Introduction

Bird flu, specifically Highly Pathogenic Avian Influenza (HPAI), continues to challenge California's agricultural sector, impacting 755 dairies and millions of birds since it was first detected in the region. The virus has not only hit California but has also been identified in poultry across several states, including recent outbreaks in Pennsylvania, Nevada, and Idaho.

Current Situation

In the past month, numerous commercial poultry facilities in Pennsylvania have confirmed cases of HPAI, highlighting the ongoing threat posed by the virus. However, Dr. Alex Hamberg, Pennsylvania's State Veterinarian and Director of the Bureau of Animal Health and Diagnostic Services, expressed optimism during a recent webinar. He noted that Pennsylvania has maintained Stage 4 status, indicating an ongoing absence of the virus in its dairy herds, a significant milestone that places it alongside only two other states. This status gives a sense of security to dairy farmers, bolstering confidence that HPAI is not present among Pennsylvania's dairy cows.

National Overview

On a national scale, alarming findings reveal the continued circulation of the B3.13 strain across California and Idaho, which has been notorious for crossing between cattle and poultry. Dr. Hamberg explained that most cases in Nevada and Arizona, as well as some in California, are predominantly the D1.1 strain, commonly found in wild birds across the United States. He confirmed that there is currently no evidence of the virus spreading from one farm to another but emphasized the risk of transmission from wild birds to dairy farms.

Clinical Impact and Ongoing Monitoring

Despite the apparent lower clinical impact on cattle from this current strain, Dr. Hamberg stressed the necessity for ongoing vigilance. "The clinical illnesses appear to be fewer than what we saw with B3.13," he stated, echoing the need for constant monitoring of the evolving situation.

Research on Raw Dairy Products

A recent study aimed to explore the safety of raw cheese and milk in relation to HPAI has also emerged, raising concerns about the potential survival of the virus during cheese production. Researchers added the H5N1 virus to milk, subjecting it to a rigorous 60-day aging process to determine whether the virus could survive. The findings revealed that cheeses aged at a pH level of between 5.8 and 6.6 still retained viable virus after 60 days, while those with a pH of 5 or lower effectively eradicated the virus.

Preliminary Findings and Public Assurance

Dr. Hamberg noted this study is still in preprint, indicating a need for further evaluation. He mentioned a national study currently underway surveying raw milk cheeses for the H5N1 virus, which thus far has tested nearly 100 samples from commercial channels without detection of the virus.

Conclusion

"While it's encouraging that we've not found any virus in a third of the samples tested, we still have a significant number left to test," he said, urging the public to remain cautious but not overly alarmed by preliminary findings.

In closing, Hamberg reiterated the critical importance of biosecurity for farmers, particularly as new strains of the virus emerge. "Biosecurity measures differ significantly between species," he explained. This mantra is vital, especially in states like Pennsylvania that have so far managed to keep the virus at bay. As the situation evolves, vigilance among producers remains paramount to safeguarding the agricultural industry against bird flu outbreaks.