Some countries are reporting that as many as 15 percent of patients infected with the new H1N1 pandemic virus need hospital care, further straining already overburdened healthcare systems, WHO said in an update on the pandemic. "During the winter season in the southern hemisphere, several countries have viewed the need for intensive care as the greatest burden on health services," it said. "Preparedness measures need to anticipate this increased demand on intensive care units, which could be overwhelmed by a sudden surge in the number of severe cases."

Earlier, WHO reported that H1N1 had reached epidemic levels in Japan, signalling an early start to what may be a long influenza season this year, and that it was also worsening in tropical regions. "Perhaps most significantly, clinicians from around the world are reporting a very severe form of disease, also in young and otherwise healthy people, which is rarely seen during seasonal influenza infections," WHO said. "In these patients, the virus directly infects the lung, causing severe respiratory failure. Saving these lives depends on highly specialized and demanding care in intensive care units, usually with long and costly stays."

Minorities at Risk

Minority groups and indigenous populations may also have a higher risk of being severely ill with H1N1. "In some studies, the risk in these groups is four to five times higher than in the general population," WHO said. "Although the reasons are not fully understood, possible explanations include lower standards of living and poor overall health status, including a high prevalence of conditions such as asthma, diabetes and hypertension."

WHO said it was advising countries in the Northern Hemisphere to prepare for a second wave of pandemic spread. "Countries with tropical climates, where the pandemic virus arrived later than elsewhere, also need to prepare for an increasing number of cases," it said.

Every year, seasonal flu infects between 5 percent and 20 percent of a given population and kills between 250,000 and 500,000 people globally. Because hardly anyone has immunity to the new H1N1 virus, experts believe it will infect far more people than usual, as much as a third of the population.

It also disproportionately affects younger people, unlike seasonal flu which mainly burdens the elderly, and thus may cause more severe illness and deaths among young adults and children than seasonal flu does. "Data continue to show that certain medical conditions increase the risk of severe and fatal illness. These include respiratory disease, notably asthma, cardiovascular disease, diabetes and immunosuppression," WHO said. "When anticipating the impact of the pandemic as more people become infected, health officials need to be aware that many of these predisposing conditions have become much more widespread in recent decades, thus increasing the pool of vulnerable people." WHO estimates that more than 230 million people globally have asthma, and more than 220 million have diabetes. Obesity may also worsen the risk of severe infection, WHO said.

The good news -- people infected with AIDS virus do not seem to be at special risk from H1N1, WHO said.

Medclincian R.N.

One of the biggest fears has been that the virus, which first appeared in April in the U.S. and Mexico and which people don't have any built-up immunity to, might mutate into an even more dangerous form. Health officials have been keeping a close watch on the Southern Hemisphere, which is in its winter season now, to see what form of the virus is likely to travel north as fall comes to the U.S. and the rest of the Northern Hemisphere.

A new H1N1 virus (aka swine flu) mutation, a subtype strain named A/Sao Paulo/1454/H1N1, has been isolated in a 26-year-old patient in Brazil. With the new H1N1 mutation comes fear that the current pandemic swine flu virus will spread more rapidly, possibly to new hosts and, yet, it is unknown if such mutation will prove more deadly than the current A(H1N1) pandemic.

The genetic sequence of the new H1N1 virus subtype (A/Sao Paulo/1454/H1N1) was isolated by a virology team lead by Terezinha Maria de Paiva at the Instituto Adolfo Lutz, formerly named Adolf Lutz Bacteriolocial Insitute – the latter an outdated name in use by many news reports -- located in San Palo, Brazil. [This name clarification may be useful when conducting online research on the new influenza A virus.]

Discovered in a patient on Tuesday, the new H1N1 virus mutation includes alterations in the hemagglutinin protein. Hemagglutinin is one of the reasons that the influenza virus is so effective as the protein allows the virus to infect new hosts.

Why is the new H1N1 virus subtype and mutation important?

Every couple of decades, a new strain of influenza appears that is far more infectious, allowing it to spread rapidly -- including that which occurred during the 1918/1919 H1N1 pandemic, or Spanish flu, which killed a roughly estimated 50 million people and infected at least 500 million.

The newly identified H1N1 virus strain -- a mutation from the A(H1N1) swine flu pandemic isolate -- may or may not prove more lethal or infectious, but scientists are concerned and vaccine efforts continue.

Additionally, the Insituto Adolfo Lutz website reveals details on A/Sao Paulo/1454/H1N1 but the related Technical Note is written in Portuguese-Spanish requiring translation for most readers. An excerpt and translation instructions follow.

Photo (adaptation) of Hemagglutinin by TimVickers (Wikimedia)
"The structure and receptor binding properties of the 1918 influenza hemagglutinin"

Learn more about hemagglutinin and influenza at the RCSB Protein Data Bank and the multimedia exhibit at California Lutheran.
 

Excerpt from the Technical Note from Instituto Adolfo Lutz on a new type of influenza virus A (swine flu):

Human cases of respiratory infection caused by a new type of influenza virus A, subtype H1N1 were of porcine origin reported by the Center for Disease Control and Prevention from 21 April 2009. So far, the disease was detected in 73 countries, with 25.3 thousand confirmed cases, 139 of them fatal. The new virus presents a unique combination of gene segments that in the past had been reported between the influenza virus from swine or human origin.

In Chicago, the first case of human infection caused by the new strain was identified in a man of 26 years who presented the symptoms of flu to return from a trip to Mexico. The patient was hospitalized on April 24 at the Institute of Infectious Diseases Emilio Ribas and is fully recovered.

Respiratory secretion sample of this patient was subjected to molecular rt PCR methodology (§ reaà the polymerase chain in real time) with probe specific for the new subtype H1N1 by the team of molecular biologist Claudio Sacchi, and the result for the new viral subtype .

comment: sounds pretty mutation to me.