Bird Flu Infects Five in Colorado, Possibly from Cows to Poultry
Bird flu seems to have transmitted from a dairy farm in Colorado to a neighboring poultry farm, resulting in the infection of five workers assigned to cull the affected birds.
The highly contagious avian influenza H5N1 virus poses pandemic risks, prompting urgent efforts to develop a vaccine to mitigate its severe consequences.
The US Centers for Disease Control and Prevention (CDC) confirmed four human cases linked to the commercial egg laying business, while the fifth case is pending confirmation but presumed positive at this stage.
The source and transmission route of the poultry farm infection are currently unclear, but there is a hypothesis that the virus may have spread from dairy cattle to the poultry farm.
Genomic Sequencing and Viral Adaptation
According to acting senior adviser Eric Deeble from the US Department of Agriculture, genomic sequencing of samples from the poultry operation shows the same genotype of highly pathogenic avian influenza found in nearby dairy herds.
This suggests the virus can thrive in various animal hosts without significant mutation, although it does not provide enough evidence to trace its interspecies transmission.
This potential for cross-species transmission is a major concern for scientists because a virus that can jump between different species can spread more efficiently. Earlier this year, avian flu began affecting cows in the US, with the virus subsequently spreading to two humans.
“The CDC’s assessment of the risk to the general population remains low, and CDC recommendations have not changed,” stated Nirav Shah, principal deputy director of the CDC, during the press briefing.
CDC Recommendations on H5-Specific Vaccines
“For instance, the CDC is not recommending H5-specific vaccines for livestock workers due to the observed mild symptoms so far and the absence of genetic changes in the virus that would indicate increased risk to human health.”
Preliminary analysis of the virus’s genetic sequence from one of the infected poultry farm workers did not reveal any concerning mutations, according to Nirav Shah, principal deputy director of the CDC.
“The sequence closely matches two sequences obtained from infected chickens at the farm where the worker likely contracted the virus,” Shah explained. “Furthermore, one of the virus subunits was identical to those found in cases from Texas and the initial human case in Michigan.”
Impact on Agriculture and Livestock Numbers
While human symptoms have been mild with rapid recovery, the primary concern lies in the potential impact on agriculture. Milk from cows infected with the virus becomes unfit for consumption, and the large-scale culling measures, such as the 1.8 million birds at the Colorado poultry farm, significantly impact livestock numbers.
These culling operations appear to increase the risk of human infection. According to the Colorado Department of Public Health and Environment, the five infected workers participated in loading birds into carbon dioxide gas chambers for culling.
“There were large industrial fans in place that helped to cool the barns, but these fans also circulated feathers, which are known carriers of the virus,” Shah explained.
“Moreover, the culling method involved workers moving from chicken to chicken, increasing the level of interaction with each potentially infected bird.”
Despite typically extensive personal protective equipment (PPE) for such tasks, workers likely faced challenges maintaining these measures as temperatures in Colorado soared to nearly 40 °C (104 °F) on the day, Shah noted during the briefing.
An industrial hygienist has been engaged to explore improved strategies for preventing transmission.
Read the original article on: Science Alert
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