Tuesday, February 11, 2025

Undetected Bird Flu Cases in Humans Emerged in the US

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Recent blood analyses conducted on 115 dairy workers in Michigan and Colorado have illuminated previously undetected instances of highly pathogenic avian influenza (H5N1) affecting humans. A study by the US Centers for Disease Control and Prevention (CDC) revealed that 7 percent of participants tested between June and August 2024 exhibited antibodies indicative of exposure to this virulent strain.

Encouragingly, the findings suggest that the majority of those infected have not experienced severe health repercussions; in fact, half of the individuals who tested positive for antibodies reported no significant illness, indicating they may have encountered only mild symptoms.

Nonetheless, researchers express concern regarding the unchecked spread of the virus, which heightens its chances of mutation into more dangerous variants. Indeed, a troubling development has emerged in Cambodia, where at least three patients have succumbed to a hybrid strain of the virus, contracted from poultry. This variant—resulting from genetic reassortment between strains 2.3.2.1c and 2.3.4.4b—exhibits mutations that may enhance its capacity for airborne transmission and infection in mammals.

Fortunately, surveillance efforts indicate that the Cambodia outbreak remains contained, with no signs of human-to-human transmission thus far. In Canada, however, the first known human case of bird flu has been documented—a teenager currently in critical condition due to a mutated strain associated with the California dairy cow outbreak. Genetic sequencing has uncovered alterations in a specific gene linked to the virus’s ability to infect humans.

Although this Canadian case appears to be isolated, such incidents underscore the dynamic nature of viral threats, necessitating vigilant monitoring and robust outbreak management. To date, there is only one recorded instance of bird flu with no discernible animal source, raising apprehensions about the potential for human-to-human transmission.

The CDC has emphasized the importance of personal protective equipment (PPE) in mitigating infection risks among dairy workers. Reports suggest that many workers involved in milking activities did not utilize appropriate protective gear, highlighting a gap in compliance with safety protocols.

Given the substantial impact of the highly pathogenic bird flu, which has led to the culling of over 90 million domestic birds in the US since 2022, strategizing effective vaccination programs and enhancing public awareness about hygiene practices during interactions with animals are imperative. Ongoing research efforts are crucial for the development of a human vaccine, reinforcing the need for a comprehensive public health response to this evolving threat.

The CDC’s findings are published in the Morbidity and Mortality Weekly Report, accessible here.


Vocabulary List:

  1. Pathogenic /ˌpæθəˈdʒɛnɪk/ (adjective): Causing or capable of causing disease.
  2. Virulent /ˈvɪr.jə.lənt/ (adjective): Extremely severe or harmful in its effects.
  3. Reassortment /ˌriːəˈsɔːrtmənt/ (noun): The process by which genetic material is exchanged between organisms resulting in new combinations of genes.
  4. Mutation /mjuːˈteɪʃən/ (noun): A change in the genetic structure of an organism which may result in altered characteristics.
  5. Surveillance /sərˈveɪləns/ (noun): Close observation especially of a suspected spy or criminal.
  6. Proficient /prəˈfɪʃənt/ (adjective): Competent or skilled in doing or using something.

How much do you know?


What percentage of dairy workers tested between June and August 2024 showed antibodies indicative of exposure to highly pathogenic avian influenza (H5N1)?
3%
5%
7%
10%


Where was the first known human case of bird flu documented?
Michigan
Colorado
Cambodia
Canada


What mutation has been observed in the hybrid strain of avian influenza contracted from poultry in Cambodia?
2.3.2.1a
2.3.4.4a
2.3.2.1c
2.3.4.4c


What is emphasized by the CDC for mitigating infection risks among dairy workers?
Use of personal protective equipment (PPE)
Increased milking activities
Avoiding vaccination programs
Enhancing public awareness only


How many domestic birds have been culled in the US since 2022 due to highly pathogenic bird flu?
50 million
70 million
90 million
110 million


What is crucial for the development of a human vaccine against avian influenza?
Regular hand washing
Social distancing
Ongoing research efforts
Vitamin supplements


The majority of individuals infected with highly pathogenic avian influenza experienced severe health repercussions.


The variant of avian influenza in Cambodia exhibits mutations that enhance its capacity for airborne transmission.


The Canadian case of bird flu is associated with the California dairy cow outbreak.


There have been multiple instances of bird flu with no animal source recorded to date.


The CDC's findings on avian influenza were published in the Morbidity and Mortality Weekly Report.


The containment of the Cambodia outbreak has shown signs of human-to-human transmission.

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