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zoom RSS ブタインフルエンザ重症型への警告/新型インフルエンザH1N1 WHO

<<   作成日時 : 2009/08/30 13:04   >>

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 WHOは金曜日、健康な若者にたいして直接肺に障害を起こし高価な入院治療が必要となるブタインフルエンザの重症型が報告されていることを公表した。
 いくつかの国では、新型H1N1パンデミックウイルスの感染により15%以上の人が入院治療を必要とし、すでに負担がかかりすぎている医療体制にさらなる負担を強いるものだと、WHOはパンデミック最新情報として明らかにした。南半球の冬季にあたり、いくつかの国では集中治療の必要性が公共医療サービス上の最も大きな負担であるとみている。重症例の急増に対して集中治療室の需要増加を予期して準備する必要がある。
 すでに日本で流行レベルに達し、今年の長いインフルエンザ・シーズンが早くも開始された可能性があり、熱帯地域でも悪化していると、WHOは報告している。
 季節性インフルエンザではめったに見られない健康な若者での重症型の発症がかなりの数で報告されている。患者の肺が直接感染し重症の呼吸障害を起こす。救命のために長期間、高価なICU集中治療室入院を必要とし、非常に専門的で濃厚な治療が求められる。
 少数民族や先住民の人々がH1N1重症化のリスクがいくつかの研究で4-5倍も高い。理由は完全にはわかっていないが、生活水準が低く、喘息・糖尿病・高血圧などの割合が高く健康管理が不充分なことによる可能性がある。
 WHOはパンデミックの第2波に準備するよう北半球の国々にアドバイスした。熱帯地域の国ではパンデミックウイルスの感染が遅れてやってくるので感染拡大に準備するようにという。
 毎年季節性インフルエンザは人口の5-20%に感染し、全世界で25-50万人が死亡している。新型H1N1ウイルスへの免疫はほとんどの人が持っていないので人口の1/3以上が感染するだろう。季節性インフルエンザでは主に高齢者で重症化するが、新型は若年者が感染し、若年性人や子どもで重症者は死者が出るだろう。さらに、喘息などの呼吸器疾患、心血管系疾患、糖尿病、免疫不全などの病気がある場合は重症化しやすい。
 WHOは、2億3000万人以上が喘息を持ち、2億3000万以上が糖尿病であると概算している。肥満も感染症悪化のリスクとなる。
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WHO Warns of Severe Form of Swine Flu
Doctors Reporting Form of the Disease That Rapidly Affects the Lungs
By Maggie Fox, Health and Science Editor
August 28, 2009
http://abcnews.go.com/Health/SwineFluNews/wireStory?id=8436490

画像A nurse carries test for A (H1N1) influenza on a woman on August 21, 2009 at the Noumea flu treatment center.Doctors are reporting a severe form of swine flu that goes straight to the lungs, causing severe illness in otherwise healthy young people and requiring expensive hospital treatment, the World Health Organization said on Friday. Collapse
(MARC LE CHELARD/AFP/Getty Images)

WASHINGTON (Reuters) - Doctors are reporting a severe form of swine flu that goes straight to the lungs, causing severe illness in otherwise healthy young people and requiring expensive hospital treatment, the World Health Organization said on Friday.

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, signaling 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."

"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.

(Editing by Mohammad Zargham)

Copyright 2009 Reuters News Service. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

----------------------------------------------------
Preparing for the second wave: lessons from current outbreaks
Pandemic (H1N1) 2009 briefing note 9
http://www.who.int/csr/disease/swineflu/notes/h1n1_second_wave_20090828/en/index.html

28 AUGUST 2009 | GENEVA -- Monitoring of outbreaks from different parts of the world provides sufficient information to make some tentative conclusions about how the influenza pandemic might evolve in the coming months.

WHO is 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.

Countries in temperate parts of the southern hemisphere should remain vigilant. As experience has shown, localized “hot spots” of increasing transmission can continue to occur even when the pandemic has peaked at the national level.
H1N1 now the dominant virus strain

Evidence from multiple outbreak sites demonstrates that the H1N1 pandemic virus has rapidly established itself and is now the dominant influenza strain in most parts of the world. The pandemic will persist in the coming months as the virus continues to move through susceptible populations.

Close monitoring of viruses by a WHO network of laboratories shows that viruses from all outbreaks remain virtually identical. Studies have detected no signs that the virus has mutated to a more virulent or lethal form.

Likewise, the clinical picture of pandemic influenza is largely consistent across all countries. The overwhelming majority of patients continue to experience mild illness. Although the virus can cause very severe and fatal illness, also in young and healthy people, the number of such cases remains small.
Large populations susceptible to infection

While these trends are encouraging, large numbers of people in all countries remain susceptible to infection. Even if the current pattern of usually mild illness continues, the impact of the pandemic during the second wave could worsen as larger numbers of people become infected.

Larger numbers of severely ill patients requiring intensive care are likely to be the most urgent burden on health services, creating pressures that could overwhelm intensive care units and possibly disrupt the provision of care for other diseases.
Monitoring for drug resistance

At present, only a handful of pandemic viruses resistant to oseltamivir have been detected worldwide, despite the administration of many millions of treatment courses of antiviral drugs. All of these cases have been extensively investigated, and no instances of onward transmission of drug-resistant virus have been documented to date. Intense monitoring continues, also through the WHO network of laboratories.
Not the same as seasonal influenza

Current evidence points to some important differences between patterns of illness reported during the pandemic and those seen during seasonal epidemics of influenza.

The age groups affected by the pandemic are generally younger. This is true for those most frequently infected, and especially so for those experiencing severe or fatal illness.

To date, most severe cases and deaths have occurred in adults under the age of 50 years, with deaths in the elderly comparatively rare. This age distribution is in stark contrast with seasonal influenza, where around 90% of severe and fatal cases occur in people 65 years of age or older.
Severe respiratory failure

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. 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.

During the winter season in the southern hemisphere, several countries have viewed the need for intensive care as the greatest burden on health services. Some cities in these countries report that nearly 15 percent of hospitalized cases have required intensive care.

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.
Vulnerable groups

An increased risk during pregnancy is now consistently well-documented across countries. This risk takes on added significance for a virus, like this one, that preferentially infects younger people.

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.

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.

Obesity, which is frequently present in severe and fatal cases, is now a global epidemic. WHO estimates that, worldwide, more than 230 million people suffer from asthma, and more than 220 million people have diabetes.

Moreover, conditions such as asthma and diabetes are not usually considered killer diseases, especially in children and young adults. Young deaths from such conditions, precipitated by infection with the H1N1 virus, can be another dimension of the pandemic’s impact.
Higher risk of hospitalization and death

Several early studies show a higher risk of hospitalization and death among certain subgroups, including minority groups and indigenous populations. In some studies, the risk in these groups is four to five times higher than in the general population.

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.
Implications for the developing world

Such findings are likely to have growing relevance as the pandemic gains ground in the developing world, where many millions of people live under deprived conditions and have multiple health problems, with little access to basic health care.

As much current data about the pandemic come from wealthy and middle-income countries, the situation in developing countries will need to be very closely watched. The same virus that causes manageable disruption in affluent countries could have a devastating impact in many parts of the developing world.
Co-infection with HIV

The 2009 influenza pandemic is the first to occur since the emergence of HIV/AIDS. Early data from two countries suggest that people co-infected with H1N1 and HIV are not at increased risk of severe or fatal illness, provided these patients are receiving antiretroviral therapy. In most of these patients, illness caused by H1N1 has been mild, with full recovery.

If these preliminary findings are confirmed, this will be reassuring news for countries where infection with HIV is prevalent and treatment coverage with antiretroviral drugs is good.

On current estimates, around 33 million people are living with HIV/AIDS worldwide. Of these, WHO estimates that around 4 million were receiving antiretroviral therapy at the end of 2008.


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