South Korea: Joint Government-Wide Response to Livestock Infectious Diseases during the Lunar New Year Holiday

 

#19,051

South Korea is no stranger to dealing with outbreaks of Avian Influenza, African Swine Fever (ASF), and Foot & Mouth Disease (FMD), but this year their messaging and response have taken on a more urgent tone. 

Even before the fall avian flu season began, last September South Korea Conducted A 19-day, Nationwide, Mock-Training Exercise to Prepare for Zoonotic Influenza, immediately followed by South Korea: MAFRA Conducts A Preemptive Virtual Quarantine Exercise (CPX). 

In November, South Korea MAFRA Ordered Strengthened Quarantine Measures After 3 HPAI H5 Subtypes (H5N1, H5N6, H5N9) Detected In Wild Birds, and issued stern warnings to farms over lapses in biosecurity South Korea: MAFRA Identifies Biosecurity Breaches On HPAI Infected Poultry Farms).

By the end of December, MAFRA Reported Increased Infectivity & Pathogenicity of This Year's Avian Flu Strains, and in early January announced Special Quarantine Measures Implemented for one Month to Prevent the Spread of HPAI,

By the end of January, however, MAFRA was also reporting an uptick in ASF outbreaks, and an outbreak of FMD; all just two weeks before the biggest holiday travel period for Asian countries (see South Korea: MAFRA Warns on Risks From HPAI, ASF & FMD During Upcoming Lunar New Year).

While we've seen worse avian flu outbreaks in South Korea in past years, and even concurrent outbreaks with ASF and FMD, this year's response continues to be unusually robust. 

Last week, the South Korea CDC announced `Traveler Respiratory Disease Testing Service' Expanded to 13 Airports & Ports Nationwide and today South Korea's Quarantine Policy Bureau has announced an all-out effort to prevent the spread of livestock diseases during the Lunar New Year holiday. 

Typically, Asia government agencies revert to a skeleton crew, and often `go dark', during the extended Lunar New Year Holiday period. 

The fact that they are making their Central Disaster and Safety Countermeasures Headquarters (CDSCHQ) the hub of a 24‑hour, multi‑ministry system specifically through Seollal speaks to how seriously they view the current situation.

Due to its length, I've only posted some (translated) excerpts from today's announcement.  I'll have a brief postscript after the break. 

Joint government-wide response to livestock infectious diseases during the Lunar New Year holiday

2026.02.12 15:00:00 Quarantine Policy Bureau, Quarantine Policy Division

The Central Disaster and Safety Countermeasures Headquarters for Highly Pathogenic Avian Influenza (AI), African Swine Fever (ASF) , and Foot-and-Mouth Disease ( Headquarters: Minister of Agriculture , Food and Rural Affairs Song Mei-ryeong , hereinafter referred to as the Central Disaster and Safety Countermeasures Headquarters ) will, in cooperation with relevant ministries such as the Ministry of the Interior and Safety and the Ministry of Climate, Energy and Environment, and local governments, promote quarantine rules for livestock farms and the public in preparation for the Lunar New Year holiday, operate an emergency response system during the holiday period , and thoroughly inspect and implement quarantine management measures for livestock infectious diseases 

Since the first outbreak of highly pathogenic avian influenza in Paju, Gyeonggi Province, on September 12th of last year, 43 cases have occurred in poultry farms . Recently, the wild bird population * and the number of AI detections ( 49 cases in total ) have also increased, so the risk of additional outbreaks in poultry farms remains high .

* AI outbreak status ( total 43 cases ): 9 cases in Gyeonggi , 18 cases in South and North Chungcheong , 11 cases in South and North Jeolla , 3 cases in South and North Gyeongsang , 1 in Sejong , 1 in Gwangju

** Status of wild bird population ( Ministry of Climate ): (December ) 1.25 million → ( January ) 1.35 million (8% increase )

In addition, in the case of African swine fever, since the first outbreak in Gangneung, Gangwon Province on January 16th of this year, sporadic outbreaks ( 11 cases in total ) have occurred in areas where there had been no outbreaks before, so thorough quarantine management is necessary to prevent the virus from entering farms .

* ASF outbreak status ( total 11 cases ): 4 cases in Gyeonggi , 1 in Gangwon , 2 in Chungcheongnam- do, 1 in Jeollabuk-do , 2 in Jeollanam-do , 1 in Gyeongsangnam -do

Foot-and - mouth disease broke out in Ganghwa-gun, Incheon on January 30 , about 10 months after it first appeared in Yeongam and Muan, South Jeolla Province, in March of last year . To prevent further spread, a temporary 48- hour movement ban was issued for Incheon and the neighboring Gimpo area, and emergency vaccinations (865 cases , 92 cases ) were quickly completed (February 6). Quarantine management such as disinfection and testing was strengthened, and there have been no additional outbreaks to date .

        (SNIP) 

□ Operation of a 24- hour response system centered on the Central Disaster and Safety Countermeasure Headquarters , comprehensive disinfection , and public relations for livestock farms and the public

The Central Disaster and Safety Countermeasures Headquarters will maintain a 24-hour emergency response system even during the holiday period. In addition, in order to block the spread of the virus due to the increase in people and vehicles during the Lunar New Year holiday, February 13 (Friday) and February 19 ( Thursday ) before and after the holiday have been designated as “ National Disinfection Days ” and disinfection resources will be fully mobilized ( 1,023 disinfection vehicles ) to intensively disinfect livestock farms , livestock - related facilities , and livestock vehicles . In particular, for highly pathogenic avian influenza, disinfection of high-risk areas such as roads around migratory bird arrival sites will continue at least twice a day for two weeks from February 7 to February 20 , including the holiday period .

In addition, we will strengthen publicity by using various means such as text messages on quarantine rules, village broadcasts, posters and banners, electronic bulletin boards at railway stations and highways, broadcast subtitle exposure*, and websites in cooperation with local governments, public institutions, and producer groups. We will also strengthen publicity by informing livestock farmers of quarantine rules , asking people returning home to refrain from visiting livestock farms , prohibiting entry into migratory bird arrival areas and wild boar ASF outbreak areas , and prohibiting the bringing in of illegal livestock products when entering the country after traveling abroad .

* Disaster subtitle broadcasting (2.9.~2.18, 144 companies including KBS , twice a day ) , etc.

        (SNIP)

□ Requests during the Lunar New Year holiday period

Park Jeong-hoon, director of the Food Policy Bureau at the Ministry of Agriculture, Food and Rural Affairs , said , “ We plan to maintain the emergency response system centered around the Central Disaster and Safety Countermeasures Headquarters even during the Lunar New Year holidays, ” and urged , “ Livestock farms across the country should immediately report any suspected symptoms of livestock infectious diseases to livestock quarantine authorities , and all livestock officials should also be careful to prevent safety accidents from occurring during quarantine activities due to the cold wave in winter . ” He continued , “ I ask farms to do their best to quarantine their farms during the holiday period , and I ask those returning home to actively participate in livestock quarantine, such as refraining from visiting livestock farms and migratory bird arrival sites, to prevent the spread of livestock infectious diseases . ”

He also added , “ Despite the outbreak of livestock infectious diseases such as highly pathogenic avian influenza and African swine fever , the supply conditions for livestock products such as eggs and pork during the Lunar New Year holiday are relatively stable , and we will closely monitor the supply and demand situation going forward . ”

* ( Egg ) Production : ('25) 49.53 million / day → ('26p) 4,925 ( 7.6% ↑ compared to the average year , 0.6% ↓ compared to the previous year ) Retail price : (1. Lower ) 6,928 won / 30 eggs → (2. Upper ) 6,107 ( 6.3% ↓ compared to the average year , 8.1% ↓ compared to the previous year )

* ( Pig ) Slaughter (January ) : ('25) 1.572 million → ('26) 1.589 million ( 0.4% ↑ compared to the average year , 1.1% ↑ compared to the previous year ) Retail price : (1. Lower ) 26,270 won /kg → (2. Upper ) 26,360 ( 12.2% ↑ compared to the average year , 4.4% ↑ compared to the previous year )

Hong Jong-wan, Director of the Social Disaster and Safety Bureau at the Ministry of the Interior and Safety, said, “ Compliance with the core quarantine rules for farms is essential for preventing livestock infectious diseases , and if these are violated, strict measures such as fines and reductions in compensation for culling will be taken .”

He added , “ Local governments, led by heads of sub-organizations, should make an all-out effort to prevent the spread of livestock infectious diseases , and the Ministry of the Interior and Safety will not spare administrative and financial support . ”

Lee Chae-eun, Director of the Nature Conservation Bureau at the Ministry of Climate Change, said , “ If you find a carcass of a wild bird or wild boar, please report it to your local government or the National Institute of Wildlife Disease Control and Prevention instead of contacting it directly . We ask local governments to prevent contamination from being left unattended or leaking from the affected farm and spreading it to the surrounding area . ” She added , “ We will do our best to maintain an emergency work system during the Lunar New Year holiday period in cooperation with relevant organizations to ensure that there are no quarantine gaps . ”

While one could argue that this heightened response is due to the triad of livestock disease threats in South Korea, we were seeing extraordinary measures being ordered last December, before the recent spike in ASF and FMD.

Regrettably, few countries are as open about their avian flu problem - and their response - as is South Korea. Which means we don't have a good handle on how the virus is spreading, and evolving, around the globe.

The fact, however, that South Korea - which has 20 years experience dealing with Avian flu - is this concerned, should give all of us pause. 

Viruses: Avian Influenza H5N1 Infection During Pregnancy: Preparing for the Next Flu Pandemic and Improving Perinatal Outcomes

Photo Credit – CDC

#19,050

During the 1918 pandemic an abnormally high number of pregnant women died from the influenza, and those that survived endured a very high miscarriage rate. Again, during the much milder 1957 Asian Flu, pregnant women reportedly suffered disproportionately higher mortality rates than non-pregnant women of the same age.

Historical reviews of both events are available in a Perspective, written by 3 CDC physicians (Sonja A. Rasmussen, Denise J. Jamieson, Joseph S. Bresee) and published in the CDC Journal of EID article, Pandemic Influenza and Pregnant Women in February of 2008.

A year after its publication, the arrival of the 2009 H1N1 pandemic saw similarly high rates of influenza complications among pregnant women, often with tragic results. 

• During the 2009 H1N1 pandemic, pregnant women were six times more likely to be hospitalized than non-pregnant women (see Pregnancy & Flu: A Bad Combination).
• And in 2011, in BMJ: Perinatal Outcomes After Maternal 2009/H1N1 Infection we saw a study where pregnant women who were admitted to the hospital with an  H1N1 infection experienced a 3 to 4 times higher rate of preterm birth, 4 to 5 times greater risk of stillbirth, and a 4 to 6 times higher rate of neonatal death.

In late 2024, in EID Journal: Systematic Review of Avian Influenza Virus Infection and Outcomes during Pregnancy - among 30 pregnant women diagnosed with avian flu (H5N1 n = 16, H7N9 n = 13, and H5N6 n = 1) - researchers reported high mortality rates for both mothers (90.0%, 27/30) and their babies (86.7%, 26/30).

Admittedly, this data is biased towards hospitalized cases with severe disease, and many other pregnant women with milder infections likely saw less dire outcomes. 

 

But we also continue to see evidence of the harm to the developing fetus from  maternal seasonal flu infection (see Nature: Severe Influenza in Pregnancy Linked to Neurodevelopmental Disorders in Offspring).

Despite these dangers, pregnant women and young children are often the last cohort to be approved to receive a novel flu (or CoV) vaccine, since most early clinical trials exclude them over safety concerns.

All of which brings us to a narrative review article published in Viruses that looks at the limited data we have on novel flu and pregnancy, and argues that H5N1 could be particularly dangerous to pregnant women and their offsprings if it should begin to spread in humans.

The authors propose a basic algorithm for initial clinical management of suspected H5N1 in pregnancy and lobby for prioritizing both antivirals and vaccines (when available) for high-risk patients, including those who may be pregnant. 

I've only posted the abstract and a few excerpts, so follow the link to read it in its entirety.  I'll have a bit more after the break. 

Avian Influenza H5N1 Infection During Pregnancy: Preparing for the Next Flu Pandemic and Improving Perinatal Outcomes
Matthew J. Zuber1,2,*, Callie L. Brown2,3 and Cara B. Janusz2,4
Viruses2026, 18(2), 212; https://doi.org/10.3390/v18020212

Abstract

Influenza (flu) is a common respiratory virus with seasonal global spread. Zoonotic viruses can occasionally cross species, leading to pandemic-level spread, and for flu viruses, this is considered an “antigenic shift”. The flu can be particularly severe during pregnancy due to immune system adaptations that occur during pregnancy, with prior global pandemics causing excess hospitalizations, deaths, and other complications in the mothers and the neonates.

We aim to review the current literature with respect to novel avian H5N1 and the potential impact of infection with flu during pregnancy. A systematic literature search was conducted.

Here we provide a rapid summary of epidemiology and understanding of viral spread, published risks of H5N1 in pregnancy, the unique physiologic, cellular, and molecular adaptations making H5N1 infection unique in pregnancy, implementation of an effective vaccine program in event of a pandemic specific to pregnant individuals, optimizing peripartum care for infected individuals, and direction for future research to direct vaccine strategy and mitigate risks in a future flu pandemic.

(SNIP)

Pregnancy has long been recognized as a risk factor for severe disease. Historically, pregnant persons have suffered increased rates of morbidity and mortality compared to their non-pregnant peers during the last several flu A pandemics of the past century, most recently during the 2009 H1N1 pandemic [2]. Similarly, pregnant persons had elevated morbidity and mortality during the recent COVID-19 pandemic [3]. Vaccine clinical trials continue to routinely exclude pregnant persons, creating substantial limitations in closing equitable care gaps for pregnancy and generating robust and early data during a pandemic to help support vaccine programs for pregnant persons at heightened risk for severe disease. 

(SNIP)

 (SNIP)

7. Conclusions

While there is limited data on H5N1 or novel avian influenza viruses’ effects during pregnancy, the available data suggest we should prepare for and anticipate cases of severe disease in the perinatal setting in the event of a future global pandemic. We outlined here the current epidemiology, unique pathophysiology of the disease in the setting of pregnancy, suggested clinical approach during pregnancy and birth, and suggested future directions regarding vaccine research and policy approaches to vaccination strategy. As new viral strains evolve, so should the approach in pregnancy management and close surveillance that will help mitigate risk and improve perinatal outcomes.

       (Continue . . . ) 

While COVID hit the elderly the hardest (see CIDRAP Older adults made up 90% of US COVID deaths in 2023), there are reasons to believe that an H5Nx pandemic might severely impact a much younger cohort (see Preprint: Immune History Shapes Human Antibody Responses to H5N1 Influenza viruses).

As far back as 2007  - in A Predilection For The Young - we looked at the disturbing skewing of H5N1 cases (and deaths) among younger individuals (see WHO Chart below).

We've seen similar patterns in past pandemics, including in 1918 and again in 2009. Here is what the CDC had to say about the impact of the 2009 pandemic virus in 2012's First Global Estimates of 2009 H1N1 Pandemic Mortality Released by CDC-Led Collaboration.

2009 H1N1 Pandemic Hits the Young Especially Hard

This study estimated that 80% of 2009 H1N1 deaths were in people younger than 65 years of age which differs from typical seasonal influenza epidemics during which 80-90% of deaths are estimated to occur in people 65 years of age and older.

Complicating matters, vaccine hesitancy continues to grow, with nearly a 33% drop in uptake of influenza vaccine by pregnant women since 2019.

While an H5 pandemic is by no means assured, these are two (of many) reasons why HPAI H5 might have an even greater impact on society than COVID. 

Making it imperative that we consider the risks - and how we might handle them - now, while we still have the luxury of time. 

Hong Kong CHP: Cryptic Announcement of 1 New H10N3, and 2 H9N2 Cases on the Mainland.

 

#19,049

As we've discussed previously, in HK CHP: Another Cryptic Announcement of H9N2 Cases From the Chinese Mainland, reports out of China are often belated, and lack many critical details.

The barebones report above is a prime example. 

It is worth noting that the WHO's WPRO published an update last Friday, which reported no new human novel flu infections in the region, including the following summary on H10N3:

Human infection with avian influenza A(H10N3) virus

From 30 January to 5 February 2026, no new case of human infection with avian influenza A(H10N3) virus was reported to WHO in the Western Pacific Region. The last case was reported from China with an onset date of 21 April 2025. To date, six cases of human infection with avian influenza A(H10N3) have been reported globally. 

Hopefully we'll learn more about this 7th case, including its severity and likely source of infection, from the next WHO Influenza at the human-animal interface report.  

While most confirmed H10N3 cases have produced severe illness, we have no idea how many mild, or subclinical, infections may have gone unreported. We continue to see cautionary reports, however, from Chinese researchers on the human health threat from this emerging subtype.

• In July 2024, in Frontiers: Phylogenetic and Mutational Analysis of H10N3 Avian Influenza A virus in China: Potential Threats to Human Health, we looked at a report that described 4 mutations of concern in the 2023 case (HA Q226L, PB2 D701N, PA S409N, and M2 S31N), along with the patient's treatment and course of illness.

• Also in 2024 in Vet. Microbiology: The novel H10N3 Avian Influenza Virus Acquired Airborne Transmission Among Chickens: An Increasing Threat to Public Health reported the virus has become better adapted to poultry, is highly pathogenic in mice, can be transmitted via respiratory droplets between guinea pigs, and can also be transmitted via the airborne route by chickens.

• And last June in Vet. Research: E627V Mutation in PB2 Protein Promotes the Mammalian Adaptation of Novel H10N3 Avian Influenza Virus reported that that PB2-626V is becoming increasingly common in AIV poultry isolates - including H10N3 - and that it significantly enhances mammalian adaptation while maintaining fitness in avian hosts.

Meanwhile, H9N2 cases continue to be reported sporadically across China, although testing is generally restricted to those sick enough to be hospitalized.  While children are most frequently diagnosed, we continue to see occasional adult infections reported as well. 

Last October, in China CDC Weekly: Epidemiological and Genetic Characterization of Three H9N2 Viruses Causing Human Infections, we looked at a local CDC investigation into 3 pediatric cases which were reported last April from Changsha City, Hunan Province, China.

Their report found a number of indicators of increased mammalian adaptation within the virus, including an enhanced ability to infect upper respiratory (α2,6-sialic acid) tract receptors, and a number of HA protein mutations, including; H191N, A198V, Q226L, and Q234L.

Both viruses are reminders that while H5N1 may garner the bulk of avian flu headlines, there are a number of legitimate contenders for becoming the next pandemic threat.

Nature Comms: Assessing HPAI-H5 Transmission Risk Across Wild Bird Migratory Flyways in the United States

 

#19,048

The world has been watching HPAI H5N1 for nearly 3 decades, but today's HPAI H5 viruses are a far cry from the A/Goose/Guangdong/1/1996 strain that emerged  in Southern China 30 years ago.  

Between 1996 and early 2005, HPAI H5N1 was considered primarily a disease of poultry (ducks, geese, and chickens), and was only sporadically detected in wild or migratory birds. 

All that changed in May of 2005 when a large outbreak of HPAI H5 occurred in Qinghai Lake, China, causing the deaths of thousands of bar-headed geese, great black-headed gulls, and brown-headed gulls (see H5N1 Influenza Continues To Circulate and Change 2006 by Webster et. al.).

A new clade (2.2) had emerged - one which was particularly pathogenic in some species - while some migratory birds were better able to transport it over long distances.

Over the next couple of years HPAI escaped the confines of Southeast Asia, and spread to Europe, Africa, and the Middle East. Despite this, many still clung to the notion that `sick birds don't fly'; a debate that would rage for nearly a decade (see 2014's Bird Flu Spread: The Flyway Or The Highway?).

But the HPAI H5 virus continued to evolve, generating new subclades (H5N8, H5N5, H5N9, etc.), and new subclades (e.g. 2.3.2.1a, 2.3.2.1c, 2.3.4.4b, etc.), and hundreds of genotypes. 

For a while, it appeared that aquatic migratory birds (ducks & geese) were the primary drivers of international spread.  Other species - particularly resident birds - were thought either immune or dead-end hosts.  

Following North America's first H5 epizootic (2015) researchers were unable to detect HPAI in wild or migratory birds, leading them to surmise that they were not an efficient long-term reservoir for H5 viruses (see PNAS: The Enigma Of Disappearing HPAI H5 In North American Migratory Waterfowl).

But avian flu continued to evolve, and in the fall of 2016 a new reassortant arrived in Europe that caused unusual mortality in a wide range of avian species (see Europe: Unusual Mortality Among Wild Birds From H5N8). 

After a series of H5N8 epizootics, that virus was eventually supplanted by a new & improved H5N1 virus, which further expanded its host range (see 2022's DEFRA: The Unprecedented `Order Shift' In Wild Bird H5N1 Positives In Europe & The UK). 

Increasingly, shore birds, passerines, and even raptors were being affected by the virus. The spread to resident birds increased, allowing the virus to persist over the summer, turning HPAI into a year-round threat. 

At the same time, HPAI H5 viruses have become better adapted to mammalian species, including livestock, cats, foxes, marine mammals, and even humans. 

All of which brings us to a remarkably detailed (albeit U.S. centric) analysis of the spread of HPAI H5N1 via wild (resident & migratory) birds across the 4 North American flyways between Jan 2022 and Apr 2025.

The authors not only rate the risk across U.S. flyways, they provide R₀  (pronounced R-nought) or Basic Reproductive Number estimates for transmission by various avian species.

R₀  is an estimate of a virus's transmissibility in a naive and susceptible population. In the simplest of terms; anything < 1.0 and a virus (as an outbreak) begins to sputter and die out. Above 1.0, and an outbreak can have `legs’.

This is a lengthy and detailed report, with a lot to unpack. But among its many findings, they report:

• The greatest viral genotype diversity was detected in 2022, with multiple  genotypes in circulation.

• By spring of 2025 genotype D1.1 (which only emerged the previous fall) had become the absolute dominant genotype, with its transmission mainly concentrated in Accipitriformes (birds of prey).

• The Mississippi Flyway had the highest R₀  in resident birds (6.4); higher than any other bird group or flyway in the analysis.

• While the Atlantic flyways' overall R₀ i was just under 1, Georgia and Florida provided persistent, multi‑season resident hotspots for HPAI. 

• Quite unexpectedly, Strigiformes (owls) had the strongest transmission capacity, with an R₀ of 3.164. Previously owls (and raptors in general) had been thought highly susceptible, but likely to succumb before spreading the virus. 

• Anseriformes (waterfowl), surprisingly, had the weakest transmission capacity, with an R₀ of 0.992.  

• Moderate (not extremely wet or dry) drought conditions (Palmer Index of about −3.3) corresponded to the highest numbers of infections.

The authors write:

The traditional transmission concept centred on Anseriformes is being challenged by the reality of highly efficient transmission and high pathogenicity of the virus in nontraditional hosts such as raptors and mammals. It is essential to quantify the transmission risk of avian influenza in different categories of birds and analyse their roles in the transmission chain. 

I've only reproduced the abstract below. Follow the link to read it in its entirety. I'll have a brief postscript after the break.

Assessing HPAI-H5 transmission risk across wild bird migratory flyways in the United States

Kang Fang, Jiahui Li, Hongfeng Zhao, Jiangshaya Bahati, Zeyu Zhao, Wentao Song & Tianmu Chen

Nature Communications , Article number: (2026)

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Abstract

As natural hosts of avian influenza viruses, wild birds pose an increasing threat to public health. Here, using surveillance data from wild bird infections across the United States (2022-2025), we show that HPAI-H5 transmission exhibits strong interspecific variation, seasonality, and spatial heterogeneity linked to migratory flyways.

Phylogeographic analysis reveals that viral genotypes evolve from early, limited transmission along single migratory routes to a nationwide dispersal pattern spanning multiple migratory flyways.

Anseriformes exhibits the highest number of infections but the lowest transmission risk, whereas Strigiformes demonstrates the greatest transmission risk. The HPAI-H5 transmission in wild birds along migratory flyways exhibits significant spatial heterogeneity and is associated with bird migration. Meteorological conditions are correlated with outbreak timing and may inform early warning efforts; however, these relationships are nonlinear. These findings provide a foundation for risk assessment, early warning systems, and integrated management of avian influenza in wild bird populations.

Despite overachieving at almost every turn (see Avian Flu's New Normal: When the Extraordinary Becomes Ordinary), the world continues to treat HPAI H5 as if it were the same virus that threatened - and failed - to produce a pandemic 20 years ago. 

While we might get lucky, and find that there is some (as yet, unknown) species barrier that prevents HPAI H5 from becoming a human pandemic, that bit of luck is by no means assured. 

Meanwhile the virus continues along an evolutionary path that remains, to a large extent, hidden from our view.  

Despite constant calls for better surveillance, testing and sharing of data (see here, here, here, here, and here), most of the world appears content to don blinders and hope for the best. 

Unfortunately, in the event things take a bad turn, hope isn't much of a plan.

Preprint: Efficient Replication of Influenza D Virus in the Human Airway Underscores Zoonotic Potential

Credit NIAID

#19,047

One of the more intriguing influenza discoveries of the past dozen years has been the identification of a previously unknown type of flu - Influenza D - infecting swine, cattle, and apparently even humans.

We first learned of this new flu early in 2013 when researchers reported finding a novel influenza virus in swine from Oklahoma - initially classified as a novel Influenza C virus - but which would later be designated as Influenza D. 

Their research – published PLoS Pathogens – was called Isolation of a Novel Swine Influenza Virus from Oklahoma in 2011 Which Is Distantly Related to Human Influenza C Viruses, and it immediately caused a stir in the flu research community.

The authors found that this new (provisional) influenza C virus could infect, and transmit, in both ferrets and pigs. The following year, in mBio: Characterizing A Novel Influenza C Virus In Bovines & Swine, cattle were added to the list, and identified as the virus's primary reservoir.

Over time the virus was reclassified as `Influenza D', and researchers found evidence of a much wider spread of this virus than just in the American Midwest. (see EID journal’s Influenza D Virus in Cattle, France, 2011–2014 and EID Journal: Influenza D In Cattle & Swine – Italy).

And while it isn't known if Influenza D can cause symptomatic illness in humans, in 2016's Serological Evidence Of Influenza D Among Persons With & Without Cattle Exposure, researchers reported finding a high prevalence of antibodies against Influenza D among people with cattle exposure. 

They wrote:

IDV poses a zoonotic risk to cattle-exposed workers, based on detection of high seroprevalence (94–97%). Whereas it is still unknown whether IDV causes disease in humans, our studies indicate that the virus may be an emerging pathogen among cattle-workers.

Since then, we've revisited Influenza D research often, including these recent posts.

EID Journal (Perspective): Emerging Respiratory Virus Threats from Influenza D and Canine Coronavirus HuPn-2018 

EID Journal: Influenza D Virus in Domestic and Stray Cats, Northern China, 2024)

Today we've a preprint with an excellent pedigree (by researchers from Ohio State University,  St. Jude Children's Research Hospital, and the Abigail Wexner Institute) which provides even more reasons to continue to track this emerging influenza type. 

Not only did they find that influenza D replicates efficiently in the human respiratory tract, they discovered it did not set off the innate immune system's `alarm bells' (interferon and ISG signaling) to the extent that influenza A typically does.

For now, Influenza D appears to produce a muted immune response in humans, which likely explains its extremely mild or subclinical presentation. This stealthy behavior, however, gives it more opportunities to spread unnoticed while potentially better adapting to human hosts. 

I've just reproduced the abstract and a brief excerpt from the preprint. Follow the link to read it in its entirety.  I'll have a bit more after the break.

Efficient replication of influenza D virus in the human airway underscores zoonotic potential
Christina G Sanders, Min Liu, Jovanna A Fusco, Elizabeth M Ohl, Natalie N Tarbuck, Emily M King, Devra Huey, Thomas P Fabrizio, Phylip Chen, Amanda R Panfil, Richard J Webby, Mark E Peeples, Andrew S Bowman, Cody J Warren
doi: https://doi.org/10.64898/2026.02.07.704474
This article is a preprint and has not been certified by peer review [what does this mean?].
 
Preview PDF

Abstract

Influenza D virus (IDV), primarily found in livestock species, has demonstrated cross-species transmission potential, yet its threat to humans remains poorly understood. Here, we curated a panel of IDV isolates collected during field surveillance from 2011 to 2020 from swine and cattle to assess their ability to infect human airway cells as a proxy for zoonotic threat assessment.

Using lung epithelial cell lines, primary well-differentiated airway epithelial cultures, and precision-cut lung slices, we demonstrated that IDV efficiently propagates in cells and tissues from the human respiratory tract, reaching titers comparable to human influenza A virus (IAV).

Infection kinetics in primary porcine airway cultures and respiratory tissues mirrored those from human, suggesting similar infectivity across species.

To define host responses to IDV infection, we evaluated innate immune sensing and downstream interferon signaling in human respiratory cells. IDV infection resulted in markedly reduced activation of interferon regulatory factor (IRF) signaling and diminished induction of interferon lambda 1 and interferon-stimulated genes compared to IAV, indicating inefficient activation of innate immune sensing pathways.

However, IDV replication was potently restricted in interferon-pretreated cells, demonstrating sensitivity to interferon-mediated antiviral effector mechanisms once an antiviral state was established.

Together, these findings show that IDV can efficiently infect the human airway while limiting innate immune sensing, a feature that may facilitate zoonotic spillover. Our study highlights the need for enhanced surveillance of IDV at the animal-human interface and provides a foundation for further investigation into its biology and potential for causing human infection and disease.

        (SNIP)

Taken together, our findings indicate that IDV can infect and replicate efficiently in human respiratory tissues with minimal innate immune restriction. Although human infections documented so far appear subclinical, published studies demonstrate that IDV transmits efficiently among mammalian hosts—including airborne transmission between ferrets (49)— suggesting that the virus already possesses several traits compatible with respiratory spread in humans.

While our study did not directly evaluate the evolutionary steps required for sustained human-to-human transmission, these observations raise important questions about the degree of additional adaptation needed.

This uncertainty underscores the importance of intensified surveillance and mechanistic studies that define the viral and host determinants of IDV transmissibility. What appears today as a quiet livestock virus could, with little warning, ignite the next influenza pandemic. 

        (Continue . . . )

IDV is not detected by routine human influenza surveillance programs, and while some research is underway (see Novel Influenza D Virus Vaccine Strategy) there are currently no vaccines available for humans or animals.

Admittedly the zoonotic potential of Influenza D appears to be low right now, but that could change over time. Like influenza A viruses, influenza D and C viruses have segmented RNA genomes, which allows for reassortment.

The  discovery of frequent reassortment between IDV clades D/660 and D/OK, along with spillovers into new hosts (like dogs and cats), makes influenza D a virus very much worthy of our attention.

More Than One Way To Start An Epidemic . . .

#19,046

Last week, in Taiwan: Another Avian Flu `Incident', we looked at the latest in a series (see here, here, and here) of high profile illegal (avian or swine) vaccine smuggling and/or manufacturing operations detected by Taiwanese officials. 

Counterfeit vaccines are particularly worrying, since they may exacerbate existing epizootic threats, but they are far from the only imported zoonotic threats. 

There is a huge global trade in both illegal bushmeat, and in smuggled wildlife, both of which can transport infectious diseases into new regions of the world. Just yesterday Hong Kong Customs reported their seizure of more than 100 wild birds at one of their border crossing points with the Mainland. 

Hong Kong Customs seizes suspected illegally imported live birds (with photo)

 

Hong Kong Customs today (February 7) detected a suspected case of illegal importing of live bird at the Lo Wu Control Point. 112 live birds with an estimated market value of about $15,000 were seized.

Customs officers today intercepted an incoming 26-year-old female passenger at the arrival hall of the said control point. Upon examination, 112 live birds contained in bird cages were seized from the trolley she carried, and she was subsequently arrested.

The case was handed over to the Agriculture, Fisheries and Conservation Department for follow-up investigation.

Under the Public Health (Animals and Birds) Regulations, it is an offence to import any bird unless it is accompanied by a valid health certificate. The maximum penalty upon conviction is a fine of $25,000.

Members of the public may report any suspected activities of illegal import of live birds to Customs' 24-hour hotline 182 8080 or its dedicated crime-reporting email account (crimereport@customs.gov.hk) or online form (eform.cefs.gov.hk/form/ced002).

Ends/Saturday, February 7, 2026

The most obvious concern is of accidentally importing avian flu, which has happened before:

Vienna: 5 Smuggled Birds Now Reported Positive For H5N1

Taiwan Seizes H5N1 Infected Birds

Bulgarian NVS: Confirmed Avian Flu In 2 Illegally Transported Birds

But avian flu isn't the only concern, as we've seen literally dozens of reports over the years of `parrot fever' (see China: Media Reports Of A Psittacosis Outbreak (Parrot Fever) in Zhejiang Province) outbreaks in Asia and in Europe.

The United States famously saw a national panic over `Parrot Fever' in 1929 (see How Parrot Fever Changed Public Health In America), with many fearing a return of the 1918 pandemic.

We've seen horrific examples of the lengths that some people will go to in order to illegally import live birds, including in 2010, when two men were indicted for attempting to smuggle dozens of song birds (strapped to their legs inside their pants) into LAX from Vietnam. 

Sadly, many of the birds did not survive the plane trip.

 Last December Interpol reported on their enforcement efforts in 2025, reporting:

30,000 live animals seized in global operation against wildlife and forestry crime

11 December 2025

134 participating countries make record seizures of protected plants, animals and timber

LYON, France — A global operation against the illegal trafficking of wild fauna and flora has led to the seizure of nearly 30,000 live animals and the identification of 1,100 suspects.

From 15 September – 15 October, law enforcement agencies comprising police, customs, border security and forestry and wildlife authorities from 134 countries made a total of 4,640 seizures during Operation Thunder 2025. This record number of seizures included tens of thousands of protected animals and plants and tens of thousands of cubic metres of illegally logged timber, as well as more than 30 tonnes of species classified as endangered under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Coordinated by INTERPOL and the World Customs Organization (WCO), with the support of the International Consortium on Combating Wildlife Crime (ICCWC), the operation sought to intercept and seize illegally traded wildlife and forestry commodities across the global supply chain and identify, disrupt and dismantle criminal networks involved in these types of environmental crime.

(SNIP)

While live animal seizures reached a record high this year — driven largely by demand for exotic pets — most wildlife trafficking involved animal remains, parts and derivatives, often used in traditional medicine or specialty foods.

Estimates put the annual value of wildlife crime at USD 20 billion, but the clandestine nature of the trade suggests that the real figure is likely much higher.

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The full report is very much worth reading in its entirety (but warning, some of the photos are hard to look at . . ).

In the summer of 2010 headlines were made when a study – published in the journal Conservation Letters looked at the amount of smuggled bushmeat (est. 5 tons a week) that was coming into Paris's Charles de Gaulle airport over a 17 day period on flights from west and central Africa. 

Not all cases of smuggling are part of elaborate criminal conspiracies, sometimes it's just a traveler trying to bring a bit of `home' back to the United States. 

In May of 2013, in All Too Frequent Flyers, we saw a Vietnamese passenger, on a flight into Dulles Airport, who was caught with 20 raw Chinese Silkie Chickens in his luggage. 

But in some cases, illegal imports are being done on a commercial scale, as evidenced by the next two reports which came during the height of China's ASF epidemic. 

• In 2022's USDA/APHIS Seize Nearly 1 Ton Of Illegal Pork Products in NYC Imported From China

• In 2019 (see Feds Seize 1 Million Pounds of Illegal Chinese Pork Products In New Jersey).

Much of the global spread of ASF over the past 15 years has been attributed to careless or illegal transport of contaminated products, making this a serious and ongoing concern. 

An infamous example of the potential zoonotic risks, in 2003 the United States experienced a multi-state (Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin) outbreak of Monkeypox when a Texas animal distributor (legally) imported hundreds of small animals from Ghana, which in turn infected prairie dogs that were subsequently sold to the public (see MMWR Update On Monkeypox 2003).

By the time that outbreak was quashed, the U.S. saw 37 confirmed, 12 probable, and 22 suspected human cases. Among the confirmed cases 5 were categorized as being severely ill, while 9 were hospitalized for > 48 hrs; although no patients died (cite).

At roughly the same time the United States was dealing with Monkeypox, Asia, Canada, and the rest of the world were dealing with another zoonotic threat; the first SARS-CoV outbreak (see SARS and Remembrance).

That outbreak was linked to the practice of serving exotic animals - including masked palm civets (and possibly raccoon dogs) - in `wild flavor' restaurants (see A Hong Kong Civets Lesson).

China and the United States (along with many other countries) have since  tightened up their laws and regulations regarding the importation, or consumption, of many of these exotic animals, but the evidence suggests that better laws haven't proven to be an effective deterrent. 

All reasons while increased vigilance is needed if we are to prevent the next global (human or agricultural) infectious disease crisis.