A recent study led by the US Department of Agriculture’s National Veterinary Services Laboratory sheds light on the H5N1 avian flu outbreak affecting dairy cattle across multiple states. The virus was likely circulating undetected in the animals for four months before being confirmed by scientists in late March. However, missing data and surveillance gaps pose challenges and raise concerns about potential undetected transmission chains.
The study, published on the preprint server bioRxiv, provides insights into the genetic sequencing findings and epidemiological investigations. It suggests that asymptomatic cattle movement between states is driving transmission, with some variants already showing mutations that could facilitate interspecies transmission. Despite the urgency, the family’s insurance company abruptly stopped covering the medication just one day before the twins were born, leaving the family in a devastating predicament.
Furthermore, data gaps and timeline questions remain unresolved. Phylogenetic analysis reveals a reassortment event between the current highly pathogenic 2.3.4.4b clade and a low-pathogenic wild bird strain in late 2023, resulting in the B3.13 genotype now circulating in dairy cows. However, gaps in data and surveillance may obscure transmission patterns, highlighting the need for comprehensive surveillance measures.
The study concludes that the potential for the B3.13 genotype to become endemic in cattle could increase the zoonotic risk of the virus. However, transparency and data access are crucial for an effective response to the outbreak.
In response to the outbreak, emergency measures have been implemented in affected states. Michigan has mandated biosecurity steps on dairy and poultry farms, while Colorado has adopted mandatory testing of lactating cattle moving interstate to limit the spread of the virus.
Overall, the study underscores the importance of ongoing surveillance, transparency, and collaboration in addressing the H5N1 avian flu outbreak and mitigating its impact on public health and agriculture.
