Germany: Nuremberg Tiergarten (Zoo) Closed Over HPAI H5

 
Credit Wikipedia

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Just as we're seeing with zoos here in North America (see Chicago: Lincoln Park Zoo Confirms H5N1 Deaths of Harbor Seal & Flamingo and Arizona: Maricopa County Health Dept. Statement On H5 At Local Zoo), zoos around the world are having to deal with sporadic introductions of the HPAI H5 virus into their exhibits. 

Last October Vietnam reported `Dozens' Of Tiger Deaths (H5N1 Suspected) at two wildlife parks, and today we have confirmation of an outbreak at the Nuremberg Tiergarten, which is one of Europe's largest zoos. 

Yesterday, the deaths of several white storks forced the closing of the facility. The following (translated) press release come  from the City of Nuremberg.

         Nr. 35 / 16.01.2025

Avian flu contact company: Tiergarten closed as a precaution until further notice

At the branch of the zoo of the city of Nuremberg Gut Mittelbüg there is a suspected case of bird flu. Since the Nuremberg zoo is considered a contact company, it remains closed as a precaution until further notice. Three white storks from the zoo were tested positive for the bird flu virus on Gut Mittelbüg. The animals died a few days after being transported from the Tiergarten to the branch in the Nürnberger Land district. The Friedrich-Loeffler-Institut (FLI) is currently examining the submitted samples – until a clear diagnosis by the FLI, the incident is considered a suspected case.

The veterinary office of the Nürnberger Land district reported three cases of bird flu in the branch of the Nuremberg Tiergarten Gut Mittelbüg in Schwaig. On Wednesday 15 January 2025, three storks were tested positive for the avian influenza virus. The virus strain is not yet clear. The animals died on Gut Mittelbüg and were until 10 January in the zoo. Since then there have been no further findings. Nevertheless, offers for the public are currently not possible on the estate.

The veterinary offices of the Nürnberger Land district and the city of Nuremberg have ordered special measures for the Mittelbüg estate and the Tiergarten to prevent further spread. This includes the so-called erection of various birds, the examination of susceptible bird species in the branch and in the zoo itself, as well as special hygiene measures that employees in the zoo and in the branch must comply with. The epidemic plan, which the zoo developed in the event of an outbreak, also includes the division of the zoo and its bird populations into disease units. Areas and objects that come into contact with infected animals are cleaned and disinfected.

Poultry farmers in the region are currently not subject to a general stables for poultry. However, the poultry farmers are required to check the biosecurity measures (e.g. protection against wild bird contact, hygiene when handling animals) to protect their animal populations and to strictly adhere to them.

As soon as further information is available, the city of Nuremberg will provide the public with comprehensive information. fra

Today, the Friedrich-Loeffler-Institut  has confirmed the infections as H5N1.

No. 45 / January 17, 2025

Suspected bird flu confirmed

The Friedrich-Loeffler-Institut was able to demonstrate the highly pathogenic bird flu subtype H5N1 at Gut Mittelbüg, the branch of the Nuremberg Tiergarten in Schwaig. The responsible district of Nürnberger Land announced this last night. Because the animals until Friday, 10 January 2025, still in the Tiergarten itself, the veterinary offices of the district and the city of Nuremberg had already taken special measures for Gut Mittelbüg as well as for the Tiergarten to prevent the disease from spreading further. These remain.

This includes the so-called erection of various birds, the examination of susceptible bird species in the branch and in the zoo itself, as well as special hygiene measures that employees in the zoo and in the branch must comply with. The Nuremberg zoo will remain closed as a precaution until further notice.

Poultry farmers in the region are currently not subject to a general stables for poultry. However, they are required to review and strictly comply with biosecurity measures, such as protection against wild bird contact and general hygiene when handling animals, to protect their animal populations. Yes

While most of our attentions have been focused on North American avian influenza outbreaks since the spring of 2024, the following FLI map of European HPAI outbreaks from Oct 1st - Dec 31st of 2024, shows how widespread the virus is in Europe.

While they aren't currently dealing with HPAI in cattle, they continue to report spillovers into mammals, and occasional outbreaks due to HPAI H5N5 (see Norway Veterinary Institute Reports 1st Outbreak of HPAI H5N5 In Domesticated Birds).

A reminder that HPAI is truly a multi-faceted, and global, concern. 

EID Journal: Human Infection with Avian Influenza A(H9N2) Virus, Vietnam, April 2024

 

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Despite being an LPAI (low path avian influenza) virus, and generally producing relatively mild symptoms in humans, H9N2 is viewed by many as an important and influential player in the avian flu world.  

Although most cases undoubtedly go undetected, 2024 saw a near-record 22 confirmed cases (see FluTrackers H9N2 list), with cases reported by 4 nations (China - 19, India - 1, Ghana -1, and  Vietnam - 1). 

As an LPAI virus, H9N2 is not considered a `reportable' disease by WOAH (formerly the OIE), even though it is clearly zoonotic. We've seen seroprevalence studies which suggest people with exposure to infected poultry often develop H9 antibodies, suggesting a significant number of unreported mild or asymptomatic infections.

Over the past 15 years we've watched as H9N2 has expanded its geographic range - spreading out of Asia into Europe, the Middle East and Africa. While it occasionally spills over into humans, H9N2's biggest threat may come from its unique ability to reassort with other, potentially more dangerous, avian viruses.

 

Its internal genes have often been found inside many HPAI viruses (including H5N1, H5N6, H7N9, and most recently zoonotic H3N8) - (see The Lancet's Poultry carrying H9N2 act as incubators for novel human avian influenza viruses).  

H9N2 is such a versatile virus, it has even been detected in  Egyptian Fruit bats (see Preprint: The Bat-borne Influenza A Virus H9N2 Exhibits a Set of Unexpected Pre-pandemic Features).

While admittedly not at the very top of our list of pandemic concerns, the CDC has 2 different lineages (A(H9N2) G1 and A(H9N2) Y280) on their short list of influenza viruses with zoonotic potential (see CDC IRAT SCORE), and several candidate vaccines have been developed.

Last April Vietnam reported their first confirmed H9N2 cases (see Vietnam MOH Statements On A/H9 Case In Tien Giang Province).  Aside from being Vietnam's first case, this report was unusual in that it involved an adult, and the patient (who had significant comorbidities) was described as being severely ill.

Yesterday the CDC's EID journal published a letter from researchers at the Pasteur Institute in Ho Chi Minh City, Vietnam, which provides us with our first detailed look at Vietnam's first confirmed case. 

As this report explains, surveillance and testing for novel flu viruses in Southern Vietnam is patchy at best.  The delay between the patient's admission date (March 16th) and a positive H9N2 subtype test (April 8th), was 23 days. 

These types of delays are not unusual, even here in the United States, which is why yesterday the CDC issued a HAN advisory, urging hospitals to speed up the subtyping of all influenza a patients (see CDC HAN: Accelerated Subtyping of Influenza A in Hospitalized Patients).

The exact source of exposure for this Vietnamese patient is unknown, although genetic analysis suggest a poultry source.   I've posted some excerpts from their report below, but follow the link to read it in its entirety. 

I'll return with a postscript after the break.

Human Infection with Avian Influenza A(H9N2) Virus, Vietnam, April 2024
Minh Hang Duong , Thi Ngoc Uyen Phan, Trung Hieu Nguyen, Ngoc Hien Nhon Ho, Thu Ngoc Nguyen, Viet Thinh Nguyen, Minh Thang Cao, Chan Quang Luong, Vu Thuong Nguyen, and Vu Trung Nguyen
Author affiliation: Pasteur Institute in Ho Chi Minh City, Ho Chi Minh City, Vietnam

 
Abstract

In April 2024, Vietnam confirmed its first human case of influenza A(H9N2) in a 37-year-old man, marking a critical point in regional infectious disease monitoring and response. This case underscores the importance of robust surveillance systems and One Health collaboration in managing emerging zoonotic threats.

Influenza A(H9N2) virus is a low-pathogenicity avian influenza virus endemic in poultry across the world. The virus presents ongoing zoonotic risk; according to the GISAID database (https://www.gisaid.orgExternal Link), ≈100 human cases were detected since 2010, and the virus’s unique evolutionary trajectory shows it could cause pandemics (1).

The risk for transmission and genetic mixing of avian influenza viruses, including H9N2, among wild birds, swine, and humans highlights the necessity for robust surveillance systems to manage the potential threat of these influenza viruses (2–4). In Vietnam, H9N2 accounts for 36% of detected avian influenza viruses (5) and shares genetic similarities with strains from neighboring countries, particularly China (3,6). Although human H9N2 cases have been reported in Asia (7,8), Vietnam had not previously reported a human case until 2024. The first human case of H9N2 influenza in Vietnam was officially confirmed in April 2024, marking a significant event in regional surveillance and response efforts.

A 37-year-old man with a known history of alcohol abuse from Tien Giang Province, Vietnam, experienced fever and cough on March 9, 2024. He sought medical care on March 16 at a provincial hospital, where he received a diagnosis of cirrhosis and was transferred to the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam, the same day. Initially, his chest radiograph results were unremarkable. However, on March 19, he had pneumonia with dyspnea, fatigue, and extensive alveolar and interstitial damage evident on chest radiograph. He was intubated on March 21; osletamivir treatment was initiated, which improved his condition and enabled him to be weaned from the ventilator. He continued treatment in a negative-pressure intensive care unit; diagnoses were sepsis, influenza A, invasive fungal infection, respiratory failure, pulmonary hemorrhage, gastrointestinal bleeding, acute kidney injury, alcohol-related cirrhosis, and a suspected liver tumor. On May 5, 2024, he was discharged from the hospital to receive palliative care; he died on May 6, 2024.

The patient had not received influenza or COVID-19 vaccinations and had no known exposure to sick or dead poultry. All 15 close contacts, including family, neighbors, a driver, and healthcare workers, remained asymptomatic during 24 days of monitoring; we did not collect samples from them. His neighborhood had informal markets for poultry and other animals, but no avian influenza outbreaks were reported in the preceding 3 months. Testing geese from his home 27 days after symptom onset found no influenza H5 or H9 viruses, whereas 1 sample from nearby poultry markets tested positive for H5N1 virus but none for H9 viruses.

At the time of this case, southern Vietnam lacked surveillance for severe acute respiratory infection, and influenza-like illness surveillance was limited to 6 sentinel sites, excluding the hospitals involved in this study. The patient was enrolled in Pasteur Institute in Ho Chi Minh City (PIHCM) severe viral pneumonia (SVP) surveillance system, active since 2020, after developing pneumonia with significant respiratory symptoms and chest radiograph findings. On April 1, 2024, PIHCM received the patient’s sample, which had been collected by Hospital for Tropical Diseases on March 21, 2024. 

On April 8, we performed real-time reverse transcription PCR in accordance with the H9N2 protocol of the Regional Animal Health Office No. 6 Vietnam (RAHO6). The Ct value for H9 was 28.81 and for N2, 29.6, indicating significant viral presence. 

          (SNIP)

The genetic distances between our sequence and other human and poultry viruses in Asia and America (Figure 2) suggest household poultry as the likely source of exposure. In addition, our findings highlight the geographic spread of H9N2 virus.

Moving forward, several key research questions arise from this case. First, it is crucial to understand the progression of the disease, particularly the mechanism by which H9N2 influenza contributed to the worsening of the patient’s condition, ultimately leading to multiorgan failure. Second, analyzing samples from close contacts to determine H9N2 positivity is important to identify potential human-to-human transmission, understand transmission dynamics, and guide public health interventions.

Although Vietnam lacks a formal One Health rapid response team, this case highlighted the value of cross-sector collaboration. Contributions from public health and animal health sectors, including sequencing expertise and environmental testing, underscore the need to strengthen One Health partnerships for effective surveillance and outbreak response.

Dr. Duong is a medical doctor at the National Influenza Center Respiratory Viruses Laboratory of the microbiology and immunology department of Pasteur Institute in Ho Chi Minh City, Vietnam. Her research focuses on influenza viruses, SARS-CoV-2, and other viruses such as RSV and measles.

While we count and obsess over every reported novel flu detection, at best we are probably only hearing about a small fraction of actual infections. Many countries do little or no testing, while others hold data close to their vest (see From Here To Impunity).

But even where there is relatively robust surveillance and reporting, official case counts can be deceivingly low (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012).

Seven years ago, in EID Journal: Two H9N2 Studies Of Note, we looked at two reports which suggested that H9N2 continues to evolve away from current (pre-pandemic and poultry) vaccines and is potentially on a path towards better adaptation to human hosts.

Some more recent (2024) H9N2 studies, include:

Recent Papers On The Zoonotic Potential of Bat-borne H9N2

Infectious Medicine: Rapid Adaptive Substitution of L226Q in HA protein Increases the Pathogenicity of H9N2 Viruses in Mice

Transboundary & Emerg. Dis.: Novel Human-Avian Reassortment H9N2 Virus in Guangdong Province, China

Frontiers in Public Health: Human Infections of H9N2 Avian Influenza Virus in China (in 2021)

CDC HAN: Accelerated Subtyping of Influenza A in Hospitalized Patients

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Today in an HHS teleconference, the CDC confirmed that the 67th confirmed H5N1 case - announced last night - was the child in San Francisco, who has now recovered.  As with the Missouri, British Columbia, and Delaware cases, the source of their infection remain unknown. 

Most of these community cases have only been identified as H5 belatedly, sometimes only after the patient has recovered or been released by the hospitals. The reality is, most hospitals only submit samples in batches to state labs for subtyping. 

Since it is important to identify H5 cases earlier rather than later, today the CDC is recommending that hospitals endeavor to subtype influenza A patients in the first 24 hours - or as early as possible - in order detect cases in a timely manner.  

Doing so will:

• Improve case investigations & interviews while memories are fresh
• Allow for timely contact tracing and/or testing 
• Guide infection control and antiviral use among hospital staff
• Better define the scope of the problem

The CDC's HAN Advisory follows:

Accelerated Subtyping of Influenza A in Hospitalized Patients

Distributed via the CDC Health Alert Network

January 16, 2025, 10:00 AM ET
CDCHAN-00520

Summary

The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Advisory to clinicians and laboratories due to sporadic human infections with avian influenza A(H5N1) viruses amid high levels of seasonal influenza activity. CDC is recommending a shortened timeline for subtyping all influenza A specimens among hospitalized patients and increasing efforts at clinical laboratories to identify non-seasonal influenza. Clinicians and laboratorians are reminded to test for influenza in patients with suspected influenza and, going forward, to now expedite the subtyping of influenza A-positive specimens from hospitalized patients, particularly those in an intensive care unit (ICU). This approach can help prevent delays in identifying human infections with avian influenza A(H5N1) viruses, supporting optimal patient care and timely infection control and case investigation.

Background

A panzootic of highly pathogenic avian influenza A(H5N1) viruses is currently affecting wild birds. In the United States, there have been outbreaks with these viruses among poultry and dairy cows, as well as infections among other animals. Since 2022, 67 total human cases of avian influenza A(H5) virus infection have been identified in the United States, with 66 of these cases occurring in 2024. Most infections in humans have been clinically mild, but one fatality has been reported. Many individuals infected with avian influenza A(H5) viruses have reported unprotected workplace exposures, such as handling infected or sick dairy cows or poultry without using recommended personal protective equipment. However, one case involved exposure to backyard poultry or wild birds. The source of the exposure in two confirmed cases in the United States could not be determined.

CDC has routinely recommended influenza testing for hospitalized patients with suspected influenza. In light of the ongoing avian influenza A(H5) virus animal outbreak in the United States, CDC now recommends subtyping of all influenza A virus-positive specimens from hospitalized patients on an accelerated basis. This accelerated subtyping is part of a comprehensive strategy to identify severe human infections with avian influenza A(H5) viruses, in addition to characterizing seasonal influenza viruses in a timely fashion.

Enhancing and expediting influenza A virus subtyping of specimens from hospitalized patients, especially from those in an ICU, can help avoid potential delays in identifying human infections with avian influenza A(H5) viruses. Such delays are more likely while seasonal influenza activity is high, as it is now, due to high patient volumes and general burden on healthcare facilities. Additional testing also ensures optimal patient care along with timely infection control. Furthermore, expediting transportation of such specimens to commercial or public health laboratories for additional testing may also accelerate public health investigation of severe A(H5) cases and sharing of information about these viruses.

• Most influenza tests ordered in clinical settings do not distinguish avian influenza A(H5) viruses from seasonal influenza A viruses; a positive result simply confirms influenza A virus infection. Therefore, using tests that identify the seasonal influenza A virus subtype will help identify whether infection with a seasonal influenza A virus is present. If a test result is positive for influenza A virus but negative for seasonal influenza A virus subtypes [i.e., A(H1) and A(H3)], the virus detected might be a novel influenza A virus, such as influenza A(H5), and specimens should be prioritized for shipment to a public health laboratory for additional testing. Alternatively, there are now a few commercial laboratories offering influenza A(H5) subtyping in the clinical setting. Additionally, the Food and Drug Administration offers a list of influenza A typing and subtyping tests. Services like diagnostic and subtype testing that are reasonable and necessary to diagnose illness are covered in most cases by both public and private health insurers.

Subtyping is especially important in people who have a history of relevant exposure to wild or domestic animals infected or possibly infected with avian influenza A(H5N1) viruses.

CDC still considers the risk from avian influenza A(H5) viruses to the public to be low but is closely monitoring this dynamic situation. At this time, while seasonal influenza levels are high nationally, nearly all people who are currently hospitalized with influenza A virus infections probably have seasonal influenza.

Recommendations for Testing of Hospitalized Patients

In addition to jurisdiction-specific instructions for sending specimens for subtyping, CDC now recommends that all influenza A positive respiratory specimens from hospitalized patients, especially from those in an ICU, be subtyped for seasonal influenza A viruses [A(H1) and A(H3)] as soon as possible following admission—ideally within 24 hours—to support optimal patient care and proper infection prevention and control measures and to facilitate rapid public health investigation and action.

Recommendations for Clinicians

• When collecting a thorough exposure history from a patient with suspected or confirmed influenza who is hospitalized, ask about potential exposure to wild and domestic animals, including pets (e.g., cats), and animal products (e.g., poultry, dairy cows, raw cow milk and raw cow milk products, raw meat-based pet food), or recent close contact with a symptomatic person with a probable or confirmed case of A(H5).
• Implement appropriate infection control measures when influenza is suspected.

• • If avian influenza A(H5) virus infection is suspected, probable, or confirmed in a hospitalized patient, place the patient in an airborne infection isolation room with negative pressure with implementation by caregivers of standard, contact, and airborne precautions with eye protection (goggles or face shield).

• Test for seasonal influenza A in hospitalized patients with suspected seasonal influenza or novel influenza A virus infection such as avian influenza A virus infection, using whatever diagnostic test is most readily available for initial diagnosis.

• • If the initial diagnostic test does not subtype [e.g., identify A(H1) and A(H3)], order an influenza A subtyping diagnostic test within 24 hours of hospital admission for patients who tested positive for influenza A.
  • Subtyping should be performed with assays available to the testing laboratory, as follows:
    • Subtyping tests should be performed in the hospital clinical laboratory, if available.
    • Alternatively, specimens should be sent to a commercial clinical laboratory.
    • If influenza A virus subtyping is not available through one of these routes, arrangements can made for influenza A virus-positive specimens to be subtyped at a public health laboratory.

• Any hospitalized patients, especially those in an ICU, with suspected seasonal influenza or avian influenza A(H5) should be started on antiviral treatment with oseltamivir as soon as possible without waiting for the results of influenza testing.

• • Consider combination antiviral treatment for hospitalized patients with avian influenza A(H5) virus infection.

• Notify the health department promptly if avian influenza A(H5N1) virus infection is suspected, probable, or confirmed in a hospitalized patient.

• Questions about appropriate clinical management or testing of hospitalized patients with novel influenza A virus infection [e.g., A(H5)], including about combination antiviral treatment dosing or testing for antiviral resistance, can be directed to the CDC Influenza Division for consultation with a medical officer via the CDC Emergency Operations Center at 770-488-7100.

Recommendations for Clinical Laboratories

• Subtype and send respiratory specimens that are positive for influenza A but negative for seasonal influenza A virus subtypes [i.e., negative for A(H1) and A(H3)] to a public health laboratory as soon as possible and within 24 hours of obtaining the results. Do not batch specimens for consolidated or bulk shipment to the public health laboratory if that would result in shipping delays for any such specimen.
• If influenza A virus subtyping is not available at the hospital or the clinical laboratory of the treating facility, public health officials should be notified, and arrangements made for influenza A virus-positive respiratory specimens to be subtyped at a public health laboratory or a commercial laboratory with this testing capability. Specimens should be clearly linked to clinical information from the patient to ensure specimens from severely ill and ICU patients are prioritized.
• Immediately contact the state, tribal, local, or territorial public health authority if a positive result for influenza A(H5) virus is obtained using a laboratory developed test (LDT) or another A(H5) subtyping test to initiate important time-critical actions.

Recommendations for Public Health Laboratories

• Complete influenza A virus subtyping assays within 24 hours of receipt and report results to CDC, as required.

Recommendations for the Public

• People should avoid direct contact with wild birds and other animals infected with or suspected to be infected with avian influenza A viruses.
• If you must have direct or close contact with infected or potentially infected birds or other animals, wear recommended personal protective equipment (PPE).
• Additional information on protecting yourself from avian influenza A(H5) infection is available from CDC.

For More Information

• H5 Bird Flu: Current Situation | CDC

• 2024-2025 Influenza Season: Surveillance for Novel Influenza A and Seasonal Influenza Viruses | CDC

• Interim Guidance for Infection Control Within Healthcare Settings When Caring for Confirmed Cases, Probable Cases, and Cases Under Investigation for Infection with Novel Influenza A Viruses Associated with Severe Disease | CDC

• Interim Guidance on Specimen Collection and Testing for Patients with Suspected Infection with Novel Influenza A Viruses Associated with Severe Disease or with the Potential to Cause Severe Disease in Humans | CDC

• Case Definitions for Investigations of Human Infection with Avian Influenza A Viruses in the United States | CDC

• Interim Guidance on the Use of Antiviral Medications for Treatment of Human Infections with Novel Influenza A Viruses Associated with Severe Human Disease | CDC

Texas Parks and Wildlife Department (TPWD) Recommends Removing Bird Feeders Due to HPAI H5

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While it is far from a universal recommendation, over the past month we've begun to see advice from some local Health Departments, and Wildlife Departments, to take down bird baths and feeders due to the (currently low, but not zero) risk of HPAI H5. 

On December 23rd, the LA County Health Department issued a statement on that county's first confirmed case, which included the following advice:

Best Practices to Reduce Risk for the General Public

Public Health encourages residents to follow these best practices:

• Avoid Raw Dairy and Undercooked Meat Products: Do not drink raw milk or eat raw cheeses and undercooked meat products. Do not feed these to your pets.
• Limit Contact with Animals: Avoid unprotected contact with sick or dead animals or birds or any materials contaminated with bird feces. Avoid handling wild birds and observe them only from a distance. If you have to handle wild birds, even if they appear healthy, wear a well-fitting mask and gloves, and practice good hand hygiene, as some birds may carry the virus without showing symptoms.
• Report sick or dead birds: Contact your local animal control agency if you see sick or dead birds. Symptoms can vary; infected birds or animals may be unable to fly, have seizures, have difficulty walking or be found dead.
• Protect pets or poultry: Keep pets or poultry away from wild animals and birds. Ensure that wild birds cannot defecate into areas holding or housing pet birds or poultry.
• Remove Bird Feeders and Baths: Take down bird feeders and communal bird baths to reduce the risk of the virus spreading from bird-to-bird.
• Get a Seasonal Flu Vaccine: Everyone should receive a seasonal flu vaccine. While this vaccine does not prevent avian influenza infection, it can reduce the risk of getting sick with human and bird flu viruses at the same time. 

This past week, the Texas Wildlife Department issued similar advice (see below). 

Highly Pathogenic Avian Influenza Causes Duck Mortalities in Austin Area

Jan. 9, 2025

Media Contact: TPWD News,  Business Hours, 512-389-8030

AUSTIN — Highly Pathogenic Avian Influenza (HPAI) has been confirmed by preliminary test results in multiple domestic ducks recovered at the pond on the NE corner of the Arboretum Blvd and 360 Capital of Texas Highway intersection in northwest Austin.

Disease experts indicate HPAI is circulating among wild birds in Texas as waterbirds and waterfowl visit their wintering grounds.

Widespread detections have occurred across Texas with most recent findings in Wharton, Galveston, El Paso, Potter and Harris counties.

Detected in all states across the U.S., HPAI is a highly contagious virus that transmits easily among wild and domestic birds. It can spread directly between animals and indirectly through environmental contamination.

Because of the ease of transmission, Texas Parks and Wildlife Department (TPWD) recommends wildlife rehabilitators remain cautious when intaking wild animals with clinical signs consistent with HPAI and quarantine animals to limit the potential for HPAI exposure to other animals within the facility.

The public can assist in interrupting HPAI transmission by limiting all unnecessary contact with wild birds, including not feeding or causing waterfowl to congregate in parks. To help combat this outbreak, it is recommended that all bird feeders and bird baths be taken down as these allow birds to congregate and spread disease easily to each other. Do not handle any sick or dead wildlife or allow any pets to consume any wild carcasses.

Additionally, game bird hunters should consider precautions such as:

• Disposing carcasses properly
• Wearing gloves when processing
• Avoiding consumption or processing of any sick bird
• Cleaning and disinfecting tools between carcasses
• Cooking meat to proper temperatures

Currently, the transmission risk of avian influenza from infected birds to people remains low, but the public should take basic protective measures if contact with wild animals cannot be avoided. The public and health care professionals can find more information about HPAI in humans from the Texas Department of State Health Services. If you had contact with an HPAI-positive or suspect animal and develop signs of illness, immediately contact your health care provider and let them know about the exposure.

If you encounter a wild animal with signs consistent with HPAI, contact your local TPWD wildlife biologist.

In the fall of 2022 the California Audubon Society urged Backyard Birders to Empty Bird Baths and Feeders as Avian Flu Spreads, but the the US Fish & Wildlife Service has an avian flu page which takes a different view. 

Feeding Birds

• Bird feeders are unlikely to result in increased spread of avian influenza since the species of bird that tend to come to feeders are not commonly infected.

• However, feeders do concentrate passerines and increase the risk of transmission of other infectious diseases that do impact their health, including salmonella, E. coli and mycoplasma.

• Creating natural spaces that attract birds to the cover and food provided by native vegetation appropriate to the location is far healthier than feeders

Recently we've seen an increase in the range of avian species susceptible to H5N1. 

While it used to be primarily waterfowl and gallinaceous birds, we are now seeing passerines (including songbirds) and other orders being affected (see Prevalence of Avian Influenza Virus in Atypical Wild Birds Host Groups during an Outbreak of Highly Pathogenic Strain EA/AM H5N1).

Obviously, there isn't a consensus on this topic right now.  

But given the small, but growing, number of human H5 cases without a known exposure, it may be worth going the extra mile to avoid exposure to birds right now. 

Chicago: Lincoln Park Zoo Confirms H5N1 Deaths of Harbor Seal & Flamingo

HPAI Poultry Outbreaks last 30 Days - USDA

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After several months of seeing mostly Western states reporting HPAI, last November we began to see a decided eastward shift;  in poultry outbreaks (see USDA map above), in wild birds, and in human infections with H5N1.  

In December, we looked at a number of reports, including:

Illinois Dept Public Health Monitoring A Large-scale Waterfowl Mortality Event Due to HPAI

Louisiana & Missouri Report Waterfowl Die Offs As H5N1 Moves East

Texas: Galveston County Reports H5N1 in Wild Bird - Monitoring Two People With Exposure

And of course, a severe (and ultimately fatal) HPAI H5 human infection in Louisiana (see CDC Statement: First H5 Bird Flu Death Reported in United States) and a `probable' mild human infection in Delaware.

Most of these cases have been linked to the D1.1 genotype, which arrived last fall via migratory birds, and is genetically distinct from the `bovine' B3.13 genotype reported in dairy cows.  

Earlier this week, in USDA: APHIS Statement On 1st Detection of HPAI H5N1 in Puerto Rico, we saw the virus make it into the Caribbean.     

Last yesterday Chicago's Lincoln Park Zoo announced that a harbor seal and a flamingo have both succumbed to the virus.  While the source of exposure remains unknown, it was likely carried in by an infected wild or migratory waterfowl. 

This is a reminder that the virus remains at high levels in the environment, and that people need to be cognizant of the threat it poses, particularly to their pets (see CDC What Causes Bird Flu in Pets and Other Animals).

I've reproduced the Lincoln Park Zoo's press release below.

Avian Influenza Cause of Death in Harbor Seal and Chilean Flamingo at Lincoln Park Zoo

Lincoln Park Zoo reports that testing has confirmed highly pathogenic avian influenza was the cause of death for a Chilean flamingo on January 8 and harbor seal on January 9.

Chicago (January 15, 2025) – Lincoln Park Zoo reports that testing has confirmed highly pathogenic avian influenza was the cause of death for a Chilean flamingo on January 8 and harbor seal on January 9.

The zoo is saddened by the loss of a Chilean flamingo named Teal and a harbor seal named Slater. Teal hatched this fall and was just getting acquainted with her flock and keepers. Slater was 7 years old and was a beloved seal known for his rambunctious and curious nature. He was a quick learner and often could be seen participating in training sessions with keepers. Both will be deeply missed.

“This is sad news for wildlife and for the zoo team. Not only are we facing the first known cases of HPAI in animals in our care, but we’ve lost two amazing animals,” said Lester E. Fisher Director of Veterinary Services Dr. Kathryn Gamble, DVM, Dipl. ACZM, Dip. ECZM. “While highly pathogenic avian influenza is a naturally occurring virus in free-ranging waterfowl, more mammal species have been reported to be susceptible to HPAI since 2022.”

While the confirmed source of exposure is unknown for either case, it is near certain the cause is from contact with a waterfowl infected with HPAI. The Centers for Disease Control shares that HPAI is spread through saliva, nasal secretions, and feces of infected birds. Safety is a top priority at the zoo. Zoo visitors are not at risk of contracting HPAI from Lincoln Park Zoo animals.

“Because highly pathogenic avian influenza is spread by free-ranging birds, it is no riskier to visit Lincoln Park Zoo than to enjoy a walk outdoors,” said President & CEO and ornithologist Megan Ross, Ph.D. “The zoo remains a safe place to connect with the animals in our care.”

Prior to these results, the zoo had been monitoring HPAI reports and had enacted its multi-tier proactive HPAI Response Plan which addresses considerations for staff and animals alike. Such measures include additional personal protective equipment, removing opportunities for cross contamination between species, and focused monitoring for changes in individual animal health or behavior. To protect the animals in the zoo’s care, some bird species will remain behind the scenes and the McCormick Bird House will be closed until further notice.

“Sharing this news of highly pathogenic avian influenza in the area is important for our community at large,” said Director of the Urban Wildlife Institute Seth Magle, Ph.D. “To protect yourself, do not handle wildlife. Additionally, keep your pets safe by keeping cats indoors and dogs on leash away from wildlife.”

Nature: Pathogenesis of Bovine H5N1 Clade 2.3.4.4b Infection in Macaques

 

#18,561

The journal Nature has published a study on various routes of exposure of Macaques to the `bovine' (genotype B3.13)  H5N1 clade 2.3.4.4b virus (see citation below), much of which, alas, is behind a paywall. 

Rosenke, K., Giffin, A., Kaiser, F. et al. Pathogenesis of bovine H5N1 clade 2.3.4.4b infection in Macaques. Nature (2025). https://doi.org/10.1038/s41586-025-08609-8

Received 30 September 2024  Accepted 07 January 2025  Published 15 January 2025

Luckily, we have a brief summary from the NIH, which suggests that the route of exposure (oral vs upper/lower respiratory) makes a difference in the severity of infection (at least in Macaques).  First the summary, after which I'll have a brief postscript.

 

Subclinical Disease in Monkeys Exposed to H5N1 by Mouth and Stomach

NIAID Now | January 15, 2025

Credit: CDC and NIAID

A new study published in Nature found that highly pathogenic H5N1 avian influenza virus (HPAI H5N1) administered directly into the mouth and stomach of research monkeys caused self-limiting infection with no recognizable clinical signs of disease. By comparison, other routes of transmission resulted in mild or severe disease. The findings suggest that drinking raw milk contaminated with H5N1 virus can result in infection but may be less likely to lead to severe illness. Nevertheless, exposure by raw milk – which is a source of several foodborne illnesses – should be avoided to prevent H5N1 infection and potential further spread.

The research team, from NIH’s National Institute of Allergy and Infectious Diseases (NIAID), exposed cynomolgus macaques to the same clade 2.3.4.4b HPAI H5N1 virus circulating in U.S. cattle. Transmission routes included via the nose, windpipe (trachea) or directly into the mouth and stomach to mimic infection routes in people. Animals exposed via the nose and windpipe became infected, developed pneumonia and had varying degrees of disease. Animals infected in a manner that mimicked drinking had a more limited infection with no obvious disease signs. To what extent this work mirrors human infection remains unclear.

The study does suggest that infection through contaminated liquids like raw milk represents a risk for HPAI H5N1 infection of primates. The work cites the “local environment” in the stomach as potentially inactivating the virus and thus, possibly reducing the exposure dose. Scientists at NIAID’s Rocky Mountain Laboratories in Hamilton, Montana, led the work.

They exposed six animals each via the nose to mimic an upper-respiratory tract infection; the windpipe to mimic a lower-respiratory tract infection; and in the mouth and stomach to mimic consuming contaminated products. They used a dose of virus close to what has been found in contaminated raw milk. Researchers regularly monitored and examined animals for up to 14 days.

Animals exposed in the mouth and stomach became infected but showed no signs of influenza illness throughout the study. Animals exposed in the nose showed mild respiratory disease, peaking at day 10. Animals exposed in the windpipe showed severe respiratory illness within a week.

Reference: K Rosenke, A Griffin, F Kaiser, et al. Pathogenesis of bovine H5N1 clade 2.3.4.4b infection in Macaques. Nature DOI: 10.1038/s41586-025-08609-8 (2025).

 

While this may shed some light on why most human infections with the `bovine' H5N1 strain have been mild - we've already seen some genetic diversity within the B3.13 genotype - and its behavior could change over time.  

But even if B3.13 is a `lighter' version of H5N1, when introduced into the trachea, it produced severe respiratory illness in test animals. 

Meanwhile, the D1.1 genotype - which has caused at least 2 severe infections in North America - appears far more widespread, and may well be more dangerous. 

While it is possible that neither of these genotypes have the `right stuff' to spark a larger epidemic - there are scores of others in the wild - and any one of them might serve as a `stepping stone' to a new and improved version of the virus.