated and more contagious form of bird flu, to be published.
In the new report, researchers from Mount Sinai School of Medicine in New York City launched a combined analysis of 20 studies that examined blood test results from than 12,500 people. They found that 1 percent to 2 percent of them had signs that they'd been infected with the H5N1 infection. Most of those said they hadn't recently had cold or fever symptoms.
The research suggests that few people are being infected by the strain, Siegel said. It would be unusual for this particular type of flu to mutate in a dangerous way that could cause it to become contagious between people, he said.
Philip Alcabes, a professor of public health at City University of New York's School of Public Health at Hunter College, cautioned that the findings do show that the strain infects people more easily than previously thought.
"Does this mean H5N1 is more or less of a threat to human health? Really, the report changes nothing in that regard -- because the public health concern about avian flu is about the possibility of future change in the virus-human relationship. With this study we know a little more about the present virus-human relationship -- but we still don't have a crystal ball," Alcabes said.
"So it remains important to understand how animal viruses, including H5N1 and others, circulate among animals and how they migrate to human populations," added Alcabes, who was not involved in the new study.
The analysis appears in the Feb. 23 online issue of Science.
SOURCES: Marc Siegel, M.D., associate professor, medicine, New York University,New York City; Philip Alcabes, Ph.D., professor, public health, City University of New York's School of Public Health, Hunter College, New York City; Feb. 23, 2012, Science, online
TUESDAY, Feb. 21 -- Giving flu shots to pregnant women seems to reduce their risk of having a baby that is small for its gestational age, a new study has found.
Babies who are small for their gestational age have an increased risk of health problems and other issues throughout their lives.
The study included 340 pregnant women in Bangladesh who were divided into two groups -- 170 who received the flu vaccine and 170 who received a different vaccine that does not protect against the flu. All of the women were in their third trimester.
When the seasonal influenza virus was circulating in the population, the flu vaccine group had fewer babies who were small for their gestational age than the other group -- about 26 percent versus 45 percent.
The percentage of small-for-gestational-age births was similar in both groups when the influenza virus was dormant, according to the study published Feb. 21 in CMAJ (Canadian Medical Association Journal).
When the influenza virus was circulating, the mean birth weight was 7 pounds in the flu vaccine group and 6.6 pounds in the group that didn't get flu shots, the investigators found.
"Our data suggest that the prevention of infection with seasonal influenza in pregnant women by vaccination can influence fetal growth," Dr. Mark Steinhoff, of Cincinnati Children's Hospital Medical Center in Ohio, and colleagues wrote in their report.
If further research supports these findings, adding a flu vaccine to routine vaccinations during pregnancy could help give children a better start in life, the study authors suggested in a journal news release.
-- Robert Preidt
SOURCE: CMAJ (Canadian Medical Association Journal), news release, Feb. 21, 2012
SATURDAY, Feb. 18 -- Research on a mutated, more contagious form of the bird flu virus can be published in full, the World Health Organization announced Friday, despite concerns that bioterrorists could use the information to start a pandemic.
The decision came during a special meeting of 22 bird flu experts in Geneva that was convened by the WHO to discuss the "urgent issues" that have swirled around possible publication of the two bird flu studies since last November, The New York Times reported Saturday.
Most of those at the meeting felt that any theoretical terrorist risk was outweighed by the "real and present danger" of similar flu virus mutations occurring naturally in the wild, and by the need for the scientific community to share information that could help identify exactly when the virus might be developing the ability to spread more easily, Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, told the Times. Fauci represented the United States at the meeting.
"The group consensus was that it was much more important to get this information to scientists in an easy way to allow them to work on the problem for the good of public health," Fauci said. "It was not unanimous, but a very strong consensus."
However, Fauci added, the United States was not part of that consensus. U.S. bio-security chiefs had urged last November that critical specifics of the papers remain unpublished.
Although the bird flu virus, known as H5N1, rarely infects people, it appears to be highly lethal when it does. Of about 600 known cases, more than half have been fatal. If the virus were able to spread more easily from birds to humans, experts have estimated that millions of people could die after being infected.
The two studies at the center of the debate were to be published in the journals Science and Nature late last year. The papers, which were funded by the U.S. National Institutes of Health, describe how the H5N1 virus could mutate relatively easily into a strain that could spread rapidly among humans. The research was done by scientists at the University of Wisconsin and in the Netherlands.
The editors of both journals said they plan to publish the papers in full at a future date.
"Discussions at the WHO meeting made it clear how ineffective redaction and restricted distribution would be for the Nature paper. It also underlined how beneficial publication of the full paper could be. So, that is how we intend to proceed," Dr. Philip Campbell, editor-in-chief of Nature, said in a statement. "As was expressed at the WHO meeting, there is a need first to explore how best to communicate the issues of publication to a concerned public, and to review safety assurance of labs who would act on this publication. I fully support the WHO's further efforts in this regard."
Speaking at a scientific meeting in Vancouver, Science editor-in-chief Bruce Alberts had this to say about the WHO decision: "So, my reading is that both Nature and Science are to wait until we get some further information from the WHO and other authorities of when, in fact, we are to publish the full manuscript."
Before the two studies can be published, the experts at the WHO meeting said that security assessments must be made, the Sydney Morning Herald reported.
Another meeting on the remaining issues will be held at a future date, the WHO said in a statement.
The scientists behind the research had agreed on Jan. 20 to honor a 60-day moratorium on further studies, the Herald reported, but that deadline will now be extended for an unspecified time to allow for a wider examination of the risks and for public discussion.
-- HealthDay staff
SOURCES: Feb. 18, 2012, The New York Times; Feb. 18, 2012, Sydney Morning Herald