Clin. Infect. Diseases: Revisiting the 2009 pH1N1 `Canadian Problem'

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Fair warning: You may want to pour a cup of coffee, we've some ground to cover before we get to today's study.

In the summer of 2009 news leaked of several unpublished Canadian studies suggesting prior seasonal flu vaccination made one more at risk of contracting the recently emerged 2009 H1N1 Pandemic virus.

At the time, delivery of the pandemic monovalent vaccine was still several months away - but there were plans to roll out the regular  seasonal vaccine first – to protect against non-pandemic strains.

Helen Branswell, science and medical reporter - writing at the time for the Canadian Press - was among the first to report (see Branswell On The Canadian Flu Shot Controversy) on what was quickly dubbed `The Canadian Problem'.

Suddenly, there were genuine concerns that with a pandemic virus on the way, that rolling out the seasonal vaccine might be the wrong thing to do.

The CDC, the World Health Organization, and other public health organizations scrambled to look at the limited data they had, and stated that they could find no correlation between the seasonal vaccine and susceptibility to the pandemic flu . . . but that they would continue to look.

Meanwhile, with concerns rising, a number of Canadian Provinces halted or announced delays in their seasonal flu shot campaign, even though the studies  had yet to be published (see Ontario Adjusts Vaccination Plan).

October saw a number of new reports and studies that failed to corroborate the (still unpublished) findings, including a study published in the BMJ (British Medical Journal) that suggested exactly the opposite - that getting the seasonal flu vaccination may be slightly protective against the swine flu  (see When Studies Collide).

By November, with no compelling corroboration of the `Canadian Problem’, Canada’s National Advisory Committee on Immunization (NACI) came out in favor of resuming seasonal flu jabs (see NACI: Canada Should Resume Seasonal Flu Vaccinations).

But the controversy was far from over.

In April of 2010 the original Canadian studies were finally published by PLoS Medicine. Writing for CIDRAP, Maryn McKenna  detailed their findings.

New Canadian studies suggest seasonal flu shot increased H1N1 risk

Maryn McKenna  Contributing Writer

Apr 6, 2010 (CIDRAP News) – Despite a rapidly launched range of studies, investigators in Canada are still unable to say—or to rule out—whether receiving a seasonal flu vaccination in the 2008-09 season made it more likely that Canadians would become ill from 2009 pandemic H1N1 flu.

Other studies, however (see 2010 Eurosurveillance On `The Canadian Problem’ and 2012’s EID Journal: Revisiting The `Canadian Problem’), failed to find a correlation.

We would revisit this controversy repeatedly over the next few years, including in 2013's Branswell: Universal Flu Vaccines & The `Canadian Problem’, which looked at a study in Journal Science Translational Medicine that raised concerns over the prospects of creating the Holy Grail of immunology; the Universal Flu Vaccine, as described by Helen Branswell:

Study raises red flag for universal flu vaccine

By: Helen Branswell The Canadian Press, Published on Wed Aug 28 2013

Phenomenon, known as the “Canadian problem,” sees vaccination against one strain of flu actually seems to raise the risk of severe infection after exposure to a related but different strain

The scientists say it’s not currently known why the effect happens. Nor is it clear that it would be seen in other species — this research was done in piglets — or with the kinds of flu vaccines used to protect people. But they suggest the findings should be considered during the development and assessment of experimental universal flu vaccines.

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The phenomenon was dubbed VAERD or vaccine-associated enhanced respiratory disease by the authors.  Somewhat related issues of OAS (Original Antigenic Sin) and ADE (Antigenic Dependent Enhancement), have come up often in this blog, including most recently in:

Nature: Declan Butler On How Your First Bout Of Flu Leaves A Lasting Impression

WHO: Audio Of SAGE Press Conference On Vaccines (including Dengvaxia (tm))

Philippines: FDA Withdraws Dengvaxia® Vaccine - Sanofi Quantifies Risk

The evidence for a problem in 2009 - while far from conclusive - remains worrisome and in theory, could have ramifications with other vaccines.

There is, however, another theory on the table on what may have happened; the Temporary Immunity Hypothesis.

In November of 2010, an article appeared in the Eurosurveillance Journal (see Eurosurveillance: The Temporary Immunity Hypothesis) that suggested that contracting seasonal flu temporarily ramped up the body’s immune system against other respiratory viruses – and that this protective effect could last for months.

Eurosurveillance, Volume 15, Issue 47, 25 November 2010

Perspectives

Seasonal influenza vaccination and the risk of infection with pandemic influenza: a possible illustration of non-specific temporary immunity following infection

H Kelly , S Barry, K Laurie, G Mercer

Unlike the Canadian researchers, these scientists could find no increased susceptibility to the pandemic H1N1 virus among Australians who had been vaccinated the previous year against seasonal flu. The difference between the two findings, they posited, came from three separate factors:

• A theory regarding temporary immunity following any influenza infection
• The timing of the arrival of the pandemic virus in Canada
• And the protective effects of seasonal flu vaccination against seasonal - but not pandemic - flu.

Simply put, Canadians who were vaccinated in the fall of 2008 were better protected against seasonal influenza infection during the winter, but their collective immunity was running low by the time pdmH1N1 appeared.

Those who had skipped the fall 2008 vaccine were more likely to have caught seasonal flu over the winter, and therefore acquired some `non-specific temporary immunity' - which carried into the spring - making them less likely to be infected with the pandemic strain. 

While only a hypothesis, it could explain why different countries reported different outcomes.

All of this, believe it or not, is only a fraction of the story. But it suffices as a broad introduction to the following study of more than 600,000 U.S. military personnel who received the H1N1 pandemic vaccine in the fall of 2009 either with, or without prior, seasonal flu vaccination. 

In this case, the authors found `. . . no clinically significant difference in ILI, influenza, or pneumonia attack rates among those receiving the pH1N1 vaccine with or without presence of the seasonal vaccine.'

I've only included an excerpt from the abstract. The full study is available at the link below:

Seasonal Influenza Vaccine Impact on Pandemic H1N1 Vaccine Efficacy

Rachel U Lee Christopher J Phillips Dennis J Faix
Clinical Infectious Diseases, ciy812, https://doi.org/10.1093/cid/ciy812
Published: 20 September 2018

Background

In 2009, a novel influenza A (pH1N1) was identified, resulting in a pandemic with significant morbidity and mortality. A monovalent pH1N1 vaccine was separately produced in addition to the seasonal trivalent influenza vaccine. Formulation of the seasonal influenza vaccine (injectable trivalent inactivated influenza vaccine [TIV] vs. intranasal live, attenuated influenza vaccine [LAIV]) was postulated to have impacted the efficacy of the pH1N1 vaccination.
 
Methods

We reviewed electronic health and manpower databases, which included vaccination records, along with healthcare encounters for influenza-like illness (ILI), influenza, and pneumonia among US military members (aged 18–49 years) in the contiguous United States. We examined rates by vaccination type to identify potential factors associated with the risk for study outcomes.

Results

Compared with those receiving the seasonal influenza vaccine alone, subjects receiving the pH1N1 vaccine, either alone (RR, 0.49) or in addition to the seasonal vaccine (RR, 0.51), had an approximately 50% reduction in ILI, 88% reduction in influenza (RR, 0.11 and 0.12, respectively), and 63% reduction in pneumonia (RR, 0.37 and 0.35, respectively). There was no clinically significant difference in ILI, influenza, or pneumonia attack rates among those receiving the pH1N1 vaccine with or without presence of the seasonal vaccine. Similarly, there was no clinically relevant difference in pH1N1 effectiveness between seasonal TIV and LAIV recipients.

Conclusions

During the 2009–2010 pandemic, the pH1N1 vaccination was effective in reducing rates of ILI, influenza, and pneumonia in young healthy adults. Administration of the seasonal vaccine should continue without concern of potential interference with a novel pandemic vaccine, though more studies are needed to determine if this is applicable to other influenza seasons.

There are, of course, some potentially significant differences between the demographics - and general health - of active duty military personnel vs. the general public.  But this is the largest, and most detailed, population study we've seen on this topic, which adds to its weight.

Even if the `Canadian Problem' can be adequately explained by the Temporary Immunity Hypothesis (which is mentioned in the full study), the role and potential impact of OAS and ADE remain poorly understood. 

For more on these thorny issues, you may wish to revisit:

PLoS Comp. Bio.: Spring & Early Summer Most Likely Time For A Pandemic.

PLoS Currents: Another In Vitro Study Suggests Previous Dengue Exposure May Exacerbate Zika Severity

Flu Vaccines & The Temporary Immunity Hypothesis

EID Journal: Original Antigenic Sin And Pandemic H1N1

#NatlPrep : First Aid Kits - One For The Home, And One More For The Road

 

Note: September is National Preparedness Month . Follow this year’s campaign on Twitter by searching for the #NatlPrep hash tag.
 
This month, I’ll be rerunning some edited and updated older preparedness essays, along with some new ones.

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A little over forty-six years ago - when I still a high school student in a sleepy central Florida town - I took a 3-night first aid class offered by the American Red Cross, taught by our local fire chief.  Part of our homework was to put together a `cigar-box’  first aid kit, which we would pledge to carry in our cars, or keep in our home.

I made two.  One for the home, and one more for the trunk of my car.

While they weren’t exactly of professional quality, and I’ve upgraded many times since, I’ve never lost the habit. The following year I went on to become an EMT, and two years after that, I was a paramedic. I confess to still feeling a bit naked these many years later without having a decent first aid kit within easy reach.

I’ll admit that owning two ambu-bags and 3 BP cuffs (one for personal use) borders on the excessive, but I certainly feel better knowing they are there. 

In addition to my two main `jump bags', I've a couple of `minor' cuts & scrapes kits I keep stashed in my medicine cabinet and in an overnight bag I keep for traveling. 

Well equipped first aid kits are a necessity in every home, and ideally should also be found in the trunk of every car. While you can purchase a ready-made kit (the quality of which varies depending on price), I’ve always preferred to create my own. 

I undoubtedly have a more elaborate kit than most, but perhaps a look inside my auto first aid bag will inspire some of my readers to make one of their own.

The `bag’ is an old style Laptop computer case, with a handle and a shoulder strap.  I like these, because they have numerous compartments, are soft, and are reasonably waterproof.

On the `trauma’ side of the bag, I’ve got `Kling’-style roll bandages, an ACE bandage, a couple of cravat `Triangle’ bandage (sling & swath), sterile 4x4 gauze pads, paper tape, Band-Aids, antibiotic cream and several absorbent feminine pads (they make excellent trauma dressings). 

On the opposite side, I’ve got an `ambu’ bag-mask resuscitator along with a selection of adult and child airways, a foam C-Collar, a B/P cuff, stethoscope, flashlight, and some ammonia caps – hidden away where you can’t see them are bandage shears, tweezers, and a magnifying glass, along with a spare pair of reading glasses.

There is also a penlight, a felt tipped pen, and a note pad.

Under the front `cover’ flap, I keep some basic OTC medicines, including aspirin, acetaminophen, some hand antiseptic, and a bulb syringe (can be used for minor suctioning).

Under the flap on the other side, I’ve got surgical & N95 masks, exam gloves, and a `space’ blanket.

And if that weren't enough, I've a non-medical emergency kit in my trunk as well. Some water, another space blanket, glow sticks (safer than road flares), gloves, a few tools, flashlight, etc.

Of course, having a kit isn’t enough.  You need to know how to use it. 

And for that, you need first aid training.  If you haven’t already taken a course, contact your local Red Cross chapter, and find out what is available in your area.   And don’t forget the CPR training (or recertification!) as well.

Whether you buy a ready-made kit, or make your own, now is a good time to make sure you are fully equipped to deal with a medical emergency.
 
For more information I would invite you to visit:

FEMA http://www.fema.gov/index.shtm
READY.GOV http://www.ready.gov/
AMERICAN RED CROSS http://www.redcross.org/

Upcoming COCA Call: 2018-2019 Recommendations for Influenza Prevention and Treatment in Children

Credit CDC

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It's been a few months since we saw our last COCA (Clinician Outreach and Communication Activity) Call, but their summer hiatus is over. On Thursday the CDC will present:

2018-2019 Recommendations for Influenza Prevention and Treatment in Children: An Update for Pediatric Providers

Free Continuing Education

Date: Thursday, September 27, 2018

Time: 2:00pm-3:00pm (Eastern Time)

Please join the COCA Call / Webinar with digital audio, video, and presentation formats from a PC, Mac, iPad, iPhone, or Android device.
At the time of the call, please click this link below to join the webinar: https://zoom.us/j/512836971
Or iPhone one-tap :
US: +16699006833,,512836971# or +16468769923,,512836971#

Or Telephone:
Dial (for higher quality, dial a number based on your current location):
US: +1 669 900 6833 or +1 646 876 9923

Webinar ID: 512 836 971

International numbers available: https://zoom.us/u/dEIDbmM25       

Overview

Influenza remains a serious threat to children due to its potential to cause serious morbidity and mortality. More than 175 flu-associated deaths in children were reported to the Centers for Disease Control and Prevention (CDC) during the 2017–2018 influenza season.

Clinicians play a critical role in taking action to immunize children, the children’s family members and caregivers, and themselves. The early use of antiviral drugs in children can reduce the duration of symptoms and prevent serious complications of influenza. However, immunization remains the most effective way to prevent influenza illness and its complications, including death.

During this COCA call, subject matter experts from the American Academy of Pediatrics (AAP) and CDC will discuss strategies primary care providers and medical subspecialists can use to improve flu prevention and control in children for the 2018-2019 season. The presenters will share AAP and CDC recommendations about influenza vaccination and antiviral treatment, including updated recommendations for the use of intranasal live attenuated influenza vaccine (LAIV4) in children.

Primarily of interest to clinicians and healthcare providers, COCA (Clinician Outreach Communication Activity) calls are designed to ensure that practitioners have up-to-date information for their practices.

COCA calls are archived on the CDC's website, and may be accessed HERE within a few days of airing.  Older presentations - going back to 2016 - are also available at that link 

China MOA: Inner Mongolia Reports 4th Outbreak Of African Swine Fever

Credit Wikipedia

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Nine days ago Inner Mongolia became the 7th Chinese Province/Territory to report an ASF outbreak (see China: MOA Reports 2 New ASF Outbreaks (Inner Mongolia, Henan Province), which was quickly followed by a 2nd notification last Monday, and a 3rd on Friday. 

On Friday, an 8th Province/Territory (Jilin) reported an outbreak as well.

Today we have a 4th outbreak from Inner Mongolia, detected this time - not on a farm - but in pigs already sent to a slaughterhouse in Hohhot.  While an investigative team has been dispatched, we aren't told exactly where the infected pigs were sourced from.

A case of African swine fever in Hohhot, Inner Mongolia Autonomous Region

Date: 2018-09-24 15:56 Author: Source: Ministry of Agriculture and Rural Press Office 

The Information Office of the Ministry of Agriculture and Rural Affairs was released on September 24, and the Hoghot City of Inner Mongolia Autonomous Region was diagnosed with an African pig swine epidemic.

On September 22, the official veterinarian of a slaughterhouse in Hohhot, Inner Mongolia Autonomous Region, found that the pigs to be slaughtered died during the inspection. On the afternoon of the 23rd, the Inner Mongolia Autonomous Region Animal Disease Prevention and Control Center was diagnosed as suspected African swine fever.

On the 24th, the Ministry of Agriculture and Rural Affairs received a report from the China Animal Disease Prevention and Control Center and was diagnosed as an African swine fever epidemic by the China Center for Animal Health and Epidemiology (National Center for Animal Disease Research). The slaughterhouse is 388 pigs to be slaughtered, with 4 heads and 2 deaths.

Immediately after the outbreak, the Ministry of Agriculture and Rural Affairs sent a steering group to the local area. The local government has started the emergency response mechanism as required, and adopted measures such as blockade, culling, harmless treatment, disinfection, etc., to treat all the sick and culled pigs harmlessly. At the same time, all pigs and their products are prohibited from flowing out of the blockade area, and pigs are prohibited from being transported into the blockade area. At present, the above epidemic has been effectively disposed of.

Meanwhile Shandong Province - which is bordered by a couple of provinces reporting ASF, but has yet to find a case - has ordered their hog market closed in an attempt to prevent the entry and spread of the virus.

Shandong's prevention and control of African piglets temporarily shut down the province's live pig market

September 23, 2018 04:18 Beijing News

The Beijing Newsletter (Reporter Li Yukun intern Liang Hanbin) Recently, the Shandong Provincial Animal Husbandry and Veterinary Bureau issued the "Notice on Printing and Disclosing an Open Letter to Prevent and Control African Hog", temporarily closing the province's live pig trading market.

The notice publicized the "open letter to the majority of pig farms (households)" organized by the Provincial Animal Husbandry and Veterinary Bureau, the "Open Letter to the Slaughter Enterprises of All Pigs in the Province" and the "Open Letter to All the Pig Trafficking Brokers in the Province".

Among them, in the "Open Letter to the majority of pig farms (households)", Shandong Provincial Animal Husbandry and Veterinary Bureau clearly pointed out that "the province temporarily closed the live pig trading market, suspended the transfer of pigs outside the province (excluding breeding pigs), suspended from outside the province Transfer to pigs."

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While not a health risk to humans, ASF is truly a nightmare disease for pig producers - and with no vaccine available - the only way to control it is to cull all of the pigs that may have been exposed.    

The FAO, which a little over two weeks ago announced that ASF in China was `Here to stay', has warned of the spread of ASF beyond China, into neighboring countries in Asia (see African swine fever (ASF) threatens to spread from China to other Asian countries).

Similar concerns extend beyond Asia as China exports feed products for swine, which some believe may have introduced PED (see mBio: PEDV - Porcine Epidemic Diarrhea Virus – An Emerging Coronavirus) into the United States in 2013.

A dispatch last week from the Swine Health Information Center warned:

ASF in China Prompts Call for Pork Producers to Think Feed Safety
September 19, 2018

Which was followed up today by:

Five Possible Pathways ASF Could Enter Canada

September 24, 2018

Given the inroads ASF is making in Europe (see UK: DEFRA Preliminary Assessment Of ASF Reported In Belgium) this level of concern among pork producers around the world is more than justified. 

ECDC: RRA On Imported Monkeypox Cases From Nigeria

 
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Over the past several days we've learned a great deal more about the two imported cases of Monkeypox into the UK from Nigeria, and about the coordinated public health responses from the UK, Nigeria, and other EU nations.

Nigeria: CDC Monkeypox Update Epi Week 37

Eurosurveillance Rapid Comms: Two cases of Monkeypox imported to the UK

Report: UK PHE Imports Smallpox Vaccine For HCWs Caring For Monkeypox Cases

In the fall of 2017, Nigeria saw their first confirmed Monkeypox outbreak in nearly 40 years, resulting in more than 200 confirmed and suspected cases. While that outbreak was reportedly quelled in February, a small number of isolated cases have continued to be reported over the past 6 months.

Fortunately, the West African Monkeypox virus is considered to be less virulent, and less easily transmitted, than its Central African counterpart (cite).

Nevertheless, the importation of any infectious disease into a country where community immunity is believed very low, is a concern.  And the importation of two separate Monkeypox cases in a matter of a few days - when no cases had ever been seen in the UK before - quite unusual.

Hence the vigorous response from public health.

As reflected in the ECDC chart above, nearly 50,000 people arrive to EU countries from Nigeria each month, with the vast majority of those ending up in the UK.  Other African nations (Cameroon, DRC, Sierra Leone, Liberia & Central African Republic) where Monkeypox outbreaks have been reported provide nearly 400,000 annual EU visitors.

As we've seen with recently imported cases of MERS in South Korea and the UK, and with briefly quarantined flights in the United States (for flu), international air travel is a highly efficient way to spread any infectious disease (see JFK Quarantined Flight & Airport Screening For Infectious Diseases).

Although hyperbolic headlines in the tabloid press have badly overstated the current threat, the risk of seeing additional cases arrive - or even limited transmission to close contacts in the EU - is not zero. 

On Friday the ECDC published a Rapid Risk Assessment (RRA) on the UK's imported Monkeypox cases, excerpts from which I've posted below.  By all means, follow the link and download the full document.

RAPID RISK ASSESSMENT
Monkeypox cases in the UK imported by travellers returning from Nigeria, 2018
21 September 2018

(EXCERPTS)

Situation in the rest of West and Central Africa in 2018

Cameroon: On 30 April 2018, two suspected cases of monkeypox were reported to the Directorate of Control of Epidemic and Pandemic Diseases (DLMEP) by the Njikwa Health District in the Northwest Region of Cameroon bordering Nigeria. On 14 May 2018, one of the suspected cases tested positive for monkeypox virus by PCR. On 15 May 2018, an incident management system was set up at the National Emergency Operations Center. An investigative mission to the Northwest and Southwest Regions from 1 to 8 June 2018, found 21 new suspected cases without active lesions. As of 13 June 2018, a total of 36 suspected cases have been reported from both the Northwest and Southwest Regions [30].

Central African Republic: The outbreak was officially declared on 17 March 2018 in the sub-province of Ippy, Bambari district. Since the beginning of the outbreak, three districts have been affected, namely Bambari, Bangassou and Mbaïki districts. Cumulatively, 40 cases of monkeypox with one death (CFR 2.5%) have been reported from 2 March to 22 August 2018 in the country and 13 cases have been laboratory confirmed out of 23  samples tested. No new cases have been notified in the three districts after the end of the epidemic.

Democratic Republic of the Congo: From weeks 1 to 33, 2018, there have been 2 585 suspected cases of monkeypox, including 42 deaths (CFR 1.6%). Suspected cases have been detected in 14 provinces. Sankuru Province has had a remarkably high number of suspected cases in 2018.

Liberia: Since the beginning of 2018 and as of 19 August, four suspected cases have been reported from Sinoe, Rivercess, Nimba and Maryland Counties [31].

Sierra Leone: In April 2017, an isolated case of monkeypox was confirmed in Pujehun District, Sierra Leone. This is the third known occurrence of monkeypox in the country, with the first reported case in 1970 and the second in 2014 [32].

ECDC risk assessment for the EU

The notification of imported cases in Europe is not unexpected due to the circulation of monkeypox virus in West and Central Africa and the travel volume pattern observed from this region into the EU.

According to the International Air Transport Association (IATA) database, over half a million people travelled from Nigeria to the EU Member States in 2017. Among these travellers, the UK has the highest travel volume of passengers from Nigeria (59%), followed by Italy (9%), Germany (7%) and Ireland (6%). France, the Netherlands, Spain and Sweden account for less than 5% each. In total, these eight countries accounted for 93% of the travellers from Nigeria to the EU in 2017 (See Annex 1). In 2017, travellers came from other countries with reported monkeypox virus circulation to the EU Cameroon (215 658), DRC (97 380), Sierra Leone (40 023), Liberia (29 768) and Central African Republic (10 853).

The notification of two imported cases in a short period of time could indicate an enhanced circulation of monkeypox virus in West Africa in 2017 to 2018. This is supported by continuous reports of sporadic cases in Nigeria after the outbreak reported in late 2017 and the notification for the first time of an outbreak in southern Cameroon in 2018.

Risk of introduction and further spread within the EU/EEA

The risk of new introductions of monkeypox to Europe depends on the extent of the circulation of the virus in Nigeria and other countries in West and Central Africa. Cases continue to be reported from several countries, but present information indicates that the peak of the outbreak in Nigeria occurred in October 2017.

Overall, the likelihood of monkeypox importation to Europe remains very low, but new travel-related cases into EU/EEA countries cannot be excluded. Therefore, public health professionals should follow the development of the situation in West and Central Africa and maintain healthcare awareness about  the risk of occurrence of potential monkeypox cases among individuals travelling back from affected areas with compatible clinical presentation.

With regard to this event, due to the epidemiological link with Nigeria, the West African clade is expected to be the aetiological agent, pending genomic confirmation. The risk of spread in the EU/EEA is very low due to the moderate transmissibility of the disease reported to date, its distinctive clinical picture − although physicians should be aware of the similarities with and differences from varicella and other poxvirus infections in humans − the available laboratory capacity in Europe for rapid diagnostic and capacities for appropriate management of cases and their contacts in EU/EEA countries.

Risk of infection with regard to different settings for EU/EEA citizens

In the community, the risk of transmission is considered negligible.

The individual risk of infection through contact with a patient depends on the nature and duration of the contact. Close contacts (e.g. immediate neighbour on aircraft, family members with close contact), or persons who have provided care to patients, including HCWs whoo have not applied preventive measures, have a moderate risk for infection. Consequently, HCWs and others caring for patients should implement necessary precautionary measures to reduce the risk of infection.

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For a more detailed look at the Monkeypox virus in Africa, and a limited 2003 outbreak in the United States - you may wish to revisit this blog from last May.

MMWR: Emergence of Monkeypox — West and Central Africa, 1970–2017

NOAA: Update On Seal Strandings & Deaths In New England

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Five weeks ago, in NOAA Investigating Unusual Seal Strandings & Deaths In New England we looked at reports of an unusual spike in seal mortality along the Maine, New Hampshire, and Massachusetts coastlines, which was reminiscent of a 2011 event caused by a novel H3N8 avian flu (see New England Seal Deaths Tied to H3N8 Flu Virus).

A week later, NOAA announced that avian influenza (subtype not specified), along with Phocine Distemper virus, was confirmed as being present in at least some of the seals recovered in this latest die off (see NOAA: Seals in New England Test Positive for Avian Flu & Phocine Distemper Virus).

Earlier this month, with the number of dead seals continuing to climb,  NOAA Declared An Unusual Mortality Event - Harbor & Grey Seals In The Northeast.

NOAA's latest update - 2018 Pinniped Unusual Mortality Event along the Northeast Coast - now implicates Phocine Distemper, and minimizes the likely role of avian flu, in these deaths. 

Why are seals stranding?

Full or partial necropsy examinations have been conducted on some of the seals and samples have been collected for testing.  Based on tests conducted so far, the main pathogen found in the seals is phocine distemper virus. Phocine distemper virus is not zoonotic, which means it cannot be transferred to humans, but it may still be able to affect pets. 

The test results do not provide strong evidence that avian influenza virus is a cause of the current Northeast Pinniped UME. We are continuing additional testing to identify any other factors that may be involved in this event and will share those findings when available. 

As part of the UME investigation process, an independent team of scientists (Investigative Team) is being assembled to coordinate with the Working Group on Marine Mammal Unusual Mortality Events to review the data collected and provide guidance for the investigation.

(Continue . . . )

Although we've seen high seal mortality in the past with avian viruses (see H3N8 in New England and H10N7 in Europe), two years ago in Emerg. Microbes & Inf.: Prevalence Of Influenza A in North Atlantic Gray Seals we looked at a study showing that some seals can carry certain types of influenza A viruses - including avian subtypes - without obvious signs of illness. 

Essentially, they found a high level of influenza A infection in the sampled seal population, but with little or no sign of illness.  Grey seals in particular, were found to carry these viruses without ill effect.

And in 2013 we saw a report (and a study) from UC Davis showing the human 2009 pandemic H1N1 virus had jumped to wild California Elephant Seals just one year after that virus emerged (see The 2009 H1N1 Virus Expands Its Host Range (Again)).

All of which means that the detection of avian influenza in sick seals could end up being an incidental finding, and not the cause of their illness. 

As this latest update mentions, additional tests are underway, and so we'll keep an eye on this story for any additional developments.