Though prepared, dairy ‘baffled’ by spread of bird flu 

Even though he has been bracing for impacts of H5N1 bird flu since April, Tulare County, CA, dairy farmer Preston Fernandes said it still came as a surprise when milk samples from his farm tested positive for the virus last month. 

His friends from out of state were already dealing with the disease running through their herds. As a precaution, he had tightened biosecurity on his farm months before California confirmed its first bird flu case in dairy cows on Aug. 30. 

“We thought we were being very careful,” said Joey Fernandes, Preston’s dad. “We’re all baffled. How is it spreading?” 

Though the farm has moved mostly younger stock between the six dairy facilities the family operates, Preston Fernandes said none of the animals were from out of state—certainly not from bird flu-infected regions. Despite his preparedness, he said he knew “it was just a matter of time” before his cows caught the bug, considering the rate at which it has moved through Central Valley dairies in recent weeks. 

As the leading dairy state in the nation, California now also has the most bird flu cases in its milking herds. As of Oct. 11, 100 cases have been confirmed. Of the 14 states hit by bird flu in dairy cattle, California is one of two that have reported new infections in the past 30 days. Idaho recorded its last one on Sept. 30. 

Human cases of bird flu affecting Central Valley dairy workers also continue to rise. There have been six such cases confirmed and five presumptive positive cases as of Oct. 14, according to the California Department of Public Health. The workers had direct contact with infected dairy cattle at nine different farms. 

At the Fernandes dairies, four of the facilities have so far been affected, the first of which tested positive on Sept. 24—days before any cows showed symptoms. The dairies were tested because of their proximity to other infected farms. They remain under quarantine, which means heightened biosecurity and limited cattle movement off the farm. 

Preston Fernandes said cows on two of the affected farms began showing clinical signs earlier this month, with one herd exhibiting severe symptoms. It started with five cows, then 10 the next day, and then 60. Some of them have died. 

“This has been a pretty stressful period for us,” he said. “It’s nothing short of a complete disaster.” 

To help identify infected herds more rapidly and slow the spread, the state has ramped up testing, said State Veterinarian Annette Jones. Targeted are those within a 6-mile radius of infected farms. Some 350 dairies statewide are being tested, she noted, with plans to widen the net in the coming weeks. 

Because the dairies being tested are large—with more than 1 million cows being monitored altogether—the state has had to increase the number of dairies tested in priority order, Jones said. Regulatory testing of this scale entails “new logistical approaches to accommodate the number of samples handled,” she said, as tests must be run in an accredited lab with other mandatory steps in place. 

Exactly how the virus spreads from herd to herd is not fully understood. For this reason, dairy farmers say some of the biosecurity measures animal health authorities have asked them to implement may be done in vain. They also say some of the recommendations are simply not practical in real life, especially when dairies already have “all hands on deck” trying to manage sick animals, Preston Fernandes said. 

“It’s a ton of work,” Joey Fernandes said, describing some of the treatments farms are administering, including drenching, in which fluids are pumped directly into a cow’s rumen to keep her hydrated. Dairies are also giving cows aspirin, vitamin B12 and electrolytes to reduce their fevers and promote eating and drinking, so the animals can produce milk. 

Jones acknowledged the lack of scientific knowledge on how bird flu circulates, but she said biosecurity requirements are intended to reduce viral load in the environment so that population immunity can develop safely. That doesn’t mean every cow needs to become infected, she noted. Just a percentage needs to develop an immune response to disrupt spread, she added. 

Though some dairy farmers suspect the virus may be airborne, Jones said it is unlikely because the cow respiratory phase is limited, and the virus has not been isolated in manure, “so great clouds of virus are unlikely.” Of concern is the role birds, flies, mice, cats and other critters play in moving virus around, she said. 

Scientists do know that the virus “has an affinity for the mammary gland,” Jones said. Therefore, biosecurity related to cow movement and movement of contaminated vehicles and equipment will reduce the amount of virus in the environment, she stressed. 

“When a dairy cannot or will not follow them (biosecurity protocols), cows are exposed to higher doses of virus, get sicker and spread virus faster,” she said. “Similarly, if cows are suffering from other stressors, their immune system is suppressed, and they may get sicker when exposed to flu and spread virus faster.” 

The early autumn heat wave has not helped. Preston Fernandes said cows were already tired from the prolonged triple-digit temperatures all summer, with milk production taking a hit. Coupled with bird flu, losses have topped 30%, he estimated. 

Early reports indicate some cows do not return to full milk production even after they recover and are being euthanized or culled at 10% to 15%—higher than previously thought. 

The younger Fernandes said dairy farmers must make challenging decisions about whether to sell animals that can’t “climb back to their profitability metrics.” Heavy culling could result in the cost of replacement heifers—already in short supply nationwide—soaring to new heights, he added. 

Bird flu has also complicated business at auction yards, which are not allowed to sell infected animals. 

With cases in the state soaring and the need to move cattle growing more urgent, Jones said the state has been looking for ways to “create sales channels for healthy cattle from affected dairies through markets, but with separation and oversight.” That means increasing enforcement at auction yards and “looking for safe continuity of business options,” she added. 

The effort remains a work in progress, said Tyson Howze, a representative of Overland Stockyard in Hanford, CA. For this reason, Howze said Overland is accepting only animals from uninfected dairies sold for beef. To be safe, he said the company has chosen to disinfect its premises after every such sale, even though it isn’t required to. With labs backlogged, he said, there’s concern that asymptomatic cattle that might later test positive could be sent unknowingly to stockyards. 

“We don’t have a whole lot of our customers right around here that are infected yet, but that may change,” Howze said. 

Tulare County dairy farmer Joey Airoso, whose farm has not been affected by bird flu, said few protocols have changed on his farm “because we operate a pretty tight ship anyway.” 

He has restricted salespeople who don’t call ahead before coming. Breeders are required to change into a clean set of clothes on the farm. Haulers that transport day-old calves to ranches that raise them must either make his farm their first stop of the day or the farm sends the calves to the ranches. Because his dairy ships full loads of milk, tankers make a one-way trip and return to the milk plant, where the trucks are washed. Feed trucks, however, do go from farm to farm, he acknowledged, and he’s not requiring them to hose off. 

“You can’t put everything into a disinfected bubble,” Airoso said. “It would be impossible.” — Ching Lee, Ag Alert assistant editor, California Farm Bureau Federation