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Vaccines for Avian Influenza Virus

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发表于 2-25-2023 13:39:36 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式
本帖最后由 choi 于 2-25-2023 13:40 编辑

Patrick Thomas, America Is Losing Bird-Flu Battle; Farmers fear the poultry-killing avian influenza isn't going away anytime soon. Wall Street Journal, Feb 24, 2023, at page A1.
https://www.wsj.com/articles/bir ... egg-prices-eb8cced2
(text displayed at bottom)

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(1) Erik Stokstad, Wrestling with Bird Flu, Europe Considers Once-Taboo Vaccines, Science (magazine), 376: _ (May 11, 2022)
https://www.science.org/content/ ... once-taboo-vaccines

Quote:

"In March, Christian Drouin, a French farmer in the Vendée, discovered that his chickens were dying of avian influenza. He had to take drastic action to cull his flock and prevent the infection from spreading. Normally, veterinarians would arrive to gas the birds with carbon dioxide. But the veterinary teams were overwhelmed with calls to cull flocks infected with the virus, now apparently endemic in Europe.  So Drouin was advised to switch off the ventilation fans in his poultry buildings. As the temperature rose, most of his 18,000 birds died of heat stroke [around 40ºC (104ºF)] over several hours. The next day, his neighbors helped him bury the carcasses.

"Seeking to stamp out the highly pathogenic H5N1 strain of avian influenza, France and other countries have been culling record numbers of poultry—more than 16 million birds since December 2021 in France alone. Last year, the cost there exceeded €150 million.

"The United States has not authorized the use of avian influenza vaccines because of the trade [export] implications, hoping culling will stop its current outbreak.

"The risk for the European Union and United States, although low, is probably the highest since H5N1 emerged 25 years ago, [Richard] Webby[, Richard Webby, a virologist at St Jude Children's Research Hospital (based in Memphis, Tenn),] says.

"In an encouraging sign, vaccines have lessened the impact of recent outbreaks, at least in China. In 2017 the country began mandatory vaccination of poultry against an H7N9 strain that was able to spread to people. Vaccination slashed the prevalence of the virus in poultry and the number of human infections dropped to zero. * * * And the United States continued to accept Chinese poultry products * * *

"Still, the virus strain now in Europe, H5N1, can be difficult to control with vaccines because it infects many species [called 'reservoirs' in epidemiology; therefore, the same virus can be reintroduced into farms from the wild; vaccinated farm chickens are not protected from mutations], including ducks, whereas H7N9 is chiefly a problem in chickens, Webby says. And economics may favor culling for sporadic [universal vaccination increases costs in labor and vaccines] outbreaks.

"One vaccine, Volvac Best, is made by Boehringer Ingelheim and already used in countries outside Europe, including Mexico and Egypt * * * Ceva created the other vaccine * * *

"After farmers vaccinate flocks, they'll need to make sure the virus isn't circulating silently in any birds that were missed or didn't respond fully to a vaccine. They will need to swab birds and test for the virus [chickens tested positive still need to be culled]

Note:
(a) Boehringer Ingelheim
https://en.wikipedia.org/wiki/Boehringer_Ingelheim
(i) The German surname Böhringer came from names of three places of the same spelling. The g in Böhringer is pronounced same as that in English verb go.
(ii) Working on Disease Control. Boehringer Ingelheim, undated
https://www.mea.boehringer-ingel ... ing-disease-control
("Volvac® is the umbrella brand of the Boehringer Ingelheim Animal Health poultry vaccine range"/ table: Indication: "Various viral and bacterial diseases in poultry")
(iii)
(A) B.e.s.t. or B.E.S.T. stands for "Baculovirus Expression System Technology."
(B) The baculovirus (etymology: Latin noun neuter baculum rod, stick; describing virus shape) infects insects.
(b)
(i) Ceva Santé Animale
https://en.wikipedia.org/wiki/Ceva_Santé_Animale
(table)
has an American subsidiary "Ceva Animal Health."
(ii) French-English dictionary:
* santé (noun feminine; from Latin noun feminine sānitās health): "health"
https://en.wiktionary.org/wiki/santé


(2) Bird Flu Alarm Drives World Towards Once-Shunned Vaccines. Reuters, Feb 17, 2023
https://kfgo.com/2023/02/17/bird ... e-shunned-vaccines/
"CASTELNAU-TURSAN, France (Reuters) -- * * * Most of the world’s biggest poultry producers have resisted vaccinations due to concerns they could mask the spread of bird flu and hit exports to countries that have banned vaccinated poultry on fears infected birds could slip through the net.  But since early last year, bird flu, or avian influenza, has ravaged farms around the world, leading to the deaths of more than 200 million birds because of the disease or mass culls, the World Organisation for Animal Health (WOAH) told Reuters. * * * China, which consumes most of its poultry production domestically, has been vaccinating against avian influenza for nearly 20 years and has managed to sharply reduce outbreaks.  But the biggest producer of poultry meat in the world, the United States, is holding out for now [on avian flu vaccine].  The United States has been hit hardest worldwide in the latest outbreak with a toll of more than 58 million birds in the past year, followed by Canada, while France has suffered the most within the EU, WOAH data showed. * * * Brazil, the world’s largest poultry exporter, has so far avoided an outbreak – and the need for vaccines * * * France, which spent 1.1 billion euros ($1.2 billion) last year compensating poultry farmers for their losses")


(3) Vincent Guyonnet and Andew R Peters, Are Current Avian Influenza Vaccines a Solution for Smallholder Poultry Farmers?  Gates Open Research 4: 122 (2020)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7578560/
("vaccination of poultry has only been added as a control tool since 1995 * * * Vaccination along with other measures has been successful in eradicating AI in very few countries where the competence of national veterinary services (e.g. France, the Netherlands) or the geography and bird density (Hong Kong) have favorably contributed to the outcome. In the four countries (China, Egypt, Indonesia and Vietnam) where massive vaccination campaigns have been initiated since 2004 (accounting for more than 99% of the use of AI vaccines [in the world])' )

(4) My comment:
(a) Annual flu shots for humans are not meant to protect recipients from AVIAN influenza virus (that occasionally jumps to humans but rather human influenza virus that transmits among humans).
"Many poultry flu vaccines protect birds from serious illness and death but do not prevent them from transmitting [shedding] the virus." from the Web. This is one criticism against vaccination of domestic fowls (chickens, dicks and turkeys), swines and si on with flu vaccines/
(b)
(i) "Although other strains of avian influenza viruses (AIVs) are likely to have infected humans from time to time, the most well-known strains to cause infection are H5N1 and H7N9." from a medical journal.
(ii) The 1918 Spanish flu (in humans) was H1N1.
(iii) Avian flu kills chickens almost 100%, because the virus not just infects respiratory tract, but brain, heat, liver and spleen also.
(iv) "Many poultry flu vaccines protect birds from serious illness and death but do not prevent them from transmitting [shedding] the virus." from the Web. This is one criticism against vaccination of domestic fowls (chickens, dicks and turkeys), swines and si on with flu vaccines/
(c) However, flu vaccines for humans and fowls are similar in almost every aspect. In humans, flu vaccines induce immunity from 10 to 60% of vaccine recipients, depending on whether predictions for coming vaccines are more or less correct. And some people simply do not respond to certain vaccines (or medications, for that matter). If a vaccine does not induce immunity in some recipients, they will get flu and infect others. Even for those have immunity, they can still be infected and contagious -- but not as serious or long in duration compared with those not vaccinated. Think Covid-19 vaccines. But one can not kill those people who do not respond to vaccination, as one will do chickens.



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 楼主| 发表于 2-25-2023 13:41:02 | 只看该作者
本帖最后由 choi 于 2-26-2023 13:47 编辑

-----------------------WSJ
After losing eight million egg-laying hens to avian influenza in 2015, Versova Management Co. spent tens of millions of dollars on laser systems, sound cannons and on-site worker showers to shield flocks from the virus spread by wild birds.

Versova lost another two million or so hens in the latest outbreak, showing the limits of costly industry protections.

“We’re fighting an epic battle,” said J.T. Dean, president of Versova, one of the five largest U.S. egg producers. “We have to be perfect.”

The avian flu has a nearly 100% mortality rate in chickens, according to the Centers for Disease Control and Prevention. It is so contagious that even a chance gust of wind can carry wild-bird droppings toward a barn vent and spread the virus inside, Mr. Dean said. Poultry farms routinely destroy entire flocks after a single case is found to try to prevent further spread.

Since February of last year, the avian flu has led to the death of around 58 million farm-raised birds in the U.S., the deadliest outbreak on record. It sent the price of turkey to record highs for Thanksgiving. Weeks later, egg prices hit their high.

Avian flu outbreaks have long been a risk in the chicken, turkey and egg businesses. In the past, though, the outbreaks subsided after a few months, easing price spikes. Some government officials, scientists and poultry industry executives now say the avian flu is likely to stick around, potentially keeping egg and turkey prices elevated for the foreseeable future.

The loss of poultry flocks to bird flu coincided with a broad rise in the cost of labor, en- ergy and livestock feed, squeezing consumers with higher grocery store prices.

More than 43 million egg-laying hens have died in the past year, making up about three-quarters of the total number of poultry lost. U.S. egg inventories were 29% lower in the final week of De- cember than at the start of 2022, according to the Agri- culture Department. The shortfall sent wholesale prices of Midwest large eggs to a record $5.46 a dozen in December, according to research firm Urner Barry.

Smaller egg producers, facing rising costs and the threat of new outbreaks, have been hesitant to restock farms at full capacity, also crimping supply, industry analysts said.

Large egg producers including Versova and publicly traded Cal-Maine Inc., egg processor and agriculture giant Cargill Inc., and family-run Hickman's Egg Ranch Inc., are all ramping up protections to try to limit their losses.

The virus can be spread to commercial flocks by workers stepping on wild-bird feces outside of a barn and spreading the virus inside with every step. Buzzards, wild ducks or pests that sneak into barns also can  
spread the flu virus through mucus or saliva.

Egg farms now have procedures for washing and disinfecting trucks carrying feed to the chickens. They have upgraded barn ventilation and require workers to wear jumpsuits and booties.

Some farms are going as far as installing loud motion-detecting alarms known as sound cannons and brightly illuminated laser systems to shoo away wild birds without harming them. Workers have installed netting over lagoons and other spots where wild birds gather.

Bird-flu cases in commercial flocks slowed in January, with fewer than 500,000 bird deaths in January compared with more than 5 million in December, USDA data show. But agency officials have said the virus will likely resurge in spring, when wild birds migrate across the U.S.

"The threat of continued infection is out there," said Glen Hickman, chief executive of Hickman's Egg Ranch in Arizona. "We're going to have to develop a way to cope."

Guard the henhouse
Versova, based in Sioux Center, Iowa, has about 17 million egg-laying hens, making it one of world's largest egg processing companies.

Criag Rowles, who oversees Versova's protocols for disease prevention, said the company has been upgrading its farm facilities to defend against outbreaks. Barn complexes are being built with protective barriers and entryways.

Farmworkers entering Versova facilities are required to shower and change into freshly washed clothes before going inside the barns.

During the avian flu out break in 2015, only one of Versova's facilities was equipped with showers and other biosecurity measures. Since then, the company has upgraded 10 of its 13 facilities.

The company also has hired veterinarians and changed practices for cleaning feed spills to keep away wild birds. It installed vibrating mechanisms in the containers holding chicken feed to shake loose clogs without involving workers. Even those precautions haven't eliminated outbreaks. Mr. Dean said.

Egg-laying hens are more susceptible to contracting bird flu because they are kept producing for as long as a year, increasing their risk of infection compared with broilers, which are raised for meat and slaughtered within 10 weeks.

Starting this spring, Versova will work with the Agriculture Department's wildlife services to clear the area around barns to make it less attractive to wild birds, company officials said. The project is similar to the USDA joining with airports to clear runways, company officials said.

In October, workers at one of Versova's upgraded facilities in northern Iowa noticed an increase in the number of dead birds in one of the barns, The company called state veterinary officials to swab the birds' saliva for a test.

The test was positive, Mr. Dean said, and all one million birds at the farm were killed. Workers cleared out the dead birds and disinfected every inch of the facilities. Barns were heated to more than 100 degrees for several days to help eliminate the virus.

After the 2015 outbreak, it took Versova a year to restock poultry farms. This time, the Iowa facility reopened in February after the October outbreak, Mr. Dean said.

"We had people that had experience," he said. "We had all of our materials ready to go, all the cleaning equipment, the pressure washers, tape and plastic and sheeting."

The egg industry as a whole also is recovering from bird-flu outbreaks faster than it did eight years ago--roughly three to six months for most farms, compared with six to nine months previously, according the American Egg Board, an industry group.

Mr. Hickman of Hickman's Egg Ranch said his largest facility houses about 4 million cage-free chickens, which are too many chickens in one locale. "We would never do that again,” he said.

New facilities will be smaller, housing about one million birds each, he said, and spaced farther apart to help thwart the threat of continued outbreaks.

In December, workers at one of Hickman's farms in Colorado found dead birds in one of the barns. After test results came back positive for avian influenza, all 300,000 birds at the farm were asphyxiated using carbon dioxide gas.

Mr. Hickman said he suspected that a worker inadvertently spread the virus, possibly on their boots or clothing. To stress vigilance against transmission, the company requires people entering its corporate offices in Arizona to walk through a dry chlorine foot bed to disinfect their shoes, he said.

'It's everywhere'
The previous large-scale outbreak in the U.S. lasted from December 2014 to June 2015 and killed more than 50 million chickens and turkeys. Government officials attributed the high toll to the virus spreading from farm to farm.

In this outbreak, wild birds carrying the virus are responsible for 84% of cases, said Rosemary Sifford, the USDA's chief veterinary officer.

Puddle ducks, which include mallards and pintails, carried the virus to wild-bird breeding grounds, helping spread the bird flu around the country, said John Clifford, a former U.S. chief veterinary officer who oversaw the USDA response to the 2015 outbreak.

"It's everywhere," Dr. Clifford said.

In its latest securities filing. Cal-Maine, the largest U.S. egg producer, said in December that it hasn't had a single bird-flu case and that it was working to mitigate the risk of outbreaks. The company declined to comment.

Merck & Co. and other drugmakers have avian flu vaccines, but they might not be worth the cost and effort to use, said egg-company executives and industry experts. Farmworkers would have to give shots, and likely more than one, to millions of bens that generally produce eggs for no more than a year.

Vaccine use could also disrupt trade. Other countries would have to approve products made from vaccinated poultry, the USDA said. The U.S. is the world's second-largest exporter of poultry meat.

"It's kind of easy to say, Well, we'll vaccinate, and it'll solve the problem," Mr. Dean said. "But the truth is, it's far, far more complicated."

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