To further protect the U.S. livestock industry from the threat posed by highly pathogenic H5N1 avian influenza, USDA has announced that it is taking specific actions with its federal partners to limit the disease’s spread.

USDA’s Animal and Plant Health Inspection Service (APHIS) announced a Federal Order requiring the following measures, effective Monday, April 29, 2024:

Mandatory Testing for Interstate Movement of Dairy Cattle

• Prior to interstate movement, dairy cattle are required to receive a negative test for Influenza A virus at an approved National Animal Health Laboratory Network laboratory.
• Owners of herds in which dairy cattle test positive for interstate movement will be required to provide epidemiological information, including animal movement tracing.
• Dairy cattle moving interstate must adhere to conditions specified by APHIS.
• As will be described in forthcoming guidance, these steps will be immediately required for lactating dairy cattle, while these requirements for other classes of dairy cattle will be based on scientific factors concerning the virus and its evolving risk profile.

Mandatory Reporting

• Laboratories and state veterinarians must report positive Influenza A nucleic acid detection diagnostic results (e.g. PCR or genetic sequencing) in livestock to USDA APHIS.
• Laboratories and state veterinarians must report positive Influenza A serology diagnostic results in livestock to USDA APHIS.

USDA has identified spread between cows within the same herd, spread from cows to poultry, spread between dairies associated with cattle movements, and cows without clinical signs that have tested positive. On April 16, APHIS identified a shift in an H5N1 sample from a cow in Kansas that could indicate that the virus has an adaptation to mammals.

CDC conducted further analysis of the specimen sequence, which did not change their overall risk assessment for the general public, because the substitution has been seen previously in other mammalian infections and does not impact viral transmission. Additionally, the APHIS National Veterinary Services Laboratories found H5N1 in a lung tissue sample from an asymptomatic cull dairy cow that originated from an affected herd and did not enter the food supply.

The novel movement of H5N1 between wild birds and dairy cows requires further testing and time to develop a critical understanding to support any future courses of action, USDA said in a statement, adding that requiring positive test reporting will help the agency better under the disease and testing before interstate movement will limit its spread.

The agency has not found changes to the virus that would make it more transmissible to humans and between people and CDC believe that the current risk to the public remains low.

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It’s somehow fitting that we’ve been reduced to using riddles to explain why the cost of eggs is out of control.

Egg prices, like many grocery items, skyrocketed during the pandemic primarily due to supply chain issues, but remained a cost-effective protein source. While coronavirus cases have stabilized, egg prices have continued increasing to the point that many families have had to cut them out completely, losing access to a breakfast staple and a valuable non-meat source of protein.

According to U.S. Department of Labor statistics, the national average price for a dozen eggs hit $3.59 in November 2022 which is slightly more than double the $1.72 cost per dozen from a year earlier; however, year-over-year data doesn’t give the entire picture on the price of eggs.

Rather than using generic national averages for egg pricing, let’s look at a more complete history of egg prices in Florida, where it just so happens that I shop. Apparently, Floridians have some exclusive chickens living in some pricey neighborhoods providing our eggs. As the pandemic surged in the summer of 2021, a flat of eggs cost between $3.50 and $5.00. A flat contains 30 eggs, or 2.5 dozen, so that’s roughly $2.00 per dozen or 10 to16 cents per egg. These prices align with the national figures noted for 2021, so this is a good starting point. As 2021 transitioned into 2022 in Florida, a flat of eggs more than doubled in price, hitting a $7.00 to $8.00 per flat price range, or about $3.20 per dozen. Still affordable, but noteworthy to shoppers on a budget.

Moving into late 2022, eggs reached a jaw dropping $16.00 per flat in Florida, which is more than $6.40 per dozen, or in excess of 53 cents per egg in comparison with prior prices. Eventually, prices did come down some and, as of February 2023, the current price for a dozen eggs is $4.50, which is definitely better but still much higher than the national average of $3.46 per dozen. Admittedly, most of the data on Florida egg prices is anecdotal and could even be considered an isolated case, but these are real prices paid at a variety of national chain stores in the state over the period indicated.

Assuming the reality for most shoppers is likely somewhere in the range of the two data sets, that is still a massive price increase not fully explained by the pandemic or inflation. With inflation, groceries are up an average of 12%, which doesn’t come close to explaining the increase in egg prices. On a related issue, the price of chicken has not experienced these dramatic price increases, so that leaves us with a single burning question.

What on Earth Happened to All the Egg-Laying Chickens?

I recently came across an article that brought some levity to the egg situation while also shining a light on how the internet has chosen to explain the huge jump in egg prices. Social media users claim to have found a culprit for sky-high egg prices: The chicken feed did it.

Josh Kelety, a writer for the Associated Press, in a February 6, 2023 article (“Fact Focus: Egg Shortage Breeds Chicken-Feed Conspiracies”) wrote that social media users on Facebook, TikTok, and Twitter were reporting that their backyard hens had slowed down or stopped laying eggs. While this can be a common occurrence during the shorter days of winter, no one seemed to accept this train of thought as an explanation. Instead, social media users began speculating that common chicken feed products were the cause of the reduced production. Curious, I wondered whether they may be onto something that should be investigated by product testing to look for contamination; however, I soon remembered that this was social media, not a scientific journal, which meant that somebody was going to come up with a conspiracy theory instead of a scientific solution.

Kelety goes on to say that some users went further and suggested that feed producers had intentionally made their products deficient to stop backyard egg production, forcing people to buy eggs at inflated prices. The fact that commercial feed producers and egg producers are often vertically integrated entities doesn’t seem to affect their theory, as one Facebook user wrote in a post shared more than 2,000 times: “One of the largest egg producers in the country cut a deal with one of the largest feed producers in the country to change their feed formula so it no longer contains enough protein and minerals for your chickens to produce eggs. They are now price gouging eggs to make bank.”

Certainly, feed quality can affect hen egg-laying abilities; however, no widespread issues with feed or feed affecting egg production were reported in the article, and several major feed suppliers contacted by Kelety said they had not changed their formulas.

I did find a notice for a February 5, 2023 Purina prescription pet food recall due to elevated vitamin K levels in a dry dog food product. The symptoms of vitamin K toxicity in dogs are similar to some of the reports on social media; certainly, it’s at least possible backyard hens would eat dry dog food if accessible

There are other factors that can have a negative impact on egg production. For example, the amount of light chickens are exposed to can affect egg production—chickens are sensitive to lengthening daylight that triggers laying to increase. The amount of light laying hens receive is manipulated using artificial light, so those lights you see in chicken houses late at night are not there because the birds are insomniacs.

The group discussing egg prices on social media may have inadvertently identified a product that was eventually recalled, but instead chose to create a baseless theory to blame the feed guys. So, before another conspiracy theory is born, let’s look at the most likely cause for the painfully high egg prices.

Truth Versus Conspiracy

For several months, U.S. officials have been battling a bird flu outbreak that could break existing records. In December 2014, the National Wildlife Health Center detected HPAI viruses of Asian origin in wild waterfowl in the state of Washington. By the end of 2015, losses associated with this outbreak exceeded 50 million poultry, resulting in more than $3 billion dollars in economic impacts.

A map of confirmed detections in North America. Credit: U.S. Geological Survey

The wild migrating bird population is monitored year-round for the presence of strains of bird flu that could decimate domestic poultry flocks if not caught early. The virus spreads easily in bird populations through droppings or the nasal discharge of an infected bird, which can contaminate dust and soil and be carried onto farms on boots and clothing or on truck tires. If a single case is detected, any domestic flocks that could have potentially come into contact with an infected bird must be destroyed.

According to data from the Centers for Disease Control and Protection, more than 58 million birds have died or were depopulated so far in the 2021-2023 ongoing outbreak. Of the total birds affected, nearly 43%, or almost 29 million of those lost, have been laying hens.

That’s a lot of chickens no longer laying eggs.

This is the most probable reason for the ongoing high cost of eggs, and prices should continue to fall as producers work to replace the birds lost in the outbreak.

Wester is the professional industry editor for Food Quality & Safety. Reach her at fqseditor@pawesta.com.

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The Nebraska Department of Agriculture, in conjunction with USDA’s Animal Plant Health Inspection Service, announced this week that more than 1.8 million chickens would need to be killed after bird flu, caused by the H5N1 highly pathogenic avian influenza (HPAI) strain, was discovered on an egg-laying farm in Dixon County.

Roger Dudley, the department’s state veterinarian, noted in a statement that the affected flock will be depopulated and disposed of in an approved manner. Additionally, the department will establish a 6.2-mile control zone, as is USDA policy, around the affected premises.

Overall, Nebraska has seen 6.8 million birds on 13 farms impacted, second only to Iowa’s 15.5 million birds killed earlier this year. NDA is encouraging bird owners to prevent contact between their birds and wildlife and to practice strict biosecurity measures.

Additionally, the Oregon Department of Agriculture announced last week that bird flu was found in a non-commercial flock, resulting in a flock of 20 chickens being killed, and The Utah Department of Agriculture and Food has found HPAI in a flock of backyard chickens in Utah County and a flock of game birds in Iron County.

These are just the latest outbreaks of the disease, which has already been responsible for the slaughter of 52.3 million birds (both chickens and turkeys) in 46 states, according to USDA, which added that this is the worst toll on the poultry industry in seven years. That outbreak, in which more than 50 million birds were killed during 2014-2015, was driven by farm-to-farm transmission, while this current outbreak is being driven by wild birds.

According to the CDC, the public health risk associated with these avian influenza detections in birds remains low. The high number of birds killed offers little risk to U.S. consumers, as infected birds aren’t allowed to enter the nation’s food supply, and heating poultry and eggs to an internal temperature of 165 ˚F is recommended as a general food safety precaution.

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The USDA’s Animal and Plant Health Inspection Service (APHIS) is taking immediate action to ensure a rapid response to a highly pathogenic avian influenza (HPAI) outbreak in the United States.

Tom Vilsack, USDA Agriculture Secretary, approved the transfer of approximately $263 million from the Commodity Credit Corporation to APHIS to directly support the response, which allows APHIS to continue the critical work with state and local partners to quickly identify and address cases of HPAI.

As of May 12, the virus has been confirmed in 29 states, impacting more than 33 million domestic birds, with the latest positive tests coming in Oregon, Washington, Vermont, Alaska, and Oklahoma. The virus was initially detected in a flock of pheasants earlier this year.

Agriculture and avian flu expert Chris Helm, executive vice president of global business at Longhorn Vaccines & Diagnostics, notes that USDA is expanding its surveillance of wild birds with the goal of preventing new cases from entering the poultry population, or at least tracking where new cases appear. This way, the agency can get ahead of any new cases and take action before it’s too late.

“Wild birds are the carriers of avian flu and carry it from farm to farm, which is why we’re seeing an uptick in avian flu among the U.S. poultry population,” he tells Food Quality & Safety. “If the USDA is able to track how the virus is spreading, they have the opportunity to get ahead of any new cases.”

This is critical, because the virus kills birds and often necessitates flocks be culled, which affects both the U.S. egg supply and the broilers and turkey supply. This could lead to inflation on these products or scarcity unless the virus is tamped down.

So, testing in both wild birds and chicken and turkey flocks is expanding, and remains a critical part of tracking the spread of the virus and preventing new cases. “Early detection can prevent spread, and we don’t want to see the virus jump from bird and poultry to humans, which we saw in the early 2000s,” Helm says.

“Highly pathogenic avian influenza is a serious concern for our nation’s poultry industry, and we need to continue our nationwide response to minimize the impact,” says Jenny Lester Moffitt, USDA’s undersecretary for marketing and regulatory programs. “The agency’s actions during this ongoing emergency serve to safeguard U.S. poultry and egg producers and reduce the effects of avian influenza on agriculture and trade, while also enhancing readiness for other animal health emergencies.

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On February 14, USDA’s Animal and Plant Health Inspection Service (APHIS) confirmed the presence of highly pathogenic avian influenza (HPAI), or bird flu, in birds in two states—a flock of commercial broiler chickens in Fulton County, Ky., and a backyard flock (non-poultry) in Fauquier County, Va. In response, more than 100,000 birds have been culled in an effort to contain the spread.

“It’s definitely considered a period of high risk now that we have a confirmed case of highly pathogenic avian influenza in the commercial poultry industry,” Dr. Denise Heard, vice president of research for the U.S. Poultry & Egg Association, said in a statement. “I feel positive that we can tackle this situation better and I have my fingers crossed that this will be an isolated case; however, I would [say to] hope for the best and be prepared for the worst.”

Over the course of the following nine days, APHIS confirmed additional cases of the disease in Dubois County, Ind.; New Castle County, Del.; Webster County, Ken.; Suffolk County, N.Y.; and Knox County, Maine. Similarly, tens of thousands of turkeys and chickens have been culled to eliminate the virus.

Catie Beauchamp, PhD, a microbiologist and vice president of food science, quality, and safety at ButcherBox in Greeley, Colo., says that outbreaks of bird flu occur due to the migratory flight pattern of water fowl and that it has a cycle similar to the seasonal flu, with different strains and transmission rates that change from year to year. “Bird flu is primarily an animal health issue,” she says. “Infected animals do not enter the food supply, [and] therefore HPAI is not a food safety issue. The risk to human health is very low, as human-to-human transmission is very low. Poultry workers are the most at risk, but even then, the risk is still low.”

She noted that bird flu can’t be eradicated because it is a virus carried by wild, migrating birds.

The response, says Dr. Beauchamp, involves robust monitoring, testing, and transmission mitigation. “Biosecurity measures are already in place,” she adds, “and once the risk is heightened in an area, industry partners look for any changes in animal behavior to increase the monitoring and testing—whether that’s decreased water intake, lack of appetite, etc.”

One only needs to look back seven years to 2015 to see how significant a problem the bird flu can be. A large spread of the virus resulted in the culling of 50 million birds across 15 states, with a cost of almost $1 billion to the federal government. “Since the 2015 outbreak, APHIS has been very purposeful about the preventive measures they take in seeking out and testing wild flocks in high-risk areas,” Dr. Beauchamp says. “This is an event that, in some cases, is expected, so being prepared is key,” adding that the learnings from the 2015 outbreak have helped the industry to be better prepared.

The 2015 outbreak also caused prices for eggs and turkey to increase substantially, with eggs costing up to 61% more and boneless, skinless turkey breasts increasing as much as 75%.

At the current frequency and scale, Dr. Beauchamp notes that these bird flu confirmations won’t impact supply in a significant way that will impact cost, and that widespread shortages will likely not occur. However, she notes that the outbreak will put pressure on an industry that is already stressed due to worker shortages and supply chain challenges from the pandemic.

“There is a short replenishment cycle for birds, so even if there are flocks that have to be depopulated, producers can catch up more quickly,” she adds. “It would take extreme depopulation to impact the consumer and, from an industry standpoint, we do not expect to see the fallout we saw in 2015.” She adds that producers that have prepared their systems to be able to identify and confirm cases quickly, depopulate as needed, and move on will have limited hurdles compared with those who are not prepared from a biosecurity standpoint.

The Centers for Disease Control and Prevention noted that these new HPAI detections currently do not present an immediate public health concern as no human cases of the avian influenza viruses have been detected in the U.S.

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Earlier this month, the USDA Animal and Plant Health Inspection Service (APHIS) confirmed the presence of highly pathogenic H7N3 avian influenza (HPAI) in a commercial turkey flock in Chesterfield County, South Carolina. At press time, no new detections had been found since April 8. The outbreak was the first confirmed case of HPAI in commercial poultry in the United States since 2017.

“There was increased mortality in the flock, so samples were taken from several birds,” says Michael Stepien, BS, public affairs specialist for USDA APHIS in Riverdale, Md. “When birds on a premise test positive for HPAI, all of them must be depopulated to stop the virus’ further spread.”

Initially, APHIS found low pathogenicity avian influenza infections in 12 premises. Then, the low-path virus mutated and became a highly pathogenic strain which infected an additional premise. To ensure the safety of birds across the country, state officials quarantined the affected premises and approximately 346,012 birds were depopulated from all 13 premises, Stepien says.

At press time, APHIS had completed its surveillance of the area. No new human cases of H7N3 virus had been detected and there wasn’t any public health concern. “Birds from the affected flocks did not enter the food supply, and there is no safety concern at this time,” Stepien says.

The organization stressed, however, that it was important for both commercial and backyard poultry owners to be vigilant with their biosecurity practices to ensure they prevent the spread of avian influenza, Stepien says.

In commenting on the outbreak, Beth Breeding, vice president of communications and marketing for the National Turkey Federation in Washington, D.C., says the organization’s biggest concern was animal health and making sure the situation was contained to prevent other flocks from being impacted. “The joint actions by state and federal officials, as well as the grower and integrator, to quickly address the situation gave us the best possible chance of limiting its impact,” she says.

In a statement regarding the outbreak, Joel Brandenberger, president of the National Turkey Federation, stated, “Thorough disinfecting and cleaning procedures were initiated on premises as well as surveillance of commercial flocks in the surrounding area.”

Breeding believes that USDA and everyone else involved handled the case correctly. “APHIS officials and animal health officials in South Carolina responded quickly and appropriately to identify the problem, depopulate the flock, and monitor nearby flocks,” she says.

“This case is a textbook example of the effectiveness and importance of continuous monitoring to quickly identify and mitigate any potential animal disease issues,” Breeding continues. “Additionally, it highlights the work APHIS has done to implement a strong response plan to these types of cases.”

Concludes Breeding, “The public can continue to have complete confidence that the poultry industry is working hard to ensure that safe, nutritious products are available to consumers.”

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As the U.S. poultry industry begins a slow recovery from what some are calling the worst outbreak of avian flu the country has ever experienced, the USDA, recently announced that rodent presence in poultry houses, as well as sharing of equipment between infected and non-infected farms, were among several causes behind the spread of the virus.

The federal government expects to spend $191 million to pay chicken and turkey farmers for birds lost to avian flu according to U.S. Secretary of Agriculture Tom Vilsack, who says that’s in addition to the nearly $400 million spent on cleaning up dead birds and disinfecting barns. The government also is paying to research and stockpile a bird flu vaccine.

Commercial poultry facilities are an ideal rodent habitat as they provide everything they need to survive and thrive, such as unlimited amounts of food, water, and shelter. Furthermore, because of their habits such as contact with garbage and sewer systems, rodents can intensify or accelerate disease outbreaks with their droppings, fur, urine, or saliva. Lastly, rodent presence in food sources results in major losses with some experts estimating that these pests destroy enough food each year to feed 200 million people.

As several rodent species, including the house mouse, Norway rat, and roof rat are commonly found in and around farms, it’s imperative poultry farmers know how to control these species to prevent spread of disease, such as the avian flu, and contamination of poultry and eggs.

Finding the Rodents
Infestations often can go unnoticed because rodents living in farm facilities tend to be most active just after dusk and right before dawn. But since mice produce between 30 to 100 droppings a day and rats about 30 to 50, droppings are one of the most common signs of an infestation.

Before implementing rodent-proofing methods, it’s important to conduct regular, visual inspections of the premises for droppings, tracks, burrows, pathways, fresh gnaw marks, as well as live and/or dead rodents. If rodents are seen repeatedly during the day, it indicates an established infestation. According to the Mississippi State University Extension Service, there are fairly reliable guides to determine rodent populations, which include:

• Observed signs, but no rodents seen: 1 to 100 on the premises;
• Occasional sightings at night: 100 to 500 on the premises;
• Nightly sightings and occasional daytime sightings: 500 to 1,000 on the premises; and
• Several seen during the day: up to 5,000 on the premises.

Rodent-Proofing Poultry Facilities
As noted in the USDA avian flu report, cross-contamination of equipment and rodent presence were partially responsible for the transmission of the virus, placing even greater significance on sanitation and maintenance of poultry houses. Considering most rodents enter the barn directly from the fields, it’s important to eliminate any vegetation within a 3-foot area around buildings they can use as hiding spots. Additionally, poultry farm personnel should clean up spilled feed on a regular basis, keep all feeds in rodent-proof bins or covered cans, remove loose wood and garbage, and eliminate any areas that can be used by rodents as hiding and nesting spots, such as loosely piled building materials or old feed bags.

Similarly, farmers should regularly inspect the premises for cracks around door frames, under doors, broken windows, water and utility hookups, and vents and holes surrounding feed augers as all can be used by rodents to gain entry into the facility. It’s advisable to use coarse steel wool, hardware cloth, or sheet metal to cover any entrances instead of plastic, wood, or insulation since rodents can easily gnaw through such materials. In addition, after eliminating food and shelter, farmers need to eliminate water sources such as leaky taps, open water troughs, and open drains. Without readily available food and water, rodent populations cannot expand.

As elimination of rats and mice from poultry facilities is extremely difficult, implementing significant prevention efforts is the best way for poultry farmers to prevent any and all rodent-related disease outbreaks and contaminations. However, any signs of a problem can and must be quickly addressed through a population-reduction program designed and executed by a professional pest control company with extensive experience in servicing farm facilities.

Mannes is vice president of public affairs and Dr. Fredericks is chief entomologist and vice president of technical and regulatory affairs for the National Pest Management Association. Reach Dr. Fredericks at jfredericks@pestworld.org.

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Image Credit: Bioo Scientific

Avian influenza is a major health and economic risk throughout the world. For example, the most notorious influenza epidemic, the Spanish Flu of 1918, caused the death of 20 to 50 million people worldwide. The avian influenza virus (bird flu) has been detected in six western states in the U.S., British Columbia, Asia, and Europe since the beginning of December. This disease is caused by certain strains of the influenza A virus, a type of highly infectious, negative sense, single-stranded RNA virus. Bird flu virus can be intermittently detected in chicken and turkey flocks in many parts of the world. These viruses can sometimes infect humans in food production sites and rapidly mutate to produce strains capable of causing global pandemics.

The World Health Organization (WHO) states that the primary risk factor for human transmission is exposure to live or dead poultry or contaminated environments in farms and animal markets. Additionally, the U.S. FDA says transmission is possible by exposure to environments contaminated by infected birds. It is transmitted by saliva, feces, and nasal secretions of infected birds. While the virus is generally located in the gastrointestinal and respiratory tracts of infected animals, it can also be found in the meat of infected birds. Avian influenza virus can also be located outside surface shell or within the interior of chicken eggs. According to the FDA, avian influenza is not transmissible by eating poultry or eggs that have been prepared properly and the chance of infected poultry or eggs entering the food chain is extremely low because of the rapid onset of symptoms as well as the safeguards in place. However, because of the devastating economic consequences of avian flu to poultry producers and the potential zoonotic hazards presented by exposure to infected birds, avian influenza is a major disease concern to poultry producers and human health officials alike. A great deal of time, effort, and expense is expended each year in curtailing the spread of avian influenza in chicken and turkey farms worldwide.

Individual strains of avian influenza viruses are classified according to the specific structures of two antigens, hemagglutinin (H) and neuraminidase (N), on the viral surface. These antigens control virus-host cell binding interactions during infection. Different virus strains possess different pathogenicity and zoonotic characteristics and can be classified into two different types: weakly pathogenic strains and highly pathogenic strains.

While weakly pathogenic strains of avian influenza can adversely affect poultry (chicken and turkey flocks), the more deadly highly pathogenic strains can cause tremendous economic damage to poultry farms and, more importantly, pose a direct threat to human health by occasionally crossing over the “species boundary” to infect and sicken humans. Highly pathogenic strains tend to be of type H5 and H7 and can rapidly infect an entire flock, killing 100 percent of the birds in less than 48 hours, according to WHO; infection can easily destroy an entire flock and threaten neighboring farms in the region. Some highly pathogenic strains, called zoonotic strains, can be transmitted to humans; these strains also usually possess the H5 or H7 subtype of hemagglutinin antigen. It is important to note however that some H5 and H7 avian influenza strains can possess low pathogenicity at first and gradually mutate to high pathogenicity forms. A minority of avian flu strains can be transmitted from birds to humans. These strains are most problematic since zoonotic strains, such as H5N1 and H7N9, can put farm workers’ health at risk and trigger global human influenza pandemics.

Measures to Detect and Control

The serious disease risks posed by poultry farming have created a need to prevent, detect, and control the spread of avian influenza throughout poultry farming regions and into the human food supply chain. The rapid mutation rates of the influenza virus make effective implementation of these control measures especially challenging.

Vaccination. Over the years, there have been numerous efforts to vaccinate poultry against bird flu to prevent infection or spreading of the disease. However, these programs have been generally unsuccessful and actually may hasten the evolution of more pathogenic influenza strains.

Improved sanitation and hygiene. Influenza is spread between birds through contact with feces as well as saliva and nasal secretions. Considerable reductions in the rate of spreading of influenza are achieved in farms and throughout neighboring farms through improved hygiene and feces handling techniques. For example, removing soiled shoes or boots after walking through influenza-contaminated areas can help to reduce the spread of the disease within a farm. Thorough cleaning and disinfection of contaminated areas has also been shown to be essential to limit the spread of the disease.

Detection/surveillance. There are a number of approved diagnostic techniques to detect the presence (and subtype) of influenza in bird flocks.

These methods include agar gel immunodiffusion, ELISA (enzyme-linked immunosorbent assay), AGP (alpha acid glycoprotein), ACIA (antigen capture immunoassays), and rtRT-PCR (real-time reverse transcriptase polymerase chain reaction). While a number of these diagnostic assays can be performed using “home brew” methods, a number of influenza assays are commercially-available including FluDetect, Binax, or Directigen.

Between 2006 and 2013, 569,000 flocks of broiler chickens in the U.S. were monitored by the USDA for the presence of either H5 or H7 avian influenza using these diagnostic tests; no samples from these flocks contained H5 or H7 type avian influenza virus.

Culling and quarantining of infected poultry. The adverse economic and human health consequences of the spread of avian influenza through poultry flocks creates a need for drastic measures; accordingly, the appearance of avian influenza in poultry flocks often necessitates the culling of infected birds in flocks and using quarantines to restrict the movement of eggs, poultry, and poultry products within infected areas. This very common practice has been shown to be highly effective at limiting the spread of bird flu in flocks and between farms. However, this practice tolls a heavy economic price on individual affected producers, in some cases all the birds in a large region are culled to eliminate bird flu from an agricultural region. In the case of persistent infections, culling and instating quarantines must be repeated over several years to completely eliminate the virus.

Antiviral drug treatments. Veterinary drugs are highly useful for the control of many diseases in livestock and poultry farms. For example, antimicrobial agents such as antibiotics and anticoccidal drugs are routinely used in poultry farms to combat a wide variety of diseases such as mycoplasmosis and coccidiosis. Several different antiviral agents, such as amantadine and ribavirin, have been shown to have strong anti-influenza virus activity. These drugs inhibit influenza virus replication at different points in the viral life cycle: Amantadine blocks the release of the virus into the cytoplasm from endocytotic vesicles by binding to the M2 channel; and ribavirin, on the other hand, is a nucleoside analogue which blocks viral RNA replication. Consequently, there was a great deal of initial interest in using antiviral drugs to control the spread of bird influenza.

Initially considered to be a useful facet of controlling avian influenza in poultry flocks, farmers sometime treat their flocks with antiviral medications to prevent and control avian influenza. Unfortunately, antiviral drugs are not effective at preventing or in controlling the spread of bird influenza in poultry flocks. It also has been shown to increase the mutation rate of the influenza virus towards higher pathogenicity and increased resistance to antiviral drugs. These changes have greatly reduced the therapeutic efficacy of these drugs in humans, and also created concern that poultry meat products will contain toxic residues of antiviral drugs. For these reasons, governments have banned the use of amantadine and ribavirin antivirals for veterinary use. Nevertheless, there are continued reports that these drugs are still being illegally used to combat bird flu in poultry farms and there is concern that residues from these drugs will adulterate the food supply. In fact, researchers have recently detected amantadine in chicken meat samples using liquid chromatography–mass spectrometry, or LC-MS. These residues pose a hazard to human health and have created great concern among international food safety regulatory agencies regarding the adulteration of poultry food products with antiviral drug residues. This concern has created an imminent need for methods to detect anti-influenza drug residues in poultry and egg products.

Antiviral Drug Detection in Meat

While several analytical methods have been developed to detect the amantadine and ribavirin antivirals, there are only two methods to detect these chemicals in poultry meat: LC-MS and immunoassay. While LC-MS methods work quite well for low-throughput meat sample testing applications, they have significant limitations that reduce their usefulness for routine and cost-effective sample analysis required to screen the world’s poultry meat and egg supply, these include:

• Expense and time: LCMS instrumentation can be expensive and operation requires considerable time for sample preparation and to perform the actual test;
• Throughput: Each instrument can only test one sample at a time; and
• Operator skill: A high degree of technical skill is required to perform LC-MS assay methods as well to perform maintenance on the instrument.

Immunoassays utilize the binding power and specificity of antibodies to overcome the practical limitations of LC-MS methods for the cost-effective detection of amantadine and ribavirin in chicken and turkey products.

Antivirals and Immunoassays

Immunoassays present many powerful benefits for the screening for antiviral drug residues in food samples. They are rapid and inexpensive to perform. ELISA immunoassays are used in microwell plates so many assays can be performed simultaneously. The highly specific nature of the detection minimizes the need for extensive sample preparation while allowing detection at very low levels similar to those achievable with LC-MS techniques.

Because of the recent use of amantadine to try to prevent bird flu in flocks and the danger it poses to the food supply, Bioo Scientific has developed an ELISA assay to detect amantadine in poultry products, including meat and eggs. The MaxSignal Amantadine ELISA Test Kit, with detection limits of 0.25 parts per billion (ppb) in poultry meat and 0.5 ppb in egg, is based on a competitive colorimetric ELISA assay. This kit incorporates a rapid sample preparation protocol for the extraction of amantadine from poultry samples. Amantadine residues present in the sample will compete for HRP-conjugated antibodies against amantadine, thereby preventing the amantadine-HRP from binding to the antibody attached to the well. The resulting color intensity, after addition of the HRP substrate (tetramethylbenzidine), has an inverse relationship with the concentration of amantadine residue in the sample. This assay can be completed in less than one hour. The kit is manufactured to the international quality standard ISO 9001:2008 (ISO CI#: SARA-2009-CA-0114-02-A).

In addition, Bioo Scientific is developing an ELISA for the detection of ribavirin in turkey and chicken food products. The ribavirin ELISA kit should be commercially available in the second quarter of 2015.

Dr. Krebs is director of Protein Chemistry and Engineering for Bioo Scientific. Reach him at jkrebs@biooscientific.com.

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