H5N1

MMWR: Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Viruses in US Dairy Cattle and Detection of Two Human Cases — United States, 2024

Via MMWR: Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Viruses in U.S. Dairy Cattle and Detection of Two Human Cases — United States, 2024. The summary:

What is already known about this topic? 

Influenza A(H5) virus infection was detected in two U.S. farm workers during a multistate outbreak of A(H5N1) viruses in dairy cows; these are the first known instances of presumed cow-to-human transmission of avian influenza A viruses.  

What is added by this report?  

Approximately 350 exposed farm workers are being monitored; one of the two cases was identified via daily, active monitoring. Surveillance has identified no unusual influenza activity trends in the United States. A(H5) candidate vaccine viruses are available, and laboratory analyses indicate that A(H5N1) viruses circulating in cows and other animals are susceptible to FDA-approved antivirals.  

What are the implications for public health practice?  

Current risk to the U.S. public from A(H5N1) viruses is low; however, persons exposed to infected animals or contaminated materials, including raw cow’s milk, are at higher risk and should take precautions and self-monitor for illness. A One Health (human, animal, and environmental) approach is critical to preparing for circumstances that could increase risk to human health.

WHO: Dengue - Global situation

WHO has published a DON: Dengue - Global situation. The situation at a glance:

As of 30 April 2024, over 7.6 million dengue cases have been reported to WHO in 2024, including 3.4 million confirmed cases, over 16 000 severe cases, and over 3000 deaths. 

While a substantial increase in dengue cases has been reported globally in the last five years, this increase has been particularly pronounced in the Region of the Americas, where the number of cases has already exceeded seven million by the end of April 2024, surpassing the annual high of 4.6 million cases in 2023. Currently, 90 countries have known active dengue transmission in 2024, not all of which have been captured in formal reporting. 

In addition, many endemic countries do not have strong detection and reporting mechanisms, so the true burden of dengue globally is underestimated. In order to control transmission more effectively, real-time robust dengue surveillance is needed to address concerns about potential undetected cases, co-circulation and misdiagnosis as other arboviruses, and unrecorded travel movements. These factors could contribute to unrecognized disease spread and establish a potential risk for local transmission in non-endemic countries. 

Dengue virus is transmitted to humans through the bite of infected mosquitoes. Cases are most commonly asymptomatic or result in mild febrile illness. However, some cases will develop severe dengue, which may involve shock, severe bleeding or severe organ impairment. 

To strengthen global surveillance, and monitor temporal trends and disease incidence, WHO has established a global dengue surveillance system with monthly reporting across all WHO regions with a new dashboard now live (https://worldhealthorg.shinyapps.io/dengue_global/). 

The overall capacity for countries to respond to multiple, concurrent outbreaks continues to be strained due to the global lack of resources, including shortages of good quality dengue diagnostic kits for early disease detection, lack of trained clinical and vector control staff and community awareness. 

Emergency response mechanisms have been established, and WHO supports high-risk countries across affected regions. Given the current scale of the dengue outbreaks, the potential risk of further international spread and the complexity of factors impacting transmission, the overall risk at the global level is still assessed as High and thus dengue remains a global threat to public health.

Compound mortality impacts from extreme temperatures and the COVID-19 pandemic

Via Nature Communications: Compound mortality impacts from extreme temperatures and the COVID-19 pandemic. The abstract:

Extreme weather and coronavirus-type pandemics are both leading global health concerns. Until now, no study has quantified the compound health consequences of the co-occurrence of them. We estimate the mortality attributable to extreme heat and cold events, which dominate the UK health burden from weather hazards, in England and Wales in the period 2020-2022, during which the COVID-19 pandemic peaked in terms of mortality. 

We show that temperature-related mortality exceeded COVID-19 mortality by 8% in South West England. Combined, extreme temperatures and COVID-19 led to 19 (95% confidence interval: 16–22 in North West England) to 24 (95% confidence interval: 20–29 in Wales) excess deaths per 100,000 population during heatwaves, and 80 (95% confidence interval: 75–86 in Yorkshire and the Humber) to 127 (95% confidence interval: 123–132 in East of England) excess deaths per 100,000 population during cold snaps. 

These numbers are at least ~2 times higher than the previous decade. Society must increase preparedness for compound health crises such as extreme weather coinciding with pandemics.

MMWR: Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Viruses in U.S. Dairy Cattle and Detection of Two Human Cases — United States, 2024

Via MMWR: Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Viruses in U.S. Dairy Cattle and Detection of Two Human Cases — United States, 2024. The summary and abstract:

Summary

What is already known about this topic?  

Influenza A(H5) virus infection was detected in two U.S. farm workers during a multistate outbreak of A(H5N1) viruses in dairy cows; these are the first known instances of presumed cow-to-human transmission of avian influenza A viruses.  

What is added by this report?  

Approximately 350 exposed farm workers are being monitored; one of the two cases was identified via daily, active monitoring. Surveillance has identified no unusual influenza activity trends in the United States. A(H5) candidate vaccine viruses are available, and laboratory analyses indicate that A(H5N1) viruses circulating in cows and other animals are susceptible to FDA-approved antivirals.  

What are the implications for public health practice?  

Current risk to the U.S. public from A(H5N1) viruses is low; however, persons exposed to infected animals or contaminated materials, including raw cow’s milk, are at higher risk and should take precautions and self-monitor for illness. A One Health (human, animal, and environmental) approach is critical to preparing for circumstances that could increase risk to human health.

Abstract  

On April 1, 2024, the Texas Department of State Health Services reported that a dairy farm worker had tested positive for highly pathogenic avian influenza A(H5N1) virus after exposure to presumably infected dairy cattle; CDC confirmed these laboratory findings. A(H5N1) viruses were found in high concentrations in unpasteurized (raw) milk from infected cows.  

CDC is collaborating with the U.S. Department of Agriculture, the Food and Drug Administration, the Administration for Strategic Preparedness and Response, the Health Resources and Services Administration, the National Institute of Allergy and Infectious Diseases, and state and local public health and animal health officials using a coordinated One Health approach to identify and prepare for developments that could increase the risk to human health.  

Activities include monitoring of exposed persons, conducting syndromic and laboratory surveillance, planning epidemiologic investigations, and evaluating medical countermeasures. As of May 22, 2024, approximately 350 farm workers with exposure to dairy cattle or infected raw cow’s milk had been monitored.  

These monitoring efforts identified a second human A(H5) case with conjunctivitis in Michigan, which was reported on May 22, 2024. CDC considers the current risk to the U.S. public from A(H5N1) viruses to be low; however, persons with exposure to infected animals or contaminated materials, including raw cow’s milk, are at higher risk for A(H5N1) virus infection and should take recommended precautions, including using recommended personal protective equipment, self-monitoring for illness symptoms, and, if they are symptomatic, seeking prompt medical evaluation for influenza testing and antiviral treatment if indicated.  

Pasteurization inactivates A(H5N1) viruses, and the commercial milk supply is safe for consumption; however, all persons should avoid consuming raw milk or products produced from raw milk.  

Importantly, the risk to the public might change based on whether A(H5N1) viruses acquire genetic changes that increase their transmissibility to and among humans, which could increase the risk of an influenza pandemic.

Human case of H5N1 avian influenza (bird flu) detected in returned traveller to Victoria

Thanks to FluTrackers for posting this report from the Victoria health department: Human case of avian influenza (bird flu) detected in returned traveller to Victoria. This case seems unrelated to the avian flu reported yesterday in poultry farms in Victoria. The key points:

• A human case of avian influenza A(H5N1) infection, also known as “bird flu”, has been reported in Victoria.  

• There is a current global outbreak of avian influenza in birds and animals. Avian influenza does not usually infect people, but in rare cases human infection can occur.  

• The recently reported case in Victoria was in a child who returned to Australia from overseas in March 2024. The child experienced a severe infection but is no longer unwell and has made a full recovery.  

• There is no evidence of transmission in Victoria and the chance of additional human cases is very low as avian influenza does not easily spread between people.

Australia reports avian influenza at an egg farm

Via Agriculture Victoria: Current situation — 22 May 2024. Excerpt:

We are investigating poultry deaths at an egg farm near Meredith.  

Preliminary tests have confirmed the presence of avian influenza. Samples have been delivered to the Australian Centre for Disease Preparedness at Geelong for further tests which will determine the strain of the disease.  

The property has been placed into quarantine and Agriculture Victoria staff are on the ground to support the business and investigate further.  

Every producer should have an on-farm biosecurity plan and know the signs of diseases that could affect their animals.  

Any suspicion of an emergency animal disease (EAD) should be immediately reported to the 24-hour EAD Hotline on 1800 675 888 or to your local vet.  

While cases among humans in direct contact with animals infected with highly pathogenic avian influenza viruses are possible, the current risk to the public remains low. Find out more about avian influenza in humans from the BetterHealth Channel.

There's no question H5N1 bird flu has 'pandemic potential.' How likely is that worst-case scenario?

Via CBC News, a report by Lauren Pelly: There's no question H5N1 bird flu has 'pandemic potential.' How likely is that worst-case scenario? Excerpt"

As early as 1997, just a year after H5N1 was first discovered, there were warning signs this form of avian flu was capable of wreaking havoc far beyond birds.  

That year, poultry outbreaks in China and Hong Kong were linked to 18 human infections — and a third of those people later died.   

In the decades that followed, alarm bells from the scientific community rang louder and louder. H5N1 began infecting dozens more species, from tens of millions of wild and farmed birds, to raccoons and foxes, to seals and sea lions to, most recently, U.S. dairy cattle. The virus eventually caused more than 800 human infections around the world with a stunning death rate — for known cases — of roughly 50 per cent.  

"The increasing host range of the virus, [its] potential spread among mammals and between a mammal and a human, its wide geographical spread, and the unprecedented scale of the outbreaks in birds, raise concerns about the pandemic potential" of H5N1, warned a May editorial in leading medical journal The Lancet Infectious Diseases.  

Given those factors, an avian flu pandemic may feel not just inevitable, but imminent.  

Yet the reality is murkier. Though influenza viruses have a knack for rapid evolution, this one hasn't managed to adapt to sustain human-to-human transmission, despite circulating for the last three decades.  

"But that could still potentially happen," said epidemiologist Timothy Sly, a longtime influenza researcher and professor emeritus with Toronto Metropolitan University's school of public health.  

"And if it ever did happen… it would be a global health catastrophe."