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Concerns Grow Over Possible
H1N1-H5N1 Reassortment

Virologists and influenza authorities are becoming increasingly concerned that the 2009 A-H1N1 flu virus could “reassort” with the highly virulent H5N1 avian flu that’s still prevalent in parts of the world like China, and that a mutation could occur resulting in a new strain that has the lethality of H5N1 and the human transmissibility of A-H1N1.

The concerns have grown in the wake of revelations that mutations of the H1N1 flu virus had been found in Norway and elsewhere, leading experts to fear that it might just be a matter of time before there’s a reassortment of H1N1 and H5N1.

This comes as the World Health Organization (WHO) reported very high pandemic activity in Italy, Norway, the Republic of Moldova, the Russian Federation (Urals region), and Sweden.

Bulgaria, Denmark, Finland, Germany, Iceland, Ireland, Lithuania, Luxembourg, Poland, Portugal, the Russian Federation, Serbia, Turkey, and Ukraine also reported high pandemic activity.

Meanwhile, authorities said they believe the peak of the A-H1N1 pandemic's second wave hasn’t yet been reached in some parts of the world.

WHO said it’s keeping a "very careful” eye on the reported mutations in order to ascertain whether it is causing more severe illness diseases than the A-H1N1 virus.

"We really need to look at this very carefully to see whether it is in fact associated with severe cases," WHO spokesman Thomas Abraham told reporters. He said investigations by WHO's collaborating network of labs will be able to provide a better "understanding … about clinical features associated with the infection of this particular form of the virus."

Since it emerged, the A-H1N1 virus has constantly been mutating, authorities said. So far, most of these mutations have no clinical significance, but "occasionally we come across a virus that might have clinical significance,” Abraham said.

WHO warned that the H5N1 virus has emerged in poultry in Egypt, Indonesia, Thailand and Vietnam just as the H1N1 pandemic influenza continues its rampage across the world.

Not only does this place “those in direct contact with birds - usually rural folk and farm workers - at risk of catching the often-fatal disease,” but “the virus could undergo a process of ‘reassortment’ with another influenza virus and produce a completely new strain," WHO stated.

"The most obvious risk is of H5N1 combining with the pandemic ... [H1N1] virus, producing a flu virus that is as deadly as the former and as contagious as the latter."

That the two flu strain could merge, reassert, and produce a new hybrid influenza strain combining the worst elements of each of the viruses is a possibility that authorities have been worrying about ever since the spread of the A-H1N1 virus increased to pandemic level.

“We don’t know if this is possible, but we are certainly aware of the risk,” Dr. Shin Young-soo, WHO Regional Director for the Western Pacific,” told The Philippine Star. “We are on alert for this development.”

“Influenza viruses are unpredictable. In areas where [A-H1N1] is endemic, we and our partners and national governments are working to build surveillance systems to identify changes in the behavior of the virus,” Shin said. “We are also focusing on early-response capacity to reduce the potential threats to human health.”

Virologists told that “it’s very possible that the two flu strains could combine – this reassortment that we talk about – that could result in a mix of the two,” as one explained. “Of course, what we are concerned about is a mutation that contains the worst characteristics of the two viruses.”

Zhong Nanshan, director of the Guangzhou Institute of Respiratory Diseases in China's southern Guangdong province, warned that China has to be on high alert to any mutation and changes in the virulence of A-H1N1.

"This is something we need to monitor, the change, the mutation of the virus. This is why reporting of the death rate must be really transparent,” he told Reuters Television, adding, China, as you know, is different from other countries. Inside China, H5N1 has been existing for some time, so if there is really a reassortment between H1N1 and H5N1, it will be a disaster.”

WHO reported more than half-a-million laboratory confirmed cases of H1N1 worldwide in mid-November and close to 7,000 deaths, but stressed that in reality that figure is likely much, much higher.

Across Europe, the number of deaths related to pandemic H1N1 has doubled nearly every two weeks since mid-October.

US influenza and public health authorities agreed in interviews with They said the number of people infected in the US is undoubtedly “much higher” than the number of lab-confirmed cases given that most people who exhibit traditional H1N1 sickness symptoms are not tested to determine if they have H1N1 or a seasonal flu virus strain. reported last week that four patients at Duke University Medical Center in Durham, NC, at least five persons in a hospital in Wales, and a father in Quebec, Canada become infected with an apparently mutated strain of H1N1 that is resistant to Tamiflu (oseltamivir), the leading antiviral of choice to treat influenza in lieu of having a vaccine.

Meanwhile, Norwegian health authorities reported a potentially significant mutation in H1N1 that could be responsible for the severest symptoms in those infected by the strain - especially persons most at risk to the virus.

Authorities have been monitoring this development very carefully because of concerns that it, too, might become resistant to Tamiflu, and, possibly, other antivirals if they become as widely administered as oseltamivir.

Similar mutations have been reported elsewhere, but haven’t necessarily provoked a more virulent virus or proven to be less resistant to Tamiflu or other antivirals. Nevertheless, authorities increasingly are concerned.

Virologists have been worried for some time that antiviral-resistant influenza could become a serious problem during a pandemic, as antivirals are the primary defense against a pandemic until an effective vaccine is developed and distributed.

Additionally, the Centers for Disease Control and Prevention (CDC) reported during a November 25 press briefing that there's been "a worrisome spike in serious pneumococcal disease" linked to A-H1N1 had appeared in the CDC's Active Bacterial Core surveillance program that monitors infections at ten locations across the nation.

CDC reported a tripling of cases of severe, life-threatening bacterial infections at the monitoring sites.

* A full list of h1n1 vaccine ingredients, alerts and warnings.

Reference Sources:
December 3, 2009

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