The disease syndrome has not been reported in California, nor in beef cattle in any state. As new laboratory and epidemiologic data are released, we are gaining a better picture of the disease and how it might be spread.
Pasteurization kills the HPAI virus in dairy products.
The FDA’s national milk sampling study of 297 commercial retail dairy products from 38 states demonstrated the presence of viral fragments in about 1 in 5 retail samples. However, subsequent testing of positive samples using the “gold standard” Embryonated Egg Inoculation Test demonstrated that no live virus survives the pasteurization process. Additional sampling of powdered infant and toddler formations also contained no live virus. Separately, a survey of retail ground beef samples in affected states all have tested negative for the virus.
The disease is potentially passed by asymptomatic cattle or contaminated equipment.
Dairy herds in Idaho, Michigan, Ohio, and North Carolina reported to have recently received animals from affected herds or states, suggesting potential “lateral transmission” from transported asymptomatic cows. Genetic analysis suggests that the outbreak likely began in Texas when the virus jumped from wild birds on a single dairy and subsequently spread to other herds via either clinically normal cows or potentially contaminated trailer equipment.
This highlights the importance of pressure washing and disinfecting trailers that have been used to transport potentially infected cattle. This also reinforces the importance of knowing the history of herd additions and completing segregation (“quarantine”) of new arrivals for at least 30 days. Producers should be aware that there is evidence that infected dairy herds have transmitted the virus to previously uninfected nearby commercial poultry flocks.
Testing is now required for interstate movement of lactating dairy cattle.
A new Federal Order issued by USDA requires mandatory testing of lactating dairy crossing state lines. Cattle samples originating in California will be tested by the California Animal Health & Food Safety (CAHFS) laboratory in Davis. Milk samples must be collected within 7 days prior to movement and results will be provided within 3 days of arrival at the lab. A premise location number is required for submission. CDFA has summarized new requirements on its HPAI homepage.
Cattle samples originating in other states would be submitted to a to a National Animal Health Laboratory Network (NAHLN) lab in that state. USDA will pay for the cost of testing, but the cost of sample collection and submission are the responsibility of the owner. Similar testing of non-lactating dairy animals (youngstock and dry cows) may also be required in the future. Lactating dairy cattle moving interstate direct to slaughter are exempted from testing, but will still require a Certificate of Veterinary Inspection, CVI or “Owner Shipper Statement.” Questions about testing can be answered by your herd veterinarian or your local CDFA district office.
Producers should ensure employees don’t consume raw milk.
The virus’s genetic sequence is similar between cattle and wild birds found on affected farms, barn cats, and the single human case in a Texas dairy employee. CDC has released interim guidance for employees working on infected farms. Producers are advised to ensure employees don’t consume raw milk. The FDA and CDC continue to warn of the danger of consuming unpasteurized milk.
Different parts of the county experience peak migration at different times and producers can check the BirdCast website for local predictions. About 80% of migration occurs at night, so early morning is a good time to spot waterfowl when they are looking for a place to rest after long night of flying.
Since the initial detection of the current HPAI H5N1 in 2021, the program has been tracking the prevalence of the virus in wild birds. During this time the program has tested over 84,000 wild bird samples and has found that viral detection peaks during the fall (north-to-south) migration. This potentially could be due to younger, disease-naïve birds flying for the first time in the fall.
Right now, during the south-to-north spring migration, positive viral samples from wild birds are infrequent. Since early March the program has tested over 1,600 samples across the U.S. and only 12 have been positive. Importantly however we can expect an increase in viral detection starting around September.
Wild Bird Deterrence on Dairies
Brian Popper is a wildlife biologist and a District Supervisor for USDA’s Wildlife Services, a program that helps with issues involving problem wildlife. His central message was that there was no “Silver Bullet” for nuisance birds. Rather, effective wild bird control was more like Integrated Pest Management (IPM) for fly control: habitat needs to be addressed in addition to direct control. Popper also highlighted that nuisance bird control needed active management to remain effective.
Popper explained that there was no “one-size-fits-all” control program; each animal facility needs a control program tailored to it. Developing an effective program starts by identifying the type of bird species causing damage and when and how birds are interfering with the farm operation. Before USDA can authorize the use of a poison, non-lethal methods will need to be employed.
Non-lethal methods can include both feed storage/management changes as well as roosting exclusion such as spike strips hardware cloth. Other non-lethal methods include harassment techniques such as balloons, predator decoys/recordings or propane cannons. Birds can learn to skirt exclusion methods however and can become habituated to harassment methods. For this reason, a control program must be constantly monitored for effectiveness and updated as needed.
If non-lethal management, exclusion and harassment methods do not adequately control nuisance birds, the USDA can issue a permit for the use of a poison for non-protected species such as Starlings and Sparrows. When and how such an avicide can be applied will be specified in the permit to protect certain protected species such as migratory waterfowl and Tri-colored blackbirds. Producers needing help developing a wild bird control program or acquiring permits can contact their local USDA Wildlife Services district.
Fighting HPAI: Lessons from the Poultry Industry.
The final presenter was John Bedell, who has 30 years of experience in the California poultry industry as both a poultry producer and Vice President of Agriculture Operations with J.S. West Milling Company. Bedell shared some hard lessons learned while fighting to keep HPAI off poultry farms since about 2015. While dairy and poultry facilities are different, there are some fundamentals of biosecurity that remain the same. His central message was to start as simple as you can:
“A complicated plan, one dealing with every single aspect of possible contamination becomes overly burdensome and people won’t follow it. The leader of the ship won’t follow it; the hourly employees won’t follow it.”
Bedell suggests producers start by thinking about everything that comes on to the farm and everything that goes out. After you are controlling movement, expect that things are going to change, so be prepared to adapt. Bedell shared photos of how poultry farms managed access, signage, and exclusion to structures, all of which are pertinent to dairy facilities.
He also described deterrents like lasers, decoys, and balloons, which may be helpful, especially with migratory water fowl. He emphasized that for smaller birds like sparrows and finches, knocking down nests and exclusion efforts are essential to “reclaiming” areas they are habitually using. Rodent control is also important, since rodents can attract raptors that can also carry HPAI.
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