Overview
of Information on H1N1 influenza (Swine Flu)
The
swine flu was declared a global pandemic
on June 11, 2009, in the first designation by the World Health Organization of
a worldwide pandemic in 41 years. The
heightened alert came after an emergency meeting with flu experts in Geneva that
convened after a sharp rise in cases in Australia, and rising numbers in Britain,
Japan, Chile and elsewhere. But
the pandemic is "moderate" in severity, according to Margaret Chan,
the organization's director general, with the overwhelming majority of patients
experiencing only mild symptoms and a full recovery, often in the absence of any
medical treatment. The
virus is now widespread in the United States and continues to spread from one
country to another, and the W.H.O. has recommended against attempts to contain
it, arguing that it has already spread too widely. Many
experts have been questioning whether the new strain of flu is deadlier than normal
seasonal flu. But as the disease moves into the developing world, where rates
of chronic disease are high and health systems typically poor, Dr. Chan said,
"it is prudent to anticipate a bleaker picture." A number of countries,
particularly China, had been taking rigorous quarantine measures against Mexicans
or people who had traveled to Mexico. ORIGINS The
origins of the flu, also known as the A
(H1N1) strain, are unclear; it seems to have first surfaced in Mexico or the
southwestern United States. The outbreak was first identified in Mexico, where
health authorities became alarmed over the death of several young and healthy
adults. Mexico's
first known case, which was later confirmed, was from Perote, in Veracruz State,
according to Health Minister José Ángel Córdova. The case
involved a 5-year-old boy named Edgar, who recovered. On
April 30, the W.H.O. said that it would stop referring to the virus as swine flu,
after a number of countries banned pork imports or slaughtered pig hers, opting
for the more clinical sounding A(H1N1). There is not yet any genetic proof that
this strain of influenza ever came from a pig. The virus has pieces of North American
swine, bird and human flus and of Eurasian swine flu, according to the C.D.C. SYMPTOMS
AND TRANSMISSION The
most common method of transmission is airborne, and it is also possible to become
infected by touching a surface with the virus on it and then touching one's mouth
or nose. The C.D.C. has advised people to wash their hands frequently, and also
to avoid surfaces that might be contaminated. 
Most
people lack immunity to this new virus. But in one sign that the disease may not
be as serious as feared, Mexican Health Minister José Ángel Córdova
said that the flu, influenza A(H1N1), appears only slightly more contagious than
the seasonal flu, less than thought. Each sufferer is, on average, passing the
disease along to between 1.4 and 1.8 people, a statistic known as the R factor. Among
the many unknowns, perhaps the biggest is how deadly A(H1N1) will be. Even
a flu with a low percentage of lethality can cause a large number of deaths if
vast swaths of populations are infected -- seasonal flus kill an estimated 250,000
to 500,000 people worldwide each year. This outbreak has caused concern because
officials have never seen this particular strain of the flu passing among humans
before, said Dr. Anthony S. Fauci, director of the National Institute of Allergy
and Infectious Diseases. PANDEMIC
VIRUSES Some
scientists are arguing that the H1N1 flu lacks some of the genetic earmarks of
a highly lethal strain. However, as it circulates in humans, especially in the
Southern Hemisphere winter, the virus could pick up dangerous human flu genes. Much
of the intiial worry concerned the ages of the victims in Mexico. Unlike typical
flu seasons, when infants and the aged are the most vulnerable, none of the initial
deaths in Mexico were in people older than 60 or younger than 3, a spokeswoman
with the World Health Organization said. Pandemic
flus -- like the 1918 flu and outbreaks in 1957 and 1968 -- often strike young,
healthy people the hardest. This flu strain it appears to infect an unusually
high percentage of young people. The median age of patients is 17. The
sudden detection of the new virus occurred just as scientists were focusing on
behavioral changes observed in another virus, the A(H5N1) bird flu strain, in
Egypt. Virologists have tracked the avian virus since its discovery in Hong Kong
in 1997. The
avian flu has kept world health authorities anxious for years because 257 of the
421 people who contracted it died, or 61 percent. But it has shown very little
ability to pass from person to person, mainly infecting poultry, and some experts
have suggested that there may be something about the H5N1 virus that makes it
inherently less transmissible among people. As
a benchmark, the deadliest influenza pandemic in the past century, the Spanish
influenza of 1918 to 1919, had an estimated mortality rate of around 2.5 percent
but killed tens of millions of people because it spread so widely. Many of those
lives would have been saved if anti-flu drugs, antibiotics and mechanical ventilators
had existed. The
virus that caused widespread panic in Asia in 2003, SARS -- severe acute respiratory
syndrome -- is both easily spread and virulent. In the 2003 outbreak in Hong Kong,
it killed 299 of the 1,755 people infected, or 17 percent. RESPONSE
FROM PUBLIC HEALTH OFFICIALS Health
authorities around the world took extraordinary measures to combat the epidemic
and mitigate its effects as it quickly spread across the globe in late April and
early May 2009. The W.H.O. raised its alert level on H1N1 flu to Phase 5 on April
29, based on the flu's continuing spread in the United States and Mexico. It is
the first time that Phase 5, the next-to-highest level, has been declared since
the W.H.O. system was introduced in 2005 in response to the avian influenza crisis. Phase
6 means a pandemic is underway. A W.H.O. spokesman, Dick Thompson, said in mid-May
that there was still not enough evidence to conclude that the disease was spreading
in a sustained way outside of North America, which would be required for the organization
to raise its pandemic alert level to 6. Britain,
Japan and other nations have urged the W.H.O. to change the way it decides to
declare a pandemic - saying the agency must consider how deadly the virus is,
not just how fast it is spreading. There has been concern that by raising the
global alert level to 5, the United Nations health agency had unduly raised alarm. International
health experts, who say the epidemic will spread regardless of attempts at containment,
advised against closing borders. They encouraged governments to focus on mitigating
the disease's spread through public health measures. For
the W.H.O., the approach is an about-face from the strategy that has contained
the H5N1 avian flu, which has caused fewer than 300 deaths. The avian flu was
contained in 1997 by killing every chicken in Hong Kong, and later cases have
been met with aggressive efforts at culling nearby birds and vaccinating poultry
in a ring around them. Many
countries ignored the advice against containment efforts, leading to a welter
of bans, advisories and alerts on certain pork products. In China, authorities
quarantined Mexican travelers in hospitals and hotels - many of whom had shown
no sign of illness. Mexico
City, one of the world's largest cities, closed schools, gyms, swimming pools,
restaurants and movie theaters. Mexicans donned masks for protection outdoors.
Mexican officials said on May 4 that they would lower the public alert against
the virus and allow most of the nation's businesses to reopen. THE
VIRUS IN NEW YORK CITY In
the early days of the swine flu outbreak in the United States the cases were concentrated
in New York City. The city's first reported cases were diagnosed in late April
2009 among teenagers from a high school in Queens who had traveled to Mexico for
spring break. In
the following weeks the public schools seemed to become an incubator for the flu,
and numerous facilities were closed. But after an early period of high alert when
the virus was first detected, officials toned down their concern. On
May 17, Mitchell Wiener, the assistant principal at a school in Queens, became
the first person to die from the virus in New York. Health officials said that
the death was not surprising, since even in a normal flu season, thousands of
victims die of complications from the disease, and because he had a history of
medical problems that may have put him at greater risk. Some
parents, school staff and teachers' union officials wondered whether the city
was moving too slowly to close schools with high absenteeism. FLU
DRUGS Federal
officials said it would take until January, or late November at the earliest,
to make enough vaccine to protect all Americans from a possible epidemic of the
H1N1 flu. And beyond this nation and a few other countries that also make vaccines,
it could take years to produce enough vaccine to satisfy global demand, health
experts said. Although
the production of flu vaccine has increased, it may not fast enough to avert death
and illness if the virus starts spreading widely and becomes more virulent, some
experts said. Federal officials have not yet decided whether the flu threat warrants
the production of more vaccine, but they are taking the initial steps. The problem
is that production of a vaccine might interfere with the manufacture of seasonal
flu vaccine for next winter. There
have been no immediate signs of any drug shortages. Roche, the Swiss maker of
Tamiflu, said on May 1 that the W.H.O. has enough stockpiled to treat up to 5
million people, on top of millions more doses held by governments. Tamiflu has
been stockpiled for years by governments, companies and health authorities. Still,
manufacturers were increasing production and expressed anxiety that shortages
could develop if governments placed huge orders. Mexican health officials said
the virus responded to Tamiflu and other antiviral medications if administered
shortly after the onset of flu. 6/23/09 Source
New
York Times. June 21, 2009.
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