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This may not be the ‘biggest flu season on record’, but it is a big one – here are some possible reasons

The Conversation

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When the H3N2 strain dominates, we see bigger flu seasons and cases affecting the elderly more than the young. from shutterstock.com

Ian M. Mackay, The University of Queensland and Katherine Arden, The University of Queensland

This year, the number of laboratory-confirmed influenza (flu) virus infections began rising earlier than usual and hit historic highs in some Australian states. If you have been part of any gathering this winter, this is probably not news.

States in the south-east (central and southern Queensland, New South Wales, Victoria, Tasmania and South Australia) are more inflamed by flu than those in the north and west. For example, Queensland has seen more hospital admissions than in the last five years, mostly among an older population, while younger demographics more often test positive without needing hospitalisation.

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Meanwhile, flu numbers in New Zealand and elsewhere in the Pacific have not matched the same elevated levels. But is Australia really experiencing the biggest flu season on record in 2017, or are we just testing more and using better tools?

This is hard to answer for certain because the information we need is not usually reported until later and public databases only show the past five years. We can say for sure that 2017 is on track to be a historically big flu year.


Read more: Have you noticed Australia’s flu seasons seem to be getting worse? Here’s why


Really, a big flu season

Flu can be a nasty illness. Sometimes it’s deadly. Other times it can be mild. But even for cases that fall in the middle you may not be able to work for days, or you’ll have to look after ill children home from school, or visit the very sick who have been hospitalised.

Years ago, detection of influenza viruses mostly relied on slow, finicky methods such as testing for virus in artificial cell cultures. But, in Australia today, most laboratories use either sensitive tools to detect viral gene sequences in samples from the patient’s airway, or less sensitive but rapid dipstick methods, where a special strip is placed in a sample to detect viral proteins.

These tools have been in use since 2007 in the larger Australian laboratories, so it’s unlikely we are just seeing more positives in 2017. While newer versions of these tests are being rolled out this year, they are unlikely to detect more cases. Equally, it’s unlikely more people with suspected flu decided to change their behaviour in 2017 and get tested, compared to 2016, or the year before.

Flu can be a nasty illness and you may be off work for days. from shutterstock.com

As in all years, there are many people in the community with flu who don’t get tested. The proportion of people with flu who are tested likely remains roughly the same year to year.

State-wide flu reports provide reliable, laboratory-confirmed results. By looking at them, we can also be confident that “man flu” and severe common colds aren’t contributing to this specific and large increase in flu. We’re very likely seeing a truly huge flu season.

Why so bad this year?

Flu, caused by infection with an influenza virus, is mostly a disease with an epidemic peak during July and August in non-tropical countries. Flu viruses are broadly grouped into two types: Influenza-A and Influenza-B. Influenza-B viruses have two main sub-types while the Influenza-A viruses are more variable.

The Influenza-As you get each year are usually A/H3N2 (the main player so far this season) or A/H1N1, which lingers on from its 2009 “swine flu” pandemic. Multiple flu viruses circulate each year and serial infections with different strains in the same person in a single season are possible.

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H3N2 has played a big role in the past five flu seasons. When it clearly dominates we tend to have bigger flu seasons and see cases affecting the elderly more than the young.

H3N2 is a more changeable beast than the other flu viruses. New variants can even emerge within a season, possibly replacing older variants as the season progresses. This may be happening this winter, driving the bigger-than-normal season, but we won’t know for certain until many more viruses are analysed.

Outside winter, flu viruses still spread among us. This year, in particular, we’re being encouraged to get vaccinated even during the peak of flu season. Vaccines are a safe way to decrease the risk that we or loved ones will get a full-blown case of the flu.

Yet Australian flu vaccination rates are low. Data are scant but vaccination rates have increased in adults and some at-risk groups, but remain lower than for childhood vaccines.


Read more: Disease risk increasing with unvaccinated Australian adults


The flu vaccine

Each season new flu vaccines are designed based on detailed characterisation of the flu viruses circulating in the previous season. But the viruses that end up dominating the next season may change in the meantime.

It is not clear whether that was a factor for this year’s high numbers in Australia this year or precisely what the vaccine uptake has been in 2017. Much of this detail will not be reported until after the epidemic ends. Some testing suggests this year’s vaccine is well matched to the circulating viruses.

The flu vaccine is not the most effective of vaccines, but it is safe and the only preventive option we have for now. Of those vaccinated, 10-60% become immune to flu virus.


Read more: Flu vaccine won’t definitely stop you from getting the flu, but it’s more important than you think


Future flu vaccines promise to account for the ever-changing nature of flu virus, reducing the current need for yearly vaccination. Until they are available, though, it remains really important to book an appointment with your vaccine provider and get a quick, safe vaccination, because we are unarguably in the midst of the biggest flu season Australia has seen in years.

The ConversationWe have both vaccines and drugs to help us prevent and minimise disease and the extra load on hospitals caused by flu. The young, elderly, those with underlying disease and Indigenous Australian people are most at risk of the worst outcomes and this is reflected by government-funded vaccination for these groups.

Ian M. Mackay, Adjunct assistant professor, The University of Queensland and Katherine Arden, Virologist, The University of Queensland

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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The number of new flu viruses is increasing, and could lead to a pandemic

The Conversation

C Raina MacIntyre, UNSW; Abrar Ahmad Chughtai, UNSW, and Chau Bui, UNSW

Influenza has affected humans for over 6,000 years, causing pandemics at regular intervals. During the 1918 Spanish flu, it was thought to be a bacteria, until an American physician Richard Shope identified the virus in 1931. The Conversation

So how is it this pathogen has managed to stay around for so long, and why haven’t we beaten it yet? The answer is that influenza is a virus that changes rapidly and regularly.

New flu vaccines are required every year due to these changes and mutations of the virus. While all flu viruses which infect humans are similar, a pandemic virus (which is easily transmitted between humans) is significant because humans have no immunity to it, and so are vulnerable to severe infection and death. Seasonal viruses which we see year after year were once pandemic strains, but humans have now been exposed to these viruses and have some background immunity to them.

We have found that the last decade has seen an acceleration in the number of flu strains infecting humans.

Why are there so many flu strains today?

Around 100 years ago the world experienced the Spanish flu pandemic, and it took another 39 years for a novel influenza virus to emerge. It took a decade after that for the next one. Since 2011, however, we have seen seven novel and variant strains emerge. This is a very large increase compared to the past.

The reasons for this increase are unknown, but there could be many. One reason could be better diagnostics and testing; another could be changes in poultry farming and animal management practices, since influenza is a virus that affects humans, birds and many animal species; as well as changes in climate, urbanisation and other ecological influences.

But none of these factors have changed at the same rate as the emergence of new viruses has escalated. This warrants new research to unpack the relative contributions of all the different possible factors.

Another change is advances in genetic engineering tools, which make it possible to edit the genome of any living organism, including viruses. The possibility of a lab accident or deliberate release of engineered flu viruses is real. Experiments to engineer influenza viruses have been published since 2011, and remain controversial for the possible risk, compared to the relative possible benefit.

With so many more novel influenza viruses emerging and circulating, the probability of genetic mutation and emergence of a new pandemic strain is higher today than any time in the past. It’s a matter of when, not if.

What can we do to prevent a pandemic?

There’s actually already a lot being done to plan for and prevent another flu pandemic. This is both in terms of pharmaceutical drugs and vaccines, and non-pharmaceutical interventions like personal protective equipment, quarantine, border control and banning of mass gatherings in the event of an outbreak.

National pandemic plans outline interventions and the best sequence of different interventions, as well as prioritisation of these interventions. Most countries also conduct pandemic hypotheticals to test their systems and responses. But the best laid plans do not account for every possibility, and we usually encounter the unexpected.

For example, during the 2009 swine flu pandemic, the pandemic phases outlined in the Australian pandemic plan were revised to better fit the emerging situation. This highlights the need to be able to rapidly respond to changing circumstances and change strategies when required.

What about vaccines?

Vaccination is the most talked about strategy but producing a matched vaccine takes three to six months at a minimum. The pandemic would be expected to peak within about two months, so vaccines can’t be relied on until after the peak of the pandemic. Instead, we need to use antiviral medications, social distancing measures, personal protective equipment such as masks and gloves, isolation and quarantine to contain the pandemic.

Influenza vaccines are specific to strains of flu, and can be used for humans, birds or animals. However, they will only work against the specific strains the vaccine was designed for. There are no vaccines for many of the novel strains emerging all over the world.

It’s almost impossible to anticipate which specific virus will cause the next pandemic. At best we can prepare pre-pandemic vaccines which require an educated guess as to which virus may mutate into a pandemic strain, and make a vaccine against that.

A strain-specific pandemic planning strategy like this is not the best approach, as illustrated by the swine flu pandemic in 2009. From 2005 until 2009, the avian flu virus H5N1 (flu viruses are defined and named by proteins on their surface, haemagglutinin – H, and neuraminidase – N) was the major cause of bird flu, so the world focused heavily on preparing for a H5N1 pandemic and developing a H5 pre-pandemic vaccine.

However, the virus that caused the 2009 pandemic was H1N1, a completely different virus, so the pre-pandemic vaccines were no use.

A better approach is to try to prevent the emergence of new virus strains in birds and animals, and mitigate the risks once they emerge. This involves control strategies in both animal and human health sectors, surveillance and prevention efforts.

A targeted approach in global hotspots such as China, the source of the H7N9 influenza virus, and Egypt, which is experiencing a surge in H5N1 influenza, will also help.

Hotspots are generally where humans and livestock mix in close proximity, such as backyard poultry farms and live bird markets. Asia has historically been such a site. However, we sometimes see unusual outbreaks such as the bird flu outbreak in turkey farms in the USA in 2015.

Culling of birds is a commonly used method to control the risk once infection is detected. As are measures such as regulation of live bird markets and of the poultry and livestock industries. Excellent surveillance, rapid intelligence and picking up potential pandemics as they arise can make all the difference. We probably had a near miss pandemic strain arising in Indonesia in 2006, but the remote location and early detection mitigated the risk.

C Raina MacIntyre, Professor of Infectious Diseases Epidemiology, Head of the School of Public Health and Community Medicine, UNSW; Abrar Ahmad Chughtai, Epidemiologist, UNSW, and Chau Bui, PhD candidate, UNSW

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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Thinking about getting the 2016 flu vaccine? Here’s what you need to know

The Conversation

C Raina MacIntyre, UNSW Australia and Aye Moa, UNSW Australia

Up to one in ten adults and three in ten children are infected with influenza each year.

The vaccine we have used for decades, the trivalent vaccine (TIV), protects against three strains of flu. But in 2016, for the first time, the publicly funded vaccine program will offer the quadrivalent flu vaccine (QIV), which protects against four instead of three strains of flu.

The seasonal influenza vaccination is now available at GP clinics and pharmacies. For those not eligible for the free vaccine, it will cost around A$9$15 for the TIV and A$12$25 for the QIV, plus the cost of the consultation if your GP doesn’t bulk bill.

So, what strains do these vaccines protect against? Who should be vaccinated? And, if you’re paying, what additional benefit does the new QIV have?

What is influenza?

Influenza virus is a serious infection, which causes 1,500 to 3,500 deaths in Australia each year. Death occurs from direct viral effects (such as viral pneumonia) or from complications such as bacterial pneumonia and other secondary bacterial infections.

In people with underlying coronary artery disease, influenza may also precipitate heart attacks, which flu vaccine may prevent.

The two major types of influenza infection are influenza A and B; the A strain causes more severe disease than B. Influenza B, however, may be under-reported and causes more severe illness in children and young adults.

The Influenza A virus has much greater genetic diversity than B, probably because it has several non-human animal hosts such as birds, pigs and horses. This sets the scene for genetic mixing between human and animal strains, which accounts for the diversity of the virus, along with constant changes each year as it tries to evade its hosts’ immune responses.

The flu vax may also protect against heart attacks in those with underlying disease. Government of Alberta/Flickr, CC BY-NC-ND

Minor changes (drift) account for new viruses circulating each season, whereas major changes (shift) result in new pandemic strains, to which humans have little or no pre-existing immunity. Influenza B, in contrast, has only two major lineages and much less genetic diversity; seals are the only animal host.

Pandemic strains of the past, once established in human populations, become seasonal strains and tend to cycle over the years, with different strains dominating each year.

Seasonal vaccination

The influenza vaccine is formulated annually because seasonal flu viruses undergo continuous genetic mutation and the vaccine needs to match the major circulating strains. A vaccine from a previous year will generally not confer much protection the following year.

The holy grail of influenza vaccines is a universal vaccine, a one-off shot that would give lifelong protection. Such vaccines are being developed and may not be far off.

Until that time, every year The World Health Organisation studies the circulating viruses and decides which strains will be covered in that year’s flu vaccine. This process occurs separately for the southern and northern hemispheres. It’s usually successful, but a mismatch between the circulating flu virus and the vaccine may sometimes occur.

While live flu vaccines are available in other countries, only the inactivated vaccine is available in Australia. This cannot cause influenza, as it does not contain live virus.

The trivalent vaccine (TIV) contains protection against three strains: two of influenza A and one of influenza B. But there are two major circulating lineages of influenza B, and recent research shows that a TIV B vaccine mismatch occurs approximately 25% of the time.

The quadrivalent (QIV) strain protects against the second B lineage.

Different flu strains dominate each year. Claus Rebler/Flickr, CC BY-SA

Several different companies manufacture TIV and QIV. The vaccines are safe and effective, although one brand, Fluvax, is not approved for children under the age of five years because of an increased risk of febrile seizures.

The 2016 Australian trivalent inactivated influenza vaccine protects against:

  • A (H1N1): an A/California/7/2009 (H1N1)-like virus
  • A (H3N2): an A/Hong Kong/4801/2014 (H3N2)-like virus (H3N2 is generally the most severe form of influenza A)
  • B: a B/Brisbane/60/2008-like virus.

The quadrivalent inactivated influenza vaccine (QIV) protects against the three strains about and an additional B lineage:

  • B/Phuket/3073/2013-like virus.

Should I get vaccinated?

Australia’s national immunisation program recommends and funds free flu vaccinations for:

  • people aged 65 years and older
  • Aboriginal and Torres Strait Islander people aged 15 years or older
  • pregnant women
  • anyone over six months of age with a medical condition such as heart disease, respiratory disease, diabetes, kidney disease, asthma, immunosuppression and chronic neurological conditions
  • children on long-term aspirin therapy.

Pneumonia is a common complication of influenza, so people with risk factors are also recommended for pneumococcal vaccine.

Those at risk of complications from the flu are eligible for the free vaccine. Direct Relief/Flickr, CC BY-NC-ND

About 70% of people over 65 are vaccinated, but only 30-50% of people aged under 65 years with risk factors get vaccinated each year.

Australians who don’t fall within one of these at-risk groups may choose to get vaccinated to protect themselves, family members, colleagues/patients or friends.

The 2016 flu season

Flu seasons typically cycle between mild and severe epidemic years.

The 2015 Australian flu season was dominated by two lineages of influenza B (62% of cases), the highest influenza B season since 2008. Children five to nine years old, adults aged 35 to 44 and the elderly aged over 85 were most affected.

The major influenza A viruses in circulation last year were influenza A (H1N1) pdm09 and, to a lesser degree, influenza A (H3N2).

The effectiveness of the flu vaccine varies each year. Both TIV and QIV can protect well if the circulating strains are similar to the vaccine strains.

In the United States, the Centers for Disease Control and Prevention (CDC) reported that vaccine effectiveness for the 2015-2016 flu season was about 60%, and the vaccine strains a good match for the season.

Any person recommended for vaccination on the National Immunisation Program schedule should get vaccinated as early as possible. They will be able to benefit from the QIV, which confers greater protection by eliminating the possibility of B lineage mismatch.

But if paying for the vaccine privately and cost is an issue, the TIV is more affordable and will still confer good protection.


Further reading: Health Check: when is ‘the flu’ really a cold?

The ConversationC Raina MacIntyre, Professor of Infectious Diseases Epidemiology, Head of the School of Public Health and Community Medicine, UNSW Australia and Aye Moa, PhD candidate, UNSW Australia

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

 

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Scary berries: how food gets contaminated and what to do

The Conversation

By Martyn Kirk, Australian National University

Food distributor Patties Foods has recalled two brands of frozen mixed berries — Nanna’s and Creative Gourmet — due to reports of three people in Victoria, four in Queensland and two in New South Wales developing hepatitis A after eating the products. The cause of a fourth Queensland case is still in doubt.

Initially, only one-kilogram bags of Nanna’s mixed berries were recalled, but that has now been extended to 300-gram and 500-gram bags of Creative Gourmet mixed berries. The berries came from Chile and China.

Authorities are warning people against eating one-kilogram packets of Nanna’s mixed berries with best-before dates until and including November 22, 2016. For Creative Gourmet, the date ranges are up to and including December 10, 2017 for 300-gram packets and October 6, 2017 for 500-gram packets.

Only product lines that show sufficient evidence of risk to consumers are recalled in outbreaks such as this one. It’s common, though, for the lines affected to change as more information comes to light.

Hepatitis A

The berries are linked with an outbreak of hepatitis A, a viral infection of the liver. Symptoms include fever, nausea, abdominal discomfort, diarrhoea, dark urine and jaundice (yellow skin and eyes). The illness can be quite severe, particularly in people who are already unwell.

Most people recover within several weeks and young children often show mild or no symptoms. But the serious cases result in hospitalisation and liver failure.

Infection is acquired when people ingest the virus, which is excreted in an infected person’s faeces. Infection can result from close contact with an infected person, eating contaminated food or drinking contaminated water. Symptoms appear between 15 and 50 days after exposure to the virus, which makes it difficult to identify possible sources.

Hepatitis A is spread through food and water contamination. Source: Julien Harneis/Flickr, CC BY-SA

Food-borne outbreaks of the disease occur when a person eats food that has been contaminated by the virus – either by contamination during growing or processing, or when a person prepares food while they are infectious. Sometimes the outbreak is caused by water contaminated by human sewage.

The number of hepatitis A cases in Australia has been declining dramatically since the late 1990s. This is probably due to a range of factors, including a reduction in the number of people in high-risk groups susceptible to hepatitis A virus infection, and vaccination campaigns in target groups, such as Aboriginal and Torres Strait Islander children in 2005 and 2007.

These days Australian health authorities receive reports of a couple of hundred cases each year. Almost all of these are acquired when people who haven’t been vaccinated against the illness travel overseas.

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Scary berries

Berries have caused large outbreaks of gastroenteritis and hepatitis A in the past, particularly in Europe and the United States. Health agencies have increasingly become aware of fruits, vegetables and herbs as a cause of disease outbreaks. Awareness has grown in parallel with global food distribution networks, which started garnering the attention of food safety authorities in the late 1990s.

In Australia, we haven’t recorded large outbreaks associated with berries, but New Zealand identified an outbreak of 39 cases of hepatitis A associated with locally grown blueberries.

The main likely sources of fresh food contamination are:

  1. Being grown in contaminated water.
  2. Getting contaminated by infected animals, such as livestock, rats, mice or bats, at some stage in the production cycle.
  3. Being picked by people who are infected with hepatitis A.
  4. Mixing with other ingredients contaminated with hepatitis A virus during processing.
  5. Being washed in contaminated water.

There is evidence that fruits, such as berries, and some vegetables, such as tomatoes and sprouts, can sometimes internalise bacteria and viruses during growing. This means that the disease-causing agent may actually be inside the fruit and is almost impossible kill except by cooking.

Throw away any recalled berries you have in the freezer. Source: Philippa McKinlay/Flickr, CC BY-ND

The hepatitis A virus is easily killed by cooking to more than 85 degrees Celsius, which would deal with most other bacteria and viruses. Washing is useful for getting rid of surface contamination of fruits and vegetables, which is sufficient most of the time. But if there is a possibility that foods, such as berries, are contaminated with disease-causing agents, it is best to avoid them altogether.

After a food recall such as this one, investigations by health and food safety agencies will try to create a picture of what happened and when.

In the meanwhile, the key thing for consumers is to avoid infection by making sure they do not eat any of the recalled berries that may be in their freezer.

It is likely that only a small proportion of people who eats these berries will become infected. But if you have eaten them and started to develop any of the symptoms listed above, you should see a doctor as soon as possible.

The ConversationThis article was originally published on The Conversation. (Reblogged by permission). Read the original article.


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