WHO/FAO/OIE: Call It A(H3N2)v

 

 

H3N2 influenza virions –CDC PHIL

# 6029

 

 

When a new flu strain appears there is often some confusion of what to call it, particularly when the HA and NA components are the same as other circulating flu viruses.

 

This is the problem we ran into when a novel H1N1 virus (now officially dubbed  A(H1N1)pdm09) emerged.  The media latched on to `Swine flu’, while scientific publications used a variety of nom de flus, including A/H1N1/09 and pdmH1N1.

 

It took more than two years before a consensus was reached (see WHO: Call It A(H1N1)pdm09).  And while that does not exactly roll off the tongue, it does have the the advantage of being precise.

 

Today we’ve a joint announcement from the World Health Organization, FAO, and OIE on a standardized nomenclature for the recently emergent trH3N2 virus that has been detected in a handful of people across several states since last summer.

 

They’ve decided to go with A(H3N2)v.

 

We’ll have to wait to see if this designation is adopted elsewhere. What will be done if another variant of the A(H3N2) virus should appear is not mentioned.

 

A hat tip to Giuseppe Michieli on FluTrackers for posting the following link.

 

 

Standardization of terminology for the variant A(H3N2) virus recently infecting humans

Joint announcement of FAO, OIE and WHO

23 December 2011

FAO, OIE and WHO continue working closely together to address influenza issues related to public health and animal health.

 

Since July 2011, twelve human cases of infection with a variant influenza A(H3N2) virus have been detected in the United States. To date, no report has been received from elsewhere in the world. This virus has different virological characteristics from current circulating seasonal influenza viruses in humans, and has a new gene constellation: 7 genes from the triple reassortant A(H3N2) viruses known to have been circulating in pigs in the North America and the M gene from an A(H1N1)pdm09 virus, a seasonal virus currently circulating in humans.

 

In order to improve communications and avoid confusion, FAO, OIE and WHO have established a working group of experts to standardize the terminology for variant influenza viruses. The joint recommendation for the above mentioned A(H3N2) virus is: A(H3N2)v , where “v” stands for “variant”.

An example of use of the terminology:

• Sporadic human cases of infection with a variant influenza A(H3N2) virus A(H3N2)v have been reported in the USA. The A(H3N2)v virus is different from seasonal viruses currently circulating in humans.

»» Read More

Iowa: No New trH3N2 Cases

 

H3N2 influenza virions –CDC PHIL

 

# 6028

 

 

Over the past few months we’ve been carefully watching the evolution and spread of a novel swine flu variant called trH3N2, that is a reassortment of the swine H3N2 virus that has acquired the Matrix (M) gene segment from the 2009 H1N1 virus.

 

So far, fewer than a dozen cases have been reported across 4 states - although the suspicion is that additional cases may have gone undetected.

 

While the majority of these cases reportedly had recent contact with swine, three recent cases out of Iowa were notable as they appear to be the result of Human-to-Human (H-2-H) transmission.

 

Nearly a month ago, the CDC released a special MMWR  dispatch that provided details on these three new cases, some background on earlier SOIV (swine origin influenza viruses) cases, and some analysis. 

 

A few excerpts follow (underscores & bolding mine), but follow the link to read the entire dispatch.

 

Limited Human-to-Human Transmission of Novel Influenza A (H3N2) Virus — Iowa, November 2011

Dispatch

November 23, 2011 / 60(Dispatch);1-3

On November 20, 2011, CDC confirmed three cases of swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) virus infection in children in two counties in Iowa. None of the children were hospitalized, and each has recovered from a mild episode of febrile respiratory illness. All three were in contact with one another, and none had a known recent exposure to swine. No additional human infections with this virus have been detected in Iowa, and no evidence of sustained human-to-human transmission of this S-OtrH3N2 virus exists; surveillance is ongoing.

(Continue . . .)

 

 

Understandably, local health officials have been on increased alert, looking for more cases.  Overnight it’s been widely reported that, according to Iowa state health officials, no new cases  of this novel influenza virus have been seen since early November.

 

State Medical Director Dr. Patricia Quinlisk is quoted yesterday by The Des Moines Register (see New flu virus blips out of Iowa as quickly as it appeared) as saying the virus `apparently failed to continue spreading’.

 

Nonetheless, state health officials continue to be on watch for new cases

 

Surveillance isn’t perfect, of course, and relatively few people get tested when they get a flu-like illness. So it is possible (perhaps even likely) that there are some cases out there going undetected.

 

All of which makes it premature to sound the all-clear on this fledgling flu.

 

But this lack of new case detections in the face of enhanced surveillance would seem a pretty good indicator that this flu isn’t ready for prime time, and supports the CDC’s contention that there is no evidence of sustained human-to-human transmission of this S-OtrH3N2 virus.

 

As this trH3N2 virus has been detected in multiple swine herds, and in humans across four states, It would not be unreasonable to expect that we’ll see more cases of this novel flu crop up in the future.

 

The evolution of flu viruses is an ongoing process, and each new host infection presents the virus with another opportunity to evolve and change.

 

At some point, this virus may adapt well enough to human physiology to become a major player on the field of flu. Or it may simply fizzle out, and end up in evolution’s dustbin of failed mutations.

 

Influenza is notoriously unpredictable, and I certainly wouldn’t care to hazard a guess as to what happens next with this virus.

But for now, no flus is good news.

»» Read More

Two New Swine trH3N2 Studies To Ponder

 

 

# 6015

 

 

We’ve two studies to look at today focusing on the trH3N2 swine flu viruses that have been making headlines for several months; one appearing in the Journal of Virology and the other in the journal Eurosurveillance. 

 

First a recap of recent events.

 

Feel free to skip ahead if you are already up to speed on the history of this virus.

 

Excluding the 2009 `swine flu pandemic virus’, there have been 31 `novel’ swine flu infections detected in humans the United States since 2005.

 

Most appear to have been dead-end transmissions, and have come about from direct contact with pigs. The CDC believes only a few may have involved limited human-to-human transmission.

 

Up until last year, the most common strain of S-OIV (Swine-origin influenza virus) found in humans was a trH1N1 strain, but in 2010 we began to see a shift towards trH3N2 viruses.

 

This year, a new reassortant of trH3N2 has appeared on the scene that has picked up a the Matrix (M) gene segment from the 2009 H1N1 virus.

 

Reassorted viruses can result when two different flu strains inhabit the same host (human or otherwise) at the same time. Under the right conditions, they can swap one or more gene segments and produce a hybrid virus.

 

 

Unlike most of the earlier novel swine flu infections, this strain has shown increased signs of low level human-to-human transmission. You’ll find some recent coverage of this emerging swine flu variant in the following blogs:

 

Branswell On The New trH3N2 Flu Virus 

CIDRAP: New Details In The trH3N2 Story 

CDC Update On Iowa trH3N2 Cases

 

While only a small number of these reassorted trH3N2 viruses have been detected, the concern is, that over time it could get better at infecting humans and present a public health threat down the road.

 

 

All of which serves as prelude to today’s studies. 

 

First stop, a brief news summary by CIDRAP of a Journal of Virology article on recent H3N2 detections in Chinese pigs.

 

 

Novel reassortant H3N2 flu found in Chinese pigs

Chinese researchers have isolated three novel H3N2 reassortant viruses from pigs in southern China that contain genetic material from a pH1N1 strain, similar to those associated with 11 recent infections in US patients, according to a report yesterday in the Journal of Virology.

<SNIP>

 

In spite of their separation geographically and chronologically, they are genetically very closely related, the authors write. "This provides direct evidence that the pdm/09-like internal gene complex has been successfully incorporated into a swine H3N2 virus, and been prevalent in the pig population for a period of time," they add.

Dec 14 J Virol abstract

 

Most notable in this summary is that detections of novel trH3N2 viruses in Chinese pigs with the M gene from the pdmH1N1 strain go back well over a year.

 

Next stop, a report in Eurosurveillance that takes a detailed look at the genetic sequences, and evolution of this emerging trH3N2 virus.

 

 

S-OtrH3N2 viruses: use of sequence data for description of the molecular characteristics of the viruses and their relatedness to previously circulating H3N2 human viruses

Eurosurveillance, Volume 16, Issue 50, 15 December 2011

by B Lina, M Bouscambert, V Enouf, D Rousset, M Valette, S van der Werf

 

The authors conducted an analysis of hemagglutinin sequences (HA) from both human and swine-origin influenza A(H3N2) isolates and concluded that this new trH3N2 virus is most closely related (5.5% divergence) to the A/Wuhan/359/95 H3N2 strain that circulated in humans until the mid-1990s.

 

This strain was also incorporated into the seasonal flu shot as late as the 1997-98 northern hemisphere flu season.

 

Based on this study, they suggest that some degree of cross-protection is likely, particularly to those born before 1995.

 

They warn, however:

 

. . . it is impossible to predict if pre-existing immunity will be efficient against this virus, even if it seems likely that some cross-protection will exist; seroepidemiological surveys should be carried out to support or disprove this hypothesis.

 

The authors also express concerns over our current lab test’s ability to detect and identify these novel strains, stating that:

 

. . .  specific RT-PCR methods should be developed, or alternatively, predefined algorithms with already existing discriminating molecular tools need to be implemented.

 

Whether any of these novel swine viruses manages to adapt well enough to humans to pose a significant public health threat is something we will have to wait to see.

 

But even if these novel viruses fail to thrive - and end up as little more than a footnote in the history of influenza - they provide a stark reminder that influenza viruses are constantly evolving and mutating, looking for an evolutionary advantage.

 

We watch these novel viruses closely because history has shown that . . .  given enough time. 

 

They tend to find it.

 

»» Read More

ECDC: Updated Risk Assessment On trH3N2 Virus

 

 

# 6007

 

 

Two weeks ago the ECDC issued a risk assessment for Europe based on the recent detection of a handful of trH3N2 swine flu cases in the United States (see ECDC Risk Assessment On trH3N2 Cases In North America).

 

This assessment was contained in a 7-page PDF document dated November 29th, and concluded  the current threat these reassorted swine viruses pose to public health in Europe was low.

 

They conceded, however, that `It is possible that these triple reassortant infections will appear in Europe, particularly if there is more human-to- human  transmission, which could lead to imported cases.’

 

 

Since then, we’ve reports of at least one more detection of a trH3N2 human infection – this time in West Virginia  (see CDC Confirms 2 More Novel Flu Infections) – along with a trH1N2 virus in Minnesota.

 

In neither case did these patients have recent known contact with swine, and so these reports imply that low level human-to-human transmission may have taken place.

 

Accordingly, the ECDC today has issued an updated risk assessment that finds:

 

 

Conclusions and recommendations

•  Another case of infection with triple reassortant swine influenza SOIVtrA(H3N2)-M has been reported in humans in the US bringing the total of such cases to 11;
•  While human-to-human transmission has probably taken place in the US there are no expanding clusters of infections; 
•  The EU National Influenza Centres are in the midst of strengthening their capacity to detect this new virus which is not thought to be present in pigs in Europe;
•  The conclusions and recommendations of the ECDC Rapid Risk Assessment of 29 November remain valid. 

 

While the number of swine-origin novel flu infections detected in humans has increased this year, the overall numbers remain extremely low. 

 

Influenza activity remains low across the United States (and most of the northern hemisphere) and we are not seeing the kind of explosion in cases that heralded the arrival of the 2009 H1N1 pandemic virus.

 

These viruses are concerning because they show that a novel virus is attempting to circulate – albeit not very efficiently, as yet – among humans.

 

For now, the CDC and public health agencies are increasing their surveillance and testing for this virus, and are doing epidemiological investigations looking for signs of ongoing community transmission.

 

Whether this trH3N2 virus learns to adapt well enough to human physiology to pose a greater public health threat down the road is something we will simply have to wait to see.  

»» Read More

CDC Confirms 2 More Novel Flu Infections

 

H3N2 influenza virions –CDC PHIL

# 6001

 

 

The CDC announced today the detection of two new novel flu isolates; one in West Virginia (trH3N2) and another in Minnesota (A/H1N2).

 

The West Virginia virus isolate is described today by the CDC as being:

 

A novel influenza A (H3N2) virus with genes from swine, human, and avian lineages with the M gene from the 2009 H1N1 virus that was first identified in August 2011. Ten prior human infections with this virus in four other states have been confirmed.

 

This virus is distantly related to an H3N2 virus that circulated 20+ years ago, which may explain why those born after 1990 have made up vast majority of cases detected so far.

 

Earlier posts on those cases include:

 

Branswell On The New trH3N2 Flu Virus

CIDRAP: New Details In The trH3N2 Story

ECDC Risk Assessment On trH3N2 Cases In North America

CDC Update On Iowa trH3N2 Cases

 

The Minnesota isolate is an H1N2 virus that has been known to circulate in swine for some time, and is said to be similar to an H1N1 virus (A/New Caledonia /20/99-like) that circulated as recently as 2007.

In neither case did these patients have recent known contact with swine, and so these reports imply that low level human-to-human transmission may have taken place.

 

First stop, a notice in today’s (otherwise quiet) FluView week 48 Report, followed by some choice excerpts from the latest Have You Heard? statement from the CDC.

 

http://www.cdc.gov/flu/weekly/

Novel Influenza A Viruses:

Two human infections with novel influenza A viruses were detected in children from two states (Minnesota and West Virginia). One patient was infected with a novel influenza A (H1N2) virus and one patient was infected with a novel influenza A (H3N2) virus. Both patients have recovered from their illnesses. While both viruses are known to circulate in U.S. swine, there was no close contact with pigs reported preceding illness onset in either case. Both states have been investigating case contacts and sources of exposure, however, no additional confirmed cases have been detected at this time. Additional information on these cases can be found in the CDC Have You Heard posting.

 

CDC is required to report all cases of human infection with novel influenza viruses – including swine influenza viruses -- to the World Health Organization (WHO) as part of the International Health Regulations (IHR). Domestically, CDC reports these cases in this report and on its website. Early identification and investigation of human infections with novel influenza A viruses is critical to evaluate the extent of the outbreak and possible human-to-human transmission. Additional information on influenza in pigs and swine-origin influenza infection in humans can be found at http://www.cdc.gov/flu/swineflu/.

 

Below are some excerpts from today’s announcement (bolding & reparagraphing mine). Follow the link to read it in its entirety.

 

 

CDC confirms two human infections with novel influenza viruses

December 9, 2011 -- CDC has confirmed two cases of human infection with two different novel influenza A viruses in different states. Both patients have fully recovered. While the viruses infecting both patients have been found in U.S. swine and some of the prior human infections with these viruses have been associated with direct or close swine contact, there are no reports of direct or close contact with swine prior to illness onset in either of these cases. Laboratory testing at CDC has confirmed that both novel viruses are susceptible to the antiviral medications oseltamivir (Tamiflu®) and zanamivir (Relenza®).

<SNIP Narrative on 2 New Cases> 

 

Detection of Swine Influenza Infections in Humans

Human infections with novel influenza A viruses normally found in swine are rare events. Recently, however, the frequency of such detections has increased.

 

This could be occurring for a number of reasons, including one or more of the following factors:

 

First, laboratory methods for testing for these viruses in the United States were improved following the 2009 H1N1 pandemic. These improvements may be resulting in viruses being identified now that would have gone undetected previously.

 

Second, this could be due to increased surveillance in the United States for influenza at this time of year. CDC has requested that states analyze, and then send, their first influenza virus specimens of the season for seasonal influenza surveillance purposes. This practice, coupled with very low levels of seasonal flu activity at this time, could mean that sporadic novel influenza infections are more likely to be tested.

 

Third, it is possible that the increased frequency of detection of novel influenza viruses with swine origins identified by CDC represents a true increase in the number of such cases, possibly occurring from exposure to infected swine  or through subsequent, limited human-to-human transmission.

 

(Continue . . .)

 

 

While the CDC and public health officials are obviously taking these novel virus detections seriously, and are ramping up surveillance to track their spread, it is too soon to know whether any of these new flu strains will take hold in the human population.

 

As I wrote in Pseudo Pandemics And Viral Interlopers it is certainly possible for new strains of influenza to appear and circulate among humans, without sparking a pandemic.

 

Influenza is notoriously unpredictable.

 

For now, we are in a watchful waiting mode; looking for signs that one of these novel viruses is getting better adapted to human physiology.

 

In the meantime, maintaining good flu hygiene this winter (washing/sanitizing your hands, covering coughs & sneezes, staying home when sick), and getting your seasonal flu shot, remain the best strategies to avoid getting sick during this flu season.

»» Read More

Developing A trH3N2 Seed Vaccine

 

 

H3N2 influenza virions –CDC PHIL

# 5990

 

 

 

Excluding the 2009 `swine flu pandemic virus’, there have been 31 `novel’ swine flu infections detected in the United States since 2005. Most of these cases appear to have come about from direct contact with pigs, and the CDC believes they have only involved limited human-to-human transmission.

 

Up until last year, the most common strain of S0IV (Swine-origin influenza virus) found in humans was a trH1N1, but in 2010 we began to see a shift towards trH3N2 viruses.

In November & December of 2010 we learned of three such infections (see CDC: Statement On Swine H3N2 Influenza and CDC: Another Novel H3N2 Isolate) arising from Pennsylvania, Wisconsin, and Minnesota.

 

This year, a new reassortant of trH3N2 has appeared on the scene that has picked up a the Matrix (M) gene segment from the 2009 H1N1 virus.  Unlike most of the earlier novel swine flu infections, this strain has shown some signs of human-to-human transmission.

 

You’ll find some recent coverage of this emerging swine flu variant in the following blogs:

 

Branswell On The New trH3N2 Flu Virus

CIDRAP: New Details In The trH3N2 Story

ECDC Risk Assessment On trH3N2 Cases In North America

CDC Update On Iowa trH3N2 Cases

 

 

While only a small number of these trH3N2 infections have been detected, the assumption is that the virus may be circulating in a limited fashion under the radar. The concern is, that over time, it could get better at infecting humans and present a public health threat down the road.

 

As a precautionary measure, public health officials at the CDC have been working on getting a seed vaccine – a prototype – for this new virus into the hands of vaccine manufacturers. 

 

Robert Roos of CIDRAP NEWS picks up the story, with details on how the CDC is using a similar trH3N2 swine virus – A/Minnesota/11/2010 – as a basis for a potential vaccine.

 

 

Vaccine virus for novel H3N2 based on 2010 swine flu strain

Robert Roos News Editor

Dec 2, 2011 (CIDRAP News) – The Centers for Disease Control and Prevention (CDC) got a head start on preparing a vaccine against the novel swine-origin influenza strain recently found in four states by using a slightly different swine-origin strain that cropped up last year, CDC officials said today.

(Continue . . . )

 

 

While the development of a seed vaccine for this novel strain is a prudent step, it should be noted that even if we assume that surveillance is only picking up a fraction of the cases that are out there, we are a long way from being in a pandemic situation.

 

As I wrote in Pseudo Pandemics And Viral Interlopers it is possible for new strains of influenza to appear and circulate among humans, without sparking a pandemic.

 

Short of causing a pandemic, this emerging trH3N2 virus could just simply sputter for a while and then die out. Or it might develop just enough `legs’ to co-circulate at low levels with our other seasonal flu strains.

 

We’ll have to wait to see if and just how well this virus adapts to human physiology, what level of immunity already exists in the population, and whether this strain is virulent enough to cause significant morbidity and mortality.

 

All factors that will determine the ultimate threat posed by this – or any other – emerging flu strain.

 

For now, the news is reassuring.

 

• Flu activity remains low across the nation. 
• Only a handful of cases of trH3n2 have been identified.
• Most of those cases have involved mild to moderate illness.
• And work on a vaccine, should it be needed, is already underway.

 

Influenza, of course, is hugely unpredictable.  What is true today may not hold true tomorrow.

 

This trH3N2 strain which has captured our attention over the past year could become a big story over the next few months, or it may turn out to be an interesting footnote in the history of influenza.

 

Stay tuned.

»» Read More

Branswell On The New trH3N2 Flu Virus

 

H3N2 influenza virions –CDC PHIL 

# 5989

 

 

Helen Branswell has an article this morning in Scientific American on the trH3N2  swine flu viruses that have recently been found in a handful of patients across Indiana, Iowa, Pennsylvania, and Maine.

 

Since no one does this sort of thing better than Helen, I’m going to do the smart thing and just step aside and invite you to read:

 

 

New Flu Strain Makes Health Experts Nervous

Is a new strain of H3N2 swine flu a danger to public health or just to the reputations of public health experts?

By Helen Branswell  | December 2, 2011

 

 

For some of my earlier coverage of this story, you may wish to revisit:

 

CIDRAP: New Details In The trH3N2 Story

Pseudo Pandemics And Viral Interlopers

CDC Update On trH3N2 Swine Infections

 

»» Read More

CIDRAP: New Details In The trH3N2 Story

 

 

 

# 5984

 

 

When it comes to flu and/or infectious disease-related reporting, CIDRAP NEWS is high up on my (admittedly) short list of media sources that I consider to be sane, credible, and reliable.

 

Eschewing hyperbole and unsubstantiated speculation, News Editor Robert Roos & staff writer Lisa Schnirring do a terrific job cutting to the chase, without leaving out important details.

 

Last night Lisa put together an overview of the emerging trH3N2 story, including some news we’d not seen before; that USDA sponsored surveillance has detected a number of reassortant H3N2 viruses in swine recently, including 8 that display the 2009 H1N1 matrix (M) gene.

 

This M gene is the same one shared by the trH3N2 virus that has – at last count – infected at least 10 people across four states over the past few months.

 

At this point I’ll simply step aside and direct you to:

 

New details emerge in novel H3N2 reports

Lisa Schnirring Staff Writer

Nov 29, 2011 (CIDRAP News) – New details about the three most recent human infections with a novel swine-origin influenza virus have emerged over the past few days, along with a preliminary report of similar viruses in a few pigs.

(Continue . . .)

 

 

If you have not already done so, I would invite you to read Helen Branswell’s terrific SciAm feature from last December called Flu Factories which looks at the potential for novel flu viruses to emerge from the farm. 

 

It is an absolute must read.

Flu Factories

The next pandemic virus may be circulating on U.S. pig farms, but health officials are struggling to see past the front gate

By Helen Branswell  | December 27, 2010 |

»» Read More

ECDC Risk Assessment On trH3N2 Cases In North America

 

 

# 5983

 

My thanks to Helen Branswell for tweeting the link to this new risk assessment from the ECDC on the recent trH3N2 cases detected in a handful of people (mostly children) across four states here in the US (see MMWR Dispatch: Limited H-2-H Transmission Of Novel A(H3N2) Virus.)

 

The 7-page PDF document considers the current threat these reassorted swine viruses pose to public health in Europe to be low.

 

They concede, however, that `It is possible that these triple reassortant infections will appear in Europe, particularly if there is more human-to- human  transmission, which could lead to imported cases.’

 

 

ECDC rapid risk assessment: Swine-origin triple Reassortant influenza A(H3N2) viruses in North America

29 Nov 2011

Centers for Disease Control and Prevention (CDC) has reported recent infections in children in North America with a swine-origin triple reassortant influenza A(H3N2) virus that includes a genetic component from the pandemic 2009 virus, and with probable human-to-human transmission with these viruses.

 

ECDC has conducted a rapid risk assessment to evaluate the implications for public health in Europe.

ECDC rapid risk assessment: Swine-origin triple reassortant influenza A(H3N2) viruses in North America (29 November 2011)

A few excerpts from the summary follow, but the entire document is worth reading:

 

Conclusions and recommendations

Following recent infections in children in North America with a swine-origin triple reassortant influenza A(H3N2) virus that includes a genetic component from the pandemic 2009 virus, and with probable human-to-human transmission of these viruses, ECDC has come to the following preliminary opinion:

•  These viruses are known to be found in pigs in North America but they have not been found in pigs in Europe (EU/EEA countries). However, surveillance for influenza in pigs is weak in both North America and Europe, and surveillance for infections in humans in close contact with pigs is notably weak in Europe. Hence all such statements on the epidemiology of swine influenzas must be treated with caution.   

 

•  Most of the US cases experienced only mild disease. Those hospitalised had underlying conditions and all patients recovered completely.

•  These viruses are susceptible to the neuraminidase inhibitors (oseltamivir and zanamivir) though the current A(H3N2) component of seasonal influenza vaccines is unlikely to provide protection. Older people are likely to have some protection from exposure to earlier vaccines.

•  It is considered by the United States Centers for Disease Control (CDC) that there had already been some very limited human-to-human transmission of these and similar viruses in the US. 

•  Unlike in March 2009 (the start of the pandemic) there are no reports of numbers of unexplained influenza infections elsewhere in the Americas. Hence it is unlikely that these US cases represent outliers for a larger phenomenon. 

•  Overall, therefore, the immediate direct threat to human health in Europe is low.

•  ECDC staff are following the situation closely and are in direct contact with the WHO, the US CDC and relevant experts in EU Member States.

•  There is a need to ensure that these infections could be detected through  diagnostic testing in European national influenza laboratories. 

•  There are strong public health arguments for more active virological surveillance of pig herds in Europe (and North America) including active surveillance of infections in humans that are in direct or indirect contact with pigs.  

 
•  Equally justified are more formal approaches to assessing emerging influenza viruses for their pandemic potential and such virological risk assessments should continue to be developed. 

 

•  Unusual influenza viruses should continue to be referred to National Influenza Centres and on to the WHO Collaborating Centre in Europe, along with relevant clinical and epidemiological data.   

 

 

For more on this emerging  story, you wish to revisit some of these earlier blogs:

 

Pseudo Pandemics And Viral Interlopers

CDC Update On trH3N2 Swine Infections

CDC Update On trH3N2 Cases

CDC Update On Recent Novel Swine Flu Cases

MMWR: Swine-Origin Influenza A (H3N2) Virus Infection in Two Children

»» Read More

Branswell On The WHO Response To trH3N2

 

 

H3N2 influenza virions responsible for casing illness in Indiana and Pennsylvania in 2011 Source – CDC Phil

# 5979

 

 

We’ve a terrific behind-the-scenes look via Helen Branswell on the World Health Organization’s thinking, and initial response to the recent trH3N2 swine-origin flu cases detected across four US states.

 

Helen is not only one of the best health and science writers on the planet, she also arguably has the best rolodex in the business (ok, with that archaic reference, I’m showing my age). 

 

You’ll find quotes from a `dream team’ of flu experts including Dr. Keiji Fukuda of the WHO, Dr. Arnold Monto of the University of Michigan, Dr. Nancy Cox of the CDC,  and renown virologist Dr. Malik Peiris of the University of Hong Kong.

 

At issue is what is the appropriate early response to the recent emergence of this new trH3N2 virus?

 

First, Helen’s article.  By all means, follow the link and read it in its entirety. When you come back, I’ll have a little more.

 

WHO trying to hit the sweet spot in responding to puzzling new flu virus

By: Helen Branswell, The Canadian Press

The spread of an odd new flu virus that has been jumping from pigs to people in parts of the United States has the World Health Organization gearing up its response planning, a senior official of the agency says.

 

The UN health body is figuring out what needs to be done if the virus continues to spread and a global response is required, Dr. Keiji Fukuda, assistant director-general for health security and environment said in an interview from Geneva.

 

(Continue . . . )

 

 

As I wrote yesterday in Pseudo Pandemics And Viral Interlopers, the appearance of a new virus – even one that demonstrates the ability to transmit among humans – isn’t a guarantee of a pandemic.

 

It didn’t happen in 1951 with the Liverpool flu or in 1976 with the swine flu, and it very well may not happen with this new trH3N2.

 

But you can’t just assume this virus will go away either.  It could adapt further to humans as it circulates, and in time, it could become a larger public health threat.

 

After the pillorying that the WHO took during the summer of 2009 over their declaration of a pandemic, they are understandably cautious today.

 

Call it a public relations lesson learned . . .  even though the 2009 H1N1 virus was a pandemic. It just didn’t fit the public’s perception of what a pandemic should look like.

 

Constant readers are no doubt aware that I’ve adopted a `wait and see’ attitude on this virus. While I’ve devoted more than a dozen blogs to its recent arrival, I’m not altogether convinced that it will spark the next pandemic.

 

I only accept that it could.

 

But then, so could H5N1, H9N2, or any of a handful of other viruses circulating around the world.

 

Given the uncertainty over the timing of the next public health crisis, and the potential for seeing many other types of disasters and emergencies, it only makes sense to make individual, business, and community preparedness a priority.

 

After all, if you are well prepared for an earthquake or a hurricane, you are probably reasonably well prepared to deal with a pandemic.

 

To learn how to prepare as an individual, family, business owner, or community I would invite you to visit the following sites and use THIS LINK to access some of my preparedness blogs.

 

FEMA http://www.fema.gov/index.shtm

READY.GOV http://www.ready.gov/

AMERICAN RED CROSS http://www.redcross.org/

 

I discovered long ago the secret to sleeping soundly at night; that preparing is easy.

 

It’s worrying that’s hard

»» Read More

WHO Statement On Novel trH3N2 Cases In The US

 

 

# 5977

 

The World Health Organization has posted a statement regarding the ongoing detection of sporadic infections by a novel swine-origin triple reassorted H3N2 virus in the United States.

 

You’ll find the CDC’s Statement from yesterday HERE, and the MMWR dispatch with details on the three latest cases HERE.

 

 

Influenza like illness in the United States of America

24 November 2011 - The United States Government has reported three cases of human infection with swine origin triple reassortant Influenza A H3N2. Between 10 and 13 November 2011, three children (aged 11 months, 2 years and 3 years) experienced onset of febrile respiratory illness. All three children had visited the same health care provider in Iowa State. None of them were hospitalized and all three have recovered.

 

Laboratory testing conducted on 18 November 2011 in the State Hygienic Laboratory at the University of Iowa showed a swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) virus. This was confirmed by sequencing at the Centers for Disease Control and Prevention (CDC) on 20 November.

 

The three children attend the same daycare facility. There is an ongoing investigation and to date, no epidemiological link to swine has been identified in any of the three children. Additional investigation is currently underway to identify and characterize the illness in other daycare attendees, family members, or other contacts, and to determine any exposure to swine.

 

These are 16th, 17th and 18th cases of human infection with swine origin triple reassortant influenza A (H3N2) detected in the United States since 2009, and the 8th, 9th, and 10th cases reported this year.

 

WHO is closely following the situation with the US Government, CDC and other partners.

 

»» Read More

MMWR Dispatch: Limited H-2-H Transmission Of Novel A(H3N2) Virus

 

 

# 5976

 

 

For the past several months we’ve been watching an evolving story involving a newly identified swine flu variant (S-OtrH3N2) that has now been detected in 10 people (mostly children) across 4 states.

 

For more on those earlier cases see:

 

CDC Update On trH3N2 Swine Infections

Maine Confirms A 2nd trH3N2 Case

CDC Update On trH3N2 Cases

A 5th trH3N2 SOIV Report

CDC Update On Recent Novel Swine Flu Cases

MMWR: Swine-Origin Influenza A (H3N2) Virus Infection in Two Children

 

Although the majority of these cases have had recent potential contact with swine, the latest three cases out of Iowa appear to be the result of Human-to-Human (H-2-H) transmission.

 

Late yesterday the CDC released a special MMWR  dispatch that provides details on these three new cases, some background on earlier SOIV (swine origin influenza viruses) cases, and some analysis. 

 

A few excerpts follow (underscores & bolding mine), but follow the link to read the entire dispatch.

 

Limited Human-to-Human Transmission of Novel Influenza A (H3N2) Virus — Iowa, November 2011

Dispatch

November 23, 2011 / 60(Dispatch);1-3

On November 20, 2011, CDC confirmed three cases of swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) virus infection in children in two counties in Iowa. None of the children were hospitalized, and each has recovered from a mild episode of febrile respiratory illness. All three were in contact with one another, and none had a known recent exposure to swine. No additional human infections with this virus have been detected in Iowa, and no evidence of sustained human-to-human transmission of this S-OtrH3N2 virus exists; surveillance is ongoing.

 

Eighteen human infections with swine-origin influenza A (H3N2) viruses have been identified since 2009 (1,2). The most recent 10 cases, including the three Iowa cases described in this report, were infections with S-OtrH3N2 viruses containing the matrix (M) gene from the pandemic 2009 influenza A (H1N1) virus (pH1N1). These viruses are considered reassortant viruses between a swine-origin influenza A (H3N2) virus circulating in North American swine and a pH1N1 virus. All cases of human infection with S-OtrH3N2 virus containing the M gene from the pH1N1 virus have occurred in 2011 and have been reported from four states: Pennsylvania (three cases), Maine (two), Indiana (two), and Iowa (three) (3).

Case Reports

Patient A. In the second week of November 2011, patient A, a previously healthy female child, experienced acute onset of influenza-like illness (ILI). Three days after her illness onset (illness day four), she was seen by a health-care provider, who obtained a respiratory specimen and performed a rapid influenza diagnostic test, which was positive.

As part of routine influenza surveillance, the respiratory specimen was forwarded to the University of Iowa State Hygienic Laboratory (SHL) for further evaluation. Patient A's brother experienced onset of ILI 1 day before patient A's date of illness onset. Patient A's brother was not tested for influenza but was treated with oseltamivir by a health-care provider and has recovered. During her illness days two and three, patient A was in contact with her father, who subsequently developed ILI 2 days after his most recent contact with patient A. He was not tested for influenza. No other household member has reported respiratory illness. No family member reported exposure to swine before their illness onset. On her illness day one, patient A attended a small gathering of children.

Patients B and C. Patient B is a previously healthy male child who developed ILI 2 days after patient A's first day of illness. He is the sibling of patient C, a previously healthy male child who developed ILI 1 day after patient B's illness onset. Both children were seen by a health-care provider 2 days after patient B's illness onset; rapid influenza diagnostic testing was positive for both patients. As part of routine influenza surveillance, respiratory specimens were forwarded to SHL for further evaluation. The mother of patients B and C reported that no other household member had a respiratory illness and none had been exposed to swine before patient B became ill. On patient A's illness day one, patients B and C attended the same small gathering of children as patient A.

Epidemiologic and Laboratory Investigations

An investigation by the Iowa Department of Public Health (IDPH) determined that the families of patients A, B, and C reported no recent travel or attendance at community events. To date, the only epidemiologic link among patients A, B, and C that has been identified is attendance at a gathering of children on patient A's illness day one. No illnesses were reported among adults or among the five other children who were present at this gathering on that day. No swine exposures have been identified among adults or children attending this gathering. IDPH has detected no increase in absenteeism or reports of respiratory illness in the community where patients A, B, and C reside or in the schools in the community.

Enhanced surveillance for ILI has been implemented in health-care facilities in the communities where patients A, B, and C reside. IDPH has instructed health-care providers to obtain respiratory specimens from patients with ILI for influenza diagnostic testing at SHL. Thus far, no additional cases of S-OtrH3N2 infection have been identified, and surveillance data from the state have shown low levels of influenza activity currently and at the time of all these patients' illnesses.

(Continue . . . )

 

 

Swine are highly susceptible to the influenza virus, and are capable of serving as `mixing vessels’, allowing them to reassort into new hybrid strains.

 

Reassortment happens when two different influenza viruses co-infect the same host, swap genetic material, and produce a hybrid virus. 

 

 

That is essentially what happened in 2009, when the H1N1 swine flu virus emerged after bouncing around swine herds for a decade or more, picking up genetic changes along the way.

 

And not surprisingly, this recently emergent `humanized’  H1N1 virus has re-entered the swine population and is once again mixing and matching with other circulating swine flu viruses.

 

As a result we now have a Swine H3N2 virus that has reassorted with the 2009 pandemic H1N1 virus, producing a new hybrid that has – in a limited fashion – begun to emerge into the human population.

 

Whether this virus has `legs’, and can sustain itself in the human population, is something we’ll simply have to wait to see. 

 

Regardless of what this virus does - with our regular flu season nearly upon us - the best advice from the CDC is to maintain good flu hygiene this winter (cover your coughs, wash your hands, stay home if you are sick), and to get the seasonal flu shot.

 

While the public health threat from this emerging swine virus appears low for now, this is obviously a story we’ll continue to follow with considerable interest.

»» Read More

CDC Update On Iowa trH3N2 Cases

 

 

# 5975

 

 

The CDC has posted an update on their Have you heard? webpage on the recent detection of 3 additional trH3N2 cases, this time in Iowa.

 

You’ll find earlier blogs on these latest cases here and here.

 

The CDC is currently characterizing these latest cases as `unsustained human-to-human transmission’. I’ve reproduced the entire statement below.

 

 

Iowa Reports Novel Influenza Infections in Three Children

November 22, 2011

The Iowa Department of Public Health today reported that a “novel strain of the influenza virus has been detected in three children.” All three of the children were reportedly mildly ill and have recovered. Iowa has increased surveillance for influenza-like-illness to detect any additional cases of infection with this novel virus.

 

All three patients are young children who were in contact with one another. All cases were detected at the state public health laboratory through virologic surveillance. An investigation is ongoing but no additional cases have been identified.

 

Testing at CDC has confirmed that these viruses are similar to the swine-origin influenza A (H3N2) viruses identified in three other states. These viruses contain the “matrix (M) gene segment” from the pandemic 2009 H1N1 virus. This combination of genes was first identified in a person in July. Since then, several additional human infections with this virus have been detected, bringing the total number of human infections to 10 (Indiana 2, Pennsylvania 3, Maine 2, and Iowa 3). All 10 patients have recovered and the majority of cases had relatively mild illness, although 3 patients were hospitalized.

 

CDC has reported on the previous infections on its website, in the FluView activity report, and in the Morbidity and Mortality Weekly Report. Links to all previous reports related to this virus are available on the CDC swine influenza website at http://www.cdc.gov/flu/swineflu/index.htm.

 

These viruses are substantially different from human influenza A (H3N2) viruses, so the seasonal vaccine is expected to provide limited cross-protection among adults and no protection to children. However, laboratory testing so far indicates these viruses are susceptible to the antiviral drugs oseltamivir (Tamiflu®) and zanamivir (Relenza®). CDC recommends these drugs for treatment of seasonal and these swine-origin influenza viruses.

 

Prior to the three cases in Iowa, most human infections with this virus were associated with exposure to swine. In Iowa, however, no swine exposure has been identified. At this time, it appears that unsustained human-to-human transmission may have occurred. These viruses have been reported in swine in several states in the United States. Swine influenza viruses do not spread through contact with pork or pork products. Eating properly handled and cooked pork is safe.

 

As part of routine preparedness measures to counter possible pandemic threats posed by novel influenza viruses in the event that they gain the ability to spread easily from person-to-person, CDC has developed a candidate vaccine virus and provided it to manufacturers.

 

These cases will be officially reported in the MMWR and FluView.

»» Read More

More Details On The trH3N2 Story

 

 

 

# 5974

 

 

The announcement yesterday out of Iowa that 3 more children have contracted a rare emerging swine flu strain (see Iowa DPH Reports 3 Novel trH3N2 Cases) has produced a number of headlines over the past 18 hours.

 

The most significant piece of new information since then is that all three children had contact with one another, and that it appears that one child transmitted the virus to the other two.

 

No additional transmission has thus far been detected, and the the mystery of how and where the first child acquired the virus remains.

 

As might be expected, Helen Branswell of the Canadian Press has some of the best and most complete coverage of this story.  

 

A link to her story (which I encourage you to read in its entirety), then I’ll be back with a little more.

 

U.S. sees 3 new infections with new flu virus

The Canadian Press

Date: Tuesday Nov. 22, 2011 8:59 PM ET

U.S. health officials have spotted three more children infected with a new swine-origin flu virus, this time in Iowa.

 

And while earlier cases of infection with this virus are believed to have been cause by exposure to pigs, this time the evidence points to person-to-person spread.

(Continue . . . )

 

 

Occasionally we’ll see a novel swine influenza virus (usually an H1N1 or H3N2 variant) jump to humans. Although the 2009 swine flu pandemic was an exception, most of the time this turns out to be a one-off dead-end transmission, and goes no further.

 

The key phrase being `most of the time’. 

 

While it is a rare event, as we saw in 2009 it is possible for one of these viruses to adapt well enough to human physiology to spark an extended outbreak, or even a pandemic.

 

Since only a tiny fraction of influenza flu viruses are ever sequenced, we really don’t know how often these types of novel infections occur.

 

It’s probably more often than we think.

 

But surveillance systems must be incredibly lucky, or wait until a novel virus has infected a sufficient percentage of the population, before they are likely to start picking up cases.

 

In these ten most recently reported cases, the virus has been a swine H3N2 virus with the M segment gene borrowed from the 2009 H1N1 virus. Essentially a hybrid – a new reassortant virus - that until this summer had not been seen before.

 

Reassorted viruses can result when two different flu strains inhabit the same host (human or otherwise) at the same time. Under the right conditions, they can swap one or more gene segments and produce a hybrid virus.

 

 

Where this virus goes from here is anyone’s guess.

 

Its appearance across four states, and in some humans without direct animal contact, certainly suggests low-level human transmission.

 

But the ability to transmit from one human to another isn’t enough to ensure its survival. In order to thrive, it must have an R₀ number (basic reproductive number) sufficient to sustain an outbreak.

 

The R₀  number signifies the average number of secondary infections caused by one infectious person entering a totally susceptible population. 

 

If less than 1.0, outbreaks are likely to sputter and die out.  If greater than 1.0, the outbreak is more capable of spreading. 

 

 

And as we’ve seen with roughly two dozen other reported novel swine infections since 2005, and with a significant number of H5, H7, and H9 avian flu infections, it is possible to have limited outbreaks of a novel flu virus without it sparking an epidemic.

 

For now, this virus doesn’t appear to be sufficiently well adapted to human physiology to spread in an efficient and sustained manner.

 

This virus may simply simmer at low levels in the human population for a spell, then die out. Or it may further adapt to humans, and produce a larger public health threat down the road.

 

We’ll simply have to keep our eyes on this story, to see where it goes.

 

In the meantime, maintaining good flu hygiene this winter, and getting your flu shot, remain the best strategies to avoid getting sick during this flu season.

»» Read More

Iowa DPH Reports 3 Novel trH3N2 Cases

 

Note: This story is updated at  More Details On The trH3N2 Story

 

# 5973

 

Reassortant H3N2 virus detected in Pennsylvania,Indiana & Maine – Source CDC

The Iowa Department of Public Health announced today in a brief press release that they have detected three cases of a novel trH3N2 SOIV (Swine Origin Influenza Virus) described as being similar to the ones reported recently in Indiana, Pennsylvania, and Maine.

 

For more on those earlier cases see:

 

CDC Update On trH3N2 Swine Infections

Maine Confirms A 2nd trH3N2 Case

CDC Update On trH3N2 Cases

A 5th trH3N2 SOIV Report

CDC Update On Recent Novel Swine Flu Cases

MMWR: Swine-Origin Influenza A (H3N2) Virus Infection in Two Children

 

Unlike the majority of cases reported over the past few months, these three cases report no animal exposure, and so limited Human-to-Human spread is suspected.

 

My thanks to Carol@SC on the Flu Wiki for posting a news item that led me on a search to find this news release from the Iowa DPH.

 

 

Flu Activity in Iowa Includes Novel Strain

Posted: Tue, 22 Nov 2011 15:09 CST

Important to cover your cough and stay home when sick

Routine surveillance by the Iowa Department of Public Health (IDPH), the State Hygienic Lab and other partners across the state indicate that a novel strain of the influenza virus has been detected in three children in Webster and Hamilton Counties.

This virus, an influenza A/H3N2 recombinant virus, has also been detected in other states in recent months. Symptoms are similar to the regular seasonal flu and include fever, cough, tiredness, body aches and loss of appetite.This influenza A/H3N2 virus contains components of human, avian, H1N1, and swine influenza.

All spread has been human to human, and spread appears to be limited; no further cases have been identified in the last week. None of the cases have had any animal exposure. Because the virus is unique, IDPH has increased surveillance for this strain at clinics and emergency rooms.

 

“It appears the seasonal influenza vaccine currently available may offer some protection against this novel strain,” said IDPH Medical Director, Dr. Patricia Quinlisk. “However, we continue to stress the importance of personal protective actions. Remember the three Cs: Clean you hands frequently; Cover your coughs and sneezes; and Contain germs by staying home when ill.”

 

No serious illness or death has been reported in connection with this novel influenza A/H3N2 virus, and all cases have recovered. For more information on the virus, visit www.idph.state.ia.us/Cade/Influenza.aspx?pg=FluHome .

 

While unusual, human infections by novel swine viruses are not unheard of.  Over the past 5 years more than 2 dozen (trH1N1 & trH3N2) cases have been detected.  Most are a result of direct exposure to swine, although limited human-to-human transmission appears to have occurred.

 

Since these novel H3N2 infections continue to appear in low levels across the upper Midwest,this is obviously a story we will continue to follow.

»» Read More

MMWR Reports 8th trH3N2 Case Of 2011

* * * UPDATED * * *

 

Source – CDC

 

# 5954

While no details have been released yet (we’ll probably get something in tomorrow’s FluView ), today’s MMWR from the CDC lists an 8th trH3N2 human infection, once again from the state of Maine.

 

 

This makes the third case from Maine (or possibly not . . .see the update below), which - along with 3 others in Pennsylvania, and 2 out of Indiana – have been detected since late summer.

 

UPDATE: Based on comments offered by Alert on FluTrackers,  I’m now not certain whether this 8th case reported in today’s MMWR represents a 3rd case in Maine, or is simply a delayed reporting of the 2nd case from late October.

 

We’ll need to wait for clarification from the CDC in order to know for sure.  In any event . . .

 

Triple Reassortant (tr) influenza viruses contain genetic material from avian, swine, and human flu strains. In the case of the 7 reported over the past few months, the H3N2 swine virus has recently picked up the M gene segment from the 2009 H1N1 pandemic virus.

 

We’ll have to wait for confirmation from the CDC as to whether this latest trH3N2 virus matches the earlier isolates genetically (again, see the update above)

 

Epidemiological investigations are ongoing in all three states, and so far it appears that most of the cases have had recent opportunities for exposure to pigs. However, the exact route of transmission has not been firmly established.

 

For some background on all of this, the CDC updated their Swine Flu In Humans webpage three days ago:

 

 

Reported Human Infections with Swine Origin Influenza Viruses (SOIV) in the United States since 2005

As of October 31, 2011, 28 cases of human infection with swine origin influenza viruses have been reported in the United States. These are viruses that normally infect pigs. Like human influenza viruses, there are different subtypes and strains of swine-origin influenza viruses. The main swine influenza viruses circulating in U.S. pigs in recent years are swine triple reassortant (tr) H1N1 influenza virus, trH3N2 virus and trH1N2 virus.

 

Of the 28 human cases reported since 2005, 12 have been trH1N1 viruses, 15 have been trH3N2 viruses and one has been a trH1N2 virus. All 28 persons infected with swine viruses recovered from their illness. Twenty cases occurred in children (persons 18 or younger) and 8 cases occurred in adults. In 24 cases, direct or indirect exposure to swine prior to onset of illness has been identified.

 

Likely transmission of swine-origin influenza virus from close contact with an infected person has been observed in investigations of human infections with swine-origin influenza A virus, but has not resulted in sustained human-to-human transmission.

 

 

The concern here is that given enough opportunities, this virus might evolve into a more human-adapted virus. 

 

Over the past couple of decades we’ve seen a small number of avian, swine, and triple reassortant viruses sporadically jumping from the barnyard to infect humans – but only one has managed to spark a pandemic.

 

Given limited testing and surveillance around the globe, how often these sorts of human infections really happen is unknown. But it is probably safe to assume we only learn about a fraction of them.

 

Like the H5N1, H9N2, H7N7, and other swine and avian flu strains, we watch these sporadic human trH3N2 infections with considerable interest  - not because of the public health threat they pose today - but because of the threat they may potentially pose tomorrow.

 

Earlier blogs on these emerging triple reassortant viruses include:

 

CDC Update On trH3N2 Swine Infections

Maine Confirms A 2nd trH3N2 Case

CDC Update On trH3N2 Cases

A 5th trH3N2 SOIV Report

CDC Update On Recent Novel Swine Flu Cases

MMWR: Swine-Origin Influenza A (H3N2) Virus Infection in Two Children

»» Read More