swine flu (A-H1N1) virus

Comparing deaths from pandemic and seasonal influenza

2010-01-12T09:23:00.000-08:00

Comparing deaths from pandemic and seasonal influenza

Pandemic (H1N1) 2009

Numbers of deaths for seasonal influenza are estimates. They use statistical models designed to calculate so-called excess mortality that occurs during the period when influenza viruses are circulating widely in a given population.

Estimates using all-cause mortality

The models use data, as recorded in death certificates and medical records, indicating mortality from all causes, and compare the number of deaths during epidemics of seasonal influenza with baseline data on deaths during the rest of the year. The assumption is that infections with influenza viruses contribute to the “excess mortality” observed during the influenza season.

During epidemics of seasonal influenza, around 90% of deaths occur in the frail elderly, who often suffer from one or more chronic medical conditions. Although influenza can worsen these conditions and contribute to death, testing for influenza viruses is not done in most cases, and deaths are usually attributed to an underlying medical condition.

Methods for estimating excess mortality were introduced in the 19th century to capture these influenza-associated deaths that would otherwise be missed. Such estimates have helped counter assumptions that influenza is a mild illness that rarely kills.

Laboratory-confirmed deaths

In contrast, numbers of deaths from pandemic influenza, as notified by national authorities and tabulated by WHO, are laboratory-confirmed deaths, not estimates. For several reasons, these numbers do not give a true picture of mortality during the pandemic, which is unquestionably higher than indicated by laboratory-confirmed cases.

As pandemic influenza mimics the signs and symptoms of many common infectious diseases, doctors often do not suspect H1N1 infection and do not test. This is especially true in developing countries, where deaths from respiratory diseases, including pneumonia, are common occurrences. Moreover, routine testing for pandemic influenza is costly and demanding, and beyond the reach of most countries.

When testing confirms H1N1 infection in patients with underlying medical conditions, many doctors record these deaths as due to the medical condition, and not to the pandemic virus. These cases are also missed in official statistics.

As recent studies have shown, some tests for H1N1 infection are not entirely reliable, and false-negative results are a frequent problem. Accurate test results further depend on how and when samples were taken. Even in the best-equipped hospitals, doctors have reported seeing patients with distinctive and virtually identical disease profiles, yet only some have positive test results.

Moreover, in a large number of developing countries, systems for vital registration are either weak or non-existent, meaning that most deaths are neither investigated nor certified in terms of the cause.

Younger age groups

Comparisons of deaths from pandemic and seasonal influenza do not accurately measure the impact of the pandemic for another reason. Compared with seasonal influenza, the H1N1 virus affects a much younger age group in all categories – those most frequently infected, hospitalized, requiring intensive care, and dying.

WHO continues to assess the impact of the influenza pandemic as moderate. Accurate assessments of mortality and mortality rates will likely be possible only one to two years after the pandemic has peaked, and will rely on methods similar to those used to calculate excess mortality during seasonal influenza epidemics.

Swine flu ouestions???

2009-08-16T11:07:00.000-07:00

Swine flu has spread across the world since emerging in Mexico and is now officially the first flu pandemic for 40 years. Experts fear millions of people will be infected. Swine flu is a respiratory disease, caused by a strain of the influenza type A virus known as H1N1. H1N1 is the same strain which causes seasonal outbreaks of flu in humans on a regular basis. But this latest version of H1N1 is different: it contains genetic material that is typically found in strains of the virus that affect humans, birds and swine. Although the strain may have originated in pigs, it is now a wholly human disease. It can be spread from person to person by coughing and sneezing.

Symptoms of swine flu in humans appear to be similar to those produced by standard, seasonal flu. A fever - which is a temperature of 38ºC (100.4ºF) - is the key symptom, combined with other complaints which may include a cough, sore throat, body aches, chills and aching limbs. Some people with the virus have also reported nausea and diarrhea. As with normal flu, the severity of symptoms will depend on treatment and the individual. Many people have only suffered mildly and have begun to recover within a week. People are most infectious soon after they develop symptoms, but they cease to be a risk once those symptoms have disappeared. The incubation period may be as little as two days.

Apparently healthy people are dying from the virus. Does that means it is getting worse?

Experts say this does not change anything and that if anything it is surprising that it has taken this long in the UK for someone without underlying health problems to die. Apparently healthy people can die of any flu-related virus if it causes complications such as pneumonia so these latest deaths do not give any extra cause for concern. Indeed, so far, many people who have developed symptoms of infection have not needed drugs to make a full recovery, according to the WHO.

Flu expert Professor Peter Open Shaw, of Imperial College London, says about one in every three people who become infected will not realize they have had swine flu because they will have had no or only very few symptoms. "About 98% of people who get infected will recover fully without any hospital treatment so I think the public needs to be reassured." The real fear is that the strain will mutate and become more virulent which would pose a greater threat. This has been the feature of previous flu pandemics. But this has not yet happened - and in any event it is worth remembering that seasonal flu often poses a serious threat to public health - each year it kills 250,000 - 500,000 around the world.

What should I do if I think I have it?

Anyone with flu-like symptoms who suspects they might have the swine flu virus are being advised to stay at home and use the "swine flu symptom checker" on the NHS Direct website, or phone NHS Direct - NHS 24 in Scotland. If swine flu is suspected, your GP should be contacted - and he or she will issue a voucher for anti-flu drugs. The infected person would then be expected to arrange for a friend or family member to pick up the anti-viral treatment for them from a collection point, most probably a pharmacy. In the initial phase of the outbreak, lab testing was done to diagnose the flu but this is no longer happening routinely.

How is it treated?

Two drugs commonly used to treat flu, Tamiflu and Relenza, are effective at treating infection. However, the drugs must be administered at an early stage to be effective. Use of these drugs may also make it less likely that infected people will pass the virus on to others. The UK government already has a stockpile of Tamiflu, ordered as a precaution against pandemic.

However, there is concern that if too many people start taking anti-virals as a precaution, it could raise the risk of the virus developing resistance, reducing the drugs' effectiveness. There is however no evidence at present that this is happening.

In any event there is little point taking these drugs as a precaution as each tablet only provides a day's worth of cover. Given that the virus may be with us for many months - or indeed years - taking a regular pill is ill-advised as the long-term side effects are not known.

What measures then can I take to prevent infection?

As yet there is no vaccine, but manufacturers are trying to develop one. Good progress is being made and the first doses may be available in the UK by August. However the NHS says it may be next year before everyone can be immunised Older people and those under 16 - as well as health workers and those with existing clinical conditions - will be given priority. It is hoped that even if the virus mutates in coming months, the vaccine would still confer a high degree of protection against related strains.

In the meantime, avoid close contact with people who appear unwell and who have fever and cough. General infection control practices and good hygiene can help to reduce transmission of all viruses, including the human swine influenza. This includes covering your nose and mouth when coughing or sneezing, using a tissue when possible and disposing of it promptly.

It is also important to wash your hands frequently with soap and water to reduce the spread of the virus from your hands to face or to other people, and cleaning hard surfaces like door handles frequently using a normal cleaning product. In Mexico masks have been handed out to the general public, butexperts are sceptical about how useful this is. Some suggest it may even be counterproductive.

Why Swine Flu dangerous disease??

Why Swine Flu dangerous disease??

2009-08-15T05:26:00.000-07:00

The current swine flu outbreak is a type of influenza A virus, specifically H1N1. But what makes it more dangerous than the yearly flu epidemic, or is that just exaggeration from the media.

Many people have compared swine flu to avian influenza and SARS, saying that since neither one proved to be a global problem in the end, swine flu is going to be just similar hype. However, we cannot know for sure.

Swine flu is a bigger risk than SARS, because SARS is only infectious after the symptoms have appeared which is most likely what prevented a major epidemic. Avian influenza or the bird flu, on the other hand, was never infectious between humans, at least on a major scale.

What Makes Swine Flu Potentially so Dangerous?

The reason why swine flu is a risk is that influenza is a highly contagious illness. H1N1 influenza is not nearly as deadly as, say, Ebola or other hemorrhaging fevers, but if a pandemic happened, in the worst case up to 1/3 of the population could get sick. In that case even a 5% risk of dying from the illness could mean death of millions.

What may make swine flu more dangerous than a normal influenza season is that like the Spanish flu of 1918, it has killed mostly healthy young people. Usually influenza is only dangerous for the old and sick. This suggests that like with the Spanish Flu, the potentially deadly part could be the immune reaction the body mounts against the virus. As such young people with healthier immune systems may actually be more at risk than the old and frail.

he new swine flu virus that broke out in Mexico is unique and potentially dangerous in one way. It is a virus that has a combination of gene segments from human, bird and swine viruses, and can potentially become infectious in humans that have no immunity to the new strain.

Influenza viruses can change its make-up in one of two ways: Antigenic drift is a series of mutations that cause the virus to gradually evolve over time. Antigenic shift is an abrupt change in the surface antigen proteins that suddenly creates a new subtype of the virus. In the history of influenza outbreaks, antigenic shift is the cause behind pandemics in 1918 (Spanish Flu), 1957 (Asian Flu) and 1968 (Hongkong Flu) because the populations have not developed antibody protection against the virus.

What’s especially unique about this new swine flu strain is that it’s a type A/ strain H1N1 and it hasn’t been previously detected in pigs. Lab tests showed that the H1N1 is susceptible to the antiviral drugs oseltamivir (Tamiflu) and zanamivir and the US government is prepared to use the drugs to treat and prevent infection with swine influenza virus.

Swine Flu Symptoms

2009-08-10T05:41:00.000-07:00

Although the name 'swine flu' brings up a lot of extra fear and worry, it is important to note that swine flu is just an influenza A H1N1 virus. That means that it is just another type of flu virus, just like that causes our typical seasonal flu symptoms. The big difference is that the current swine influenza A (H1N1) virus has components of pig and bird influenza viruses in it, so that humans don't have any immunity to it. That makes it more likely to become a pandemic virus (have the ability to cause a global outbreak) if it can easily spread from person-to-person.

So far, even as you see swine flu cases increase on this swine flu map, experts don't know if this swine influenza A (H1N1) virus will become a pandemic strain of flu. It could or we just continue to see sporadic cases for a few weeks or months until it stops.

We do know that swine flu symptoms are just like seasonal flu symptoms.

Swine Flu Symptoms

According to the CDC, like seasonal flu, symptoms of swine flu infections can include:

Fever, which is usually high, but unlike seasonal flu, is sometimes absent
Cough
Runny nose or stuffy nose
Sore throat
Body aches
Headache
chills
Fatigue or tiredness, which can be extreme
Diarrhea and vomiting, sometimes, but more commonly seen than with seasonal flu
Signs of a more serious swine flu infection might include pneumonia and respiratory failure.

If your child has symptoms of swine flu, you should avoid other people and call your pediatrician who might do a rapid flu test to see if he has an influenza A infection. Further testing can then be done to see if it is a swine flu infection. (Samples are being sent to local and state health departments and the CDC for confirmation of swine flu.)

Serious Swine Flu Symptoms

More serious symptoms that would indicate that a child with swine flu would need urgent medical attention include:

Fast breathing or trouble breathing
Bluish or gray skin color
Not drinking enough fluids
Severe or persistent vomiting
Not waking up or not interacting
Being so irritable that the child does not want to be held
Flu-like symptoms improve but then return with fever and worse cough

Swine Flu Symptoms vs. a Cold or Sinus Infection

It is important to keep in mind most children with a runny nose or cough will not have swine flu and will not have to see their pediatrician for swine flu testing.

This time of year, many other childhood conditions are common, including:

Spring allergies - runny nose, congestion, and cough
Common cold - runny nose, cough, and low grade fever
Sinus infections - lingering runny nose, cough, and fever
Strep throat - sore throat, fever, and a positive strep test

What You Need To Know

Swine flu likely spreads by direct contact with respiratory secretions of someone that is sick with swine flu, like if they were coughing and sneezing close to you.

People with swine flu are likely contagious for one day before and up to seven days after they began to get sick with swine flu symptoms.

Droplets from a cough or sneeze can also contaminate surfaces, such as a doorknob, drinking glass, or kitchen counter, although these germs likely don't survive for more than a few hours.

Anti-flu medications, including Tamiflu (oseltamivir) and Relenza (zanamivir), are available to prevent and treat swine flu.

The latest swine flu news from the CDC includes advice that students should stay home if they have swine flu symptoms, but schools do not need to close unless they have large clusters of cases that are affecting school functioning. Schools that closed based on previous recommendations, such as if they had a single confirmed case or probable case, can now likely reopen.

What is Swine flu???

2009-07-29T23:26:00.001-07:00

Flu is an illness caused by an infection of the influenza virus. The flu virus constantly changes and there are many different strains of flu. Find out the differences between swine flu, pandemic flu, and ordinary flu.

Go to NHS Choices for health advice on swine flu, including causes, symptoms, prevention and treatment

A new strain of Influenza A (H1N1), also known as swine flu, was confirmed in the UK in April and has spread to more than 100 countries around the world.

Although symptoms have generally proved mild, a small number of patients will develop more serious illness. Many of these people have other underlying health conditions, such as heart or lung disease, that put them at increased risk.

A Pandemic Is Declared

On June 11, 2009, the World Health Organization(WHO) signaled that a global pandemic of novel influenza A (H1N1) was underway by raising the worldwide pandemic alert level to Phase 6. This action was a reflection of the spread of the new H1N1 virus, not the severity of illness caused by the virus. At the time, more than 70 countries had reported cases of novel influenza A (H1N1) infection and there were ongoing community level outbreaks of novel H1N1 in multiple parts of the world.

Since the WHO declaration of a pandemic, the new H1N1 virus has continued to spread, with the number of countries reporting cases of novel H1N1 nearly doubling. The Southern Hemisphere’s regular influenza season has begun and countries there are reporting that the new H1N1 virus is spreading and causing illness along with regular seasonal influenza viruses. In the United States, significant novel H1N1 illness has continued into the summer, with localized and in some cases intense outbreaks occurring. The United States continues to report the largest number of novel H1N1 cases of any country worldwide, however, most people who have become ill have recovered without requiring medical treatment.