Obesity emerges as risk factor in severe flu

WASHINGTON, 12 july 2009 - People who are obese but otherwise healthy may be at special risk of severe complications and death from the new H1N1 swine flu virus, U.S. researchers reported on Friday.

They described the cases of 10 patients at a Michigan hospital who were so ill they had to be put on ventilators. Three died. Nine of the 10 were obese, seven were severely obese, including two of the three who died.

The study, published in advance in the Centers for Disease Control and Prevention's weekly report on death and disease, also suggests doctors can safely double the usual dose of oseltamivir, Roche AG's antiviral drug sold under the Tamiflu brand name.

"What this suggests is that there can be severe complications associated with this virus infection, especially in severely obese patients," said CDC virus expert Dr. Tim Uyeki.

"And five of these patients had ... evidence of blood clots in the lungs. This has not been previously known to occur in patients with severe influenza virus infections," Uyeki said in a telephone interview.

Dr. Lena Napolitano of the University of Michigan Medical Center and colleagues studied the cases of 10 patients admitted to the university's intensive care unit with severe acute respiratory distress syndrome caused by infection with H1N1.

"Of the 10 patients, nine were obese (body mass index more than 30), including seven who were extremely obese (BMI more than 40)," they wrote in their report.

Their study was not designed to see if obesity or anything else poses a special risk factor for flu. But the researchers were surprised to see that seven of the 10 patients were extremely obese.

MULTIPLE ORGAN FAILURE

Nine had multiple organ failure, which can be seen in influenza, but five had blood clots in the lungs, and six had kidney failure.

None has fully recovered, the researchers said.

The H1N1 swine flu virus first emerged in Mexico in March and was spreading out of control in the United States by the time it was identified at the end of April. The World Health Organization declared a pandemic in June.

While it is causing moderate illness, all influenza viruses can be deadly and this one is no exception. It has killed close to 500 people globally, more than 200 in the United States alone.

However, the new virus has a slightly different pattern from seasonal flu -- it spreads in the summer months, attacks young adults and older children, and may affect the body slightly differently.

As with H5N1 avian influenza, which only rarely attacks people, patients seem to survive better if they get Tamiflu for longer than the usual five-day treatment course, Uyeki said.

"We don't know if it is necessary for a higher dose of the drug to be given to patients who are obese," he said.

"The high prevalence of obesity in this case series is striking," the CDC's commentary accompany the report reads.

"Whether obesity is an independent risk factor for severe complications of novel influenza A (H1N1) virus infection is unknown. Obesity has not been identified previously as a risk factor for severe complications of seasonal influenza."

Top flu expert warns of a swine flu-bird flu mix

MEXICO CITY, 09 may 2009 – Bird flu kills more than 60 percent of its human victims, but doesn't easily pass from person to person. Swine flu can be spread with a sneeze or handshake, but kills only a small fraction of the people it infects.

So what happens if they mix?

This is the scenario that has some scientists worried: The two viruses meet — possibly in Asia, where bird flu is endemic — and combine into a new bug that is both highly contagious and lethal and can spread around the world.

Scientists are unsure how likely this possibility is, but note that the new swine flu strain — a never-before-seen mixture of pig, human and bird viruses — has shown itself to be especially adept at snatching evolutionarily advantageous genetic material from other flu viruses.

"This particular virus seems to have this unique ability to pick up other genes," said leading virologist Dr. Robert Webster, whose team discovered an ancestor of the current flu virus at a North Carolina pig farm in 1998.

The current swine flu strain — known as H1N1 — has sickened more than 2,300 people in 24 countries. While people can catch bird flu from birds, the bird flu virus — H5N1 — does not easily jump from person to person. It has killed at least 258 people worldwide since it began to ravage poultry stocks in Asia in late 2003.

The World Health Organization reported two new human cases of bird flu on Wednesday. One patient is recovering in Egypt, while another died in Vietnam — a reminder that the H5N1 virus is far from gone.

"Do not drop the ball in monitoring H5N1," WHO Director-General Margaret Chan told a meeting of Asia's top health officials in Bangkok on Friday by video link. "We have no idea how H5N1 will behave under the pressure of a pandemic."

Experts have long feared that bird flu could mutate into a form that spreads easily among people. The past three flu pandemics — the 1918 Spanish flu, the 1957-58 Asian flu and the Hong Kong flu of 1968-69 — were all linked to birds, though some scientists believe pigs also played a role in 1918.

Webster, who works at St. Jude's Children's Research Hospital in Memphis, Tenn., said bird flu should be a worry now. Bird flu is endemic in parts of Asia and Africa, and cases of swine flu have already been confirmed in South Korea and Hong Kong.

"My great worry is that when this H1N1 virus gets into the epicenters for H5N1 in Indonesia, Egypt and China, we may have real problems," he told The Associated Press. "We have to watch what's going on very diligently now."

The U.S. Centers for Disease Control and Prevention are extraordinarily busy trying to understand the swine flu virus itself, and haven't had time to break off staff to look at the possibility of a swine flu-bird flu mix, spokesman Dave Daigle said.

Malik Peiris, a flu expert at Hong Kong University, said the more immediate worry is that swine flu will mix with regular flu viruses, as flu season begins in the Southern Hemisphere. It is unclear what such a combination would produce.

But he said there are indications that scenario is possible. Peiris noted that the swine flu virus jumped from a farmworker in Canada and infected about 220 pigs. The worker and the pigs recovered, but the incident showed how easily the virus can leap to a different species.

"It will get passed back to pigs and then probably go from pigs to humans," Peiris said. "So there would be opportunities for further reassortments to occur with viruses in pigs."

He said so far bird flu hasn't established itself in pigs — but that could change.

"H5N1 itself has not got established in pigs," he said. "If that were to happen and then these two viruses were both established in pigs in Asia, that would be quite a worrying scenario."

Michael Osterholm, an infectious disease specialist at the University of Minnesota who has advised the U.S. government on flu preparations, said while flu experts are discussing the scenario, he has yet to see specific evidence causing him to think it will happen.

"Everything with influenza is a huge guessing game because Mother Nature holds all the rules, and we don't even know what they are, so anything's possible," he said. "We don't have any evidence that this particular reassortment is that much more likely to pick up H5N1 than any other reassortment out there."

"We don't have to put these things together," he added. "This is not chocolate and peanut butter running into each other in the dark hallway."

But there is in fact discussion of putting them together — in a high-security laboratory — to see what a combination would look like, according to Webster. Similar tests have been done at the CDC mixing bird flu and seasonal human flu, resulting in a weak product, he said.

Daigle, the CDC spokesman, said the agency wants to look at the question in the future.

Webster has done groundbreaking work on both swine and bird flus in his 40-year career, and has followed the evolution of the current swine flu strain from a virus that sickened a handful of people who worked with North Carolina hogs into a bug that has spread from person to person around the world.

He is closely involved in the global effort to analyze what the virus might do next. It has killed 42 people in Mexico and two in Texas, but so far has not proven very deadly elsewhere, leading to some criticism that the World Health Organization's warnings of a potential pandemic have been overblown.

Webster said underestimating the swine flu virus would be a huge mistake.

"This H1N1 hasn't been overblown. It's a puppy, it's an infant, and it's growing," he said. "This virus has got the whole human population in the world to breed in — it's just happened. What we have to do is to watch it, and it may become a wimp and disappear, or it may become nasty."

Is it the flu, or just a sore throat?

CIBOLO, Texas, 02 may 2009 - When Hayden Henshaw came down with a new and worrying kind of influenza last month, he thought he had strep throat.

Henshaw, 18, and a senior at Steele High School northeast of San Antonio, was among the first U.S. patients to catch a new strain of the H1N1 swine flu virus, which has spread to 13 countries.

Within days Henshaw's fever spiked to 102 degrees Fahrenheit (39 degrees Celsius), and he was confined to bed.

"I couldn't lift my head up to get out of bed to take a drink. I was really sick," said Henshaw, who along with his family have been under voluntary quarantine for a week. "I couldn't stop coughing."

Mexico, the worst-hit country, has reported as many as 176 deaths from the virus. Cases have been reported around the world, mostly among travelers from Mexico, but they have been mild and most people recovered so far with little or no treatment.

The only death outside Mexico was a Mexican toddler visiting Texas.

Henshaw has recovered and is feeling better. But he's still confined to his two-story stucco house, along with his family, who were advised by local health officials to remain in "voluntary quarantine."

A "do not disturb" sign hangs from the front door and the phone has been turned off in an attempt to ward off an onslaught of calls from journalists. Inside, surgical masks hang from the doors and cans of Lysol and hand sanitizers are in plentiful supply.

Henshaw said he has grown tired of television and video games, and fears to venture onto the Internet because his class-mates are blaming him and two other flu-infected classmates for interrupting their lives.

"I tell them, hey, I didn't ask for any of this," he said. "I just want to leave."

"It's been a constant turmoil," said Patrick Henshaw, Hayden's father. "It's like we've done something wrong or something."

Mexican flu outbreak may be mild: CDC

WASHINGTON , 02 may 2009 - The outbreak of a new and worrying kind of influenza in Mexico may not be as severe as it first looked, with many mild cases that were not immediately noticed, U.S. health experts reported on Friday.

Health workers are rushing to get a fuller picture of the outbreak of H1N1 swine flu, which the World Health Organization fears could tip into a pandemic.

Mexico, the worst-hit country, has reported 176 deaths from the new strain of the H1N1 virus. Cases have been reported around the world, mostly among travelers from Mexico, but they have been mild and most people recovered so far with little or no treatment.

The only death outside Mexico was a Mexican toddler visiting Texas.

Experts have been struggling to explain why so many deaths in Mexico and nowhere else, but the CDC report suggests there is a simple explanation -- there are many cases in Mexico, most are mild, and just the bad ones have been seen so far.

"The clinical spectrum of swine-origin influenza A (H1N1) virus illness is not yet well characterized in Mexico. However, evidence suggests that swine-origin influenza A (H1N1) virus transmission is widespread and that less severe (uncomplicated) illness is common," the CDC said in a special report.

"To date, case-finding in Mexico has focused on patients seeking care in hospitals, and the selection of cases for laboratory testing has focused on patients with more severe disease. Therefore, a large number of undetected cases of illness might exist in persons seeking care in primary-care settings or not seeking care at all."

But more information is needed, the CDC team stressed. The CDC has sent test kits to Mexico that will help get a better picture of who is sick. It is difficult to know without special tests because respiratory diseases are so common and many infection look like flu.

"Additional investigations are needed urgently to evaluate the full clinical spectrum of disease in Mexico, the proportion of patients who have severe illness, and the extent of disease transmission," the CDC said.

Even garden-variety flu can be deadly, with seasonal influenza killing an estimated 250,000 to 500,000 people globally every year.