An HPAI Cattle Roundup - April 25th

 
A growing, but incomplete, picture of affected States

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It's been a busy day, with a media report by Tyne Morgan writing in the Bovine Veterinarian a report that quotes Andrew Bowman at Ohio State University - who has tested 150 samples of pasteurized milk purchased at the retail level -  as finding 38% (n=58) were PCR positive for H5N1 RNA.

PCR positive does not indicate whether the virus remains infectious (aka `viable'), so samples have been forwarded to St. Jude Children's Research Hospital, where attempts are being made to culture the virus. 

The milk was reportedly purchased from 6 states, but the manufacturing codes on the positive samples came from as many as 10 states.  Since the USDA has only confirmed 8 states with H5N1 in dairy cows, this suggests the problem is more widespread than has been reported. 

The decision announced yesterday that (starting next week) lactating cows must be tested prior to interstate transport should provide more data, but testing remains limited and voluntary for the vast majority of cattle herds. 

Another report by Rhonda Brooks, also in the Bovine Veterinarian called A Message to the Ag Industry about H5N1 warns that agricultural interests must take this threat very seriously, and quotes Texas veterinarian Dr. Barb Petersen as reporting seeing `sick humans' along with `sick cows' at multiple dairy farms.  

While only one mild case has been reported, in yesterday's HHS meeting (as reported by Helen Branswell for STAT),  CDC Deputy Director Nirav Shah acknowledged there have been obstacles to testing farm workers. 

“We’ve had a diversity of levels of engagement with farms,” Shah said. “These situations are challenging. There may be owners that are reluctant to work with public health to say nothing of individual workers who may be reluctant to sit down with somebody who identifies themself as being from the government in some way.”

At the same meeting, Mike Watson from APHIS confirmed that the USDA had `met some resistance' from some farmers with infected cows, and it is unknown whether orders to discard infected milk are being strictly enforced.  

A week ago the CDC issued recommendations for protective gear to be worn when tending to potentially infected cattle, although it isn't clear how much they are being utilized, particularly when testing for the virus is limited.

Meanwhile, the topic of testing cattle outside of the United States appear to be a third-rail that few officials are willing to touch.  Sky News is reporting the UK has no plans to test local herds with a DEFRA official saying levels of avian flu are so low in birds right now that `it does not consider cattle to be at risk.'

That optimistically assumes that no spillover occurred over the winter, when infected birds were more abundant.  Our spillover to cattle in the appears to have occurred in late 2023, but wasn't detected until cattle were tested in March of this year.

I've found very little from Mexico, which both exports and imports cattle from the United States.  While I suspect (read: hope) some testing is being conducted, no one seems to be talking about it. 

As we discussed a few days ago, the consumption of raw (unpasteurized) milk is far more common in Mexico than in the U.S., and surveillance for potential human infections is arguably less robust than here in the states.  

While there is no way to know how big of a deal this HPAI outbreak in cattle will become, this crisis has demonstrated - once again - how unprepared the world is to deal with an inconvenient, and highly unpredictable, zoonotic threat.

I get it.  

We're all traumatized and weary from the last pandemic, and by all rights we should have a few years before we must deal with another.  But viruses don't read calendars, and all indications are that the time-between-pandemics has grown shorter.  

Which means we need to get better at surveillance and testing, and far more aggressive in responding to threats.   The H5N1 virus has been honing its skills for years, if we hope to be able to cope, we need to do the same. 

As always, the volunteer newshounds on FluTrackers are all over this story, and you'll find expert reporting from Lisa Schnirring at CIDRAP and Helen Branswell at STAT News.  

CDC: Monitoring For Signs Of Human Infection With H5N1

FluView Interactive Novel Influenza

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Depending upon the strain, the method of exposure, viral load, and an individual's immune response and overall health, human influenza A infection can present a wide range of symptoms, ranging from asymptomatic-to-sub-clinical, mild-to-moderate, all the way up to severe and even life threatening..

With seasonal flu, asymptomatic carriage has been estimated to run as high as 35%, while sub-clinical cases may account for > 60% of cases (see EID Journal: Prevalence of Asymptomatic Influenza Virus Infections).

A 2015 study (CID: Viral Detection Increases With Family Size), followed 26 households over the course of one year, testing family members for 16 different respiratory viruses, including influenza, rhinovirus, and RSV on a weekly basis.

While the incidence varied widely by household size (no surprise, the more kids in the house, the more sickness), across the board only about 50% of the PRC positive cases reported cold or flu-like symptoms. 

Understandably, most influenza infections go unreported.  Most people do not consult a doctor unless their symptoms are severe, and even when they do, sub-typing for novel strains is rarely done outside of a sentinel hospital.

Since 2010, the CDC has detected 500 novel flu infections in the United States (see chart below), although this almost certainly represents just the tip of the iceberg.

During a small outbreak of H3N2v (n=13) a dozen years ago, researchers estimated that fewer than 1 in every 200 cases was identified (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. 

We've seen similar estimates with H7N9 in China and MERS-CoV in Saudi Arabia.  Quite obviously, there are some regions of the world better equipped to detect novel viruses than others, but even in the UK their Health Security Agency has warned of the difficulties in detecting community spread of HPAI H5N1. 

A little over a year ago, the UKHSA published UK Novel Flu Surveillance: Quantifying TTD) which estimated the TTD (Time To Detect) a novel H5N1 virus in the community via passive surveillance might take 3-10 weeks, and the infection of dozens (or even hundreds) of people, before community spread could be established. 

They present different scenarios based on various levels of testing, but even under the best case scenario, it could take weeks to detect ongoing community transmission of the virus. 

While we can be comforted by the detection of only one mildly symptomatic (conjunctivitis) case in Texas, before the alert to monitor dairy workers went out a month ago, that case would likely have been dismissed as a mild viral infection, and testing would not have been done. 

Mild or sub-clinical cases are obviously less worrisome in the short run, but they are much harder to detect. 

The concern is, they give the virus additional opportunities to adapt to a new species, and potentially spread to their contacts. For a virus that hasn't quite adapted to human hosts, that's quite an advantage.

Yesterday the CDC published the following update on their efforts to detect any spread of the H5N1 virus early.  Due to its length I've only posted some excerpts, so follow the link to read it in its entirety.  I'll have a brief postscript after the break.

How CDC is monitoring influenza data among people to better understand the current avian influenza A (H5N1) situation
Español | Other Languages Print

Updated April 24, 2024

Weekly Snapshot for Week Ending April 13, 2024

CDC influenza (flu) surveillance systems show no indicators of unusual influenza activity in people, including avian influenza A(H5N1).

This page provides information on how CDC systems that monitor national, state, and local level influenza data are being used during the current avian influenza A(H5N1) situation 

• Influenza virus and illness activity are monitored year-round through a collaborative effort between CDC and many partners, including state, local, and territorial health departments; public health and clinical laboratories; clinics; and emergency departments.
• Human cases of novel influenza, which are human infections with non-human influenza A viruses that are different from currently spreading seasonal human influenza viruses, are nationally notifiable. Every identified case is investigated and reported to CDC.
• CDC is actively looking at multiple flu indicators during the current situation to monitor for influenza A(H5N1) viruses, including looking for spread of the virus to, or among people, in jurisdictions where the virus has been identified in people or animals.

Monitoring for Novel Influenza A Virus Infections among People, including Influenza A(H5N1)

Rapid detection and reporting of human infections with novel influenza A viruses, including influenza A(H5N1), is important to facilitate prompt awareness and an effective public health response. For confirmed cases, the reporting jurisdiction completes a case report form, which is submitted to CDC. The information includes patient demographics, symptoms, the clinical course of illness, and exposure history. The reporting jurisdiction for influenza A(H5N1) cases reported in 2024 are summarized below.

Public Health Laboratory Reporting

Public health laboratories use CDC’s diagnostic tools to detect both seasonal influenza viruses and novel influenza A viruses including influenza A(H5N1). These diagnostic tools are used at more than 100 public health laboratories in all 50 U.S. states. The results of tests performed by these public health laboratories nationwide are summarized below.

Systems Used to Monitor Influenza Activity

Influenza activity is monitored year-round using multiple systems. These systems are used for monitoring seasonal influenza and, because influenza viruses are constantly changing in small, and occasionally more significant ways, these systems are also useful for monitoring signals and trends from novel influenza virus infections. Some examples are provided below.

Monitoring for Changes in Tests Positive for Influenza in Clinical Settings

Approximately 300 clinical laboratories located throughout all 50 states, Puerto Rico, Guam, and the District of Columbia report the results of clinical testing for influenza through either the U.S. WHO Collaborating Laboratories System or the National Respiratory and Enteric Virus Surveillance System (NREVSS). The results of tests performed by clinical laboratories nationwide are summarized below.

While these laboratories don’t test specifically for influenza A(H5N1) virus, by tracking the percentage of specimens tested that are positive for influenza A viruses, we can monitor for unusual increases in influenza activity that may be an early sign of spread of novel influenza A viruses, including H5N1.

          (Continue . . .) 

While there is currently no indication of community spread of H5N1 anywhere in the world, the reality is there are many regions of the globe where low-level transmission could go unnoticed for quite some time.  

Even in places with more advanced surveillance capabilities - like the United States, the UK, and Europe - early detection of limited community spread might require a bit of luck. 

A reminder than anything we say about the current threat posed by H5N1, COVID, H5N6,  MERS-CoV, or any other pandemic threat must be tempered by the knowledge that we are always working with incomplete information. 

USDA Statement On Mandatory Testing For Interstate Movement Of Cattle

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Earlier today the HHS hosted a teleconference with representatives from the CDC, FDA, USDA APHIS, and NIAID on the growing concerns of HPAI in dairy cattle, and while I was unable to attend I believe Lisa Schnirring will have details later today on the CIDRAP News site.

About an hour after the meeting, the USDA emailed out the following statement describing several steps - including new federal regulations on the testing of lactating cattle prior to interstate movement - that agency is taking to address the problem.

Today's statement also confirms (without providing details) that asymptomatic cattle have tested positive for the virus:

USDA has identified spread between cows within the same herd, spread from cows to poultry, spread between dairies associated with cattle movements, and cows without clinical signs that have tested positive. 

On nearly a daily basis, we continue to see signs that the scope of this outbreak is larger than has been previously assumed. I've reproduced the emailed statement below, which is also posted at this link.

USDA Actions to Protect Livestock Health From Highly Pathogenic H5N1 Avian Influenza

Federal Order to assist with developing a baseline of critical information and limiting the spread of H5N1 in dairy cattle

WASHINGTON, April 24, 2024 – To further protect the U.S. livestock industry from the threat posed by highly pathogenic H5N1 avian influenza, USDA is sharing a number of actions that we are taking with our federal partners to help us get ahead of this disease and limit its spread.    Today, USDA’s Animal and Plant Health Inspection Service (APHIS) announced a Federal Order requiring the following measures, effective Monday, April 29, 2024:    Mandatory Testing for Interstate Movement of Dairy Cattle Prior to interstate movement, dairy cattle are required to receive a negative test for Influenza A virus at an approved National Animal Health Laboratory Network (NAHLN) laboratory.  Owners of herds in which dairy cattle test positive for interstate movement will be required to provide epidemiological information, including animal movement tracing.  Dairy cattle moving interstate must adhere to conditions specified by APHIS.   As will be described in forthcoming guidance, these steps will be immediately required for lactating dairy cattle, while these requirements for other classes of dairy cattle will be based on scientific factors concerning the virus and its evolving risk profile.   Mandatory Reporting Laboratories and state veterinarians must report positive Influenza A nucleic acid detection diagnostic results (e.g. PCR or genetic sequencing) in livestock to USDA APHIS.  Laboratories and state veterinarians must report positive Influenza A serology diagnostic results in livestock to USDA APHIS.   USDA has identified spread between cows within the same herd, spread from cows to poultry, spread between dairies associated with cattle movements, and cows without clinical signs that have tested positive. On April 16, APHIS microbiologists identified a shift in an H5N1 sample from a cow in Kansas that could indicate that the virus has an adaptation to mammals. Centers for Disease Control and Prevention (CDC) conducted further analysis of the specimen sequence, which did not change their overall risk assessment for the general public, because the substitution has been seen previously in other mammalian infections and does not impact viral transmission. Additionally, APHIS’ National Veterinary Services Laboratories found H5N1 in a lung tissue sample from an asymptomatic cull dairy cow that originated from an affected herd and did not enter the food supply.    The novel movement of H5N1 between wild birds and dairy cows requires further testing and time to develop a critical understanding to support any future courses of action. This Federal Order is critical to increasing the information available for USDA. Requiring positive test reporting will help USDA better under this disease and testing before interstate movement will limit its spread.     While we are taking this action today, it is important to remember that thus far, we have not found changes to the virus that would make it more transmissible to humans and between people. While cases among humans in direct contact with infected animals are possible, our partners at the U.S. Centers for Disease Control and Prevention (CDC) believe that the current risk to the public remains low.    Additionally, we continue to see affected cows recover after supported care with little to no associated mortality. We also continue to work with our partners in the states and industry to emphasize the critical importance biosecurity plays in limiting disease spread for all livestock and poultry.    The Federal Order may be viewed here and is effective on Monday, April 29, 2024.    Further, in an effort to maximize understanding and research on H5N1 in dairy cattle, on April 21, APHIS made publicly available 239 genetic sequences from the U.S. H5N1 clade 2.3.4.4b influenza virus recently found in samples associated with the ongoing HPAI outbreak in poultry and wild birds, and the recent H5N1 event in dairy cattle. APHIS has also offered virus samples to interested researchers to facilitate epidemiological study. Increasing our understanding of this disease and how it spreads is critical to stopping it. This is why APHIS is urging dairy cattle producers and those who work in or with the industry to share epidemiological information from affected farms, even if they are not planning to move cattle interstate. APHIS further urges producer participation in public health assessments to continue to confirm worker safety and monitor for any potential changes in the virus that could impact transmissibility.      In addition, our partners in the U.S. Food and Drug Administration released an update on the ongoing work to ensure continued effectiveness of the federal-state milk safety system. It is important to emphasize that, based on the information and research available to us at this time, the U.S. Food and Drug Administration and USDA believe that our commercial milk supply is safe because of both the pasteurization process and the required diversion or destruction of milk from sick cows. Pasteurization has continuously proven to inactivate bacteria and viruses in milk. The FDA and USDA continue to work closely to collect and evaluate additional data and information specific to avian influenza in dairy cattle and to support state counterparts as this emerging disease in dairy cattle is managed.   As USDA continues to take steps to protect the health of livestock, the Department continues to work closely with federal partners at the CDC on protecting the health of people and FDA on protecting the safety of the food supply. The U.S. government is committed to addressing this situation with urgency.   To learn more about USDA’s response to HPAI in dairy cattle, visit https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/livestock.

FDA Statement On Investigation Of H5N1 Virus Particles Detected In Finished Milk

 

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As we've discussed many times (see here, here, and here), highly specific and sensitive PCR testing is great for detecting the presence of pathogens like influenza A, but it can also detect non-viable virus particles as well.   

So, despite the furor overnight in the media about the discovery of `HPAI virus' in pasteurized milk, we don't know whether it presents a public health hazard or not.  

It does, however, deflate repeated claims by the USDA/FDA that:

Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted or destroyed so that it does not enter the human food supply. 

Further testing, where attempts will be made to grow (culture) the virus, will tell us a lot more.  But that process could take days or (if the virus is toxic to the growth medium) weeks.  

While my guess is that pasteurization greatly reduces any risks of infection, it is a mystery why - a full month after the virus was confirmed in dairy cows - they don't have those answers yet.  

The FDA's low-key admission (see below) was buried well down the page in last night's Updates on Highly Pathogenic Avian Influenza (HPAI).

(Excerpt)

As noted by USDA and some press reports from the World Health Organization (WHO) and other sources, the presence of the virus has been detected in raw milk. Based on available information, pasteurization is likely to inactivate the virus, however the process is not expected to remove the presence of viral particles. Therefore, some of the samples collected have indicated the presence of HPAI using quantitative polymerase chain reaction (qPCR) testing.

During the course of the outbreak, the FDA has been evaluating milk from affected animals, in the processing system, and on the shelves. We are completing a large representative national sample, to better understand the extent of these findings. Because qPCR findings do not represent actual virus that may be a risk to consumers, the FDA is further assessing any positive findings through egg inoculation tests, a gold-standard for determining viable virus. To date, we have seen nothing that would change our assessment that the commercial milk supply is safe. Results from multiple studies will be made available in the next few days to weeks.

(Continue . . . )

Remarkably, this statement came only after repeated calls by researchers (see here, here, and here) for better surveillance and more disclosure. Under growing pressure, the USDA released  239 Sequences From HPAI H5N1 Viruses late Sunday night, but dates of collection and locations were notably absent. 

As reported by Lisa Schnirring on CIDRAP earlier this week (see Scientists find clues in early analysis of newly shared US H5N1 avian flu sequences), there is now evidence that HPAI H5 may have been circulating in cattle for weeks (or even months) longer than previously suspected.

A bias against testing cattle for influenza A (despite evidence of their susceptibility) allowed the virus to circulate undetected until a month ago.  Since then, further reluctance to test non-dairy cattle, or asymptomatic cows, has left us with no clear idea of how widespread this HPAI outbreak really is. 

This `don't test, don't tell' policy also extends to pigs, and other potentially susceptible livestock. 

We have a bad habit of assuming the `best case scenario' when it comes to emerging viruses. 

In 2020 it took weeks and even months for governments to accept that COVID couldn't be contained by travel restrictions, that it was spread via the `airborne' route, and early reports of asymptomatic spread and reinfections were dismissed by the experts.  

Those early overly-optimistic assumptions undoubtedly cost lives. 

While the jury is still out on whether HPAI H5 will spark the next global public health crisis, another pandemic is inevitable.   

Although I understand it may be politically and economically inconvenient, we have to be willing to actively look for the next threat, otherwise we'll never see it coming. 

Mixed Messaging On HPAI Food Safety

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Although the USDA and FDA continue to reassure the American public that the food chain (including milk) is safe from HPAI H5N1, there remain unanswered questions about how widespread the virus is in cattle, and how effective regular pasteurization is in killing the virus. 

While the extent of the spread in cattle remains unknown, 3 days ago the New York Times carried an article (see Scientists Fault Federal Response to Bird Flu Outbreaks on Dairy Farms) where they cite (so far, unverified) reports of positive tests from asymptomatic cattle in North Carolina.

Testing by the USDA of cattle has remained both limited and voluntary, and has so far only been recommended for symptomatic dairy cows (see APHIS/USDA Updated FAQ On Detection of HPAI (H5N1) in Dairy Herds).

This `don't test, don't tell' policy apparently extends to pigs as well, despite ongoing concerns that HPAI could find a home in swine herds (see EID Journal: Divergent Pathogenesis and Transmission of Highly Pathogenic Avian Influenza A(H5N1) in Swine).

An excellent overview by Jon Cohen in Science yesterday (see U.S. government in hot seat for response to growing cow flu outbreak) describes the parsimonious release of information by the U.S. government, along with the limited evidence on the effectiveness of standard pasteurization in deactivating the virus. 

Under what I assume to be an abundance of caution, the CDC recently revised their food safety advice (see below) regarding HPAI, which now includes guidance on safely cooking beef (which, according to the USDA, are unlikely to be infected).  

They recommend:

• Whole cuts of beef, veal, lamb, and pork, including fresh ham: 145°F
• Ground meats, such as beef and pork: 160°F
• All poultry, including ground chicken and turkey: 165°F

It is also worth mentioning that despite the mantra that `properly prepared foods are safe to consume', there may be some small risks entailed in the preparation of raw meat.  PAHO (the Pan-American Health Organization) mentions this on their Avian Influenza landing page:

Transmission

The most common way for the virus to enter a territory is through migratory wild birds. The main risk factor for transmission from birds to humans is direct or indirect contact with infected animals or with environments and surfaces contaminated by feces. Plucking, handling infected poultry carcasses, and preparing poultry for consumption, especially in domestic settings, may also be risk factors.

In Asia, more than a few human HPAI H5 infections have been linked to preparing and cooking poultry.  Although it gets mentioned, far more attention needs to be paid to safe food handling practices in this time of HPAI. 

While I fully understand the USDA's desire to reassure the public about the safety of the food supply - doing so while slow rolling the release of information is a risky strategy.

Particularly when dealing with a virus with a history of repeatedly doing the unexpected.

I&ORD: Evidence of Reverse Zoonotic Transmission of Human Seasonal Influenza A Virus (H1N1, H3N2) Among Cats

 

My strictly indoor companion

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Up until 20 years ago, cats (and dogs) were thought relatively immune to influenza A viruses.  All that changed when an equine H3N8 virus jumped to greyhounds at a racetrack in Florida in 2004, and half-way around the world, big cats in Asian zoos began to succumb to avian H5N1. 

Since then we've seen a second (avian H3N2) influenza A virus jump to dogs and begin a world tour, and dozens of reports of dogs and cats infected with a variety of (mostly novel) influenza A viruses.  

A small sampling includes:

Microorganisms: Case Report On Symptomatic H5N1 Infection In A Dog - Poland, 2023

J. Virology: Zoonotic Risk, Pathogenesis, and Transmission of Canine H3N2

Access Microbiology: Inter-Species Transmission of Avian Influenza Virus to Dogs

WHO Update & Risk Assessment On H5N1 In Cats - Poland

Nebraska Veterinary Diagnostic Center (NVDC) Report: 2 Domestic Cats Infected With HPAI H5N1

NYC Health Dept. Statement On Avian H7N2 In Cats

The most obvious concern is that a dog or a cat might pick up a novel influenza A virus (like H5N1) from exposure to birds, or a contaminated environment, and bring it home (zoonotic transmission). 

But it is equally possible that a companion animal (or farmed animals) could be infected by humans (aka `reverse zoonosis'), and even introduce that virus into the wild.  

Reverse zoonosis may help explain how SARS-COV ended up in North American deer and other peridomestic animals, and almost certainly how human influenza A viruses have spread so widely in swine (see Reverse zoonosis of influenza to swine: new perspectives on the human-animal interface). 

While we've seen a fair number of studies on novel flu infection in companion animals, relatively little is known about the spread of seasonal flu viruses to cats.  

• During the 2009 H1N1 pandemic we did see several reports of feline infection
• In late 2010 we saw a study (see EID Journal: Pandemic H1N1 Infection In Cats) that looked at the pathogenesis of novel H1N1 in domestic felines.
• Six years ago we looked at two rare fatal infections in cats from a single household in Connecticut. Reportedly, both cats had pre-existing conditions, and the owner of the cats had recently been sick with a flu-like illness. (see Connecticut: Two Cases Of Fatal H1N1 In Cats)

All of which brings us to a letter to the Editor published in Influenza & Other Respiratory Diseases, which provides details of evidence of reverse zoonotic transmission of seasonal flu viruses to cats in China, and discusses the potential for cats to serve as a `mixing vessel' . 

First, some excerpts from the letter (follow the link to read it in its entirety), after which I'll return with a postscript.

Evidence of Reverse Zoonotic Transmission of Human Seasonal Influenza A Virus (H1N1, H3N2) Among Cats

Sajid Umar, Semin Kim, Di Gao, Pu Chen
First published: 18 April 2024
https://doi.org/10.1111/irv.13296

Dear Editor,

Human–animal interactions are closely intertwined. The connection between animal, human, and environmental health is becoming increasingly complicated with globalization, industrialization, and climate change. Since the beginning of the 20th century, the number of domestic cats has increased rapidly worldwide, including in China. There are approximately 600 million domesticated cats worldwide, including 65 million cats in China, most of whom have close human contacts. 

These close contacts create more chances for pathogen spillover among humans and cats, which could lead to the emergence of new pathogenic strains or variants. Cats living in proximity to their owners carry a particular risk of catching pathogens, as they often share snuggles, kisses, dining, and beds [1, 2]. We share hundreds of pathogens with our animals, which they serve as intermediate or reservoir hosts for pathogens that affect human health. Cats, owing to their genetic similarity to humans, are more susceptible to catching diseases from their owners. Recently, it has been estimated that humans spillover far more pathogens to animals than animals transmit to humans [2, 3]. 

          (SNIP) 

The high susceptibility of cats to IAVs generates the possibility of zoonotic and reverse-zoonotic transmission events and can serve as a mixing vessel for the emergence of new IAV variants (Figure 1). A large population of animals and humans makes China an ideal location for the emergence of future IAV pandemics.

(SNIP)

IAV was detected in 2.8% of the samples (13/458), whereas influenza B virus was not detected during this study. Genetic analysis revealed the presence of A (H1N1) and A (H3N2). Among the positive strains, there were nine strains of A (H1N1) virus and four strains of A (H3N2) virus. A/H1N1 and A/H3N2 positive cats showed HAI titers against these viruses, which also supported the evidence of reverse zoonosis. Interestingly, a higher detection rate (84.61%) was observed in samples collected during autumn and winter, which could be linked to the peak flu season in Kunshan and Shanghai. Clinical signs, including sneezing, dyspnea, and coughing, varied from mild to moderate among influenza-positive cats. No deaths were reported among the positive cats.

Based on molecular and serological testing, we demonstrated human seasonal IAV-infected cats in this study. This is the first report to assess the reverse zoonotic events of influenza viruses in cats in Kunshan, China, and highlights the potential risk of catching IAV in cats living in close contact with their owners. Despite some limitations, such as the small sample size and geographical area, our study provides useful information to veterinarians, pet owners, and policymakers.

Cats could act as additional intermediate or reservoir hosts for endemic IVA evolution and thus may contribute to major public health issues. There are several reports on the natural transmission of different IAV subtypes in cats, including avian H5N1, canine H3N2, human H1N1, and H3N2 [8]. Anthroponotic spillover events for IAV have been documented among cats, suggesting close interactions between cats and owners suffering from influenza-like illness [1, 8-11]. In addition to cats, a variety of other animals (swine, dogs, turkeys, and ferrets) has been naturally infected with Influenza A/H1N1. Human-to-pig transmission of IAV is the most studied anthroponotic event. More IAVs jump from humans to swine than from swine to humans [1].

Several suggestions have been made to minimize the risk of IAV-reverse zoonosis.

First, flu vaccine shots are recommended to owners and susceptible cats to reduce anthroponotic events.

Second, people who are sick with seasonal flu need to modify their behaviors and should be more vigilant about the health of their cats. Pet owners can minimize reverse zoonotic transmission by keeping nasal discharges and other bodily secretions away from cats during the sickness period.

Third, owners can minimize their playing time and petting activities with their cats while they are sick.

Finally, they can also limit reverse zoonotic transmission by regularly cleaning and disinfecting the bedding area and providing fresh and healthy feed to their cats.

Reverse zoonotic events in IAV can pose significant health risks for cats and possibly human health if left unchecked. Therefore, it is important to keep the IAV under control before it imposes deadly consequences on the human population. Keeping in mind the close association of cats with humans and the high pandemic potential of IAV warrants a more integrated research approach to minimize reverse zoonoses. This could include greater testing and continuous human pathogen surveillance at the human-animal contact interface. This type of data could facilitate the mitigation, prevention, prediction, and preparation of future IAV pandemics.

          (Continue . . . .)

Twice in my lifetime (H2N2 in 1957 & H3N2 in 1968) pandemic influenza viruses have emerged from China that were a combination of avian and human flu viruses.  Presumably, some unknown host was co-infected with a seasonal flu virus and and avian flu virus, and produced a hybrid via reassortment.  

While that host might have been a human, it could just as easily have been a pig, a dog, a cat, or some other non-human host.

All reasons why, with the elevated amount of HPAI H5N1 virus in wild birds and the environment, it is more important than ever to heed the CDC's advice on how to keep your pets (and your family) safe. 

 CDC Updated Advice On Bird Flu in Pets and Other Animals