#USA, #Wastewater Data for Avian #Influenza #H5 (US CDC, Oct. 9 '26)

 

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A(H5) detections in the past week

Time Period: September 27, 2026 - October 03, 2026

    -- A(H5) Detection: 8 site(s) (1.9%)

    -- No Detection: 416 site(s) (98.1%)

    -- No samples: 195 site(s)

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Source: 

Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?

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#USA, #Wastewater Data for Avian #Influenza #H5 (US CDC, Oct. 2 '26)

 

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Notice

    CDC competitively awarded a new wastewater testing contract to Verily Health, Inc. (Verily) on September 28, 2026. There will be a brief gap in wastewater data affecting ~200 sites as sampling, testing, and reporting are restarted.

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A(H5) detections in the past week

Time Period: September 20, 2026 - September 26, 2026

    -- A(H5) Detection: 7 site(s) (1.9%)

    -- No Detection: 363 site(s) (98.1%)

    -- No samples: 239 site(s)

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Source: 

Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?

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Notes from the Field: #Fatal Pneumonic #Plague — Coconino County, #Arizona, July 2025

 

Summary

    ° What is already known about this topic?

        § Pneumonic plague is a rare and often fatal disease that can be transmitted by respiratory droplets from animals or persons infected with Yersinia pestis bacteria.

    ° What is added by this report?

        § In July 2025, Arizona reported its first pneumonic plague death since 2007, in a man with occupational exposure to ill cats. Two days after the patient’s death, preliminary diagnostic test results supported a suspected pneumonic plague diagnosis, prompting immediate identification of potentially exposed persons for postexposure prophylaxis.

    ° What are the implications for public health practice?

        § In areas with endemic plague, preliminary diagnostic test results combined with clinical suspicion for pneumonic plague can result in timely public health interventions.

Abstract

Pneumonic plague is transmitted through inhalation of respiratory droplets containing the bacterium Yersinia pestis and has a nearly 100% case-fatality rate when untreated. Although Y. pestis is endemic among rodents in northern Arizona, only eight human plague cases were reported in Arizona during 2000–2024. In July 2025, Arizona reported its first pneumonic plague death since 2007.

Source: 

Link: http://dx.doi.org/10.15585/mmwr.mm7538a2

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#Estimation of the #transmission #dynamics of #H5N1 HPAI #outbreak in a dairy #herd using a modeling approach

 

Abstract

The emergence of Highly Pathogenic Avian Influenza (HPAI 2.3.4.4b) in dairy herds in 2024 across 19 states in the United States of America has raised concerns regarding the potential national and global zoonotic impact. All recent modeling efforts implemented homogenous cattle-to-cattle (both intra and inter-herd) transmission models which did not capture the real-world heterogeneity in mixing of animals, individual variations in susceptibility and infectiousness and clinical incidences across pens and lactation groups. The aim of this study was to develop a heterogenous transmission model to estimate the epidemiological parameters for intra-herd HPAI transmission on Californian dairies. We developed a validated stochastic agent-based model to estimate the epidemiological parameters for intra-herd HPAI transmission on California dairies. The hierarchical agent-based model also parameterized stochastic cattle movements within-herd to simulate real dairy management practices. A cow-level SEIR transmission approach was assumed during the outbreak. A novel Bayesian Optimizer with Gaussian Process (BO-GP) was fitted to the agent-based model for validation which converged within 25-40 iterations (out of 100 per farm) with minimal loss over two distinct error metrics, namely, Poisson loss function and temporal distance metric. Our optimized simulations estimated an average R0 was around 10.7-10.8 across all farms within the first 15 days of observed outbreak on four dairy farms with a mean effective transmission rate of 4.5% per contact between susceptible and infectious cows within each pen. Our model demonstrated that the movement of cows between pens ensured localized clusters of outbreaks within the sub-herds (pen population) that prolonged the overall outbreak within farms. We estimated the total duration of infection between 14.5 and 28 days, which is higher than the estimates from the homogenous models. With an integrated hierarchical agent-based model combined with Bayesian approximation, we produced actionable insights on the epidemiology of intra-farm spread of HPAI within cow herds, thereby guiding both future model development and applied disease control strategy.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Animal and Plant Health Inspection Service (USDA-APHIS), AP25VSD&B000C007

Source: 

Link: https://doi.org/10.64898/2026.09.22.753543

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Detection of Highly Pathogenic Avian #Influenza #H5N1 Virus in #Cat and #Rats during #Outbreak in Backyard #Poultry, #USA, 2025

 

Abstract

In 2025, highly pathogenic avian influenza A(H5N1) virus was detected in a poultry flock in Illinois, USA. Quantitative reverse transcription PCR, sequencing, and histopathology on cat and rat samples from the farm showed multiple positive tissues and high sequence identity to an avian isolate. Small mammals might contribute to H5N1 transmission.

Source: 

Link: https://doi.org/10.3201/eid3210.260418

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#USA, #Wastewater Data for Avian #Influenza #H5 (US CDC, September 18 '26)

 

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A(H5) detections in the past week

Time Period: September 06, 2026 - September 12, 2026

    ° A(H5) Detection:  2 site(s) (0.5%)

    ° No Detection: 415 site(s) (99.5%)

    ° No samples: 131 site(s)

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Source: 

Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?

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#Influenza at #human - #animal #interface - #Summary & #risk assessment, 8 Aug. - 6 Sept. '26 (WHO): 1 #H5N1 case in #Bangladesh, 3 #H9N2 cases in #China, 2 #H1N2v cases in #US

 

Influenza at the human-animal interface Summary and risk assessment, from 8 August to 6 September 2026 {1}

    • New human cases {2}: 

        ° From 8 August to 6 September 2026, based on reporting date,  detections of influenza A(H5N1) in one human and influenza A(H9N2) in  three humans were officially reported. Additionally, two human cases of infection with influenza A(H1N2) variant (A(H1N2)v) viruses were detected.

    • Circulation of influenza viruses with zoonotic potential in animals: 

        ° High pathogenicity avian influenza (HPAI) events in poultry and  non-poultry animal species continue to be reported to the World Organisation for  Animal Health (WOAH).{3} The Food and Agriculture Organization of the United  Nations (FAO) also provides a global update on avian influenza viruses with  pandemic potential.{4} Additionally, low pathogenicity avian influenza viruses as  well as swine influenza viruses continue to circulate in animal populations.

    • Risk assessment {5}: 

        ° There have been no reports of sustained human-to-human transmission associated with the above-mentioned human infection events.  Based on information available at the time of this update, the overall public health  risk from currently known influenza A viruses detected at the  human-animal interface has not changed and, at present, these viruses are  not thought to be capable of sustained human-to-human transmission, although  this could change as they evolve. Whilst human infections with viruses of animal  origin are infrequent, they are not unexpected at the human-animal interface.

    • IHR compliance {6}: 

        ° This includes any influenza A virus that has demonstrated the  capacity to infect a human, and its haemagglutinin (HA) gene (or protein) is not a  mutated form of those, i.e. A(H1) or A(H3), circulating widely in the human  population. Information from these notifications is critical to inform risk  assessments for influenza at the human-animal interface.

Avian influenza viruses in humans

A(H5N1), Bangladesh

    On 30 August, Bangladesh, through the national IHR focal point, notified WHO of one laboratory-confirmed human infection with an A(H5) virus in a  child from Rangpur division. 

    On 15 August 2026, the child developed a fever, cough and rhinitis and was  admitted to hospital on 17 August. 

    On 18 August, a nasopharyngeal swab and throat swab was collected as  part of hospital-based influenza surveillance and tested positive for influenza A(H5) by real-time RT-PCR at the icddr,b laboratory on the same day. 

    The sample was subsequently confirmed positive for influenza A(H5N1)  at the Molecular and Genomic Laboratory Department of Institute of Epidemiology,  Disease Control and Research (IEDCR) and National Influenza  Centre (NIC) of Bangladesh. 

    Genetic sequencing is underway. 

    The child remained hospitalized and was improving clinically at the time  of reporting.

    There was no reported history of travel outside the area of residence. The  child had a history of exposure to duck and chickens, including some that  were sick, in the household and adjacent households. 

    Poultry meat and oropharyngeal swab specimens collected from several  backyard chickens on 26 August tested negative for influenza A(H5).

    Close contacts were identified and placed under monitoring and all  contacts remained asymptomatic during the observation period, except for two heath care workers. 

    Respiratory specimens collected from these two individuals tested negative for influenza A viruses.

    This is the 4th laboratory-confirmed human case of avian influenza A(H5)  reported in Bangladesh in 2026.

    According to reports received by WOAH, various influenza A(H5) subtypes  continue to be detected in wild and domestic birds in Africa, the Americas, Asia,  Europe and Oceania. Infections in non-human mammals are also reported,  including in marine and land mammals.{7} A list of bird and mammalian species  affected by HPAI A(H5) viruses is maintained by FAO.{8}

Risk assessment for avian influenza A(H5N1) viruses:

    1. What is the current global public health risk of additional human cases of  infection with avian influenza A(H5N1) viruses?

        ° Most human infections so far have been reported in people exposed  to A(H5N1) viruses, for example, through contact with infected poultry or  contaminated environments, including live poultry markets, and occasionally  infected mammals and contaminated environments. As long as the viruses  continue to be detected in animals and related environments humans are exposed  to, further human cases associated with such exposures are expected  but remain unusual. The impact for public health if additional sporadic cases are detected is minimal. The current overall global public health risk is low.

    2. What is the likelihood of sustained human-to-human transmission of avian  influenza A(H5N1) viruses related to the events above?

        ° No sustained human-to-human transmission has been identified  associated with the recent reported human infections with avian  influenza A(H5N1) viruses. There has been no reported human-to-human transmission of A(H5N1) viruses since 2007, although there may be gaps in  investigations. In 2007 and the years prior, small clusters of A(H5N1) virus  infections in humans were reported, including some involving health care workers,  where limited human-to-human transmission could not be excluded;  however, sustained human-to-human transmission was not reported.  Current evidence suggests that influenza A(H5N1) viruses related to these events did not acquire the ability to efficiently transmit between people.

      3. What is the likelihood of international spread of avian influenza A(H5N1) viruses by travellers?

        ° Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel  or after arrival. If this were to occur, further community- level spread is  considered unlikely as current evidence suggests these viruses have  not acquired the ability to transmit easily among humans.  

A(H9N2), China

    Between 13 August and 1 September 2026, China notified WHO of three laboratory-confirmed human cases of A(H9N2) virus infection. 

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    All cases had direct or indirect exposure to poultry and/or local live bird  markets. Samples from environments associated with the likely area of exposure  of some of the cases tested positive for A(H9) viruses. 

    No further cases were detected among contacts of these cases.

Risk assessment for avian influenza A(H9N2):

    1. What is the global public health risk of additional human cases of infection  with avian influenza A(H9N2) viruses?

        ° Most human cases follow exposure to the A(H9N2) virus through  contact with infected poultry or contaminated environments. Most human  infections of A(H9N2) to date have resulted in mild clinical illness. Since the  virus is endemic in poultry in multiple countries in Africa and Asia, additional human cases associated with exposure to infected poultry or  contaminated environments are expected but remain unusual. The impact to  public health if additional sporadic cases are detected is minimal. The  overall global public health risk is low.

    2. What is the likelihood of sustained human-to-human transmission of avian  influenza A(H9N2) viruses related to these events?

        ° At the present time, no sustained human-to-human transmission  has been identified associated with the recently reported human  infections with A(H9N2) viruses. Current evidence suggests that A(H9N2) viruses  from these cases did not acquire the ability of sustained transmission among humans.

    3. What is the likelihood of international spread of avian influenza A(H9N2)  virus by travellers?

        ° Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel  or after arrival. If this were to occur, further community level spread is considered  unlikely as current evidence suggests the A(H9N2) virus subtype has not acquired the ability to transmit easily among humans.

Swine influenza viruses in humans

Influenza A(H1N2)v, United States of America

    Since the risk assessment of 8 August 2026, two human infections with influenza A(H1N2v) viruses were detected in the state of Michigan.{7} 

    The patients, both <18 years of age, developed illness in the week of 15  August. They were not hospitalized and have recovered. Both attended the same agricultural fair where sick swine were present. The cases did not have  contact with each other and  no additional human infections with A(H1N2)v  viruses have been detected around this event. 

    Including these two cases, there have been a total of three human  infections with variant influenza A viruses reported in the United States in 2026.

Risk Assessment:

    1. What is the public health risk of additional human cases of infection with  swine influenza viruses?

        ° Swine influenza viruses circulate in swine populations in many  regions of the world. Depending on geographic location, the genetic characteristics  of these viruses differ. Most human cases are exposed to swine  influenza viruses through contact with infected animals or contaminated environments. Human infection tends to result in mild clinical illness  in most cases. Since these viruses continue to be detected in swine  populations, further human cases are expected but remain unusual. The impact  for public health if additional cases are detected is minimal. The overall risk of additional human cases is low.

    2. What is the likelihood of sustained human-to-human transmission of swine influenza viruses? 

        ° No sustained human-to-human transmission was identified  associated with the event described above. Current evidence suggests  that contemporary swine influenza viruses have not acquired the ability  of sustained transmission among humans, therefore sustained human-to-human  transmission is thus currently considered unlikely.

    3. What is the likelihood of international spread of swine influenza viruses by travelers? 

        ° Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel  or after arrival. If this were to occur, further community level spread is considered  unlikely as current evidence suggest that these viruses have not acquired the ability to transmit easily among humans.

Overall risk management recommendations:

Surveillance and investigations

    • Due to the constantly evolving nature of influenza viruses, WHO  continues to stress the importance of global strategic surveillance in animals and  humans to detect virologic, epidemiologic and clinical changes associated with  circulating influenza viruses that may affect human (or animal) health. Continued  vigilance is needed within affected and neighbouring areas to detect infections in  animals and humans. Close collaboration with the animal health and environment  sectors is essential to understand the extent of the risk of human exposure and to prevent and control the spread of animal influenza. WHO has published  guidance on surveillance for human infections with avian influenza A(H5) viruses.

    • Epidemiologic and virologic surveillance and the follow-up of suspected  human cases should continue systematically. Guidance on investigation of non- seasonal influenza and other emerging acute respiratory diseases has been  published on the WHO website.

    • Countries should increase avian influenza surveillance in domestic  and wild birds, enhance surveillance for early detection in cattle  populations in countries where HPAI is known to be circulating, include HPAI as a  differential diagnosis in non-avian species, including cattle and other livestock  populations, with high risk of exposure to HPAI viruses; monitor and investigate cases in non-avian species, including livestock, report cases of HPAI in  all animal species, including unusual hosts, to WOAH and other international  organizations, share genetic sequences of avian influenza viruses in publicly  available databases, implement preventive and early response measures to break  the HPAI transmission cycle among animals through movement restrictions of  infected livestock holdings and strict biosecurity measures in all holdings, employ  good production and hygiene practices when handing animal products, and protect  persons in contact with suspected/infected animals.{8} More  guidance can be found from WOAH and FAO.

    • When there has been human exposure to a known outbreak of an  influenza A virus in domestic poultry, wild birds or other animals – or when there  has been an identified human case of infection with such a virus – enhanced  surveillance in potentially exposed human populations becomes necessary.  Enhanced surveillance should consider the health care seeking behaviour of the  population, and could include a range of active and passive health care and/or  communitybased approaches, including: enhanced surveillance in local influenza- like illness (ILI)/SARI systems, active screening in hospitals and of groups that  may be at higher occupational risk of exposure, and inclusion of other sources  such as traditional healers, private practitioners and private diagnostic laboratories.

    • Vigilance for the emergence of novel influenza viruses with pandemic  potential must be maintained at all times, including during a non-influenza  emergency. To maximize the value of influenza surveillance platform for other  respiratory threats, WHO has updated and published practical guidance for integrated surveillance.

Notifying WHO

    • All human infections caused by a new subtype of influenza virus are  notifiable under the International Health Regulations (IHR, 2005).{9,10} State  Parties to the IHR (2005) are required to immediately notify WHO of any  laboratory-confirmed {11} case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic {12}. Evidence of illness  is not required for this report. Evidence of illness is not required for this report.

    • WHO published the case definition for human infections with avian  influenza A(H5) virus requiring notification under IHR (2005):  https://www.who.int/teams/global-influenzaprogramme/avian-influenza/case-definitions.

Virus sharing and risk assessment

    • It is critical that these influenza viruses from animals or from humans are  fully characterized in appropriate animal or human health influenza reference  laboratories. Under WHO’s Pandemic Influenza Preparedness (PIP) Framework,  Member States are expected to share influenza viruses with pandemic potential on a timely basis {13} with a WHO Collaborating Centre for influenza of GISRS. The  viruses are used by the public health laboratories to assess the risk of pandemic influenza and to develop candidate vaccine viruses.

    • The Tool for Influenza Pandemic Risk Assessment (TIPRA) provides an  in-depth assessment of risk associated with some zoonotic influenza viruses –  notably the likelihood of the virus gaining human-to-human transmissibility, and  the impact should the virus gain such transmissibility. TIPRA maps relative risk  amongst viruses assessed using multiple risk elements. The results of  TIPRA  complement those of the risk assessment provided here, and those of prior TIPRA  risk assessments are published at http://www.who.int/teams/global-influenza-programme/avianinfluenza/tool-for-influenza-pandemic-risk-assessment-(tipra).

Risk reduction

    • Given the observed extent and frequency of avian influenza in poultry, wild birds and some wild and domestic mammals, the public should  avoid contact with animals that are sick or dead from unknown causes, including  wild animals, and should report dead birds and mammals or request their removal by contacting local wildlife or veterinary authorities.

    • Eggs, poultry meat and other poultry food products should be properly  cooked and properly handled during food preparation. Due to the potential health  risks to consumers, raw milk should be avoided. WHO advises consuming  pasteurized milk. If pasteurized milk isn’t available, heating raw milk until it boils makes it safer for consumption.

    • WHO has published practical interim guidance to reduce the risk of  infection in people exposed to avian influenza viruses.

Trade and travellers

    • WHO advises that travellers to countries with known outbreaks of  animal influenza should avoid farms, contact with animals in live animal markets,  entering areas where animals may be slaughtered, or contact with any surfaces  that appear to be contaminated with animal excreta. Travelers should also wash  their hands often with soap and water. All individuals should follow good food safety and hygiene practices.

    • WHO does not advise special traveller screening at points of entry or  restrictions with regards to the current situation of influenza viruses at the  human-animal interface. For recommendations on safe trade in animals and  related products from countries affected by these influenza viruses, refer to WOAH guidance.

Links:

    ° WHO Human-Animal Interface web page https://www.who.int/teams/global-influenza-programme/avian-influenza

    ° WHO Influenza (Avian and other zoonotic) fact sheet https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)

    ° WHO Protocol to investigate non-seasonal influenza and other emerging acute respiratory diseases https://www.who.int/publications/i/item/WHO-WHE-IHM-GIP-2018.2

    ° WHO Public health resource pack for countries experiencing outbreaks of  influenza in animals: https://www.who.int/publications/i/item/9789240076884

    ° Cumulative Number of Confirmed Human Cases of Avian Influenza A(H5N1) Reported to WHO https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-a-h5n1-virus

    ° Avian Influenza A(H7N9) Information https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-influenza-a-(h7n9)-virus

    ° World Organisation of Animal Health (WOAH) web page: Avian Influenza https://www.woah.org/en/home/

    ° Food and Agriculture Organization of the United Nations (FAO) webpage:  Avian Influenza https://www.fao.org/animal-health/avian-flu-qa/en/

    ° WOAH/FAO Network of Expertise on Animal Influenza (OFFLU) http://www.offlu.org/

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{1} This summary and assessment covers information confirmed during this  period and may include information received outside of this period.

{2} For epidemiological and virological features of human infections with animal  influenza viruses not reported in this assessment, see the reports on human cases  of influenza at the human-animal interface published in the Weekly Epidemiological Record here.

{3} Avian influenza. Global situation. World Organisation for Animal Health  (WOAH) (https://www.woah.org/en/disease/avian-influenza/#ui-id-2).

{4} Global Avian Influenza Viruses with Zoonotic Potential situation update. Food  and Agriculture Organization of the United Nations (FAO)  (https://www.fao.org/animal-health/situation-updates/global-aiv-with-zoonoticpotential).

{5} Rapid risk assessment of acute public health events. World Health  Organization; 2012 (https://iris.who.int/handle/10665/70810).

{6} Case definitions for the four diseases requiring notification in all  circumstances under the International Health Regulations (2005). World Health Organization; 2009 (https://www.who.int/publications/m/item/casedefinitions-for-the-four-diseases-requiring-notification-to-who-in-all-circumstances-under-the-ihr-(2005)).

{7} Weekly US Influenza Surveillance Report: Key Updates for Week 32, ending  August 15, 2026. US Centers for Disease Control and Prevention; 2026  (https://www.cdc.gov/fluview/surveillance/2026-week-32.html).

{8} World Organisation for Animal Health. Statement on High Pathogenicity Avian  Influenza in Cattle, 6 December 2024 (https://www.woah.org/en/high-pathogenicity-avian-influenza-hpai-in-cattle/).

{9} World Health Organization. International Health Regulations (2005), as  amended through resolutions WHA67.13 (2014), WHA75.12 (2022), and  WHA77.17 (2024) (https://apps.who.int/gb/bd/pdf_files/IHR_2014-2022-2024-en.pdf).

{10} World Health Organization. Case definitions for the four diseases requiring  notification in all circumstances under the International Health Regulations (2005)  (https://www.who.int/publications/m/item/casedefinitions-for-the-four-diseases-requiring-notification-to-who-in-all-circumstances-under-the-ihr-(2005)).

{11} World Health Organization. Manual for the laboratory diagnosis and  virological surveillance of influenza (2011) (https://apps.who.int/iris/handle/10665/44518).

{12} World Health Organization. Pandemic influenza preparedness framework for  the sharing of influenza viruses and access to vaccines and other benefits, 2nd  edition (https://iris.who.int/handle/10665/341850).

{13} World Health Organization. Operational guidance on sharing influenza  viruses with human pandemic potential (IVPP) under the Pandemic Influenza  Preparedness (PIP) Framework (2017) (https://apps.who.int/iris/handle/10665/259402).

Source: 

Link: https://www.who.int/publications/m/item/influenza-at-the-human-animal-interface-summary-and-assessment--6-september-2026

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#USA, #Wastewater Data for Avian #Influenza #H5 (US CDC, Sept. 11 '26)

 

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A(H5) detections in the past week

Time Period: August 30, 2026 - September 05, 2026

    -- A(H5) Detection: 8 site(s) (1.9%)

    -- No Detection: 422 site(s) (98.1%)

    -- No samples: 95 site(s)

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Source: 

Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?

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Nationwide Increase in Reported #Human #Rabies #Exposures: Rabies #PEP Administration (US CDC, HAN, Sept. 10 '26, Summary)

 

Summary

    The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Advisory in response to recent reports of increases in human exposures to rabid or possibly rabid animals and rabies post-exposure prophylaxis (PEP) administration errors. 

    Since July 2026, multiple United States jurisdictions have reported local increases in human rabies exposures involving known rabies vectors or animals in which rabies is less commonly reported. 

    Several high-profile rabies outbreaks and mass rabies exposure events have highlighted the importance of performing careful rabies risk assessments and following evidence-based recommendations for administering PEP. 

    Health departments can help clinicians who provide rabies vaccination in their jurisdictions stay aware of the importance of rabies risk assessments before administering PEP. 

    Clinicians and healthcare facilities can work to make sure that PEP is administered only when appropriate and that human rabies immune globulin (HRIG) and rabies vaccines are administered according to Advisory Committee on Immunization Practices (ACIP) recommendations.

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Source: 

Link: https://www.cdc.gov/han/php/notices/han00533.html

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Divergent avian #strains drive an off-season #influenza A peak in municipal #wastewater

 

ABSTRACT

Wastewater sequencing is an increasingly valuable tool in tracking the spread of infectious disease agents across space and time in areas of dense human settlement. Among pathogens that can be readily detected by this approach is influenza A, which follows predictable patterns of prevalence through the winter months in North America. Here, we leverage routine surveillance of a municipal wastewater treatment plant in Northern California to describe an atypical, off-season spike in influenza A concentrations that rivals that of the winter respiratory virus season. Drawing upon metagenomic data generated through hybrid-capture sequencing, we assemble and subsequently characterize fragments of divergent influenza genomes that appear to derive predominantly from the avian H16 clade. These strains exhibit close evolutionary relationships to influenza isolated from migratory shorebirds, hinting at potential host species and mechanisms of geographic spread. Analysis of read abundances suggests that these avian strains dominate the pool of influenza circulating during the summer months, when typical human-infecting strains are essentially absent. Together, our results expand the value of wastewater sequencing to encompass sensitive tracking of outbreaks within animals in interface regions where human settlement abuts wildlands, increasing overall pandemic preparedness.

IMPORTANCE

Researchers now commonly search municipal wastewater for viral genetic material, which can indicate trends in the diversity and abundance of strains circulating in communities. Here, we show that under certain conditions, municipal wastewater can also capture the signatures of viruses circulating among animal populations, such as birds. Specifically, we draw on a targeted form of nucleic acid sequencing to discover a strain of influenza that is fairly genetically distinct from known relatives and may be circulating among shorebirds in Northern California. These findings both broaden the possible use cases of wastewater sequencing and provide new insights into avian viruses, some of which can jump host species to make other animals or people sick.

Source: 

Link: https://journals.asm.org/doi/10.1128/spectrum.02027-26

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#USA, #Wastewater Data for Avian #Influenza #H5 (CDC, Sept. 4 '26)

 

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A(H5) detections in the past week

Time Period: August 23, 2026 - August 29, 2026

    -- A(H5) Detection: 3 site(s) (0.7%)

    -- No Detection: 439 site(s) (99.3%)

    -- No samples: 74 site(s)

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Source: 

Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?

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Lessons Learned During 2024‒25 Highly Pathogenic Avian #Influenza #H5N1 Virus #Outbreak Response in #USA: Experience of State and Local Public Health Departments

 

Abstract

Objectives. 

To describe challenges and lessons learned during state and local health department responses to the 2024‒2025 highly pathogenic avian influenza A(H5N1) outbreaks.

Methods. 

We conducted semistructured interviews from August to November 2025 with Department of Health and Agriculture staff from states with confirmed or probable A(H5N1) human cases. We conducted 15 total interviews with 37 participants from 10 US states. Interview transcripts were inductively and deductively coded to identify generalizable lessons that might improve future outbreak response efforts.

Results. 

Key themes included difficulty accessing farms and reaching at-risk populations; lack of sufficient guidelines for proactively responding to zoonotic outbreaks that could have human health implications; the importance of maintaining preparedness planning, capacity, and infrastructure; and uncertainty around future capacity to respond to outbreaks because of resource constraints and changes in federal leadership.

Conclusions. 

Although this study focused on responses to A(H5N1) outbreaks, the findings are indicative of the nation’s overall readiness for biological threats. Prioritization of capacity building for infectious disease outbreaks, including robust health department funding to support continued disease surveillance, is critical to prevent more widespread transmission. 

(Am J Public Health. Published online ahead of print September 3, 2026:e1–e7. https://doi.org/10.2105/AJPH.2026.308656)

Source: 

Link: https://ajph.aphapublications.org/doi/10.2105/AJPH.2026.308656

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Characteristics and Monitoring of the 2026 #Outbreak of #Ebola Disease Caused by #Bundibugyo Virus — #DRC, August 2026 (MMWR, edited)

 

Summary

    ° What is already known about this topic?

        § In May 2026, an outbreak of Ebola disease caused by Bundibugyo virus was identified in the Democratic Republic of the Congo.

    ° What is added by this report?

        § This ongoing outbreak is now the second largest Ebola outbreak in history. The targets for five critical public health response indicators (case detection alerts, contact tracing, laboratory testing, isolation of infected persons, and safe and dignified burials) have not yet been met, and the outbreak continues to expand rapidly.

    ° What are the implications for public health practice?

        § Substantial improvements in established outbreak control measures are crucial to rapidly detect and diagnose cases and isolate and provide treatment for infected persons, prevent funeral-associated transmission to prevent additional spread, and control this rapidly expanding outbreak.

    The Democratic Republic of the Congo (DRC) Ministry of Public Health declared an Ebola outbreak on May 15, 2026. Two days later, CDC activated its Emergency Operations Center as part of the U.S. government response to this rapidly growing outbreak. This report describes the epidemiologic characteristics and monitoring of the ongoing outbreak in DRC.

Investigation and Outcomes

Background

    The 2026 Ebola DRC outbreak caused by Bundibugyo virus is now the second largest Ebola outbreak ever recorded. As of August 21, 2026, DRC reported 5,458 confirmed cases and 2,606 (48%) confirmed deaths. 

    Compared with previous Ebola outbreaks, the increase in cases in DRC is unprecedented, with approximately 5,000 cases in 100 days (Ebola Outbreak: Current Situation | CDC). 

    Cases have been reported from six of the 26 DRC provinces (Bas-Uélé, Haut-Uélé, Ituri, North Kivu, South Kivu, and Tshop), affecting 57 of 151 health zones in the affected provinces. 

    Ituri province remains the outbreak epicenter, accounting for 84% of reported cases. 

    Strategies known to control Ebola outbreaks include community-based surveillance, case detection alert notifications,* rapid and in-depth case investigations, identification and monitoring of contacts, infection control measures (e.g., prompt isolation of persons with suspected or confirmed Bundibugyo virus disease [BVD]), rapid diagnostic testing, mortality surveillance, and safe and dignified burials (SDBs).†

Data Source

    Operational indicators for five domains have been generated based on experience with previous Ebola outbreaks, including DRC’s 2018 outbreak. Targets reflect the levels necessary to end the outbreak. 

    The DRC Ministry of Public Health prepares publicly available daily situation reports, and CDC abstracts data from these reports to evaluate the established indicators each day. Indicator data are monitored over time to assess the outbreak trajectory. This activity was reviewed by CDC, deemed not research, and conducted consistent with applicable federal law and CDC policy.§

Operational Indicator Analysis

    Nearly all operational indicators remain below identified targets (...). 

    Operational indicator values were calculated for the 21-day period of July 31–August 21. 

    The average percentage of alerts investigated within 24 hours (last reported August 5, 2026) was 83% (target = >90%). 

    An average of 10.6 contacts were identified per confirmed case (target = ≥20), suggesting underreporting and underascertainment of case contacts. 

    The percentage of confirmed new cases previously identified as known contacts (last reported July 12, 2026) was 15%–20% (target = >90%); this suggests that most cases are occurring outside known transmission chains. 

    In addition, more than one half (59%) of confirmed Ebola deaths are occurring outside an Ebola treatment unit (ETU) (target = 0%), suggesting insufficient ETU capacity, fear of ETUs, and ongoing spread through unidentified transmission chains. 

    Laboratory testing was performed for 72% of validated alerts (target = >90%), indicating that a substantial number of suspected cases remain untested. 

    Test positivity was 24%, with a target of 0%. 

    Although the national ETU bed occupancy was 64%, meeting the target of <80%, occupancy varied substantially by health zone, with some facilities unable to isolate all infected persons and reporting occupancies as high as 140%. 

    Fewer than one half (49%) of affected health zones had at least one SDB team (target = 100%). 

    Current data were not available for several response indicators, such as percentage of persons with confirmed BVD receiving prompt isolation (target = >90%) and percentage of deaths with SDBs (target = 100%), underscoring ongoing data gaps in this complex public health response.

Preliminary Conclusions and Actions

    As of August 21, 2026, most operational indicator measures remained below established response targets, and data for others were unavailable, indicating gaps in surveillance, contact tracing, laboratory testing, health care–seeking, isolation, and SDB capacity that limit control of the ongoing outbreak. 

    These missing data and operational gaps, together with continued geographic expansion of the outbreak, a high percentage of deaths occurring outside ETUs, and a low percentage of cases among persons previously identified as contacts, indicate uncontrolled expansion of the outbreak. 

    Public health response activities are complicated by a protracted complex humanitarian emergency in the eastern part of DRC, including armed conflict, limited health infrastructure, population displacement and mobility, and constraints on access to affected communities.

    Containment and control of the 2026 Ebola disease outbreak requires integration and coordination of at least five response areas: 

    1) expansion of community-based surveillance systems ensuring rapid investigation of alerts; 

    2) improvements in contact tracing completeness and timeliness; 

    3) expansion of treatment and isolation capacity in affected health zones; 

    4) increased laboratory testing capacity, enabling prompt case identification; and 

    5) ensuring SDBs in affected health zones.

    

    In addition, collecting robust, high-quality data regarding these operational actions is essential at the health zone level; CDC’s continued support to the DRC Ministry of Public Health and partners with improving data collection is critical. 

    Collecting data at the level of the health zone facilitates timely local outbreak response decisions. 

    Rapidly enhancing international humanitarian coordination and mobilizing global technical, operational, and other needed support are critical for accelerating the response and controlling the outbreak.

CDC 2026 Ebola Response International Epidemiology and Laboratory Task Force

Christine Atherstone, Amy Boore, Vance Brown, Jonathan Bryant-Genevier, Nirma Bustamante, Maestro Evans, James Fuller, Timothee Kinkela, John D. Klena, Thomas C. McHale, Elissa Meites, Emmanuel A. Mensah, Mpingulu Minlangu, Pierre Muhoza, Mike Park, Jaymin Patel, Satish K. Pillai, Anne Purfield, Logan Ray, Jessica N. Ricaldi, Katrin S. Sadigh, Dean Sayre, Trevor Shoemaker, Rachel Snyder, Christina Spiropoulou, Leisel Talley, Alison Todres, Sebastien Tshipamba, Amy Whitesell, Hailey Whitmire, Kristina Wielgosz, Emily Zielinski-Gutierrez, CDC; Democratic Republic of the Congo, Ministry of Public Health.

Corresponding author: Sascha Ellington, frk5@cdc.gov.

Source: 

Link: http://dx.doi.org/10.15585/mmwr.mm7535e1

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