H1N1 Flu (Swine Flu)

Also called: Swine flu

Swine flu is an infection caused by a virus. It's named for a virus that pigs can get. People do not normally get swine flu, but human infections can and do happen. The virus is contagious and can spread from human to human. Symptoms of swine flu in people are similar to the symptoms of regular human flu and include fever, cough, sore throat, body aches, headache, chills and fatigue.

There are antiviral medicines you can take to prevent or treat swine flu. There is no vaccine available right now to protect against swine flu. You can help prevent the spread of germs that cause respiratory illnesses like influenza by

• Covering your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• Washing your hands often with soap and water, especially after you cough or sneeze. You can also use alcohol-based hand cleaners.
• Avoiding touching your eyes, nose or mouth. Germs spread this way.
• Trying to avoid close contact with sick people.
• Staying home from work or school if you are sick.

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Swine fleu N1H1 vaccination and home treatment remedies

Vaccination

WHO does not expect the swine flu vaccine to be widely available until the end of 2009, noting that current production "yield" was only about half as much as expected and would cause timeline delays.[263] Vaccine producers can normally produce about a billion doses of any single vaccine each year and as a result WHO anticipates a "global shortfall," Keiji Fukuda said in May.[264]
There is also concern that countries which produce vaccines, 70 percent of which are in Europe, may delay sending swine flu vaccines to other countries as they may come under "tremendous pressure to protect their own citizens first," note some experts. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota said that as 80 percent of the United States' pandemic vaccine supply will be coming from abroad, he is very concerned about when it might arrive. "Timing could be everything to avoid a vaccine spat."[265]
Although WHO reports that a fully licensed vaccine might not be ready until the end of 2009, some experts feel that with "little or no safety data about a swine flu vaccine," governments that are planning to roll out mass campaigns are "taking a gamble," since any rare side effects won't show up until millions of people start getting the shots.[265] Nonetheless, in late July, some European countries were planning to accelerate the approval process for the vaccine, and countries like Britain, Greece, France and Sweden all say that they will start using the vaccine once it is given approval, which could happen within weeks. Some European officials feel that "the benefit of saving lives is worth the gamble," and are letting companies skip testing large groups of people before the vaccine is approved. The U.S. is taking a more cautious approach, however.[266]
U.S. and local health officials are monitoring the Southern Hemisphere, where the "virus is already on an unstoppable course" and where it's feared it might combine with the seasonal flu strain and develop drug resistance.[267] The U.S. goal of pandemic plans is to make 600 million doses in six months, enough for two doses for each American, according to experts, with an estimated cost of $8 billion.[146]
Although the seasonal flu vaccine provides little or no protection against H1N1 swine flu, health experts recommend immunization to help prevent people from being infected with both at once. "Vaccination against seasonal influenza should begin as soon as vaccine is available and continue throughout the influenza season," the CDC's Anne Schuchat said, and wants 83 percent of the population to get an annual flu vaccine," noting that only 40 percent of the U.S. population received one last year.[268]
Two injections will be required three weeks apart for the swine flu and a third will be needed for seasonal flu to provide maximum immunity. Children younger than 9 years old will need four shots.[269] The CDC plans to administer the vaccine through clinics set up by state health organizations, but some experts feel that health departments are under-funded and could get "fatigued."[269]
Treatment


Home treatment remedies

The Mayo Clinic and Medline list a number of ways to help ease symptoms, including adequate liquid intake and rest, soup to ease congestion, and over-the-counter drugs to relieve pain. Aspirin, for instance, "is very effective for treating fever in adults" in children and adolescents, aspirin is not usually given due to the risk of Reye's syndrome.[ over-the-counter drugs relieve symptoms, they do not kill the virus.[ Most patients were expected to recover without medical attention, although those with pre-existing or underlying medical conditions were more prone to complications.

Antiviral drugs

Recommended usage and availability

According to the CDC, antiviral drugs can be given to treat those who become severely ill, two of which are recommended for swine flu symptoms: oseltamivir (Tamiflu) and zanamivir (Relenza). To be most useful, they must be taken within 2 days of showing symptoms. They work by deactivating an enzyme the virus needs to grow and spread. Therefore, when taken soon after symptoms are noticed, "they may shorten the illness by a day or so," according to the Mayo Clinic. Oseltamivir is an oral medication, but zanamivir is inhaled through a device similar to an asthma inhaler and shouldn't be used by anyone with respiratory conditions, such as asthma and lung disease.[270]
Furthermore, as the flu spreads, there could be temporary shortages of these drugs. The U.S. CDC therefore recommends Tamiflu treatment primarily for people hospitalized with swine flu; people at risk of serious flu complications due to underlying medical conditions; patients at risk of serious flu complications because they are pregnant, under age 5, or over age 65; and to prevent infection of people at risk of serious flu complications who have been exposed to someone with swine flu.

Anti-viral resistance risk

Marie-Paule Kiely, WHO vaccine research director, said that it was "almost a given" that the new strain would undergo reassortment with resistant seasonal flu viruses and acquire resistance, but it was not yet known at what level resistance would appear.[275] If the virus develops oseltamivir resistance, the "world’s Tamiflu stockpiles will be all but worthless," and doctors would have to switch to the more expensive and harder to take, Relenza.[274] [276] At least five recent instances of Tamiflu-resistant viruses were reported in July. There have also been reports of summer camps urging children to bring the antiviral drug Tamiflu and take it as a preventative measure, but that has concerned the CDC since widespread use could also lead to increased resistance. Currently, almost all seasonal flu strains are resistant to the drug and the genes for such resistance could be very easily transmitted to the new virus, the CDC warns.

Possible side effects

Both medications can cause side effects, including lightheadedness, nausea, vomiting, loss of appetite and trouble breathing and it is recommended that patients discuss possible side effects with their doctor before starting any antiviral medication. The Food and Drug Administration (FDA) has required the maker of Tamiflu to include a warning that people with the flu, particularly children, may be at increased risk of self-injury and confusion after taking Tamiflu and that individuals with the flu who take Tamiflu be closely monitored for signs of unusual behavior.[270]
Warnings of online purchasing
When buying these medications, some agencies warn against buying from online sources, with WHO estimating that half the drugs sold by online pharmacies without a physical address are counterfeit.

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Swine flue N1H1 Symptoms and expected severity

The signs of infection with swine flu are similar to other forms of influenza, and include a fever, coughing, headaches, pain in the muscles or joints, sore throat, chills, fatigue and runny nose. Diarrhea, vomiting and neurological problems have also been reported in some cases. A study concluded on May 5, published in the New England Journal of Medicine, found that 94% of confirmed patients had fever and 92% had cough.[206] People at higher risk of serious complications included people age 65 years and older, children younger than 5 years old, pregnant women, and people of any age with underlying medical conditions, such as asthma, diabetes, obesity, heart disease, or a weakened immune system (e.g., taking immunosuppressive medications or infected with HIV).[204][207] According to the CDC, more than 70% of hospitalizations in the U.S. have been people with such underlying conditions.[208]
Most cases mild
Evidence mounted through May 2009 that the symptoms were milder than health officials initially feared. As of May 27, 2009, most of the 342 confirmed cases in New York City had been mild and there had been only 23 confirmed deaths from the virus.[209] Similarly, Japan has reported 1,048, mostly mild flu cases, and no deaths,[210] with the government reopening schools as of May 23, stating that the "virus should be considered more like a seasonal flu."[211] In Mexico, where the outbreak began in April, Mexico City officials lowered their swine flu alert level as no new cases had been reported for a week.[212]

Symptoms that may require medical attention

Certain symptoms may require emergency medical attention. In children signs of respiratory distress, for instance, those might include blue lips and skin, dehydration, rapid breathing, excessive sleeping, seizures[213] and significant irritability that includes a lack of desire to be held. In adults, shortness of breath, pain in the chest or abdomen, sudden dizziness or confusion may indicate the need for emergency care. In both children and adults, persistent vomiting or the return of flu-like symptoms that include a fever and cough may require medical attention.

Underlying conditions may worsen symptoms

WHO reported that almost one-half of the patients hospitalized in the United States had underlying conditions.[214] "Among 30 patients hospitalized in California," stated the WHO report, "64 percent had underlying conditions and two of five pregnant women developed complications, including spontaneous abortion and premature rupture of membranes." And on June 5, health officials in six states that reported deaths from swine flu said that all six patients had been diagnosed with other health problems.[215]
However, doctors in New York suggested that people with "underlying conditions" who had flu symptoms should consult their doctors first. "Visiting an emergency room full of sick people may actually put them in more danger," wrote the New York Times. Dr. Steven J. Davidson, the chairman of emergency medicine department at Maimonides Medical Center in Brooklyn commented "Like the asthmatics, we’d really prefer that pregnant women would stay away from the emergency departments." Approximately one-third of New Yorkers have one of the underlying conditions recognized by the city.[207] However, no statistics for people with underlying conditions who die from seasonal flu have been reported by the media thus far.

Pneumonia

Influenza infection can cause pneumonia leading to death. This is typically described as either viral pneumonia, which has a rapid onset, often within one day after infection, or bacterial pneumonia, which often begins a week after infection after symptoms have begun to subside.[216]
Viral pneumonia has sometimes been attributed to "cytokine storm", in which an overly active immune response damages the lungs. Reports of deaths among healthy young people during the first weeks of the 2009 flu pandemic were attributed to this cause.[217]
Bacterial pneumonia is a secondary infection resulting from a weakened ability to clear common bacteria from the lower lungs, combined with reduced alveolar macrophage activity which makes it more difficult for the body to fight infection. Bacteria that cause pneumonia include Pneumococcus, Staphylococcus, and Hemophilus influenzae.[218] Bacterial pneumonia has been credited for a large proportion of deaths in the 1918 flu pandemic.[219]
Recent data has suggested that these two forms of pneumonia are not entirely unrelated. A study of 37,000 children in South Africa who received a pneumococcal vaccine (PncCV) found that they were on average one-third less likely to suffer viral pneumonia following infections with seven different respiratory viruses, as well as being protected from bacterial pneumonia afterward.[220]

Prevention

Personal hygiene

The Mayo Clinic has suggested personal measures to avoid seasonal flu infection which should be applicable to the 2009 pandemic: vaccination when available, thorough and frequent hand-washing, a balanced diet with fresh fruits and vegetables, whole grains, and lean protein, sufficient sleep, regular exercise, and avoiding crowds.

Airborne virus prevention

Masks may be of benefit in "crowded settings" or for people who are in "close contact" with infected persons, defined as 1 meter or less by the World Health Organization and 6 feet or less by the U.S. Occupational Safety and Health Administration. In these cases the CDC recommended respirators classified as N95, but it is unknown whether they would prevent swine flu infection.[222] According to mask manufacturer 3M, there are no "established exposure limits for biological agents" such as swine flu virus.
The UK Health Protection Agency considers facial masks unnecessary for the general public[223] and some experts feel it may lead to a false sense of security. Masks are not generally provided by airport security or airlines although the CDC recommends the use of surgical masks in some circumstances.[224] other U.S. officials stated in May that if the flu virus does in fact reach pandemic proportions, "there won't be enough face masks to go around."[225] A recent internal CDC briefing noted, "20,000 people die from novel 2009-H1N1 and everybody wants to wear a mask. 9 million people die from AIDS and no one wants to wear a condom."
Pork safe to eat
The leading international health agencies stressed that the "influenza viruses are not known to be transmissible to people through eating processed pork or other food products derived from pigs."

Airline hygiene precautions

U.S. airlines have made no major changes as of the beginning of June, but continued standing practices that include looking for passengers with symptoms of flu, measles or other infections, and rely on in-flight air filters to ensure that aircraft are sanitized. "We take our guidance from the professionals (such as the CDC)", stated an Air Transport Association spokesman. The CDC has not recommended that airline crews wear face masks or disposable overcoats. Alaska Airlines removed all pillows and blankets from its fleet in late April/early May.[228]

Outside the U.S. however, some airlines have modified hygiene procedures to minimize travel health risks on international flights. Asian carriers have stepped up cabin cleaning, installed state-of-the-art air filters and allowed in-flight staff to wear face masks, with some replacing used pillows, blankets, headset covers and headrest covers, while others have begun disinfecting the cabins of all aircraft. In China, some airline flight attendants are required to wear disposable facial masks, gloves and hats and even disposable overcoats during flights to select destinations.[229]
Singapore has been thermal-screening everyone coming into the country, with Singapore Airlines giving passengers traveling to the United States health kits that include a thermometer, masks and antiseptic towels. Its cabin and flight crews are getting mandatory temperature checks before flights. The government recently quarantined a passenger who was later found to have the flu along with about 60 other people on the same flight who were sitting within three rows.[229] A consultant for the microbiology division at National University Hospital in Singapore, said hygiene practices such as covering the nose and mouth when sneezing or coughing in confined areas may be the best way to limit infection and safety measures such as costly air filters may be of limited use for carriers.[229]
Further information: Influenza prevention and standard personal precautions against influenza
Containment


Chinese inspectors on an airplane, checking passengers for fevers, a common symptom of swine flu
On April 28, 2009, WHO's Dr. Keiji Fukuda said that it was too late to contain the swine flu. "Containment is not a feasible operation. Countries should now focus on mitigating the effect of the virus," he said.[230] He therefore did not recommend closing borders or restricting travel, stating that "with the virus being widespread... closing borders or restricting travel really has very little effects in stopping the movement of this virus."[230] However, on April 28, the U.S. CDC began "recommending that people avoid non-essential travel to Mexico."[231] Many other countries confirmed that inbound international passengers would be screened. Typical airport health screening involves asking passengers which countries they have visited and checking whether they feel or appear particularly unwell. Thermographic equipment was put into use at a number of airports to screen passengers.[232] A number of countries also advised against travel to known affected regions, while experts suggested that if those infected stay at home or seek medical care, public meeting places are closed, and anti-flu medications are made widely available, then in simulations the sickness is reduced by nearly two-thirds.

Quarantines

Some countries began quarantining foreign visitors suspected of having or being in contact with others who may have been infected.

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swine fleu n1h1 virus characteristics

Virus characteristics


The virus is a novel strain of influenza. Existing vaccines against seasonal flu provide no protection, and there is no vaccine for this strain. A study at the U.S. Centers for Disease Control and Prevention published in May 2009 found that children had no preexisting immunity to the new strain but that adults, particularly those over 60, had some degree of immunity. Children showed no cross-reactive antibody reaction to the new strain, adults aged 18 to 64 had 6-9%, and older adults 33%.[169][170] It was also determined that the strain contained genes from four different flu viruses: North American swine influenza, North American avian influenza, human influenza, and two swine influenza viruses typically found in Asia and Europe. Further analysis showed that several of the proteins of the virus are most similar to strains that cause mild symptoms in humans, leading virologist Wendy Barclay to suggest on May 1 that the initial indications are that the virus was unlikely to cause severe symptoms for most people.[171] Scientists in Winnipeg completed the first full genetic sequencing of the virus on 6 May.[172]

Virus origins

On June 23, the New York Times reported that U.S. federal agriculture officials, "contrary to the popular assumption that the new swine flu pandemic arose on factory farms in Mexico," now believe that it "most likely emerged in pigs in Asia, but then traveled to North America in a human." They emphasized that there was no way to prove their theory, but stated that there is no evidence that this new virus, which combines Eurasian and North American genes, has ever circulated in North American pigs, "while there is tantalizing evidence that a closely related 'sister virus' has circulated in Asia."[141]
In early June 2009, using computational methods developed over the last ten years at Oxford, Dr Oliver Pybus of Oxford University's Department of Zoology and his team attempted to reconstruct the origins and timescale of the 2009 flu pandemic. He claims "Our results show that this strain has been circulating among pigs, possibly among multiple continents, for many years prior to its transmission to humans." The research team that worked on this report also believe that it was "derived from several viruses circulating in swine," and that the initial transmission to humans occurred several months before recognition of the outbreak. The team concluded that "despite widespread influenza surveillance in humans, the lack of systematic swine surveillance allowed for the undetected persistence and evolution of this potentially pandemic strain for many years."[173]


Structure of the influenza virion. The hemagglutinin (HA) and neuraminidase (NA) proteins are shown on the surface of the particle. The viral RNAs that make up the genome are shown as red coils inside the particle and bound to ribonucleoproteins (RNPs).
According to the researchers, movement of live pigs between Eurasia and North America "seems to have facilitated the mixing of diverse swine influenza viruses, leading to the multiple reassortment events associated with the genesis of the (new H1N1) strain." They also stated that this new pandemic "provides further evidence of the role of domestic pigs in the ecosystem of influenza A."[135] Some experts also suspect that a leading cause of the new virus outbreak is insufficient surveillance by the pork industry and the fact that "animal husbandry now more closely resembles the petrochemical industry than the happy family farm"[174]
Estimates of total cases
On July 24, Keiji Fukuda, WHO's Assistant Director-General for Health Security and Environment said the pandemic was still in its early stages globally and two billion infections over the course of the pandemic was "a reasonable ballpark to be looking at."[175] On the same day, the Anne Schuchat, director of the U.S. CDC's National Center for Immunization and Respiratory Diseases, estimated that without a swine flu vaccine, current trends suggest 12% to 24% of Americans might get swine flu this fall and winter. But if large enough numbers of people get the vaccine before the next waves of the pandemic sweep the nation it would "put a dent in the pandemic," she said. Initial availability of vaccines is expected by mid-October, although healhcare workers and people most at risk would likely get them first.[176]
As for the current totals, in early July WHO officials gave up trying to count the number of cases, saying the best they can do is estimate the spread of the "unstoppable" virus. And the CDC's Schuchat declined even to hazard a guess, saying it was "more than a million." Officials do not have the tools they need to count, she pointed out. "Most people who have respiratory illnesses don't find out exactly what caused it. Even most people with influenza don't know exactly which type of influenza caused their illness."[177]
In late June, the CDC estimated that 1 million Americans had so far contracted the flu. By comparison, an estimated 15 million to 60 million Americans are infected with the seasonal flu each year, leading to roughly 36,000 deaths.[178] According to the CDC, however, only about one in 20 cases was being officially reported in the U.S. in late May.[179] In the U.K., some experts thought the number of cases was potentially 300 times more than early published estimates,[180] warning that case estimates by the U.K. and other governments were "meaningless" and hiding its true extent. There were also estimates that Japan may have had approximately 30,000 cases by late May.[180]

Virulence

The CDC has noted that most infections continue to be mild—similar to seasonal flu—and recovery is extremely quick.[181] Some experts point out that the deaths so far are "a tiny fraction" of people who die every year from seasonal flu - with barely a public murmur." One doctor said that "when there's something that's new and unknown, it scares people."[182] Some medical journalists suggest that the news media may be overreacting to the new virus and have not compared its virulence with that of the regular "seasonal" flu.[183]
Mutation potential
On May 22, 2009, WHO chief Dr. Margaret Chan said that the virus must be closely monitored in the southern hemisphere, as it could mix with ordinary seasonal influenza and change in unpredictable ways. "In cases where the H1N1 virus is widespread and circulating within the general community, countries must expect to see more cases of severe and fatal infections," she said. "[184] Experts writing in the July New England Journal of Medicine note that "historically, pandemic viruses have evolved between seasons, and the current strain may become more severe or transmissible in the coming months." They therefore stress that "international cooperation will be crucial" to engage in proper surveillance to help monitor changes in the virus's behavior, which will aid in both "vaccine targeting" and interpreting illness patterns in the fall of 2009.[143]
Other experts are also concerned that the new virus strain could mutate over the coming months. Guan Yi, a leading virologist from the University of Hong Kong, for instance, described the new H1N1 influenza virus as "very unstable", meaning it could mix and swap genetic material when exposed to other viruses. During an interview he said "Both H1N1 and H5N1 are unstable so the chances of them exchanging genetic material are higher, whereas a stable (seasonal flu) virus is less likely to take on genetic material." The H5N1 virus is mostly limited to birds, but in rare cases when it infects humans it has a mortality rate of between 60% to 70%.[185] Experts worry about the emergence of a hybrid of the more virulent Asian-lineage HPAI (highly pathogenic avian influenza) A/H5N1 strain (media labeled "bird flu") with more human-transmissible Influenza A strains such as this novel 2009 swine-origin A/H1N1 strain (media labeled "swine flu"), especially since the H5N1 strain is and has been for years endemic in birds in countries like China, Indonesia, Vietnam and Egypt.[185][186] (See the suite of H5N1 articles for details.)
Nor had federal health officials in the U.S. dismissed the possibility that the worst was yet to come. "Far from it," Ann Schuchat of the CDC says, noting that the horrific 1918 flu epidemic, which killed hundreds of thousands in the United States alone, was preceded by a mild "herald" wave of cases in the spring, followed by devastating waves of illness in the autumn. "That 1918 experience is in our minds," she said.[187]
As of late July, U.S. health officials said that the swine flu "isn't yet mutating to become more dangerous," but they are closely tracking that as the virus continues to circle the globe.

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