Thursday, July 31, 2025

CDC Reminder On Preventing the Spread of Flu Between Pigs and People

CDC Twitter/X post


#18,818


While avian flu continues to rank at - or near the top of - most people's pandemic threat lists, swine influenza viruses (which tend to spread stealthily in pigs) may actually pose bigger risks.

Unlike avian flu, these viruses are already well adapted to mammals, and in many ways porcine physiology is remarkably similar to that of humans (see The pig: a model for human infectious diseases). 

Swine flu viruses are primarily H1, H2, and H3 subtypes; all of which have a long track record of sparking human pandemics  (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?).  

Many of the viruses circulating in pigs today are decedents of human flu viruses which spilled over into swine over the years. This sharing of viruses is a two-way street. 

Spillovers of swine variant viruses to humans are likely significantly under-reported, with some estimates suggesting less than 1% of cases are ever ever confirmed (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012).

Results. We estimate that the median multiplier for children was 200 (90% range, 115–369) and for adults was 255 (90% range, 152–479) and that 2055 (90% range, 1187–3800) illnesses from H3N2v virus infections may have occurred from August 2011 to April 2012, suggesting that the new virus was more widespread than previously thought. 

The CDC's IRAT (Influenza Risk Assessment Tool) lists 3 North American swine viruses as having at least some pandemic potential (2 added in 2019). 

H1N2 variant [A/California/62/2018]  Jul   2019   5.8  5.7 Moderate
H3N2 variant [A/Ohio/13/2017]          Jul   2019   6.6  5.8 Moderate
H3N2 variant [A/Indiana/08/2011]      Dec 2012   6.0  4.5 Moderate 

Since 2010 we've seen more than 500 scattered reports of human infection with swine variant influenza viruses (H1N1v, H1N2v & H3N2v) in the United States, often associated with agricultural exhibits at county and state fairs.

In addition to the 3 North American swine-variant viruses on the CDC's IRAT list, we continue to watch the evolution of China's EA H1N1 `G4' virus, Brazil's H1N2v virus, and emerging variants (and spillovers) in Europe (see ANSES Reports A `New' Swine Flu Virus Has Taken Over Other Genotypes in France).

But most of the world isn't bothering to test, or to share reports on, swine influenza.  

While most swine influenza infections are due to H1, H2, or H3, there are outliers, including H5N1 (see Preprint: Bovine Derived Clade 2.3.4.4b HPAI H5N1 Virus Causes Mild Disease and Limited Transmission in Pigs). 

Given their ability to concurrently carry multiple flu viruses, we've seen warnings (see Netherlands: Zoonoses Experts Council (DB-Z) Risk Assessment & Warning of Swine As `Mixing Vessels' For Avian Flu) that H5N1 could increase its pandemic threat by spreading (and evolving) in farmed swine.


Although we've only seen 1 swine-variant human infection reported so far in 2025 (see CDC FluView Week 5: Seasonal Flu Rising Again - 1 Novel (H1N2v) Flu Case In Iowa), summer and fall are prime time for spillovers. 

Every summer the CDC reminds the public of the risks of swine variant flu infections (see twitter/X post) , which are often associated with state and county fair attendance. 

First a link to their guidance page (follow the link for more resources), after which I'll have a brief postscript.
Take Action to Prevent the Spread of Flu Between Pigs and People Prevention

About
  • Influenza A viruses circulate among many different animals. Influenza A viruses that circulate among pigs are called swine influenza A viruses.
  • These viruses are different from influenza A viruses that spread among people and different from avian influenza A viruses.
  • While rare, influenza A viruses--including seasonal human A viruses and swine influenza A viruses--can spread from pigs to people and from people to pigs. When an influenza A virus that normally infects pigs is found in people, it is called a 'variant influenza' virus infection.
  • When people get variant flu, it's usually after contact with infected pigs or surfaces or environments contaminated with swine influenza A virus, such as a swine barn. These infections have occurred in different settings, including agricultural fairs.
  • The Centers for Disease Control and Prevention (CDC) recommends people take the following actions to help prevent the spread of influenza A viruses between certain animals (including pigs) and people. While the content of this page focuses on pigs, similar precautions are recommended around poultry and dairy cows, which can carry and spread different influenza viruses called avian influenza A viruses.

Take Preventive Actions

  • People at increased risk for severe influenza complications should avoid exposure to pigs.
  • Don't eat, drink or put anything in your mouth in areas with pigs.
  • Don't take toys, pacifiers, cups, baby bottles, strollers, or similar items into areas with pigs.
  • Wash your hands with soap and running water before and after exposure to pigs outside or inside a swine barn. If soap and water are not available, use an alcohol-based hand rub.
  • To further reduce the risk of infection, avoid or minimize contact with pigs in the pig barns and show arenas.
  • Where possible, avoid direct contact with pigs that are known or suspected to be sick. If you must come in contact with pigs that may be ill, then wear personal protective equipment (PPE). This includes protective clothing, gloves, and a well-fitting mask that covers your mouth and nose. Parents and caregivers should review considerations for specific groups of people when selecting a respirator or mask for children.
  • If you have a pig, watch for signs of illness (like loss of appetite, fever, tiredness, eye redness, discomfort, cough, or runny nose)If you suspect your pig is sick, call a veterinarian.
  • If sick pigs are in an exhibition area, remove them right away.
  • If possible, avoid close contact with sick pigs.
  • Avoid contact with pigs if you have flu symptoms. Wait to have contact with pigs until 7 days after your illness started or until you have been without fever for 24 hours without the use of fever-reducing medications, whichever is longer. If you must have contact with pigs while you are sick, take the preventive actions listed above.

Like everyone else, people who care for pigs should get a seasonal flu vaccine every flu season. Although a seasonal flu vaccine probably will not protect people against infection with variant influenza A viruses (because swine influenza A viruses are substantially different from seasonal influenza A viruses that infect people), vaccination is important to reduce the risk of spreading human seasonal influenza A viruses to other people and to pigs. Seasonal flu vaccination might also decrease the potential for people or pigs to become infected with human influenza A viruses and influenza A viruses from pigs at the same time.

People at Higher Risk
  • Anyone who is at higher risk of serious flu complications who plans to attend an event or setting where pigs will be present, such as an agricultural fair, should avoid pigs and swine barns.
  • If people at higher risk cannot avoid exposure to pigs, they should wear a well-fitting mask that covers the nose and mouth (e.g., an N95 respirator or KN95 respirator if available, or if not available, a surgical mask) to reduce the risk of exposure to influenza viruses from pigs.
  • People at higher risk of serious flu complications who develop flu symptoms should call a health care provider. Tell them about your risk factor and any exposure to pigs or swine barns you've had recently. Human seasonal flu vaccines will not protect against influenza A viruses that commonly spread in pigs, but prescription influenza antiviral drugs can treat infections with these viruses in people when treatment is started shortly after symptoms begin.

Recommendations for Fair Exhibitors

CDC guidance for people exhibiting animals including pigs, poultry, waterfowl, and cattle is available at Key Facts for People Exhibiting Pigs at Fairs.

 

While a swine variant pandemic might not prove to be as severe as one from an avian H5 or H7 virus, the likelihood of emergence of a swine-origin pandemic is considered higher. 

This `longshot' status for H5N1 is illustrated in the following CDC IRAT chart, placing our current H5N1 virus in 11th place (emergence score) among their top 24 zoonotic influenza viruses with pandemic potential.  

EA A(H1N1) `G4' - in Chinese pigs - is ranked #1, with a swine A/H3N2 ranked #2,  and another swine A/H3N2 (ranked #6) and an A/H1N2 (#7) all in the top ten.  The European 1C and Brazilian H1N2 variants aren't ranked by the CDC, but would probably make the top 20 threats. 

And of course, there are likely scores of other swine variants we don't know about, that are all own their own evolutionary paths.  Most will be failures, but it only takes one over-achiever to change our inter-pandemic status quo. 
at

The UK's Summer HPAI H5 Surge In Poultry

 
HPAI H5 Outbreaks July 25th-30th

#18,817

Typically summer is a slow time for avian flu, particularly in temperate zones.  Over the past week, however, the UK has reported no fewer than 4 new HPAI H5 outbreaks in poultry, scattered across their Kingdom. 

This is a significant uptick, since in 2024 the UK went from February to November without reporting a single H5 outbreak.  Previously, between May 12th and June 22nd 2025, the UK reported 6 infected premises. 

 

After a lull of just over a month, over the past 6 days the UK's Defra has reported:

Bird flu: near Attleborough, Breckland, Norfolk (AIV 2025/53)
type: Bird flu (avian influenza) Control zone restriction: In force
Control zone type: Protection zone and 1 others
Virus strain: H5N1
Opened: 30 July 2025

Bird flu: near Tiverton, Mid Devon, Devon (AIV 2025/52) 
type: Bird flu (avian influenza)
Control zone restriction: In force
Control zone type: Protection zone and 1 others
Virus strain: H5N1
Opened: 30 July 2025

type: Bird flu (avian influenza)
Control zone restriction: In force
Control zone type: Protection zone and 1 others
Virus strain: H5N1
Opened: 28 July 2025

type: Bird flu (avian influenza)
Control zone restriction: In force
Control zone type: Captive bird (monitoring) controlled zone
Virus strain: H5N1
Opened: 25 July 2025

Cases are well scattered across the Kingdom, and all are reported as HPAI H5N1.  

From Defra's most recent (July 21st) High pathogenicity avian influenza (HPAI) in Great Britain and Europe, we see the following outbreak map showing increased activity in May-June-July in and around the UK. 

Map 3. HPAI events in domestic poultry and wild birds in Europe reported by WOAH between 12 May and 21 July 2025 (WOAH, 2025). Wild bird cases and poultry outbreaks are concentrated in Great Britain, Ireland and across the English Channel but only sporadic across eastern and central Europe with some cases in Spain and Portugal, as described in the main body of this report above.

This report was issued prior to the 4 most recent IPs (Infected premises), and after having gone 4 weeks (June 22nd-July 21st) without any outbreaks in poultry. 

In years past, that has suggested the expected summer lull in bird flu outbreaks had arrived.

In the report's conclusion, the authors wrote:
Since our last assessment on 12 May 2025 (HPAI in Great Britain and Europe May 2025),cases of HPAI H5Nx have continued in gulls and seabirds through June and into July. 

Therefore, the national risk level for HPAI H5 in wild birds is maintained at HIGH (occurs very often). Most of the wild bird cases in the last month have been coastal and not inland.
There have been no IPs in Great Britain for the last 4 weeks, with low numbers reported in the weeks preceding that. This suggests that the risk between infection in poultry and detection in wild birds is becoming decoupled as has been seen in previous years when HPAI H5 has over-summered in seabirds and gulls around the coast. 

The risk of infection of poultry in Great Britain with suboptimal biosecurity is therefore lowered to LOW (rare but does occur) with high uncertainty. The risk to poultry with stringent biosecurity is maintained at LOW (rare but does occur) with low uncertainty

A reasonable assessment given the patterns we've seen in recent years, and the relative drought of outbreaks reported on the Continent.  But as we've repeatedly seen, HPAI often throws curve balls.  

Whether this summer uptick is an aberration or a trend, is something we'll simply have to wait to see.  

But this is a reminder that our powers of prognostication when it comes to what avian flu will - or won't - do, remain quite limited.  
at

Wednesday, July 30, 2025

J. Virology: Zoonotic Disease Risk at Traditional Food Markets (Minireview)



Photo Credit – FAO

#18,816

While there are myriad ways by which the next pandemic virus might emerge, one of the more obvious routes is via Live Bird Markets (LBMs), Live Animal Markets (LAMs), or Traditional Food Markets (TFMs), which often deal in live poultry and other animal species (including `bushmeat'). 

Live bird markets (LBMs) have long been linked to human exposure to (and infection by) avian influenza viruses, so much so that in 2014, in CDC: Risk Factors Involved With H7N9 Infection, we looked at a case-control study that pretty much nailed visiting LBMs as the prime risk factor for infection.

Three years ago, in Zoonoses & Public Health: Aerosol Exposure of Live Bird Market Workers to Viable Influenza A/H5N1 and A/H9N2 Viruses, Cambodia, we looked at a study that documented high levels of H5 & H9 viruses in the air at a Cambodian LBM during the `high season' for avian flu, and more importantly, that a large percentage remained viable (and infectious).

While data is limited, numerous seroprevalence studies have shown higher rates of H5, H6, and H9 antibodies in poultry workers than in the general population (see EID Journal: Avian Influenza A Viruses among Occupationally Exposed Populations, China, 2014–2016).

Although we often think of this risk being largely limited to Asia, or the Middle East, or perhaps Africa, since H5N1's arrival in late 2021, the USDA has reported 54 outbreaks in live markets across the U.S. (in 6 states; NY, NJ, PA, FL, VA, CA). Of those, 62% (n=34) have been reported in the first 5 months of 2025, with the vast majority (n=23) coming from New York State.

Of course, HPAI isn't the only concern, the consumption and trade in `bushmeat' likely reintroduces dangerous pathogens (e.g. Ebola, Anthrax, Mpox, etc.) into the human population on a regular basis (see `Carrion’ Luggage & Other Ways To Import Exotic Diseases).

In 2005, the CDC’s EID Journal carried a perspective article warning on the dangers of bushmeat hunting by Nathan D. Wolfe, Peter Daszak, A. Marm Kilpatrick, and Donald S. Burke; Bushmeat Hunting, Deforestation, and Prediction of Zoonotic Disease.

It describes how it may take multiple introductions of a zoonotic pathogen to man – over a period of years or decades – before it adapts well enough to human physiology to support human-to-human transmission.

The sale and consumption of raw or unpasteurized milk - quite common in many parts of the world - presents multiple disease risks.  Between bacteria, viruses, parasites, and toxins, foodborne illnesses reportedly sicken 600 million people each year, killing 420,000.

Even modern manufacturing techniques, refrigeration, and rigorous hygiene standards can't guarantee the food we eat will be 100% safe (see CDC Outbreaks List), but they do go a long way in improving the odds.  

Earlier this year the city of Shanghai (pop 25 million) banned the sale of live poultry, but earlier attempts to restrict or close LBMs in Asia have been met with steep resistance.  

Often, when `legal' markets were shuttered during avian flu outbreaks, infected birds would be shipped to other (sometimes illicit) markets. 

All of which brings us to an excellent review article which finds that traditional food markets (TFMs)—including wet markets—provide essential community services (both economic and social), they can also be hotspots for zoonotic disease transmission. 

Due to its length, I've only provided the link a a few small excerpts. 

Their list of Priority Zoonotic Pathogens contains 17 types of bacteria, 11 varieties of parasites & protozoa, and 18 families of viruses, along with details on their routes of transmission and animal hosts.

The authors emphasize the importance of a `One Health' approach; integrating human, animal, and environmental health to improve market safety - and call for improved pathogen surveillance in TFMs - along with finding solutions tailored to local needs, rather than blanket bans. 

This is an impressive review - and while it can't offer a `one-size-fits-all' solution -  it is very much worth reading in its entirety. 
Frida E. Sparaciari, Cadhla Firth, Erik A. Karlsson, and Paul F. Horwood

Traditional food markets (TFMs) are dynamic and complex systems that play a vital role in societies across the globe. They provide fresh, affordable food, help preserve cultural traditions, and support the livelihoods of millions. However, these markets also present inherent risks associated with the trade of live animals and animal-derived products, including the emergence and spread of zoonotic diseases, which are underreport ed in these settings.

This review explores the dual role of TFMs as essential societal hubs and hotspots for zoonotic diseases, emphasizing the need for surveillance and targeted One Health research on pathogens in these environments. By assessing the health risks associated with the presence of specific animals and their pathogens in TFMs, this review lays the foundation for developing the evidence-based risk assessments and mitigation strategies needed to reduce zoonotic disease risk.

Enhancing the safety and sustainability of TFMs through integrated One Health approaches will be crucial for balancing the cultural and economic importance of TFMs with the need for increased global health security.
(SNIP)

Traditional food markets (TFMs) exist in diverse forms and are known by various names, including wet markets, live animal markets (LAMs), and informal markets. Regardless of their designation, they play a vital role in the livelihood of millions of individuals and provide affordable, fresh food to people worldwide. TFMs also serve as critical social and cultural spaces and can even be an attraction for tourists. These markets typically offer a wide range of products, including animal-derived foodstuffs, fresh produce, dried goods, and ready-to-eat meals. In some cases, live animals are housed and slaughtered on-site, contributing to negative perceptions that TFMs pose risks for zoonotic disease emergence (1).

       (SNIP) 

Despite these proposed interventions, significant challenges remain. Many TFMs operate within informal structures, lacking regulatory oversight, policy enforcement, and adequate investment in infrastructure. Moreover, data on the diversity and prevalence of zoonotic diseases in TFMs are limited, particularly in regions with high market activity but low surveillance capacity. Moving forward, a coordinated international effort is required to balance the economic and cultural importance of TFMs with public health and biosafety concerns. Strengthening global surveillance networks, fostering cross-sector collaboration, and incorporating innovative environmental monitoring technologies can enhance our ability to detect and respond to emerging threats. Future research should also prioritize underrepresented regions and pathogens to build a more comprehensive understanding of the risks associated with TFMs.
Ultimately, TFMs will continue to play a vital role in global food systems, but their sustainability and safety depend on integrating evidence-based strategies to mitigate zoonotic disease risks.

        (Continue . . . )

 

at

Tuesday, July 29, 2025

Updated joint FAO/WHO/WOAH Public Health Assessment of Recent Influenza A(H5) Virus Events in Animals and People

 
#18,815

Yesterday the FAO/WHO/WOAH released an updated assessment (based on data as of July 1st) on the threat posed by various clades and subtypes of HPAI H5.

While they continue to assess the global public health risk of influenza A(H5) viruses to be low, the risk of infection for occupationally exposed persons is deemed to be low to moderate.

These updates are released roughly every 3 months (see March 2025 update), and are based primarily on reports from member nations, which may or may not be complete or up to date (see WHO Guidance: Surveillance for Human Infections with Avian Influenza A(‎H5)‎ Viruses).

This 13-page document contains information on recent spillovers into both animals and humans, and is well worth reading in its entirety. 

There is a lot to unpack here, and you'll want to read it in its entirety, but over the last 3 months, WOAH reports:

Between 1 March and 1 July 2025, an additional 807 A(H5N1) outbreaks in animals (including bird and mammal species) have been reported to WOAH. Of these, 268 outbreaks occurred in poultry (of any farming system), 389 outbreaks in wild bird and 92 outbreaks occurred in mammalian species. In Cambodia, 9 out of 14 outbreaks in poultry occurred in the vicinity of reported human cases.

In their discussion of clade 2.3.4.4b's viral characteristics, they address a number of topics we've discussed recently, including Antiviral resistance (see EID Journal: Antiviral Susceptibility of Influenza A(H5N1) Clade 2.3.2.1c and 2.3.4.4b Viruses from Humans, 2023–2024):

Available virus sequences from human cases have shown some genetic markers that may reduce susceptibility to neuraminidase inhibitors (antiviral medicines such as oseltamivir) or endonuclease inhibitors (such as baloxavir marboxil). While these changes may reduce antiviral susceptibility in laboratory testing, the clinical impact of these genetic changes requires further studies. 

And potential preexisting community immunity (see Study: Preexisting Immunity to the 2009 Pandemic H1N1 Virus Reduces Susceptibility to H5N1 Infection and Disease in Ferrets).

Based on limited seroprevalence information available on A(H5) viruses, human population immunity against the HA of A(H5) viruses is expected to be minimal; human population immunity targeting the N1 neuraminidase is found to be present although the impact of this immunity is yet to be understood. 

Experimental studies suggest prior A(H1N1) immunity reduced virus replication and disease severity of bovine-derived B3.13 genotype A(H5N1) virus in ferrets and that ferrets with this pre-existing immunity expressed A(H5N1) cross-reacting antibodies to the neuraminidase protein. 

However, the effectiveness of quadrivalent seasonal influenza vaccine (QIV) against influenza A(H5N1) virus remains a speculation, as a recent study observed no cross-neutralisation of H5N1 viruses by sera from patients vaccinated against seasonal influenza with QIV.4 

These risk assessments are only as good as the data that these agencies have access to, and as we've discussed previously (see From Here to Impunity), many nations continue to hold avian flu information close to their vest. 

Accordingly, the FAO/WHO/WOAH cab cite only medium confidence in their assessment:

Confidence level of the assessment

The overall confidence in the risk assessment is considered medium. The information used is derived from reports from national animal and human health authorities. There may be biases in surveillance, testing and reporting. Although the results and conclusions from peer-reviewed publications, pre-print publications and unpublished data informed this risk assessment, no systematic literature review was undertaken. Critical knowledge gaps remain in the understanding of the epidemiology.

We continue to see member nations encouraged to promptly report any spillovers of novel influenza to the appropriate agency, but it is unclear how much of the bird flu iceberg remains hidden. 

at

Cambodian MOH Announces 14th H5N1 Case of 2025

 

#18,814

Cambodia's summer surge of human bird flu infections continues with their 14th H5N1 infection of 2025, making their 11th reported over the past 2 months. This is the 30th case reported since February of 2023, when the first (2) cases in nearly a decade were reported by WHO.

Unlike H5N1 cases reported in the United States - which are due to a milder clade 2.3.4.4b - recent Cambodian cases have been caused by a new reassortment of an older clade of the H5N1 virus (recently renamed 2.3.2.1e) - which appears to be spreading rapidly through both wild birds and local poultry.



This morning the Cambodia MOH posted an announcement on their Facebook page on another H5N1 case - once again from Siem Reap Province (n=5) - involving a 26-year old man who is currently in intensive care after being exposed to sick or dead chickens.

I've reproduced the screen shot (in Cambodian) and have provided an English translation below.


Kingdom of Cambodia
Nation Religion King
Ministry of Health

Press Release


The Ministry of Health of the Kingdom of Cambodia would like to inform the public: There is another case of bird flu in a 26-year-old man who was confirmed positive for the H5N1 avian influenza virus by the National Institute of Public Health on July 26, 2025.
The patient lives in Kravan village, Nokor Thom commune, Siem Reap city, Siem Reap province and has symptoms of fever, cough, sore throat, abdominal pain, and difficulty breathing. The patient is currently undergoing intensive care by the medical team. Investigations revealed that there were dead chickens in the vicinity of the patient’s house, and the patient killed and slaughtered chickens 3 days before the patient became ill.

The emergency response teams of the national and sub-national ministries of health have been collaborating with the provincial agriculture departments and local authorities at all levels to actively investigate the outbreak of bird flu and respond according to technical methods and protocols, find sources of transmission in both animals and humans, and search for suspected cases and contacts to prevent further transmission in the community. They have also distributed Tamiflu to close contacts and conducted health education campaigns among residents in the affected villages.

The Ministry of Health would like to remind all citizens to always pay attention to and be vigilant about bird flu because H5N1 bird flu continues to threaten the health of our citizens. We would also like to inform you that if you have a fever, cough, sputum discharge, or difficulty breathing and have a history of contact with sick or dead chickens or ducks within 14 days before the start of the symptoms, do not go to gatherings or crowded places and seek consultation and treatment at the nearest health center or hospital immediately. Avoid delaying this, which puts you at high risk of eventual death.

How it is transmitted: H5N1 bird flu is a type of flu that is usually spread from sick birds to other birds, but it can sometimes be spread from birds to humans through close contact with sick or dead birds. Bird flu in humans is a serious illness that requires prompt hospital treatment. Although it is not easily transmitted from person to person, if it mutates, it can be contagious, just like seasonal flu.

1/2

Address: Lot No. 80, Samdech Pen Nut Street (289)
Phone: (+855) 23 885 970
Website: www.moh.gov.kh
Sangkat Boeung Kak 2, Khan Toul Kork, Phnom Penh
Email: info@moh.gov.kh
Telegram: t.me/MOHCambodia

While summer outbreaks of avian flu are a bit unusual, the closer one gets to the equator, the more likely influenza is to circulate year-round. Siem Reap Province is only about 13 degrees N. Latitude.

As we discussed 3weeks ago, in Cambodia: Food Insecurity, Food Safety & H5N1 - despite repeated warnings to the public not to prepare or cook sick/dead poultry - scarce resources and hunger can sometimes drive people to take risks.

Given the frequent contacts reported with sick or dead poultry, there is currently no evidence to suggest human-to-human transmission of the virus.

Nevertheless, every human infection is another opportunity for the virus to better adapt to human physiology. So we watch these cases - and clusters - with considerable interest.

Stay tuned.
at

Monday, July 28, 2025

Sci. Advances: Assessing the Risk of Diseases with Epidemic and Pandemic Potential in a Changing World

 

#18,813

While novel influenza A has long been considered the greatest pandemic threat to humans, eight years ago the WHO released a short list (n=8) of priority diseases (see WHO List Of Blueprint Priority Diseases) - that in their estimation - had the potential to spark a public health emergency and were in dire need of accelerated research:
  • Crimean-Congo haemorrhagic fever (CCHF)
  • Ebola virus disease and Marburg virus disease
  • Lassa fever
  • Middle East respiratory syndrome coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS)
  • Nipah and henipaviral diseases
  • Rift Valley fever (RVF)
  • Zika
  • Disease X
In 2020, a variant of #4 on their list (SARS-CoV-2) sparked the worst pandemic in a century. Meanwhile, we've continued to see sporadic outbreaks of many of the others on the list.

Last summer the WHO unveiled an expanded 38-page Pathogens Prioritization report, increasing the number of priority pathogens to more than 30. Additions included 7 different influenza A subtypes (H1, H3, H3, H5, H6, H7, and H10), and 5 bacterial strains that cause cholera, plague, dysentery, diarrhea and pneumonia.


















Recent studies suggest that the frequency, and impact, of pandemics are only likely to increase over the next few decades.


In 2010's Influenza: The Once and Future Pandemic, authors Jeffery K Taubenberger & David M Morens wrote: `Influenza pandemics have been reported for at least 500 years, with inter-pandemic intervals averaging approximately 40 years.'

But, as the statistician who learned to his cost while attempting to ford a river that was - "on average, only 3 feet deep"  - there are sometimes outliers.

The 1957 (H2N2) and 1968 (H3N2) pandemics were only separated by a little over a decade, and more recently - after two close calls with coronaviruses (SARS & MERS) - COVID proved that non-influenza A viruses could compete on a world stage. 

The world we know is changing:

  • Our global population is 3 times greater today than when I was born (1954). That year, roughly 58 million people traveled internationally by air, while in 2025 that number is expected to approach 6 billion (a 100-fold increase)
  • Our world is also growing warmer, precipitation patterns are shifting, and we've continually encroached into previously untouched rainforests, deserts, and swamps in order to create farmlands, or cities, or in search of natural resources. 
  • In most developed countries we now raise most livestock in CAFO's (concentrated animal feeding operations), an environment which invites the spread and evolution of new diseases. 

The reality of life in this third decade of the 21st century is that disease threats that once were local, can now spread globally in a matter of hours or days. Vast oceans and prolonged travel times no longer protect us against infected travelers crossing borders.

All of which brings us to a research article, published last week in Science Advances, which attempts to identify and quantify the risks of zoonotic disease outbreaks with epidemic or pandemic potential in our continually changing world. 

This research article focuses heavily on climatic and anthropogenic drivers of pandemic risk, and given the paucity of data from many regions of the globe, a large number of assumptions had to be made. 

Due to its length and technical nature, I've only posted the abstract and a few excerpts.  Follow the link to read it in its entirety - although fair warning - some of it requires heavy lifting. 

I'll have a bit more after the break.


Assessing the risk of diseases with epidemic and pandemic potential in a changing world
Angela Fanelli , Alessandro Cescatti , Juan-Carlos Ciscar, Gregoire Dubois , Dolores Ibarreta , Rachel Lowe , Nicola Riccetti https://orcid.org/0000-0002-3178-7892, Marine Robuchon , Ilaria Capua , [...] , and Emanuele Massaro+1 authors Authors Info & Affiliations
Science Advances
23 Jul 2025
Vol 11, Issue 30
DOI: 10.1126/sciadv.adw6363

Abstract

How do human activities contribute to the emergence of zoonotic diseases that can lead to epidemics and pandemics? Our analysis of common drivers of the World Health Organization’s priority diseases suggests that climate conditions, including higher temperatures, higher annual precipitation levels, and water deficits, elevate the risk of disease outbreaks.
In addition, land-use changes, human encroachment on forested areas, increased population and livestock density, and biodiversity loss contribute to this risk, with biodiversity loss showing a complex and nonlinear relationship.
This study also presents a global risk map and an epidemic risk index that combines countries’ specific risk with their capacities for preparing and responding to zoonotic threats.

(SNIP)
 
The World Health Organization (WHO) maintains a list of priority diseases, namely, pathogens identified as having potential to cause severe public health emergency including epidemics and pandemics (14). This prioritization intends to guide global research efforts to better prepare for and mitigate potential zoonotic outbreaks.
The list includes COVID-19, Crimean-Congo hemorrhagic fever (CCHF), Ebola virus disease, Lassa fever, Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS), Marburg virus disease (MVD), Nipah virus disease (NiV), Rift Valley fever (RVF), Zika, and a placeholder for an unknown “Disease X” (14, 15).
Climate change affects the risk of these diseases, including vector-borne diseases such as RVF and Zika (16–19), and nonvector-borne diseases such as Ebola, which is affected by climate change through its effect on fruit abundance, attracting bats, and increasing the chance of human contact with infected reservoirs (20). Extreme weather events, forest fragmentation, and deforestation can also increase the risk of disease transmission, such as Lassa fever (21).

Building on the above context, our study aimed to investigate the relationship between nine key human-induced drivers and the outbreak risk of WHO priority diseases, excluding COVID-19. We also developed a global risk map and an epidemic risk index that reflects each country-specific risk versus its capacity to respond to zoonotic threats. 

        (SNIP)

We considered nine potential drivers of the WHO priority diseases, grouped into three categories: climate factors (temperature, precipitation, and water deficit), environmental factors (human-forest proximity, biodiversity loss, livestock density, and frequency of land-use change), and population (population density). In the multivariable analysis, we also incorporated the travel time to health care facilities as a bias breaker, ensuring that the probability of disease detection influenced by the proximity of health care facilities is accounted for.



No research paper can be expected to cover all the bases, so it is worth noting that there are a number of other potentially important drivers of the next pandemic that are not expressly addressed in this research paper, including:
  • ongoing reassortment or recombination in the wild has produced unprecedented diversity of zoonotic viruses around the globe
  • reverse zoonosis (human to animal) 
  • long-term infections among immunocompromised individuals leading to mutations or variants 
  • laboratory accidents 
  • bio-terrorism
  • growing antibiotic/antiviral resistance 
  • advances in synthetic biology
  • and even social media driven misinformation on vaccines and science
Given the complexity, interconnectedness, and increasing momentum of all of these risk factors, it seems unlikely that our current inter-pandemic interval will last for decades, as we've seen in the past. 

While we should certainly endeavor to mitigate zoonotic disease risks wherever we can, the reality is, nature always bats last.

And we never know when we're approaching the bottom of the 9th inning.  

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Sunday, July 27, 2025

Hawaii: Findings From DOH Bird Flu Survey For Backyard Flock Bird Owners And Bird Rescuers


Hawaii lies beneath the West Pacific Flyway


#18,812

Until last fall, the state of Hawaii had never detected any signs of the HPAI H5 virus, even though it lies beneath the West Pacific migratory bird flyway.  That happy status ended in November of 2024 when the virus was detected at a wastewater plant on Oahu.

Three days later Hawaii's Dept of Agriculture Reported the 1st Detection of HPAI H5 in a backyard flock of birds on Oahu, followed a week later by a 2nd Detection in a wild duck on Oahu. 

No human infections were reported (see Hawaii DOH Statement on Negative Testing Of Human Contacts to H5 Infected Flocks), and on Nov 22nd, we learned that the H5N1 genotype was A3 - which was first detected in Alaska in 2022 - and which supports the idea the virus arrived via migratory birds.

In mid-December the DOH reported that H5 had been Detected in Wastewater in Hilo, which was followed in January by several reports of H5 detected at the Wastewater Treatment Plant on Kauaʻi..

Even before the arrival of bird flu, the cost of eggs in Hawaii was the highest in the nation, making the raising backyard chickens very popular (cite), and feral chickens are a common sight.

Last March we looked at Hawaii's DOH announced plans to launch a Bird Flu Survey For Backyard Flock Owners & Bird Rescuers, to gauge the knowledge, attitudes, and practices of State of Hawaii residents who may be at greater risk of exposure to the virus.

This survey was done 5 nearly months after the initial - and highly publicized - outbreak in Hawaii. It was restricted to local residents aged 18 years or older who either keep birds at home, perform animal rescue, or engage in other bird-related activities. 

As the following excerpt from the Hawaii DOH press release indicates, there are major gaps in the understanding of bird flu risks, and best practices, among these high-risk cohorts. 

Posted on Jul 24, 2025 in Newsroom

HONOLULU — A survey by the Hawaiʻi State Department of Health (DOH) finds that while most local residents are aware that the bird flu had been detected in Hawai‘i, roughly two-thirds of flock owners had been unaware of related best practices.

In March 2025, the Hawaiʻi State Department of Health (DOH) invited Hawaiʻi residents who keep backyard flocks or are involved in bird rescue to participate in a survey aimed at gathering important data on bird flu awareness and preparedness.

The anonymous, online survey collected information on the understanding of bird flu, as well as the practices and needs of those who keep poultry or care for rescued birds.

Among the findings:
  • About two-thirds of backyard flock owners across the state reported they were not at all familiar with the U.S. Department of Agriculture’s Defend the Flock recommended practices to prevent bird flu.
  • Two-thirds of survey respondents also reported not knowing how to properly and safely remove and dispose of dead birds.
  • Most respondents (84%) were aware that bird flu had been detected in Hawaiʻi, and of the H5N1 variant that causes the flu.
  • Most respondents (72%) said they were very or somewhat concerned about the bird flu.
  • The top source of health information for the majority (76%) of Hawaiʻi residents is their doctor, which they ranked as very or somewhat trustworthy.
To be eligible to participate, individuals needed to be Hawaiʻi residents aged 18 years or older who keep at least one poultry bird at home, were involved in bird rescue activities, or have had direct contact with birds in the past year for other reasons.
In total, there were 420 survey responses. Of the 420 total responses, 237 respondents met the survey eligibility criteria and completed the survey entirely. Respondents participated from five islands in the state of Hawaiʻi: 43% from Hawaiʻi Island, 35% from Oʻahu, 10% from Kauaʻi, 10% from Maui, and 2% from Molokaʻi.

The report of DOH Bird Flu Survey findings is published on the DOH website, along with more information on bird flu: https://health.hawaii.gov/docd/disease_listing/avian-influenza/. Additional information can be found at the Hawaiʻi Department of Agriculture and Biosecurity’s avian flu website.
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Screenshots from the full survey document:

 


Since 2020 there has been a significant increase in the number of people who have decided to raise backyard poultry - especially hens for eggs - across the United States (see Chicken Coops Market Outlook 2025 to 2035) 

The APPA estimates `Eleven (11) million U.S. households own backyard chickens (a 28% increase from 2023)'

While the CDC has released guidelines (see Backyard Flock Owners: Protect Yourself from Bird Flu) - it is unknown how many backyard poultry owners have actually read it, or would bother to follow their recommendations. 

And while H5Nx is our biggest concern, there are other avian subtypes which have been reported in North America with zoonotic potential, including several subtypes of H7. 

This recent increase in backyard poultry raising has also been linked to increases in E. Coli and Salmonella infections, including the following ongoing CDC investigation:


A reminder that there are genuine health risks related to the raising backyard poultry, and specific knowledge and skills are required to reduce those risks.  

Those considering such an endeavor may want to visit the Small and backyard poultry extension website, which provides a wealth of free articles, blogs, and webinars on poultry raising. 

And of course, the USDA's Defend The Flock should be high on your list for  biosecurity information.  
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Saturday, July 26, 2025

Frontiers: HPAI: Pandemic Preparedness for a Scenario of High Lethality with No Vaccines


#18,811

Regardless of what pathogen causes it, one of the realities of the next pandemic is that vaccines will probably not be widely available to the public during the first 6 to 12 months of the outbreak.  

For some, particularly in developing countries, that wait could be much longer. 

This is a scenario we've covered many times (see Maggie Fox's SCI AM - A Bird Flu Vaccine Might Come Too Late to Save Us from H5N1), and it mirrors much of what we saw with SARS-CoV-2. 

But COVID, as bad as it was, is hardly the worst that a pandemic could throw at us. It has been estimated its CFR (Case Fatality Rate) was somewhere between 1% and 2% prior to the introduction of a vaccine. 

Even if we discount the oft-quoted 35% CFR estimate for MERS-CoV, and 50% CFR for HPAI H5N1 as being highly inflated (which I strongly suspect), a fatality rate 1/10th the size (3.5%-5.0%) would still exact a horrendous toll. 

We've also seen warnings that our current influenza antivirals may be lacking (see St. Jude Researchers: Current Antivirals Likely Less Effective Against Severe Infection Caused by Bird Flu in Cows’ Milk) along with signs of growing antiviral resistance in avian flu (see Emerg. Microbes & Inf: Oseltamivir Resistant H5N1 (Genotype D1.1) found On 8 Canadian Poultry Farms).

Figuring out how to deal with such a dire situation is an unenviable task, but we've started to see a small resurgence in pandemic planning around the globe. 

But far too many jurisdictions continue to rely on nearly 20-year-old pandemic plans, many of which focused heavily on how to deliver a (likely non-existent) vaccine to the public (see Where Have All The Planners Gone?).

Today we have a perspective article from researchers at Brazil's FIOCRUZ (Fundação Oswaldo Cruz) - along with local and international partners - on the challenges of preparing for a high impact pandemic for which vaccines will be (at least initially) unavailable.

While focused on HPAI viruses, it doesn't limit itself to H5N1, recognizing that both H5Nx and H7Nx viruses pose a significant pandemic threat.  The report suggests the risks of seeing an HPAI pandemic appear to be growing, and cites numerous problems with the rapid production of vaccines. 

Among the author's suggestions; adopting an integrated and digitalized One Health surveillance system, and using AI technology to create broadly protective vaccines, enhance pandemic planning, and optimize resource allocations. 

The authors close by stating: 

What is needed is a shift toward faster action and a coordinated, inclusive strategy that prioritizes preparedness before a next pandemic begins. The time to act is now.

I've reproduced the abstract below, but you'll want to follow the link to read it in its entirety.  I'll have a bit more after the beak. 


Abstract

Highly Pathogenic Avian Influenza (HPAI) viruses, particularly H5N1 and H7N9, have long been considered potential pandemic threats, despite the absence of sustained human-to-human transmission. However, recent outbreaks in previously unaffected regions, such as Antarctica, suggest we may be shifting from theoretical risk to a more imminent threat.
These viruses are no longer limited to avian populations. Their increasing appearance in mammals, including dairy cattle and domestic animals, raises the likelihood of viral reassortment and mutations that could trigger a human pandemic. 
If such a scenario unfolds, the world may face a crisis marked by high transmissibility and lethality, without effective vaccines readily available. Unlike the COVID-19 pandemic, when vaccines were rapidly developed despite inequities in access, the current influenza vaccine production model, largely reliant on slow, egg-based technologies, is insufficient for a fast-moving outbreak.
While newer platforms show promise, they remain in early stages and cannot yet meet global demand, which alerts to the urgent need for accelerating vaccine and drug development, especially universal vaccines, next-generation vaccine platforms designed to provide broad, long-lasting protection against a wide spectrum of HPAI virus subtypes and strains.
Here we propose a paradigmatic shift toward a more integrated, digitalized One Health surveillance system that links human, animal, and environmental data, especially in high-risk spillover regions. We underscore that Artificial Intelligence can revolutionize pandemic preparedness strategies, from improving early detection to speeding up vaccine and drug development and access to medical care, but should not be considered a stand-alone solution.

        (Continue . . . )
 

This is a thought provoking article, and while I have serious qualms about our head-long rush towards AI, I can certainly see how AI might help with the tracking of new zoonotic threats, the development of vaccines, and the allocation of resources during a pandemic. 

And few could doubt that developing a global One Health Surveillance system is imperative if we are to track, and hopefully contain, the HPAI threat. 

But good ideas and AI generated pandemic plans  - no matter how well conceived  - are never enough. 

As the authors state; ` . . . global cooperation, including geo-politically sensitive routes, is essential to mitigating the threat of HPAI and preventing future pandemics.

And that's the rub.  

Most countries today remain in deep denial about the potential of seeing another pandemic and are more consumed with stoking their economies, and retaining political power.   

We continue to see many countries are slow to share information, and some some appear to be burying `bad news' completely (see From Here To Impunity).

While I'd like to be optimistic, `Global Cooperation' in this highly competitive and politically polarized 21st century has become an increasingly rare commodity.  

The good news is we are not entirely held hostage to the glacial pace of government cooperation and preparedness.
 
We can still take steps to make our families, our businesses, our network of friends and neighbors, and even our local communities to become more resilient to disasters, including pandemics. 

September is National Preparedness Month, and while most people only consider threats like hurricanes, floods, earthquakes, and wildfires, there are plenty of things you can do now to prepare for the next pandemic. 

It just takes the willingness to act now, when preparing remains relatively easy and cheap.  As we saw in 2020, once the alarm is sounded, you will be competing for rapidly dwindling resources. 

Although the following cautionary quote is nearly 20 years old, it is just as valid today as it was in 2006:

“Everything you say in advance of a pandemic seems alarmist. Anything you’ve done after it starts is inadequate." - Michael Leavitt, Former Secretary of HHS

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