#USA, #Monitoring for Avian #Influenza A(#H5) Virus In #Wastewater {Jan. 5-11 '25}

 {Excerpt}

Time Period: January 05 - January 11, 2025

-- H5 Detection: 53 sites (15.8%)

-- No Detection: 282 sites (84.2%)

-- No samples in last week: 61 sites

(...)

Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/bird-flu/h5-monitoring/index.html

_____

#USA, Novel #Influenza A #H5N1 Virus: One Pediatric Case in #California {FluView}

 {Excerpt}

One confirmed human infection with influenza A(H5) virus was reported to CDC this week. To date, human-to-human transmission of influenza A(H5) virus has not been identified in the United States.

This case was reported by the California Department of Public Health and occurred in a child less than 18 years old with no known contact with influenza A(H5N1) virus-infected animals or humans. The investigation into the source of infection for this case is ongoing, and no human-to-human transmission has been identified.

A specimen from the individual was tested at a public health laboratory using the CDC influenza A(H5) assay before being sent to CDC for further testing. The specimen was positive for influenza A(H5) virus using diagnostic RT-PCR at CDC. Additional analysis including genetic sequencing is underway. In response to this detection, additional case investigation and contact monitoring are being conducted by public health officials in California.

There have now been 38 total confirmed human A(H5) cases and one probable human case of A(H5) case in California. This is the second reported pediatric case in California and in the United States.

Notification to WHO of this case was initiated per International Health Regulations (IHR). More information regarding IHR can be found at http://www.who.int/topics/international_health_regulations/en/.

The CSTE position statement, which includes updated case definitions for confirmed, probable, and suspected cases is available at http://www.cste.org/resource/resmgr/position_statements_files_2023/24-ID-09_Novel_Influenza_A.pdf

An up-to-date human case summary during the outbreak by state and exposure source is available at www.cdc.gov/bird-flu/situation-summary/index.html

Information about avian influenza is available at https://www.cdc.gov/flu/avianflu/index.htm.

Interim recommendations for Prevention, Monitoring, and Public Health Investigations are available at https://www.cdc.gov/bird-flu/prevention/hpai-interim-recommendations.html.

The latest case reports on avian influenza outbreaks in wild birds, commercial poultry, backyard or hobbyist flocks, and mammals in the United States are available from the USDA at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/2022-hpai.

(...)

Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/fluview/surveillance/2025-week-02.html

_____

Isoleucine at position 137 of #Hemagglutinin acts as a #Mammalian #adaptation #marker of #H9N2 Avian #influenza virus

Abstract

The H9N2 subtype of avian influenza virus (AIV) is widely distributed among poultry and wild birds and is also a threat to humans. During AIV active surveillance in Liaoning province from 2015 to 2016, we identified ten H9N2 strains exhibiting different lethality to chick embryos. Two representative strains, A/chicken/China/LN07/2016 (CKLN/07) and A/chicken/China/LN17/2016 (CKLN/17), with similar genomic background but different chick embryo lethality, were chosen to evaluate the molecular basis for this difference. A series of reassortants between CKLN/07 and CKLN/17 were generated and their chick embryo lethality was assessed. We found that the isoleucine (I) residue at position 137 (H3 numbering) in the hemagglutinin (HA) was responsible for the chick embryo lethality of the H9N2 virus. Further studies revealed that the threonine (T) to I mutation at HA position 137 enhanced viral replication in vitro and in vivo. Moreover, the HA-T137I substitution in H9N2 avian influenza virus increased the guinea pig transmission efficiency. We also found that the HA-T137I substitution was critical for α2,6-linked sialic acid binding preference and HA activation and stability of H9N2 virus. Our findings demonstrated that HA-137I is a key molecular marker for mammalian adaptation of H9N2 AIV.

Source: Emerging Microbes and Infections, https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2455597

_____

#Antibody responses against #influenza A decline with successive years of annual influenza #vaccination

Abstract

Influenza vaccine effectiveness and immunogenicity can be compromised with repeated vaccination. We assessed immunological markers in a cohort of healthcare workers (HCW) from six public hospitals around Australia during 2020–2021. Sera were collected pre-vaccination and ~14 and ~180 days post-vaccination and assessed in haemagglutination inhibition assay against egg-grown vaccine and equivalent cell-grown viruses. Responses to vaccination were compared by the number of prior vaccinations. Baseline sera were available for 595 HCW in 2020 and 1031 in 2021. 5% had not been vaccinated during five years prior to enrolment and 55% had been vaccinated every year. Post-vaccination titres for all vaccine antigens were lowest among HCW vaccinated in all 5-prior years and highest among HCW with 0 or 1 prior vaccinations, even after adjustment. This was observed for both influenza A subtypes and was dependent on pre-vaccination titre. Expanded cohorts are needed to better understand how this translates to vaccine effectiveness.

Source: npj Vaccines, https://www.nature.com/articles/s41541-024-01057-x

_____

#Mongolia - #Influenza A #H5N1 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification [FINAL]

Active surveillance for avian influenza was conducted in October 2024 at Ganga Lake, located in the eastern region of Mongolia along the East Asian-Australasian Flyway for migratory birds. During the surveillance period, no clinical signs of disease or mortality were observed among wild birds. However, qRT-PCR analysis using H5-specific primers for fecal samples, followed by sequencing, confirmed the detection of the Highly Pathogenic Avian Influenza (HPAI) H5N1 subtype.

Source: WOAH, https://wahis.woah.org/#/in-review/6193

_____

#WHO DG's opening #remarks at the #media #briefing – 16 January 2025 {portion on avian #influenza}

 {Excerpt}

(...)

Now to the global spread of H5 avian influenza.

Last year, 66 cases of H5 were reported from the United States, plus 10 from Cambodia, 2 from Viet Nam and one each from Australia, Canada and China.

This is the highest number of reported human cases since 2015.

So far this year, 2 cases including 1 death have been reported in the United States, and 1 death in Cambodia.

Almost all these cases are associated with infected dairy cattle or poultry.

H5N1 is of particular concern because since the first human cases were reported in 2003, it has killed almost half of those it has struck.

Fortunately, H5N1 has not yet developed the ability to transmit easily between humans. But that could be only a matter of time.

Every transmission from one animal to another, or to a human, is an opportunity for the virus to mutate, or to mix with other influenza viruses.

It’s therefore imperative that the virus is not allowed to spread unchecked in animals.

WHO is working closely with the World Organisation for Animal Health and the Food and Agriculture Organization of the United Nations in a One Health approach to managing the threat of H5 globally.

We call on all countries to strengthen biosecurity on farms, testing and surveillance, and to provide personal protective equipment to farm workers who may be at risk.

We also call on all countries with outbreaks of H5 among animals to share viral samples and sequences with the WHO Global Influenza Surveillance and Response System, or GISRS.

(...)

Source: World Health Organization, https://www.who.int/news-room/speeches/item/who-director-general-s-opening-remarks-at-the-media-briefing---16-january-2025

_____

#Human #Infection with Avian #Influenza A(#H9N2) Virus, #Vietnam, April 2024

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.

Source: Emerging Infectious Diseases Journal, https://wwwnc.cdc.gov/eid/article/31/2/24-1146_article

_____

#US #CDC Health #Alert Network (HAN): Advisory, Accelerated Subtyping of #Influenza A in Hospitalized Patients

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.

(...)

Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/han/2025/han00520.html?ACSTrackingID=USCDC_486-DM142615&ACSTrackingLabel=HAN%20520%20-%20Health%20Advisory%20(for%20COCA%20partners)&deliveryName=USCDC_486-DM142615

_____

Prior #influenza virus #infection alleviates an #arbovirus #encephalitis by reducing viral titer, #inflammation, and cellular infiltrates in the central nervous system

ABSTRACT

Respiratory and encephalitic virus infections represent a significant risk to public health globally. Detailed investigations of immunological responses and disease outcomes during sequential virus infections are rare. Here, we define the impact of influenza virus infection on a subsequent virus encephalitis. We used a model system in which mice were given influenza A virus (IAV) infection 8 days prior to Semliki Forest virus (SFV) infection (IAV→SFV). IAV infection clearly attenuated the subsequent SFV infection with reduced titers of infectious SFV and lower levels of cytokines and chemokines in the central nervous system (CNS). In contrast, the SFV viremia in both IAV→SFV and SFV-only mice was comparable. Increased type I interferon (IFN) levels in the CNS after IAV infection might have contributed to some level of protection towards SFV infection in the CNS, suggesting that early control of SFV replication in the CNS during IAV→SFV infection led to reduced adaptive response, given the lower number of CD8+ T cells recruited to the brain in IAV→SFV infection. In lungs, however, prior IAV infection elicited effector CD8+ T cells with highly activated CD38 and/or CD25 phenotypes, while SFV-only infection elicited distinct effector CD8+ T cells with increased frequencies of KLRG1 expression, a hallmark of short-lived effector T cells. Taken together, our findings demonstrate that prior IAV infection can confer protective immunity toward secondary SFV infection, confirmed by reduced disease severity and inflammatory immune responses in the brain. Our work provides important insights into therapies and vaccine regimens directed against unrelated pathogens.

Source: Journal of Virology, https://journals.asm.org/doi/full/10.1128/jvi.02108-24?af=R

_____

#Neurotropic #Tick-Borne #Flavivirus in Alpine #Chamois (Rupicapra rupicapra rupicapra), #Austria, 2017, #Italy, 2023

Abstract

The European subtype of tick-borne encephalitis virus (TBEV-Eur; species Orthoflavivirus encephalitidis, family Flaviviridae) was the only tick-borne flavivirus present in central Europe known to cause neurologic disease in humans and several animal species. Here, we report a tick-borne flavivirus isolated from Alpine chamois (Rupicapra rupicapra rupicapra) with encephalitis and attached ticks, present over a wide area in the Alps. Cases were detected in 2017 in Salzburg, Austria, and 2023 in Lombardy and Piedmont, Italy. The virus strains exhibit 94.8–97.3% nucleotide identities to each other and are more closely related to Louping ill viruses (LIV; Orthoflavivirus loupingi; 90–92% identities) than to TBEV-Eur (less than 88%). The chamois-derived virus strains, tentatively termed “Alpine chamois encephalitis virus”, form a well-supported independent genetic clade with Spanish goat encephalitis virus, clearly separated from other LIV. This supports its designation as a new virus subtype with the proposed shared taxonomic name “Spanish goat and Alpine chamois encephalitis virus subtype” within the species Orthoflavivirus loupingi. The zoonotic potential of this newly identified virus subtype as well as its host range in other animal species including farm animals needs to be further investigated.

Source: Viruses, https://www.mdpi.com/1999-4915/17/1/122

_____

Immunization with a novel #RNA replicon #vaccine confers long-lasting #protection against #H5N1 avian #influenza virus in 24 #bird species

Abstract

Highly pathogenic avian influenza viruses (HPAIV) of subtype H5N1 (clade 2.3.4.4b) have spread worldwide and caused the death of hundreds of millions of wild birds and domestic poultry. Moreover, spill over of H5N1 HPAIV from infected birds to more than 50 different mammalian species including humans has been recorded. While, licensed vaccines for protection of avian or mammalian species are not yet available, a few candidate vaccines are being trialled. Here, we report on the experimental vaccination of chickens and captive wild birds using a propagation-defective vesicular stomatitis virus (VSV), in which the essential envelope glycoprotein (G) protein gene was replaced by a modified hemagglutinin gene derived from a clade 2.3.4.4b H5N1 isolated in 2022 in the animal park of Bern, Switzerland. VSV∆G(H5mb) was produced on helper cells providing the VSV G protein in trans. Specific pathogen-free (SPF) chickens that were immunized twice via the intramuscular route with adjuvant-free VSV∆G(H5mb) replicon particles induced high levels of virus-neutralizing serum antibodies and were fully protected against lethal infection by H5N1 HPAIV (clade 2.3.4.4b). Notably, immunized animals did not shed challenge virus from the respiratory or gastrointestinal tract, suggesting that herd immunity can be achieved. The same vaccine was used to immunize a total of 317 captive wild birds at Bern Animal Park and Zoo Basel, representing 24 different species. No vaccine-associated side effects were observed. Birds without previous contact to H5Nx viruses produced high to very high H5-specific neutralizing antibody titers following the second immunization, while birds showing H5-specific antibodies prior to vaccination, already developed high neutralizing antibody titers after a single immunization. One year after vaccination, most animals still showed significant neutralizing antibody titers, indicating that VSV∆G(H5mb) is able to induce a long-lasting protective immune response. Our results indicate that VSV∆G(H5mb) is an extraordinary safe and highly efficacious vaccine to stop H5N1 replication in various avian species.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.01.15.633174v1

_____

#PuertoRico - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

Highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b was confirmed on one poultry premises in Culebra Municipality, Puerto Rico. This is the first confirmed case of HPAI in poultry from Puerto Rico. Full genotyping confirms the virus as a reassortant of the A3 genotype with North American wild bird lineage viruses (AM PB2, PA, NP). Comparisons of the virus to other recent detections from wild birds and North America reports are in progress. The USDA Animal and Plant Health Inspection Service (APHIS), in conjunction with State Animal Health and Wildlife Officials, are conducting comprehensive epidemiological investigations and enhanced surveillance in response to the HPAI H5N1 related events.

Source: WOAH, https://wahis.woah.org/#/in-review/6185

_____

#USA, #Hawaii: Dept. of Health Closely Monitoring Detection of #H5 Avian #Influenza in Kauai #Wastewater

{Excerpt}

HONOLULU — The Hawai‘i Department of Health (DOH) State Laboratories Division has detected H5 avian influenza (bird flu) at very low levels in wastewater samples collected at the Līhuʻe Wastewater Treatment Plant on Kauaʻi.

The first detection was from a sample collected on Dec. 11, 2024, that was so low that it was not considered a positive result. 

Samples collected on Dec. 18, 2024 and Jan. 8, 2025 had similar detections. 

While none is considered a positive result, the consistent very low-level detections indicate a high likelihood that H5 bird flu virus is on Kauaʻi. 

No H5 virus infections of birds, dairy cows, or humans have been detected on Kauaʻi to date. 

Detection of infected birds in the state has so far been limited to Oʻahu.

The H5 bird flu viruses include the H5N1 subtype of bird flu virus that has spread globally in birds since its initial discovery in 1996 and recently has been detected in several mammal species including dairy cows. Wastewater testing cannot determine if the detection is specifically this H5N1 subtype of bird flu virus.

The presence of the H5N1 bird flu virus in Hawaiʻi was first confirmed in November 2024 in a backyard flock of birds in Central Oʻahu. That virus strain was a different genotype of the virus that has infected birds and dairy cows on the U.S. mainland. H5 was subsequently detected at the Hilo Wastewater Treatment Plant on Hawaiʻi Island.

While the risk to the public remains low, bird flu can cause severe illness with a high mortality rate among certain bird populations such as poultry. Commercial poultry producers and residents with backyard flocks are strongly advised to increase biosecurity measures to reduce the likelihood of infection. Bird flu can also infect dairy cows. While pasteurized milk is safe, raw milk should be avoided.

The Hawaiʻi Department of Agriculture (HDOA) recommends the following for residents that need to remove a dead wild bird from their property:

-- Wear disposable gloves or turn a plastic bag inside out and use it to pick up the carcass.

-- Double-bag the carcass and throw it out with the regular trash.

-- Wash your hands and disinfect your clothing and shoes after handling a dead wild bird.

-- Be mindful of any health symptoms that may develop afterward.

To report multiple or unusual illnesses in poultry, livestock, or other wild birds or animals from any island in the state, contact HDOA Animal Industry Division at 808-483-7100 or, email: hdoa.ldc@hawaii.gov, Monday to Friday from 7:45 a.m. to 4:30 p.m., or 808-837-8092 during non-business hours and holidays.

Residents who believe they may have been exposed to sick birds or other wildlife should contact the Disease Outbreak Control Division Disease Reporting Line at 808-586-4586 for additional guidance.

(...)

Source: Department of Health, https://health.hawaii.gov/news/newsroom/doh-closely-monitoring-detection-of-h5-avian-flu-in-kaua%ca%bbi-wastewater/

_____

#USA, #California: Current #H5N1 #Influenza in #Human #Situation as of January 15 '25: One new case, total = 38

Current Bird Flu Situation

Updated January 15, 2025​

-- ​​​​The current risk to the public remains low.  ​​

-- No person-to-person spread of bird flu has been detected in California. 

-- People rarely get bird flu, but those who interact​ with infected dairy cows, poultry, or wildlife ​have a greater risk of infection.​​

-- Pasteurized milk and dairy products are safe to consume. Pasteurization inactivates the bird flu virus.​​

-- CDPH is working to protect public health related to bird flu. We monitor infection data, evolving science, and the people affected. Our knowledge will change as we learn more. We are committed to reducing the impact to those at highest risk.

Human Cases in Califo​rnia​

-- ​​​​​​​Confirmed Human Cases​:  38 {+1}

​These numbers were last updated on January 15, 2025.

California has 1 additional probable case with dairy cow exposure that meets the  Council of State and Territorial Epidemiologists (CSTE) ​probable case definition (PDF)​. That case tested positive by a local lab and confirmatory testing at CDC was negative.​​

Confirmed human case summary during the 2024 outbreak, by exposure source.

​-- Cattle​​​​: ​36

-- ​Poultry: ​0

-- ​Unkn​own: ​2

--- ​Total: ​38

(...)

Source: Department of Health, https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Bird-Flu.aspx

_____

#USA, US #CDC: #H5 #Birdflu #Response: Focus Areas for Ongoing Public Health #Risk #Assessment

{Edited}

Current H5N1 bird flu risk

People who are at increased risk include:

-- Farmers and workers who work with infected animals or their byproducts

-- Backyard bird flock owners

-- Animal care workers (e.g., veterinarians, wild animal facility workers)

-- Animal health and public health responders.

But what factors would influence a change to CDC’s current risk assessment for the general public? What follows is a description of the epidemiological and virologic characteristics of the avian influenza situation that CDC scientists are tracking to formulate the agency’s immediate avian flu risk assessment and further calibrating the avian flu response to protect the public’s health:

-- Virus transmission: How is virus spreading and how efficiently does it spread?

-- Disease severity: How ill do people with H5N1 bird flu infections become?

-- Case distribution: How widespread are cases?

-- Effects of genetic changes in the virus: What is the impact of genetic changes to the virus on infectivity or transmissibility, the accuracy of diagnostic tests, and effectiveness of antiviral drugs and vaccines?

Virus transmission

What is CDC on the lookout for? 

Sustained human-to-human transmission outside of a household increases the likelihood of significant public health impact.

Influenza A(H5N1) has been spreading in wild birds globally since the mid-1990s and in the United States since 2014. The virus initially spread to commercial and backyard poultry and has also infected mammals, including minks, sea lions and now dairy cattle. 

There have been sporadic human cases both in the United States and in other countries, and limited human-to-human transmission of avian influenza has been occasionally reported globally. 

To date, there is no evidence of human-to-human transmission associated with the current avian influenza situation in the United States. 

Transmission identified outside of a household would be of greater concern than within a household when assessing immediate public health risk.

Beyond looking out for human-to-human transmission through case investigation, CDC continues to rapidly analyze and share genetic sequences of samples from human cases and, alongside information gained from viral samples from infected animals, is monitoring for changes that would allow the virus to spread more easily—particularly to humans and other mammals.

Disease severity

What is CDC on the lookout for? 

CDC is concerned about all people who become infected with avian flu and is particularly concerned if we begin seeing people who quickly become severely ill and require hospitalization or who die of the infection. 

Severe disease may indicate the virus has changed and is now better able to make people severely ill. 

This degree of severity could have a greater public health impact, straining the healthcare system and may have other societal and economic impacts (e.g., if people cannot work).

Most cases of H5N1 bird flu associated with the ongoing outbreak in the United States have resulted in mild symptoms. 

CDC experts and other scientists continue to work to understand why some infections, including an infection reported in Canada and one reported in Louisiana, resulted in serious illness. 

Severity of illness can be impacted by a number of factors, including acquired genetic changes of the virus, the amount of virus to which the infected people were exposed, the route of transmission, underlying health conditions, how long the person was sick and the timeliness of medical care/treatment, or some combination of all these factors.

Case distribution

What is CDC on the lookout for? 

Indication that that virus may have broad dissemination among humans within specific populations or to the general population, or increasing numbers of people who are becoming infected without clear exposure to infected animals.

Human cases associated with the ongoing outbreak have been sporadic, and nearly all have followed identifiable exposures to dairy cows, poultry, and/or other animals.

Broad dissemination of cases would be evident if all of the following were to occur:

-- Numerous sporadic (i.e., occurring at irregular intervals or infrequently as isolated events) human cases unrelated to expected shared/common animal exposures

-- Cases occurring in multiple geographic locations

-- Cases occurring close together in time

Effects of genetic changes in the virus

What is CDC on the lookout for? 

Genetic changes known to be associated with increased severity or transmissibility or other viral changes seen at the same time as increased transmissibility and increasing severity of infection.

CDC conducts routine assessment of the sequences of the viruses from humans and animals for changes that might impact infectivity or transmissibility in humans, the accuracy of diagnostic tests and the effectiveness of vaccines or antivirals. 

To date, genetic analysis has not identified changes in viruses compared to available clade 2.3.4.4b candidate vaccine viruses (CVVs) that would be predicted to impact cross-protection if A(H5) vaccines were needed for use in humans. 

Nor have changes been identified in the receptor binding domain of viruses except for low frequency changes in the fatal case from Louisiana and the severe case from Canada. 

These changes were believed to have occurred after the individuals were infected rather than acquired from their infecting exposure. 

There is no evidence that viruses with these changes spread beyond these patients.

Collectively, these data indicate that A(H5N1) viruses circulating in animals retain avian receptor binding properties with no significant changes that would impact infectivity or transmissibility in humans. 

Additionally, there have been only a few sporadic changes identified in viruses detected in animals or humans associated with mammalian adaptation or slightly reduced susceptibility to commercially available antiviral drugs. 

Finally, no changes have been identified in viruses that impact the performance of H5 influenza diagnostic tests that are used for testing across all U.S. states and at CDC.

These factors are all important considerations that inform what public health actions should be implemented in the H5 avian flu public health response. 

Should we see concerning changes in these factors, additional actions may be necessary to protect the health and safety of people with potential animal exposures as well as the general public. 

Additional actions may include but are not limited to:

-- Updating guidance to better protect those who may be exposed to H5 avian flu, such as who should receive pre- or post-exposure prophylaxis, testing strategy, and how to best use personal protective equipment.

-- Procuring additional treatments and vaccines, to ensure we have sufficient supply for those who would benefit from their use.

-- Initiating a voluntary H5 vaccination program focused on people with predictable exposure to the virus.

-- Initiating a broader voluntary H5 vaccination program if the possibility of widespread transmission or increasing disease severity is found.

Such escalation will likely require additional resources.

(...)

Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/bird-flu/spotlights/h5n1-response-01142025.html

_____

#USA, Confirmed #H5N1 #influenza #human case summary since 2024, by state and exposure source: 1 new case in CA, total now = 67

{Excerpt}

Exposure Source

[State - Exposure Associated with Commercial Agriculture and Related Operations: Dairy Herds (Cattle) - Poultry Farms and Culling Operations -- Other Animal Exposure† - Exposure Source Unknown‡ - State Total]

1) California - 36 - 0 - 0 - 2 - 38 {+1}

2) Colorado - 1 - 9 - 0 - 0 - 10

3) Iowa - 0 - 1 - 0 - 0 - 1

4) Louisiana - 0 - 0 - 1 - 0 - 1

5) Michigan - 2 - 0 - 0 - 0 - 2

6) Missouri - 0 - 0 - 0 - 1 - 1

7) Oregon - 0 - 1 - 0 - 0 - 1

8) Texas - 1  - 0 - 0 - 0 - 1

9) Washington - 0 - 11 - 0 - 0 - 11

10) Wisconsin - 0 - 1 - 0 - 0 - 1

-- Source Total - 40 - 23 - 1 - 3 - 67 {+1}

NOTE: One additional case was previously detected in a poultry worker in Colorado in 2022. Louisiana reported the first H5 bird flu death in the U.S.

{†} Exposure was related to other animals such as backyard flocks, wild birds, or other mammals

{‡} Exposure source was not able to be identified

Probable human case summary during the 2024 outbreak, by state and exposure source

When a case tests positive for H5 at a public health laboratory but testing at CDC is not able to confirm H5 infection, per Council of State and Territorial Epidemiologists (CSTE) guidance, a case is reported as probable.

-- Probable cases with commercial poultry exposure (e.g., poultry farms or culling operations):

1) Washington (3)

2) Arizona (2)

Probable cases with commercial dairy (cattle) exposure:

1) California (1)

Probable cases with exposure source unknown:

1) Delaware (1)

Confirmed and probable cases are typically updated by 5 PM EST on Mondays (for cases confirmed by CDC on Friday, Saturday, or Sunday), Wednesdays (for cases confirmed by CDC on Monday or Tuesday), and Fridays (for cases confirmed by CDC on Wednesday and Thursday). Affected states may report cases more frequently.

(...)

Source: US Centers for Disease Control and Prevention, https://www.cdc.gov/bird-flu/situation-summary/?CDC_AAref_Val=https://www.cdc.gov/flu/avianflu/avian-flu-summary.htm

_____

#Pathogenesis of #bovine #H5N1 clade 2.3.4.4b #infection in #Macaques

Abstract

Since early 2022 highly pathogenic avian influenza (HPAI) H5N1 virus infections have been reported in wild aquatic birds and poultry throughout the United States (US) with spillover into several mammalian species1-6. In March 2024, HPAIV H5N1 clade 2.3.4.4b was first detected in dairy cows in Texas, US and continues to circulate on dairy farms in multiple states7,8. Milk production and quality are diminished in infected dairy cows, with high virus titers in milk raising concerns of exposure to mammals including humans through consumption9-12. Here we investigated routes of infection with bovine HPAIV H5N1 clade 2.3.4.4b in cynomolgus macaques, a surrogate model for human infection13. We show that intranasal or intratracheal inoculation of macaques could cause systemic infection resulting in mild and severe respiratory disease, respectively. In contrast, infection by the orogastric route resulted in limited infection and seroconversion of macaques which remained subclinical.

Source: Nature, https://www.nature.com/articles/s41586-025-08609-8

_____

Clinical #Features of #Human #Parvovirus B19-Associated #Encephalitis Identified in the #Dakar Region, #Senegal, and Viral Genome Characterization

Abstract

Neurological manifestations associated with human parvovirus B19 (B19V) infections are rare and varied. Acute encephalitis and encephalopathy are the most common, accounting for 38.8% of all neurological manifestations associated with human B19V. Herein, we report on the clinical features of 13 laboratory-confirmed human cases of B19V-associated encephalitis in Senegal in the framework of a hospital-based surveillance of acute viral encephalitis conducted from 2021 to 2023. Overall, B19V was detected from 13 cerebrospinal fluid samples using specific real time PCR. The mean age was 16.7 years among B19V-positive patients, with a higher prevalence in 0–5-year-old children and the sex ratio (male/female) was 2.25. The B19V-positive patients mainly exhibited hypoleukocytosis, normal glycorrhachia, and normal proteinorrachia in the cerebrospinal fluid. While the main neurological symptoms included meningeal and infectious syndromes. Furthermore, three complete B19V genome sequences were successfully characterized using next-generation sequencing. The newly characterized sequences belonged to the genotype 1a and represent, to date, the first complete B19V genome sequences from Senegal. These sequences could be useful not only in future phylodynamic studies of B19V but also in the development of prevention or treatment countermeasures. Our study is noteworthy for the identification of acute B19V-associated encephalitis in Senegal More investigations on the risk factors associated with B19V transmission in Africa are warranted.

Source: Viruses, https://www.mdpi.com/1999-4915/17/1/111

_____

#Germany - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

 A fattening turkeys farm in Baden-Württemberg Region.

Source: WOAH, https://wahis.woah.org/#/in-review/6188

_____

Clade 2.3.4.4b but not historical clade 1 #HA replicating #RNA #vaccine protects against #bovine #H5N1 challenge in #mice

Abstract

The ongoing circulation of influenza A H5N1 in the United States has raised concerns of a pandemic caused by highly pathogenic avian influenza. Although the United States has stockpiled and is prepared to produce millions of vaccine doses to address an H5N1 pandemic, currently circulating H5N1 viruses contain multiple mutations within the immunodominant head domain of hemagglutinin (HA) compared to the antigens used in stockpiled vaccines. It is unclear if these stockpiled vaccines will need to be updated to match the contemporary H5N1 strains. Here we show that a replicating RNA vaccine expressing the HA of an H5N1 isolated from a US dairy cow confers complete protection against homologous lethal challenge in mice. A repRNA encoding the HA of a clade 1 H5 from 2004 (A/Vietnam/1203/2004) as utilized by some stockpiled vaccines, confers only partial protection. Our data highlight the utility of nucleic acid vaccines to be rapidly updated to match emergent viruses of concern while demonstrating that contemporary bovine H5N1 viruses can evade immunity elicited by historical HA antigens.

Source: Nature Communication, https://www.nature.com/articles/s41467-024-55546-7

_____