ETIDIOH - NEW

{Excerpt} Time Period: March 16 - March 22, 2025 -- H5 Detection :  5 sites ( 1.2% ) -- No Detection :  401 sites ( 98.8% ) -- No samples in last week :  211 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/bird-flu/h5-monitoring/index.html ____

Situation at a glance On 11 March 2025, the World Health Organization (WHO) received a report from the International Health Regulation (2005) (IHR) National Focal Point (NFP) of the United States of America (United States) on the ongoing measles outbreak in the country , notified under IHR because it is an unusual event with potential significant public health impact , with the number of cases and deaths in 2025 exceeding the numbers in previous years. Additionally, cases linked to the outbreak in the State of Texas, United States, have been reported in Mexico . Measles is a highly contagious, airborne viral disease that can lead to severe complications and death. From 1 January to 20 March 2025, 17 States have reported a total of 378 cases of measles , including two deaths - the first deaths related to measles in the United States in a decade. The majority of cases are in children who are unvaccinated or have unknown vaccination status, and the overall hospitalization rate is 17%. In ...

ABSTRACT Unexpected outbreaks caused by the H5N1 highly pathogenic avian influenza virus (HPAIV) in dairy cows in the United States (US) have raised significant veterinary and public health concerns . When and how the H5N1 HPAIV was introduced into dairy cows and the broader epidemiology of influenza A virus (IAV) infections in cattle in the US remain unclear. Herein, we performed a retrospective study to screen more than 1,700 cattle serum samples collected from different bovine breeds in the US from January 2023 to May 2024 using an enzyme-linked immunosorbent assay (ELISA) targeting the nucleoprotein (NP) to detect IAV infections, and the positive samples were further tested by hemagglutination inhibition (HI) assay . Results showed that 586 of 1,724 samples (33.99%) from 15 US states were seropositive by the NP ELISA assay , including 78 samples collected in 2024 and 508 samples collected in 2023 . Moreover, the HI assay revealed that 45 of these ELISA-positive samples were positiv...

{Excerpt} Time Period: March 09 - March 15, 2025 -- H5 Detection :  12 sites ( 2.7% ) -- No Detection :  431 sites ( 97.3% ) -- No samples in last week :  177 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/bird-flu/h5-monitoring/index.html ____

Abstract A sustained outbreak of H5N1 influenza virus among wild fowl and domestic livestock has caused more than 70 zoonotic infections in humans in the United States , including one death. The Centers for Disease Control and Prevention has recommended rapid H5 subtyping for all hospitalized cases with influenza A virus infection to enable prompt initiation of antiviral treatment , as well as infection prevention and implementation of public health measures to control spread. To address these needs, we developed a multiplex RT-qPCR assay to subtype H5 influenza virus in nasal, nasopharyngeal, and conjunctival specimens with a limit of detection of 230 copies/mL. No cross-reactivity was observed with other common respiratory viruses, including seasonal H3N2 and H1N1 influenza A viruses. We retrospectively subtyped 590 influenza A-positive clinical specimens processed by University of Washington labs between March 2024 and February 2025, including 512 specimens collected during the 2024...

{Excerpts} Recent updates Laboratory CDC completed serology testing on blood specimens from close contacts of a child with mild illness in San Francisco who was confirmed to be positive for avian influenza A(H5N1) virus, though, there were no known animal exposures associated with that case.  -- Serology testing was conducted to look for antibodies to influenza A(H5N1) virus in this child, which would indicate recent infection.  -- The child's blood was tested and found to have antibodies to avian influenza A(H5N1) virus.  -- None of the close contacts of the case in San Francisco who were tested had antibodies to avian influenza A(H5N1) virus, which supports the conclusion that none of these close contacts were infected , and that no person-to-person spread occurred among these close contacts.  -- These findings are reassuring. To date, human-to-human transmission of influenza A(H5) virus has not been identified in the United States. CDC has sequenced the virus from...

Abstract H5N1 influenza has been circulating in birds from Eurasia and Africa for more than 146 years , but human infection has been sporadic. H5N1 (clade 2.3.4.4b) has recently infected hundreds of species of wild and domestic birds and mammals in North America . Furthermore, as of February 26, 2025, H5N1 has infected 70 humans in the United States , and one infection proved lethal . Furthermore, in attempts to control H5N1 in the United States, 10s of millions of egg-laying chickens have died or been culled . These efforts have led to very high egg prices in the United States. We have developed an analytical bioinformatics and genomics workflow to understand better how H5N1 is circulating in North America and adapting to new host species . Our workflow consists of: 1) Phylogenetic analyses of large viral sequence datasets to identify subclades of viral lineages causing the current outbreaks in humans and farm animals and closely related viral background lineages. 2) Next, we transfer...

Highly pathogenic avian influenza (HPAI) H7N9 of North American wild bird lineage was detected in a commercial broiler breeder chicken flock in Mississippi . Depopulation of the affected flock is in progress. The USDA Animal and Plant Health Inspection Service (APHIS), in conjunction with State Animal Health and Wildlife Officials, are conducting a comprehensive epidemiological investigation and enhanced surveillance in response to the detection. A commercial broiler breeder premises {in Mississippi}. Clinical signs included increased mortality. Depopulation was completed 13 Mar 2025. Source: WOAH,  https://wahis.woah.org/#/in-review/6340 ____

Abstract The current outbreak of highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype clade 2.3.4.4b in dairy cattle in the United States has affected nearly 900 dairy farms and resulted in at least 39 human infections, putting health authorities and the scientific community on high alert. Here we characterize the virus growth properties and host-pathogen interactions of an isolate obtained from a sick dairy cow in Texas in vitro and in vivo and compare it to an older HPAI isolate. Despite so far being associated with mild disease in human patients, the cattle H5N1 virus showed superior growth capability and rapid replication kinetics in a panel of human lung cell lines in vitro . In vivo, cattle H5N1 exhibited more intense pathogenicity in mice , with rapid lung pathology and high virus titers in the brain , accompanied by high mortality after challenge via different inoculation routes. Additionally, the cattle H5N1 demonstrated efficient antagonism of overexpressed RI...

  Time Period: March 02 - March 08, 2025 - H5 Detection :  29 sites ( 6.2% ) - No Detection :  438 sites ( 93.8% ) - No samples in last week :  152 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/bird-flu/h5-monitoring/index.html ____

Summary -- What is already known about this topic? -  Persons with occupational exposure to highly pathogenic avian influenza (HPAI) A(H5N1) virus–infected dairy cattle are at increased risk for infection. -- What is added by this report? -  During September 30–December 24, 2024, a total of 38 persons received a positive test result for HPAI A(H5N1) viruses in California ; 37 were dairy farm workers with occupational exposure to sick cows. One, a person aged <18 years with an undetermined exposure , was the first pediatric patient detected with influenza A(H5) infection in the United States. -- What are the implications for public health practice? -  Public health agencies should investigate influenza-like illness or conjunctivitis in workers with occupational exposure to animals infected with HPAI A(H5N1) virus. Thorough investigations of all human HPAI A(H5N1) virus infections are necessary to identify potential exposure sources, including monitoring the virus for co...

Abstract We measured stability of infectious influenza A(H5N1) virus in irradiated raw milk and wastewater and on surfaces . We found a relatively slow decay in milk , indicating that contaminated milk and fomites pose transmission risks . Although the risk is low, our results call for caution in milk handling and disposal from infected cattle. Source: US Centers for Disease Control and Prevention,  https://wwwnc.cdc.gov/eid/article/31/4/24-1615_article ____

The antiviral drug tecovirimat used without other antivirals did not reduce the time to clinical resolution of clade II mpox lesions or improve pain control among adults in an international clinical trial sponsored by the National Institutes of Health (NIH).  The trial enrollment was stopped in late 2024 when an interim analysis showed that tecovirimat monotherapy was ineffective in the study population. Detailed results were presented at the 2025 Conference on Retroviruses and Opportunistic Infections (CROI) in San Francisco. “This study brought us a step forward in better understanding mpox disease and potential treatment strategies,” said Jeanne Marrazzo, M.D., M.P.H., director of NIH’s National Institute of Allergy and Infectious Diseases (NIAID), which sponsored and funded the trial. “We are grateful to the study team and participants for their contributions to groundbreaking research on a disease that we still do not know enough about.” Mpox is caused by a virus that spreads ...

Abstract Since March 2024, highly pathogenic avian influenza A(H5N1) viruses have caused outbreaks in dairy cattle and poultry in the United States, and they continue to spill over into humans . However, data on human immune response to those viruses is limited. We report neutralizing antibody responses in 2 dairy farm worker H5N1 cases. Source: US Centers for Disease Control and Prevention,  https://wwwnc.cdc.gov/eid/article/31/4/25-0007_article ____

{Excerpt} Time Period: February 23 - March 01, 2025 - H5 Detection :  8 sites ( 1.8% ) - No Detection :  445 sites ( 98.2% ) - No samples in last week :  100 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/bird-flu/h5-monitoring/index.html ____

As of February 28, 2025 CDC assessed the risk from H5N1 viruses to the U.S. general population and to populations in the United States with contact with potentially infected animals, including through contaminated surfaces or fluids . Risk describes the potential public health implications and significance of an outbreak for populations assessed. See definitions below for more detail. {Risk posed by H5N1 viruses to the United States. Please see methods section for further information on definitions of terms.} ___ The purpose of this assessment is to evaluate the current public health risk of H5N1 viruses to the general U.S. population and to those in contact with potentially infected animals or contaminated surfaces or fluids, and to inform public health preparedness efforts. CDC assessed risk by considering both likelihood and impact of infection in each population (...). Both the likelihood and impact of infection are assessed at a population level. Likelihood of infection refers to ...

Abstract Highly pathogenic avian influenza viruses (HPAIV) pose a serious public health concern . In March 2024, a first-time outbreak of HPAIV H5N1 in dairy cattle herds was reported in the United States (US). Since then, the virus has continued to spread in cattle herds and spilt over into humans . We recently showed that the first human isolate reported in the US in Texas (HPhTX) from a dairy worker in an affected cattle farm has enhanced replication kinetics and pathogenicity in mice compared to a closely related bovine isolate (HPbTX). However, the molecular determinants of differential pathogenicity have not yet been identified. Herein, we show that HPhTX has enhanced polymerase activity , compared with HPbTX, in human cells and that the polymerase basic 2 (PB2) protein is the main factor responsible for this difference. Through single and combined site-directed mutagenesis and swapping the three amino acids different between HPhTX and HPbTX, we found that PB2 mutation E627K is t...