New H5N1 Bird Flu Strain in Cows Infects Nevada Dairy Worker

U.S. Medical News: The First Human Case of H5N1 Bird Flu in Nevada
A dairy worker in Nevada has been confirmed to be infected with a new bird flu strain that was recently found spreading among cows in the state. The strain, identified as D1.1 by scientists, differs from the B3.13 variant, which has infected at least 40 dairy workers in the United States so far. This discovery raises concerns about the potential risks posed by the virus and its impact on both human and animal health.


New H5N1 Bird Flu Strain in Cows Infects Nevada Dairy Worker
 
D1.1 has already been linked to a fatal case in Louisiana last year, where a patient was hospitalized and later succumbed to the virus. This U.S. Medical News report highlights that unlike B3.13, which has primarily caused mild symptoms such as conjunctivitis (pink eye), D1.1 has been associated with more severe cases. According to the U.S. Centers for Disease Control and Prevention (CDC), 14 other cases last year were also connected to D1.1 in birds, but none resulted in hospitalization.
 
Health authorities in Nevada have confirmed that the infected dairy worker, who was exposed while handling sick cows in Churchill County, only exhibited symptoms of pink eye and is currently recovering. The Central Nevada Health District reassured the public that there is no evidence of person-to-person transmission at this stage. Close contacts of the infected individual, including other farm workers, are being monitored for symptoms and have been provided with personal protective equipment (PPE), antiviral medication, and testing.
https://www.centralnevadahd.org/community-alerts-2/
 
Ongoing Surveillance and Precautions
Owen Truesdell, a spokesperson for the Central Nevada Health District, emphasized that this situation is evolving and that officials will continue updating the public as more information emerges. While health experts acknowledge the importance of monitoring the virus’s spread among animals, they maintain that the risk to the general public remains low. The CDC reiterated that this case of cow-to-human transmission does not alter their overall risk assessment.
 
Virologists have pointed out that several mutations would be required for the virus to gain the ability to spread efficiently between humans. So far, all recorded infections have been isolated cases of animal-to-human transmission with no further spread. Nonetheless, a recent analysis by the U.S. Department of Agriculture (USDA) detected a "mammalian adaptation" mutation in the D1.1 strain found in cows in Nevada, though there is no evidence yet of human-to-human transmission.
https://www.aphis.usda.gov/sites/default/files/dairy-cattle-hpai-tech-brief.pdf
 
The Role of Vaccines in Combating Bird Flu
Although the seasonal flu vaccine does not protect against H5N1, th ere are specialized vaccines that health authorities have been developing for a potential bird flu pandemic. Regular tests are conducted to evaluate whether existing stockpiled pandemic vaccines can provide immunity against newly emerging strains of the virus.
 
Tests on past D1.1 strains detected in wild birds suggest that the U.S. government’s pandemic flu vaccines should still offer protection. Dr. Richard Webby, a leading influenza expert from the World Health Organization (WHO) Collaborating Center at St. Jude Children's Research Hospital, noted that these assessments were based on antibodies from infected individuals. He added that vaccination is expected to generate an even stronger immune response.
 
Why Haven’t Bird Flu Vaccines Been Distributed Yet?
Despite having prepared millions of doses of a pandemic flu vaccine, the U.S. government has yet to distribute them. The previous administration took steps last year to ensure that enough vials were available to immunize 2.4 million people if necessary. However, officials decided against rolling out these vaccines at this time, citing the limited impact of the virus on humans and the absence of person-to-person transmission.
 
So far, most human cases in the U.S. have been linked to direct contact with infected animals. This includes workers caring for sick cattle and poultry, as well as individuals exposed during the culling of infected flocks. The one fatal case in Louisiana involved a patient who had direct contact with sick birds.
 
Authorities are also investigating three cases where the exposure source remains unknown. One of these cases involved a child in San Francisco, and the CDC is expected to release findings soon from a study that tested blood samples from the child’s close contacts to determine if additional infections occurred without being detected.
 
Nevada Takes Action to Contain the Spread
Following the confirmation of the D1.1 strain in Nevada’s dairy cattle, officials have implemented multiple measures to prevent further spread:
 
-Quarantines: Dairy farms in Nye and Churchill counties have been placed under quarantine. USDA laboratories have analyzed samples from infected herds and found that the virus matches strains previously seen in wild birds.
 
-Wildlife Surveillance: Efforts to track the virus in wild bird populations continue, as migratory birds may serve as a reservoir for the disease.
 
-Bird Removal: The Nevada Department of Agriculture (NDA) has initiated the removal of non-native European starlings from Churchill, Pershing, and Lyon counties to reduce contamination risks.
 
How Dangerous is Bird Flu to Humans?
The CDC has recorded 67 human cases of bird flu in the U.S., excluding the new Nevada case. Most infections have caused mild symptoms such as fever, sore throat, cough, fatigue, muscle aches, digestive issues, and conjunctivitis. In rare instances, the virus has led to severe respiratory complications.
 
Health experts continue to stress that the primary route of transmission remains direct contact with infected animals or contaminated environments. Those working in close proximity to poultry, dairy cattle, and other livestock are at the highest risk of infection. The virus can enter the body through the eyes, nose, or mouth, often through contaminated surfaces or airborne particles.
 
Genetic Findings and Future Concerns
The USDA’s recent technical briefing provided additional details about the genetic sequencing of the D1.1 strain detected in Nevada dairy cows. The virus was confirmed in milk samples from multiple dairies in early January. Interestingly, clinical symptoms in cows did not appear until after the virus was detected, suggesting a potential delay in symptom onset. Large die-offs of wild birds were reported near infected facilities, further highlighting the role of migratory birds in spreading the virus.
 
Scientists have found a significant mutation in the polymerase basic protein 2 (PB2) gene of the D1.1 virus in cows. This mutation, known as D701N, is associated with increased adaptability in mammals and has previously been observed in human cases of bird flu. However, researchers have found no evidence of human-to-human transmission linked to this mutation so far.
 
Conclusion
The emergence of the D1.1 strain in Nevada dairy cattle and the subsequent human infection serve as a reminder of the evolving nature of bird flu and its potential risks. While the CDC maintains that the overall risk to the general public remains low, health officials continue to monitor the situation closely. The case in Nevada underscores the importance of biosecurity measures on farms, timely surveillance of emerging strains, and the need for continued preparedness against potential outbreaks.
 
As more information about the virus emerges, researchers and public health officials will assess whether additional safety measures, including vaccinations, may be necessary to curb further spread. For now, individuals who work with livestock and poultry are advised to take extra precautions, including wearing protective gear and maintaining proper hygiene practices to minimize exposure risks.
 
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