Seroprevalence Study: Avian Flu In Chinese Pigs

 

Since pigs can be infected by more than one flu virus at the same time, the potential exists for two viruses to swap genetic material (reassort), resulting in a new hybrid strain.

 

# 6796

 

Although we tend to think of H5N1 whenever someone mentions `avian flu’, in truth there are many different avian influenza viruses.  If you go back far enough, all influenza A strains – even those thought of today as primarily adapted to humans, equines, or swine – appear to have an avian origin.

 

Influenza A viruses have 8 gene segments (PB2, PB1, PA, HA, NP, NA, M1, M2, NS1, NS2) and are broadly categorized by their HA (hemagglutinin) and NA (neuraminidase) genes.

 

With the recent discovery of H17N10 (see A New Flu Comes Up To Bat), scientists have now identified 17 different serotypes of Hemagglutinin (HA) and 10 serotypes of Neuraminidase (NA), which make many different combinations of HA and NA proteins possible.

Thus far, only about 100 of these combinations have been isolated in nature.

 

But the flu universe is far more diverse than that might lead to you believe, as influenza’s 8 gene segments are largely interchangeable parts. If you were to take two different influenza A viruses (say H3N2 and H5N1) and reshuffle them using reverse genetics, you can come up with 254 possible reassortments.

 

And within each of these HA/NA combinations you can have multiple clades (genetically distinct families), and within each clade, many minor variants – all of which makes for tremendous variety in these viruses.

 

Many of the the H1, H2, and H3 viruses have adapted to human physiology, but we occasionally see infection by other `novel’ strains. Most worrisome, due to its high fatality rate, is H5N1.  But we occasionally see (usually mild) infections by other avian strains.

 

MMWR: Mild H7N3 Infections In Two Poultry Workers - Jalisco, Mexico)

EID Journal: Human Infection With H10N7 Avian Influenza

PLoS One: Seroprevalence Of H9N2 In Poultry Workers – Pune, India

 

Last year scores of dead seals were discovered along the shoreline of New England, predominantly from the North Shore of Massachusetts to the southern coast of Maine.  Investigations showed (see mBio: A Mammalian Adapted H3N8 In Seals) their deaths to be due to a variant of the H3N8 avian flu strain, versions of which are known to also infect horses and dogs.

 

With the propensity of these avian strains to evolve and adapt, scientists are understandably very interested in any avian flu virus that appears to be moving towards `humanization’.

 

While it is possible for a flu virus to jump directly from birds to humans, often it requires an intermediate host to aid in its development. The graphic below illustrates that swine – which are generally susceptible to human and avian flu viruses - are considered excellent mixing vessels’ for influenza viruses.

 

 

The H1N1 `swine flu’ virus of 2009 kicked around in pigs for up to a decade before it adapted well enough to human physiology to spark a human pandemic. Over the past few years we’ve watched attempts by three other swine `variant’ viruses (H1N1v, H1N2v, H3N2v) to jump to mankind. 

 

Which makes the active surveillance of swine a potentially important tool for the early detection of emerging influenza viruses.

 

Unfortunately, while there are some surveillance systems in place, only a tiny fraction of the world’s swine population is actively monitored  (see Helen Branswell’s SciAm Article from late 2010 called Flu Factories).

 

All of which serves as prelude to a new study, recently published in the Journal of Clinical Microbiology, that found low levels of H3, H4, and H6 subtypes of avian influenza in Chinese pigs. Somewhat reassuringly, evidence of infection with the H5N1 virus was not found.

 

These H3, H4, and H6 avian viruses were not seen in a similar study done in 2001, suggesting their arrival into the swine population may be a recent development.

 

 

Seroepidemiological Evidence of Avian Influenza A Virus Transmission to Pigs in Southern China

Shuo Su, Wenbao Qi, Jidang Chen, Wanjun Zhu, Zhen Huang, Jiexiong Xie, and Guihong Zhang

J. Clin. Microbiol. published ahead of print 21 November 2012 doi:10.1128/JCM.02625-12

ABSTRACT

Recently, three novel avian-origin swine influenza viruses (SIVs) were first isolated from pigs in Guangdong Province, southern China, yet little is known about the seroprevalence of avian influenza among pigs in southern China. Here, we report for the first time the seroprevalence of avian H3, H4, and H6 influenza viruses in swine populations and the lack of seroepidemiological evidence of avian H5 influenza transmission to pigs in China.

 

A copy of the study can be downloaded here.

 

The American Society for Microbiology has published a press release with more information, excerpts of which you’ll find below:

 

 

 

Pigs in southern China infected with avian flu

WASHINGTON, DC – December 19, 2012 -- Researchers report for the first time the seroprevalence of three strains of avian influenza viruses in pigs in southern China, but not the H5N1 avian influenza virus.  Their research, published online ahead of print in the Journal of Clinical Microbiology, has implications for efforts to protect the public health from pandemics.

 

Influenza A virus is responsible both for pandemics that have killed millions worldwide, and for the much less severe annual outbreaks of influenza. Because pigs can be infected with both human and avian influenza viruses, they are thought to serve as “mixing vessels” for genetic reassortment that could lead to pandemics, and pigs have been infected experimentally by all avian H1-H13 subtypes. But natural transmission of avian influenza to pigs has been documented only rarely.

 

In the study, from 2010-2012, Guihong Zhang and colleagues of the College of Veterinary Medicine, South China Agricultural University, Guangzhou, People’s Republic of China, tested 1080 21-25 week old pigs for H3, H4, H5, and H6 subtypes of avian influenza virus, and H1 and H3 subtypes of swine influenza virus. Thirty-five percent of the serum samples were positive for H1N1, and 19.7 percent were positive for H3N2 swine flu virus, and 0.93 percent, 1.6 percent, and 1.8 percent were positive, respectively, for the H3, H4, and H6 subtypes of avian influenza A virus. However, no serum samples collected in 2001 were positive for any of these viruses, indicating that transmission into swine was recent.

 

Given the recent transmission of avian influenzas into swine, “We recommend strongly that the pork industry worldwide should monitor the prevalence of influenza in pigs, considering their important role in transmitting this virus to humans,” says Zhang.

 

Previously, novel reassortant H2N3 influenza viruses were isolated from US pigs, which “were infectious and highly transmissible in swine and ferrets without prior adaptation,” according to a 2009 paper in the Journal of Molecular and Genetic Medicine by Wenjun Ma et al. Those viruses resembled, but were not identical to the H2N2 human pandemic virus of 1957.

 

 

The ability of influenza viruses to evolve, mutate, or reassort in swine hosts has been a frequent topic of discussion in this blog.  For more on this, you may wish to revisit:

 

H3N2v: When Pigs Flu

You Say You Want An Evolution?

The (Swine) Influenza Reassortment Puzzle

»» Read More

Barnstorming Avian Flu Viruses?

Photo Credit – FAO

 

# 6782

 

 

My thanks to Helen Branswell this morning for tweeting the link to a new study that suggests that avian influenza viruses can be spread over considerable distance by the wind.  

Long time readers will recall we’ve visited this question a couple of times before. We’ll review those, but first, the new study which looked at the extensive outbreak of H7N7 in the Netherlands in 2003.

 

From the Journal of Infectious Diseases (the full study is behind a pay wall), we get a fair idea of their findings via the Abstract.

 

Genetic data provide evidence for wind-mediated transmission of highly pathogenic avian influenza

Rolf J.F. Ypma1, Marcel Jonges, Arnaud Bataille, Arjan Stegeman3, Guus Koch4, Michiel van Boven1, Marion Koopmans1,W. Marijn van Ballegooijen1 and Jacco Wallinga

Outbreaks of highly pathogenic avian influenza in poultry can cause severe economic damage, and represent a public health threat. Development of efficient containment measures requires an understanding of how these influenza viruses are transmitted from one farm to the next. However, the actual mechanisms of inter-farm transmission are largely unknown.

 

Dispersal of infectious material by wind has been suggested, but never demonstrated, as a possible cause of transmission between farms. Here we provide statistical evidence that the direction of spread of avian influenza A(H7N7) is correlated with the direction of wind at date of infection.

 

We find the direction of spread by reconstructing the transmission tree for a large outbreak in the Netherlands in 2003, using detailed genetic and epidemiological data. We conservatively estimate the contribution of a possible wind-mediated mechanism to the total amount of spread during this outbreak to be around 18%.

 

Although it occurred nearly 10 years ago, this outbreak of H7N7 continues to interest scientists, as it represents the largest cluster of human infection by H7 flu virus we’ve seen. 

 

This report from the December 2005 issue of the Eurosurveillance Journal.

 

Human-to-human transmission of avian influenza A/H7N7, The Netherlands, 2003

M Du Ry van Beest Holle, A Meijer, M Koopmans³ CM de Jager, EEHM van de Kamp, B Wilbrink, MAE. Conyn-van Spaendonck, A Bosman

An outbreak of highly pathogenic avian influenza A virus subtype H7N7 began in poultry farms in the Netherlands in 2003. Virus infection was detected by RT-PCR in 86 poultry workers and three household contacts of PCR-positive poultry workers, mainly associated with conjunctivitis.

 

More than 30 million birds residing on more than 1,000 farms were culled to control the outbreak.

 

One person - a veterinarian who visited an infected farm – died a week later of respiratory failure. The rest of the symptomatic cases were relatively mild.

 

Normally, when avian flu manages to spread among local farms, we think of transport mechanisms like the farm-to-farm movement of infected birds or eggs, or of contaminated or infected personnel or equipment, or even a bird or small mammal vector.

 

The idea that the virus might be blown (likely carried on dust, or some other particulate) – while unproven -  has come up before.

 

Back in January of 2008 I wrote a blog called The Virus My Friend, Is Blowin' In The Wind where I cast a dubious eye upon claims by the Indian Government that the bird flu virus (H5N1) was being blown by the wind across the border from neighboring Bangladesh, and was infecting hapless Indian Poultry.

 

It wasn’t impossible, of course.  And I went into some of the other types of pathogens (mostly fungi and bacteria) that are known to travel in the wind.

 

Then in May of 2010 (see Viruses Blowin’ In The Wind?) we saw a report in the journal Environmental Health Perspectives, that suggested that it was possible for H5N1 (or any Influenza A virus) to be transported across long distances in the air.

 

Although researchers demonstrated influenza RNA could be detected in ambient air samplings, they didn’t establish that the virus remained viable over long distances.

 

But we have seen studies indicating that the H5N1 virus can – under the right environmental conditions – remain viable for hours or even days in the environment (see EID Journal: Persistence Of H5N1 In Soil and H5N1: Hiding In Plain Sight)

 

Lending at least a little credence to the idea that they might survive on the wind long enough to infect downwind farms.

 

It has also been suggested that dried chicken droppings (`poultry dust’) may also serve to spread the virus, and Indonesian authorities have mentioned this as a possible vector (see Indonesian Updates And Vector Concerns).

 

Hong Kong authorities also mentioned the possibility (of at least short-range windborne transmission) in a highly detailed epidemiological report issued by the University of Hong Kong, on the outbreak of H5N1 on a solitary chicken farm in the New Territories in 2008.

 

Epidemiology Report of the Highly Pathogenic Avian Influenza H5N1 Outbreak in December 2008 in a Chicken Farm in Ha Tsuen, New Territories

 

Excerpt

(ii) The strong winds and gust from the north and north-east from 4 to 6 December 2008 could have deposited potentially contaminated dust and leaves from the trees into the nearby shed no. 17 via its north opening. These contaminated materials could then have gathered at the corner of the shed where the initial high mortality in poultry occurred.

 

 

So . . . while none of this is a slam dunk proving wind-borne transmission of viable avian (or any other flu) viruses, we have at least some credible evidence that suggests it may have happened.

 

How big of a factor this plays in the spread of viruses remains to be seen.

 

But it does provide investigators another avenue of epidemiological query when multiple farms in close proximity are infected with avian influenza.

 

 

Note: `Barnstorming’ is an Americanism that some of my readers may not be familiar with.  It refers to the early days of aviation when pilots would fly to rural areas, land in farmer’s fields, and sell rides, or put on an air show for the locals.

»» Read More

An Increasingly Complex Flu Field

 

(Click to enlarge)

 

# 6534

 

 

Up until 1977  it was considered normal that only one strain of influenza A circulated at a time.

 

When a new pandemic strain appeared (as it did in 1918, 1957, and 1968), the existing seasonal strain – for reasons that weren’t well understood – would vanish, and in time the new pandemic virus would settle in as the seasonal flu.

 

But in 1977 something unprecedented happened.

 

The H1N1 flu virus – which had been replaced by the pandemic H2N2 virus in 1957 (only to be replaced by the H3N2 strain 11 years later) - suddenly reappeared after 20 years absence.

 

The theory is that it escaped from a Russian or Chinese lab’s freezer, as it was almost unchanged from a strain not seen since the early 1950s. 

 

It was dubbed the `Russian flu’, and for a while, slammed Emergency rooms and Flu wards in a big way.

 

Most adults had some immunity left over from their exposures before 1957, and so kids under 20 were the hardest hit.  But unlike in 1918, 1957, and 1968 – this new flu didn’t depose the old flu.

 

Instead we ended up with two major Influenza A strains bumping shoulders and jockeying for position.  Some years H3N2 would dominate, and other years it would be H1N1.

 

Further complicating matters we also have Influenza B viruses, which while generally regarded as less serious than influenza A, have divided into two distinct lineages (Yamagata & Victoria.

 

And they too compete each year for dominance.

 

Which leaves us with (currently) four major flu strains to contend with; 

• A/H1N109
• A/H3N2
• B/Victoria
• B/Yamagata

 

These viruses constantly change and evolve over time, and we often have several clades of each strain at any given time. The most recent ECDC: Influenza Virus Characterization found 5 genetically distinct H3N2 strains in circulation across Europe.

 

The recent emergence of a new – antigenically different – H3N2 strain, along with the recent dominance of the Yamagata influenza B virus, has prompted a major change in this year’s flu vaccine.

 

• The H1N1 component remains essentially unchanged, with the A/California/7/2009 (H1N1)pdm09-like  still recommended.
• But the old A/Perth/16/2009 (H3N2)-like virus now gives way to the A/Victoria/361/2011 (H3N2)-like virus.
• And the Victoria lineage B/Brisbane/60/2008-like virus will be replaced by a Yamagata strain; the B/Wisconsin/1/2010-like virus. 

 

Which makes getting the flu vaccine this fall doubly important, as it is likely that community immunity to both of these strains is low.

 

Beyond these four, keeping researchers up late at night is the fact that there are no fewer than six influenza viruses that – while not well adapted to humans  – keep trying to nudge their way into the human host pool.

 

Most people by now are aware of the concerns over the H5N1 `bird flu’, but less well known are the H7 avian strains, which have managed to jump to humans several times over the past decade.

 

• In 2003 an outbreak of H7N7 at a poultry farm in the Netherlands went on to infect at least 89 people. Most of the victims were only mildly affected, but one person died.
• In 2004 two people in British Columbia tested positive for H7N3 (see Health Canada Report) during an outbreak that resulted in the culling of 19 million birds.
• In 2006 and 2007 there were a small number of human infections in Great Britain caused by H7N3 (n=1)  and H7N2 (n=4), again producing mild symptoms.

 

H9N2 is another avian strain that has, on rare occasions, infected humans and is believed to have some pandemic potential. Over the past dozen years a small handful of cases have been identified – mostly in Hong Kong (see CIDRAP Avian Influenza (Bird Flu): Implications for Human Disease).

 

• In January of 2010, in H9N2: The Other Bird Flu Threat, I wrote about the World Health Organization  recommending the creation of a candidate vaccine virus for H9N2.

• And in November 2010, in Study: The Continuing Evolution Of Avian H9N2, we looked at computer modeling that suggested that the H9N2 virus moving towards becoming more `human-adapted’.

 

And since 2005 the CDC has been reporting a growing number of swine flu variants that have managed – on rare occasions – to jump to humans.

 

The three main flu strains circulating in pigs are:

• H1N1
• H1N2
• H3N2

When one of these swine viruses jumps to a human host, it is then called a `variant’ virus. 

 

Up until last year, it was the trH1N1 swine virus (now called H1N1v) that had been most commonly reported. The numbers were very low – rarely more than 2 or 3 infections each year.

 

Over the past year, the focus has shifted to the H3N2v virus, which emerged in the summer of 2011. After a quiet winter and spring, this summer it has infected several hundred people in the Midwest – most (but not all) appear to have contracted it directly from exposure to pigs.

 

And as an added surprise, on Friday of last week we learned of 1 confirmed and 2 suspected cases of a variant flu strain that had only been reported twice during the previous 7 years, in Minnesota Reports Swine H1N2v Flu.

 

Next week this chart will likely need updating.

 

There are other flu strains out there, of course.

 

Earlier this year, concerns were raised over an H3N8 flu virus that had killed seals off the coast of New England, and which conceivably could infect other mammals as well (see mBio: A Mammalian Adapted H3N8 In Seals).

 

And given the propensity for flu viruses to reassort (swap gene segments), the possibility of seeing an entirely new flu strain emerge can’t be ignored.

 

Nature’s laboratory is open 24/7, and unlike human researchers suffers neither from bureaucratic rules or budgetary constraints.

 

That said, history has shown that pandemic events only happen rarely; just three times during the last century (albeit with a couple of close-but-no-cigar events thrown in to keep us on our toes). 

 

Even with all of these potential threats on the viral horizon we could easily see average flu season.

 

So far, none of these novel viruses has demonstrated the ability to transmit among humans in a sustained and efficient manner while producing significant illness.

And if we get lucky, they never will. 

 

But as schools open, and cooler weather arrives, the conditions conducive for the spread of influenza improve. And that holds true whether we are talking seasonal flu, or one of these upstart strains.

 

Today is day three of National Preparedness Month, and while most people think of emergency preparedness as something you do for hurricanes and earthquakes, flu epidemics are also worth planning for as well.

 

Preparedness should include practicing good flu hygiene (hand washing-sanitizing, covering cough & sneezes, staying home if sick) all year round, and getting the flu shot early each year.

 

No one can predict with certainty the kind of flu year we will see, and I certainly have no special insight into the matter. The CDC states it pretty succinctly:

 

What sort of flu season is expected this year?

Flu seasons are unpredictable. The CDC and WHO closely monitor flu cases to identify new viruses or potential epidemics or pandemics.

 

The CDC and the WHO obviously take pandemics and epidemics very seriously, which is reason enough for us to take a more in-depth look at pandemic preparedness later this month as National Preparedness Month continues.

»» Read More

The CDC’s Updated Avian Flu Pages

 

 

H5N1 Virus – Photo Credit CDC PHIL

# 6400

 

 

Yesterday’s publication of Ron Fouchier’s H5N1 research papers – along with a small avalanche of related reports and articles in the journal Science - has generated a good deal of renewed interest in the avian flu virus around the world. 

As one might expect, the CDC updated and revamped their avian flu and pandemic resources web pages this week, since many people will be seeking out more information on the subject.

 

Our first stop is the CDC Resources for Pandemic Flu page, where you’ll find links to:

 

Highly pathogenic avian influenza A (HPAI) H5N1

Influenza Pandemics

International Surveillance for Pandemic Preparedness 

CDC’s international surveillance activities monitor trends in influenza activity

Risk Assessment

Risk assessments help assess the threat of influenza viruses with pandemic potential

Influenza Pandemic Preparedness Tools

Resources to help hospital administrators and state and local health officials prepare for the next influenza pandemic

 

 

A visit to the revised Avian Flu page, provides:

 

Information on Avian Influenza

Avian influenza refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses. These viruses occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species. Avian flu viruses do not normally infect humans. However, sporadic human infections with avian flu viruses have occurred. The links below offer information about avian influenza for different audiences.

• Current Situation
• Avian Influenza
  • in Birds
  • in Humans
  • Past Outbreaks in North America
• Highly Pathogenic Avian Influenza A (H5N1) virus
  • in Birds and Other Animals
  • in Humans
  • H5N1 Genetic Changes Inventory: A Tool for International Surveillance
  • Public Health Threat of Highly Pathogenic Avian Influenza A (H5N1) Virus
• Prevention and Treatment of Avian Influenza A Viruses in People
• Influenza Type A Viruses and Subtypes
• Transmission of Avian Influenza A Viruses Between Animals and People
• Related Links

Since these links lead to other links, there appears to be quite a bit of new information available.

Certainly worth exploring.

 

 

»» Read More

WHO Report : Antigenic & Genetic Characteristics of H5N1 & H9N2 Viruses

 

 

# 5874

The World Health Organization has published a 12-page document (dated 9/29) – that summarizes recent global activity of A(H5N1) and A(H9N2) avian influenza viruses and describes the current status of candidate vaccines under development.

 

Similar reports have been issued twice each year since 2006.

 

This latest report may be read, and downloaded at:

 

Antigenic and genetic characteristics of influenza A(H5N1) and influenza A(H9N2) viruses and candidate vaccine viruses developed for potential use in human vaccines

September 2011

This summary provides a review on the influenza A(H5N1) and A(H9N2) virus activity and virus characterization, and describes the current status of the development of new A(H5N1) and A(H9N2) candidate vaccine viruses. It is meant to provide guidance for national authorities and vaccine companies on the selection of candidate viruses for use in vaccine development.

• Full Text - September 2011

As you can tell by the above chart, the H5N1 virus continues to diversify into additional clades - and there  remain substantial gaps in our knowledge of the virus – particularly among strains circulating in Indonesia.

 

The spread of the 2.3.2.1 clade of the virus – which was the subject of an FAO announcement (see FAO Warns On Bird Flu) a month ago – is particularly  pronounced in this report with detections in Bangladesh, China Hong Kong SAR, India, Japan, the Republic of Korea, Myanmar, and Vietnam.

 

This `new’ clade differs antigenically from the poultry vaccines currently being used in many Asian countries, and the concern is that a new wave of bird flu may spread through poultry this winter.

 

This document summaries this new clade by saying:

 

Clade 2.3.2.1 (previously part of clade 2.3.2) viruses were detected in wild birds in Bangladesh, Japan and  the  Republic of Korea, and  also  in poultry in  Bangladesh,  China  Hong Kong Special
Administrative Region (China Hong Kong SAR), India, Japan, Myanmar, Republic of Korea and Viet
Nam.

Although  there is some genetic  (Figure 3) and antigenic heterogeneity  among  viruses of this
clade, recently  isolated viruses reacted well with post-infection ferret antisera against either A/Hong
Kong/6841/2010  (an  A/Hubei/1/2010-like virus)  or  A/barn swallow/Hong Kong/D10-1161/2010
(Tables 2 and 3), from which candidate vaccine viruses have been developed (Table 5). 

 

While newer 2.3.2.1 clade samples reacted well against a couple of candidate vaccines already selected, the 2.3.4.2 clade out of Bangladesh does not. Therefore, the development of a new clade 2.3.4.2 candidate vaccine virus is proposed.

Similarly, after the detection of a human infection by the avian H9N2 virus in Bangladesh earlier this year, a proposal has been made to develop a candidate vaccine for that strain as well.

 

And lastly, the document addresses the detection of several SOIV (Swine Origin Influenza Virus) infections this year in Indiana, and Pennsylvania.

 

Swine-Origin Influenza A(H3N2) 

Swine influenza A(H3N2) viruses are enzootic in swine herds of North America and other parts of the
world. Characterisation of recent A(H3N2) viruses from swine in North America indicates that their HA genes have evolved from the human virus precursors that circulated in the mid-1990s. Isolation of swine-origin influenza viruses (SOIV) A(H3N2) from humans has been reported infrequently.  The United States of America reported eight infections due to A(H3N2) SOIV between January 2005 and 15 February 2011. 

A(H3N2) SOIV infections from 16 February 2011 to 19 September  2011

There have been four human infections  with A(H3N2) SOIV  in the states of Indiana (1) and Pennsylvania (3), United States of America, in this period. The HA and neuraminidase genes of these four viruses were similar to those  of swine viruses that circulate  in the United States  of America.

Sequencing data indicated that the  matrix  genes of these viruses were acquired  from an A(H1N1)pdm09 virus, unlike SOIV isolates from previous human cases.

Antigenic analysis indicated that these viruses were distinct from currently circulating human  A(H3N2)  viruses  but  similar to  swine A(H3N2) viruses from previous years as well as to A/Minnesota/11/2010 (H3N2) SOIV (Table 7), from which a candidate vaccine virus is under development.

 

 

Avian viruses, like all influenza A viruses, are constantly under pressure to change and mutate, looking for a biological advantage. Most of these mutations, thankfully, are evolutionary dead ends and fail to spread and thrive.

 

But in this viral version of king-of-the-hill, nature occasionally produces a more `fit’ and competitive virus, and it begins to dominate and spread.

 

Which is why continual monitoring of the genetic and antigenic changes in these viruses is so crucial.  As avian viruses evolve, new candidate vaccines must be developed, else we could be caught flat footed if a pandemic suddenly began.

 

Having a candidate vaccine already in hand could save weeks in the time it would take to produce and deploy an emergency vaccine. 

 

And during a severe pandemic, a few weeks delay could translate into the loss of thousands of lives.

»» Read More

Eurosurveillance: Avian Flu In Humans -Insights From A Line List

 

 

# 5750

 

 

In epidemiology, a Line Listing is one the most basic methods used to collect, display, and analyze outbreak information.

 

It is essentially a table that displays individual cases in rows, and their characteristics in columns. If you’ve ever prepared a spreadsheet, you know the format.

 

A simple example might look something like this:

Photo Credit – CDC Excite Epidemiology in the Classroom

 

Today, in what may be the most comprehensive line listing of human H5N1 avian flu cases published to date, researchers from the Robert Koch Institute have released data describing nearly 300 H5N1 infections from around the globe.

 

Their research appears in today’s edition of the Eurosurveillance journal. With the release of this data the authors call for the creation and maintenance of a publicly accessible line list of anonymized human AI cases by an internationally renowned organization such as the World Health Organization.

 

A motion I would enthusiastically second.

 

The Eurosurveillance article is available at the link below.

 

Avian influenza A(H5N1) in humans: new insights from a line list of World Health Organization confirmed cases, September 2006 to August 2010

L Fiebig , J Soyka, S Buda, U Buchholz, M Dehnert, W Haas  Euro Surveill. 2011;16(32):pii=19941.

 

You can download this spreadsheet/database in MS-EXCEL (xls) format from the RKI website. 

 

Avian influenza A(H5N1) in humans

New insights from a line list of WHO confirmed cases, September 2006 to August 2010

The Robert Koch Institute (RKI) had established a routine monitoring instrument condensing information on all human avian influenza cases worldwide reported from the following sources into a line list.

• WHO Global Alert and Response System
• ECDC: Avian influenza
• Global Electronic Reporting System for emerging infectious disease outbreaks (ProMED)
• Reuters Alertnet: Bird flu

A scientific article evaluating confirmed avian influenza cases in humans captured from September 2006 to August 2010 September 2006 to August 2010, as well as the established line list and the description of variables are available online:

• RKI avian influenza line list (VND.MS-EXCEL, 112 KB)

 

The Eurosurveillance article is long, detailed, and would be impossible to summarize here and do it justice. It really deserves reading in its entirety.

But a few choice excerpts from the abstract (below) provide a glimpse of some of the data gleaned from this line list.

 

The 235 confirmed AI cases captured from September 2006 to August 2010 had a case fatality rate of 56% (132/235), ranging from 28% (27/98) in Egypt to 87% (71/82) in Indonesia.

 

In a multivariable analysis, odds of dying increased by 33% with each day that passed from symptom onset until hospitalisation (OR: 1.33, p=0.002).

 

In relation to children of 0–9 years, odds of fatal outcome were more than six times higher in 10–19 year-olds and 20–29 year-olds (OR: 6.06, 95% CI: 1.89–19.48, p=0.002 and OR: 6.16, 95% CI: 2.05–18.53, p=0.001, respectively), and nearly five times higher in patients of 30 years and older (OR: 4.71, 95% CI: 1.56–14.27, p=0.006) irrespective of the country, which had notified WHO of the cases.

 

The situation in Egypt was special in that case number and incidence in children were more than twice as high as in any other age group or country. With this study, we show that data from the public domain yield important epidemiological information on the global AI situation.

 

 

I expect that this release of data will be welcomed by many interested observers in Flublogia, and around the world.

»» Read More

Satellite Images Show Where The Wild Goose Goes

.



#5639



Wild water birds (ie. duck, geese, swans, terns, gulls) are the natural reservoir for avian influenzas (including, but not limited to H5N1), and unlike many terrestrial species, can often carry the virus with little or no ill effect.

Avian influenza is primarily a gastrointestinal infection among birds, and it can be spread through virus laced feces deposited in shared ponds and lakes.

The role of wild birds in the spread of bird flu is not without its controversy. Over the years we’ve a number of studies that either implicate migratory birds in the spread of the virus, or minimizes their role.

In September 2010 (see Another Migratory Bird Study) a paper appeared in the British Ecological Society's Journal of Applied Ecology, that claimed that the global spread of the H5N1 virus through migratory birds was possible . . . but unlikely.

In a blog from 2009, called  India: The Role Of Migratory Birds In Spreading Bird Flu I wrote about an article entitled  Scientists rule out spreading of bird flu by migrant birds in India  from Xinhua News.

And in January of 2008, Reuters carried a report called: Don't blame wild birds for H5N1 spread: expert

Despite these dissenting opinions, there have been plenty of other reports that strongly associate migratory birds with the spread of the virus.

A few include:

Korea: Migratory Birds Behind Spread Of H5N1

EID Journal: H5N1 Branching Out

Japan: Hooded Crane Positive For H5N1

FAO: On The Trail Of Avian Influenza

Despite overlapping migratory flight paths, avian strains common in Eurasian birds have yet to appear in North America.   Monitoring continues in every year, however.


Which brings us to a fascinating bit of research presented as a doctoral thesis by Ms Yali Si, a graduate student at the University of Twente in the Netherlands.


Using satellite imagery and field tests, Yali Si has worked to determine which grasslands are more likely to attract water birds to feed. She found that the age and quality of the grass affects selection by migratory birds.


Using this information, she has produced risk maps of Europe showing the areas most likely to visited by wild water birds, and therefore most vulnerable to the spread of avian flu.


While demonstrating the feasibility of this method, Yali Si states that additional study will be needed to refine the system and the resultant maps.


For more on this, we have a press release from the University of Twente, and a link to the thesis. 

First the press release:

Satellite images to combat avian flu

The entire 139 page PDF of her thesis is available at http://www.itc.nl/library/papers_2011/phd/yalisi.pdf


As the author points out, global environmental change (including climate and land use) has the potential to shift migratory and nesting behavior of wild water birds.


Through the use of GIS (geographic information systems), remote sensing (primarily satellite data), and new spatial techniques scientists will be better able to predict where the avian influenza threat is likely to be the highest.


Which ought to give researchers a better idea where to test for the arrival of new avian viruses, and could serve as a warning to poultry producers of when and where to beef up their biosecurity.

»» Read More

EID Journal: Novel H5N5 Avian Influenza Detected In China

 

 

# 5581

 

 

 

Not that I’m trying to promote paranoia, but a recurring theme in this blog is that nature’s laboratory is open 24/7, and that it is constantly trying out new genetic combinations looking for an evolutionary advantage.

 

We see this with growing antimicrobial resistance in bacteria (see here, here, and here), emerging anti-viral resistance in influenza viruses (here and here), and even resistance in mosquitoes to DEET repellant (see From the `Nature Bats Last’ Dept).

 

If you build a better mousetrap, nature will begin work on constructing a better mouse.

 

Viruses - which generally leave behind some degree of post-infection immunity - must change over time to evade that immune response, else they would run out of susceptible hosts.  

 

Nowhere is that more apparent than in the world of influenza, where flu viruses mutate at an astonishing rate, and thus are able to spark global epidemics every year.

 

Adding to this constantly evolving pool of human influenzas are rare introductions of new, `novel’ viruses that can jump from other species (usually avian or porcine).

 

 

 

In The (Swine) Influenza Reassortment Puzzle last December, I wrote about the 19 (now 20) detected human infections by novel swine viruses in the United states.   This from the CDC report":

 

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

Of the 19 human cases reported since 2005, 12 have been trH1N1 viruses, six have been trH3N2 viruses and one has been a trH1N2 virus. All 19 persons infected with swine viruses recovered from their illness. Twelve cases occurred in children (persons younger than 19) and 7 cases occurred in adults. In 15 cases, exposure to swine has been identified.

 

The H1N1 virus that sparked the 2009 pandemic was a descendent of a triple reassorted H1N1 swine flu virus that first appeared in American swine herds in 1998.  It apparently bounced around in swine herds for a decade before finding the right genetic mutations to adapt to humans.

 

But H1N1 isn’t the only swine flu virus out there.  Known Swine influenza A viruses include H1N1, H1N2, H3N1, H3N2, and H2N3.

 

 

But for sheer diversity of influenza viruses, we look to avian species for the mother lode. 

 

Ducks, geese, and other aquatic birds are believed to be the natural reservoir – and the ultimate source – of all influenza A viruses.

 

 

While we’ve been focused on the H5N1 avian flu virus for a number of years, other avian strains (like the H7s, H9s, and H11s) have demonstrated the ability to infect humans as well.

 

Which brings us to this dispatch from the CDC’s EID Journal from the People’s Republic of China, that tells us of the discovery of a new reassortment of the avian H5 virus in domestic ducks.

 

 

Novel Reassortant Highly Pathogenic Avian Influenza (H5N5) Viruses in Domestic Ducks, China

Min Gu, Wenbo Liu, Yongzhong Cao, Daxin Peng, Xiaobo Wang, Hongquan Wan, Guo Zhao, Quangang Xu, Wei Zhang, Qingqing Song, Yanfang Li, and Xiufan Liu

Abstract

In China, domestic ducks and wild birds often share the same water, in which influenza viruses replicate preferentially. Isolation of 2 novel reassortant highly pathogenic avian influenza (H5N5) viruses from apparently healthy domestic ducks highlights the role of these ducks as reassortment vessels. Such new subtypes of influenza viruses may pose a pandemic threat.

(Continue . . . )

 

 

Undoubtedly, influenza reassortments like these happen all the time and outside the view of scientists. Most are viral flashes in the pan, are unable to compete with more biologically fit flu viruses, and so we rarely learn of them.

 

But occasionally, the right genetic combination will be generated, and a new emerging virus is born. 

 

The authors of this study write:

 

Ducks have been considered "Trojan horses" for influenza (H5N1) because of their pivotal role in virus propagation and evolution (11–13).

 

In our study, the 2 reassortant influenza viruses (008 [H5N5] and 031 [H5N5]) and their 3 possible parent viruses (108 [H5N1], 909 [H5N1], and 013 [H6N5]) were all isolated from apparently healthy domestic ducks.

 

We speculate that domestic ducks may serve as reassortant vessels for creating new subtypes of influenza viruses. In view of the practice of raising ducks in a free-range system, these novel strains could be transmitted to other domestic poultry and even humans.

 

There is evidence that these subtype H5N5 viruses have been transmitted to terrestrial poultry (Zhao et al., unpub. data). Thus, the role of domestic ducks in the influenza virus ecosystem should not be neglected.

 

Systematic surveillance should be instituted to identify emerging HPAI (H5N5) viruses and to reduce their potential threat to animal and human health.

 

Whether the H5N5 virus has evolutionary `legs’, and will ever pose a threat to poultry or humans, is unknown at this time.

 

All we really know is that it is a novel reassortment that was detected in two healthy ducks in eastern China in December 2008 and January 2009, and that it is highly pathogenic in poultry and moderately pathogenic in mice.

 

But what this does show is that without good systematic global surveillance of human, avian, and swine populations, we have no way of knowing what other emerging viruses might be fluing just under our radar.

»» Read More

WHO: Update On Cambodian Bird Flu Situation

 

# 5302

 

The World Health Organization has published an update this afternoon on the H5N1 fatality I blogged on earlier today.   In addition, they have updated their cumulative confirmed H5N1 infections by country chart as well.

 

 

Avian influenza – situation in Cambodia

9 February 2011 - The Ministry of Health of Cambodia has announced a new confirmed case of human infection with avian influenza A (H5N1) virus.

 

The 5 year old female, from Prek Leap village, Sangkat Prek Leap, Khan Reussey Keo, Phnom Penh, developed symptoms on 29 January, was admitted to a hospital on 3 February and died 12 hours following admission. The presence of H5N1 virus in nasopharyngeal specimens was confirmed by Institut Pasteur, the National Influenza Centre in Cambodia. The case had been in contact with sick poultry during the 7 days before onset of symptoms.

 

The Ministry of Health has been coordinating the response. Actions have included contact tracing, collecting specimens from suspected cases, and providing oseltamivir prophylaxis to close contacts; active surveillance and joint investigation with animal health authorities; community education; and public communications coordination with the assistance of WHO.

 

Of the 11 cases of human H5N1 virus infection confirmed since 2005 in Cambodia, 9 have been fatal.

 

To date, since 2003, there have been 520 confirmed H5N1 infections across 15 counties, with 307 fatalities.

 

(Click to view chart)

»» Read More

IRIN: Indonesia’s Avian Flu Challenge

 

 

# 5147

 

 

Via IRIN humanitarian news and analysis this morning, a short feature on some of the reasons why Indonesia’s case fatality rate for avian flu is an astounding 83%.

 

Compare that to the CFR from Egypt, which is 34%, and globally, which runs just about 60%.

 

 

Most of these are items mentioned here before;

 

• a reliance on traditional medicine
• a fear of hospitals (understandable considering how few bird flu patients come home)
• concerns over paying for medical care
• challenges posed by having 250 million people scattered across nearly 2 million sq km and thousands of islands

 

 

 

 

INDONESIA: Avian flu deadliest in the world

Indonesia- deadliest place in the world to be hit with avian flu

BANGKOK, 16 December 2010 (IRIN) - The number of deaths from avian flu in Indonesia is the highest worldwide, due to a slow response rate and surveillance challenges, say specialists.

(Continue . . . )

 

 

Alluded to, but not specifically mentioned in this article, has been the general ineffectiveness of many central government edicts which have been issued to try to control bird flu.

 

Perhaps most famously, in January of 2007, Jakarta announced an ambitious plan to remove, permanently, the backyard and residential raising of poultry throughout the nation, starting first in the capital.

 

Residents were given until February 1^st to sell, consume, or destroy their small flocks.

 

Even as the central government was announcing that this policy would be extended first to 9 provinces, then across the entirety of Indonesia, cracks in the coalition were developing.

 

Authorities in the Central Javan Province, Pandeglang regency and Cilegon municipality all stated they would not go along with this edict.

 

A few blogs from that time period include:

 

Eight Months After The Jakarta Poultry Ban

Indonesian Culling Plan Finding Resistance

Resistance to Indonesian Poultry Ban

 

With an estimated 350 million backyard chickens across the nation - and a population that depends heavily upon them for food security, barter, and as a source of income -  this plan was probably doomed from the start.

 

In the parlance of today’s twitterverse, it was an Epic Fail.

 

 

Whether well advised or not, this poultry eradication program’s failure illustrates just how difficult it is to get everyone on the same page when it comes to controlling the virus.

 

And so four years later, Indonesia’s poultry remains rife with H5N1, they have the highest (known) case fatality in the world, and permanent solutions to the problem remain as elusive as ever.

»» Read More

OIE Report: Manitoba Bird Flu Identified As H5N2

 

 

 

# 5091

 

 

My thanks to Ironorehopper on FluTrackers for posting the link to this OIE notification detailing the avian flu outbreak at a turkey farm in Rockwood, Manitoba.

 

I’ve excerpted part of the report below.

 

 

Low pathogenic avian influenza (poultry), Canada

Information received on 25/11/2010 from Dr Brian Evans, Chief Food Safety Officer/Chief Veterinary Officer, Office of the President, Canadian Food Inspection Agency, OTTAWA, Canada

New outbreaks

Outbreak 1 (NAI-2010-MB-001)
Rockwood municipality, MANITOBA

Date of start of the outbreak
17/11/2010

Outbreak status
Continuing (or date resolved not provided)

 

Affected Population

Turkey breeders farm, with four barns on site. Barn 1 is empty, barn 2 contains 600 toms (approx.), barn 3 contains 3,000 hens (approx.) and barn 4 contains 3,800 hens (approx.). The hens in both barn 3 and 4 are 44 weeks old and were lethargic with a 45% decrease in egg production but the egg production has improved since the start of the event. No respiratory disease was observed. The mortality in the flock has not increased.

Epidemiology

Source of the outbreak(s) or origin of infection

• Unknown or inconclusive

Epidemiological comments

This is the first outbreak of Notifiable Avian Influenza (NAI) detected in the province of Manitoba.

The farm has been quarantined by the Canadian Food Inspection Agency (CFIA) and investigation will be conducted in compliance with the Canada's Notifiable Avian Influenza Hazard Specific Plan. A stamping out policy will be applied.

Preliminary results from the National Center for Foreign Animal Diseases in Winnipeg indicate the presence of a H5N2 subtype avian influenza virus (PCR).

Sequence analysis of the PCR products indicates that the cleavage site is consistent with low pathogenic avian influenza virus H5. Closest matches (99% identity) in Genbank are to North American H5N2 viruses from wild birds.

Virus isolation is underway and additional testing is to come, including the intravenous pathogenicity index test.

NAI surveillance has been in place in domestic poultry in Canada for many years and this outbreak is limited to the province of Manitoba.

Note by the OIE Animal Health Information Department: H5 and H7 avian influenza in its low pathogenic form in poultry is a notifiable disease as per Chapter 10.4. on avian influenza of the Terrestrial Animal Health Code (2010).

Control measures

Measures applied

• Quarantine
• Movement control inside the country
• Screening
• Vaccination prohibited
• No treatment of affected animals

Measures to be applied

• Stamping out
• Disinfection of infected premises/establishment(s)

»» Read More

CTV Reporting Low Path H5 On Canadian Turkey Farm

 

 

# 5086

 

 

Although first announced several hours ago, details remain sketchy on the type avian flu strain detected in number of turkeys at a farm in the rural municipality of Rockwood, Manitoba.

 

CTV Winnipeg is reporting this as an H5 strain, likely low path, and not the highly pathogenic H5N1.

 

Other media outlets are not specifying a strain, so these details could change or evolve over the next few hours. 

 

A hat tip to Ironorehopper on FluTrackers who posted the following report.   An ongoing thread (started by Shiloh) tracking new developments is available at this link.

 

 

 

Turkeys in RM of Rockwood test positive for form of bird flu, officials believe strain is non-deadly

Officials have not yet said how many of the animals tested positive for an H5 strain of bird flu.

Updated: Wed Nov. 24 2010 14:19:36
ctvwinnipeg.ca

Provincial and federal officials have quarantined a turkey farm in the RM of Rockwood.

 

Some turkeys have tested positive for an H5 strain of bird flu, but there is no evidence it is the deadly form known as the Asian strain of the H5N1 influenza, said provincial officials.

 

There has been no indication of human illness.

(Continue . . .)

 

 

Low path outbreaks of avian influenza have been recorded in North America (and around the globe) in the past, and rarely present a human health threat.

 

CIDRAP’s overview on avian influenza Avian Influenza (Bird Flu): Agricultural and Wildlife Considerations  details many of these outbreaks.

 

Low Pathogenic avian viruses, if left  unchecked, have the potential to mutate into a more highly pathogenic strain. For that reason low path outbreaks of the H5 and H7 variety are taken seriously, and are a reportable disease to the OIE.

 

Culling is generally the recommended response.

»» Read More

A Prospective Avian Influenza Transmission Study For Egypt

 

 

 

# 5045

 

 

One of the great mysteries surrounding avian influenza (primarily, but not exclusively H5N1) is how often these viruses jump to and infect humans.   

 

In the relatively short history of our observation of the influenza virus, only the H1, H2, and H3 strains have adapted well to people.  

 

On rare occasions humans have been infected by other influenza strains, such as H5N1, H7N7, and H9N2. These strains are primarily seen in birds, but since they are constantly evolving and mutating, the worry is one might eventually adapt to human hosts.

 

The H5N1 bird flu virus remains at the top of our list of concerns, because it is endemic (in birds) in a number of countries, has shown the rare ability to infect humans, and when it does, it has a incredibly high fatality rate.

 

The two countries reporting the greatest number of human H5N1 cases are Indonesia and Egypt.  The Case fatality rate in Indonesia remains well over 80%, but in Egypt, it runs a much lower (but still disturbing) 32%.

 

Which has led some researchers to wonder if their might be ongoing transmission of a `milder’ or even asymptomatic strain of H5N1 in Egypt.

 

In order to find out, a 3-year seroprevalence study has been designed that would track 1,000 people with various levels of exposure to poultry, and test them regularly for antibodies to the bird flu virus.

 

 

The full details are available at the link below. Here is the abstract.

 

 

 

Prospective study of avian influenza transmission to humans in Egypt

Ghazi Kayali , Richard J Webby , Xiaoping Xiong , Lobna S Sherif , Esmat A El-Ghafar  and Mohamed A Ali

BMC Public Health 2010, 10:685doi:10.1186/1471-2458-10-685

Published:
9 November 2010

Abstract (provisional)

Background

The highly pathogenic avian influenza (HPAI) H5N1 virus remains a public health threat and continues to cause outbreaks among poultry as well as human infections. Since its appearance, the virus has spread to numerous geographic areas and is now considered endemic in Egypt and other countries. Most studies on human H5N1 cases were conducted to investigate outbreak situations and were not designed to address fundamental questions about the epidemiology of human infection with H5N1 viruses. Our objective for this study is to answer these questions by estimating the prevalence and incidence rates of human cases and determine associated risk and protective factors in areas where H5N1 viruses are endemic.

Methods

We designed a 3-year prospective cohort study of 1000 individuals of various exposure levels to poultry in Egypt. At onset, we will collect sera to estimate baseline antibody titers against AI viruses H4-H16. Two follow-up visits are scheduled at 1-year intervals following initial enrollment. At follow-up, we will also collect sera to measure changes in antibody titers over time. Thus, annual prevalence rates as well as incidence rates of infection will be calculated. At each visit, exposure and other data will be collected using a specifically tailored questionnaire. This data will be used to measure risk and protective factors associated with infection. Subjects will be asked to contact the study team any time they have influenza-like illness (ILI). In this case, the study team will verify infection by rapid influenza A test and obtain swabs from the subject's contacts to isolate and characterize viruses causing acute infection.

Discussion

Epidemiologic studies at the influenza human-animal interface are rare, hence many questions concerning transmission, severity, and extent of infection at the population level remain unanswered. We believe that our study will help tackle and clarify some of these issues.

 

 

The few previous seroprevalence studies on H5N1 that we have to date show little or no asymptomatic or mild human infections.

 

Most of these are several years old, however, and are based on older clades of the virus.

 

In May of 2009 (see Cambodian Study Finds Rare Asymptomatic H5N1 Infections) we saw a seroprevalence study published in the Journal of Infectious Diseases  conducted on more than 600 members of a Cambodian village where 2 human H5N1 cases were detected in 2006.

 

Antibody titers showed that only 1% (7 of 674) of the villagers tested had contracted, and fought off, the H5N1 virus.   A figure much lower than many had expected.

 

 

Risk Factors Associated with Subclinical Human Infection with Avian Influenza A (H5N1) Virus—Cambodia, 2006

Sirenda Vong, Sowath Ly, Maria D. Van Kerkhove, Jenna Achenbach, Davun Holl, Philippe Buchy, San Sorn, Heng Seng, Timothy M. Uyeki, Touch Sok, and Jacqueline M. Katz

Abstract-Full Text-PDF Version (175 kB)

 

 

Another study – presented at the Options For Influenza Control VI  Conference in Toronto in 2007, came up with similar results (see Seroprevalence Study).

 

This is how it was reported in MedPage Today .

OPTIONS VI: No Evidence For Mild Avian Flu

By Michael Smith, Senior Staff Writer, MedPage Today

Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
June 19, 2007

TORONTO, June 18 -- Highly pathogenic avian flu is rarely transmitted to people and apparently never in a mild or asymptomatic form, a Thai researcher said here.

 

A study of 901 people who lived near confirmed victims of the H5N1 avian flu strain showed no serological evidence that they had been infected and fought off the disease, Rapeepan Dejpichai, M.D., of the Thai Ministry of Health told attendees at the Options for Influenza Control meeting.

(Continue . . .)

Given the relative dearth of good seroprevalence studies in the past, this prospective study could go a long way to help answer some very important questions regarding the threat posed by avian influenza viruses to the human population.

»» Read More

Birds Of A Feather . . . .

 

 

 

# 4675

 

 

Yesterday Scott McPherson took a fascinating look at the role of of terrestrial wild birds (as opposed to waterfowl) in the spreading of various avian influenzas across the United States (see Songbirds, not just fowl, represent avian flu threat to US).

 

This morning, we’ve new research (that appeared yesterday) in PLoS One, suggesting that waterfowl may be acquiring and spreading avian flu viruses because their preening oils bind the virus to their feathers.

 

The persistence of avian flu viruses in bodies of water has been demonstrated in the past (Persistence of H5 and H7 avian influenza viruses in water  and  Persistence of avian influenza viruses in water).

 

Under the right conditions, the virus can remain viable for days or even weeks.

 

While avian influenza surveillance efforts among wild birds have concentrated on cloacal and tracheal samples, this research suggests that the additional step of sampling bird’s feathers might yield additional positives.

 

First, excerpts from the press release (slightly reparagraphed for readability), then a link to the PLoS One  Article.

 

 

 

Bird flu: In the plumage the secret of virus spread success

Today in PLoS ONE

International team of Italy-US scientists reports discovery of a new mechanism of avian influenza virus circulation and transmission in nature

 

A team of scientists, led by Mauro Delogu, virologist from the Veterinary Faculty of the Bologna University and researchers from the Istituto Superiore di Sanità, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia and St. Jude Children's Research Hospital (Memphis, Tennessee) have discovered a new way of avian influenza transmission.

 

<SNIP>

The scientists actually discovered that the preen oil gland secretions, by which all aquatic birds make their feathers waterproof, support a natural mechanism that concentrates AIVs from water onto birds' bodies. They found that a progressive virus "sticking" on feathers occurs because AIV-contaminated waters interact with the preen oil gland secretion.

 

Since waterbirds use to spread preen oil over their own (self-preening) or other birds' (allo-preening) plumage, it is easily understandable how these preening activities could facilitate the diffusion of the viruses in nature.

 

The discovery, adds Delogu, has also important implications in the surveillance of avian influenza viruses.

 

In fact, virus on feathers could escape detection by the current surveillance strategies which assay the virus secreted in the cloacal and tracheal samples only. Lack of detection of these viruses may greatly complicate surveillance and rapid responses to new virus emergence and spread. For this reason, Delogu said, in routine surveillance programs, additional sampling methods could be necessary to detect AIVs on birds' bodies.

(Continue . . . )

 

 

The PLoS One  link and abstract follow:

 

Can Preening Contribute to Influenza A Virus Infection in Wild Waterbirds?

 

Mauro Delogu, Maria A. De Marco, Livia Di Trani, Elisabetta Raffini, Claudia Cotti, Simona Puzelli, Fabio Ostanello, Robert G. Webster, Antonio Cassone, Isabella Donatelli

Abstract

Wild aquatic birds in the Orders Anseriformes and Charadriiformes are the main reservoir hosts perpetuating the genetic pool of all influenza A viruses, including pandemic viruses. High viral loads in feces of infected birds permit a fecal-oral route of transmission.

 

Numerous studies have reported the isolation of avian influenza viruses (AIVs) from surface water at aquatic bird habitats. These isolations indicate aquatic environments have an important role in the transmission of AIV among wild aquatic birds.

 

However, the progressive dilution of infectious feces in water could decrease the likelihood of virus/host interactions. To evaluate whether alternate mechanisms facilitate AIV transmission in aquatic bird populations, we investigated whether the preen oil gland secretions by which all aquatic birds make their feathers waterproof could support a natural mechanism that concentrates AIVs from water onto birds' bodies, thus, representing a possible source of infection by preening activity.

 

We consistently detected both viral RNA and infectious AIVs on swabs of preened feathers of 345 wild mallards by using reverse transcription–polymerase chain reaction (RT-PCR) and virus-isolation (VI) assays. Additionally, in two laboratory experiments using a quantitative real-time (qR) RT-PCR assay, we demonstrated that feather samples (n = 5) and cotton swabs (n = 24) experimentally impregnated with preen oil, when soaked in AIV-contaminated waters, attracted and concentrated AIVs on their surfaces. The data presented herein provide information that expands our understanding of AIV ecology in the wild bird reservoir system.

»» Read More