Avian influenza, or bird flu, has public health officials on alert after an unprecedented spread in dairy cows in the United States this year. Four dairy workers have also tested positive in the country.

A particularly severe variant of the H5N1 strain has been spreading around the world in animals since 2020, causing lethal outbreaks in commercial poultry and sporadic infections in other species from alpacas to house cats. Until this year, it had never infected cows.

Different bird flu strains have been found in Australia and Mexico in humans, while different H5 subtypes are also present around the world in both animals and humans, in countries including China and Cambodia.

Most of the human cases reported exposure to poultry, live poultry markets, or dairy cattle prior to infection, but scientists are worried the virus could mutate in ways that make it more easily spread from person-to-person, which could spark a pandemic. The World Health Organization says the risk to people is low at this point.

Below are occurrences of varying types of the bird flu virus that have been found in humans this year.

UNITED STATES:

The first known cases of infected dairy cattle occurred in Texas in March, and is now in dairy herds in 12 states. The U.S. Agriculture Department said tests so far indicate that the virus detected in cows is the same H5N1 virus affecting wild birds and commercial poultry flocks. The four dairy workers who have tested positive for the virus this year had mild symptoms such as conjunctivitis, or pink eye.

The H5N1 virus in the United States belongs to the clade 2.3.4.4b, genotype B3.13, a genotype detected only in North America so far, the European Food Safety Agency said in a scientific report.

MEXICO:

A resident of Mexico died with the first known cases of H5N2 avian influenza in humans, the WHO said on June 5. Mexico’s government said chronic illness, rather than bird flu, was the cause of death. The person had no known exposure to animals.

AUSTRALIA:

The WHO on June 7 said a child with H5N1 bird flu reported by Australia had traveled to Kolkata, India. Genetic sequencing showed the virus was a subtype of H5N1 and part of a strain that circulates in Southeast Asia and has been detected in previous human infections and in poultry.

Australia is separately dealing with three outbreaks of different strains of the virus on poultry farms – H7N3, H7N8 and H7N9 – that authorities say likely arrived on farms via wild birds.

INDIA:

The WHO on June 11 reported a case of human infection with bird flu caused by the H9N2 subtype in a four-year-old child in the eastern Indian state of West Bengal. It was the second human infection of H9N2 bird flu from India following a case in 2019, the agency said. While the H9N2 virus typically tends to cause mild illness, the United Nations agency said further sporadic human cases could occur as this is one of the most prevalent avian influenza viruses circulating in poultry in different regions.

VIETNAM:

Vietnam reported a 21-year-old student had died from the H5N1 bird flu in March. He had no underlying medical conditions, but had been exposed to wild birds from hunting a couple of weeks prior to onset of symptoms. No contact with dead or sick poultry was reported at the time.

Vietnam also reported an outbreak of H9N2 in a 37-year-old man, EFSA said.

CAMBODIA:

The Southeast Asia nation and Vietnam neighbor has reported five human cases of H5N1 as of June 20.

CHINA:

China this year detected human cases caused by the H5N6, H9N2 and H10N3 strains, with two fatal H5N6 cases in the Fujian province. Both of those cases had exposure to backyard poultry before the onset of symptoms, EFSA said.

The case of H10N3 avian influenza was the third one ever reported globally.

GERMANY:

Germany reported a rare outbreak of highly pathogenic H7N5 bird flu on a farm in the western part of the country, near the border with the Netherlands, the World Organisation for Animal Health said on July 4. It was the first outbreak anywhere of H7N5 on WOAH’s public records.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

New Delhi:

The Centre has asked all states to be vigilant for any unusual deaths amongst the domestic birds and poultry, and share the information with the Animal Husbandry Department immediately so that public health action can be initiated as per the national action plan for Avian influenza.

A joint advisory issued on May 25 by the National Centre for Disease Control (NCDC) and Department of Animal Husbandry and Dairying stated that in 2024, four states — Andhra Pradesh (Nellore), Maharashtra (Nagpur), Kerala (Alappuzha, Kottayam, and Pathanamthitta districts), and Jharkhand (Ranchi) — have already reported outbreaks of Avian influenza in poultry.

“Given that Avian Influenza (H5N1) infection is highly pathogenic and has the potential to be transmitted to humans, it is imperative to take all necessary measures to minimize and prevent the spread of this infection,” the joint advisory said.

The Avian Influenza virus (bird flu virus) is normally maintained in circulation in nature among mainly migratory birds and is known to cause outbreaks among domesticated poultry birds probably due to spill over events when migratory birds come in contact with poultry, it said.

The H5N1 is the main Avian influenza virus that has caused multiple outbreaks among poultry globally. Both types of viruses (HPAI and LPAI) may occasionally affect other mammalian species, including humans.

Human infections are primarily acquired through direct contact with infected poultry or contaminated environments, the joint advisory said.

Although there have been sporadic reports in humans and outbreaks among domestic and wild birds, since March 2024, there is a global concern over Avian influenza outbreaks in cattle from multiple states in the US that have resulted in one reported human case of H5N1, the joint advisory stated.

Avian influenza outbreaks from India in poultry have been reported since 2006 and have been jointly investigated by the Animal Husbandry and Health Departments (IDSP, NCDC).

The states and Union Territories have been advised to orient all the health care workers/private practitioners on case definitions, signs and symptoms of Avian influenza.

“Be vigilant for any unusual deaths amongst the domestic birds/poultry in your state, and if observed, please share the information immediately with the Department of Animal Husbandry so that public health action can be initiated as per the national action plan for Avian Influenza,” the joint advisory said.

The states have been advised to strengthen biosecurity measures in all poultry establishments, zoos, poultry markets, etc. after conducting a thorough assessment.

“Comprehensive biosecurity assessments on all poultry farms are recommended. Access to farms should be restricted and stringent hygiene protocols, including the use of disinfectant footbaths and protective clothing, should be enforced. Measures to prevent contact between wild birds and domestic poultry should be implemented,” it stated.

The states have been asked to enhance information, education and communication tools among the general public regarding preventive measures such as minimizing the handling of dead or sick birds with bare hands and without adequate respiratory protection and following food safety measures while consuming products of animal origin.

Besides, they have been asked to be prepared for all preventive measures like stockpiling of an adequate number of antiviral drugs (Oseltamivir), PPE, masks etc.

Isolation wards/beds at dedicated hospitals may be required to handle any suspect case of Avian Influenza if confirmation among birds occurs in your state, the joint advisory stated.

It also called for enhanced surveillance (in wet markets, abattoirs, poultry farm workers etc.) as well as expanded surveillance (in sewage samples, water bodies, crows etc.) for Avian Influenza in collaboration with National Centre for Disease Control (NCDC), Indian Council of Medical Research (ICMR) and Department of Animal husbandry and Dairying (DAHD).

It emphasised on timely sharing of information besides underlined the need for strict compliance with the SARI surveillance guidelines of the Ministry of Health and Family Welfare by all states and its monitoring at senior level.

For the states where there is an active outbreak of Avian Influenza, the joint advisory advised some additional measures.

They have been asked to collect samples from cullers and surveillance workers (considered as ‘at-risk’ groups) on the 5th and 10th days following sanitization operations for H5N1 testing.

The joint advisory has stressed on conducting surveillance for suspected human cases and providing health check-ups for cullers and poultry workers, with a duration of 10 days and stated that recommended measures for chemoprophylaxis, management, and use of personal protective equipment (PPE) should be implemented.

It also advised following the SOPs for collecting and transporting samples from suspected cases to designated laboratories.

“A coordinated response involving experts from veterinary services, health departments, wildlife and forest departments, local authorities and other relevant stakeholders is required in all Avian Influenza outbreaks. Regular meetings should be conducted to share information, assess the situation and adjust strategies accordingly,” the joint advisory said.
 

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

Washington:

Mice fed raw cow’s milk infected with bird flu experienced high levels of the virus in their lungs, according to a study published Friday that suggests risk to humans who consume the drink.

Over the past few years, a highly pathogenic avian influenza virus called HPAI H5N1 has spread to infect more than 50 animal species, including, from March, dairy cattle in the United States.

To date, 52 herds across the country have been affected, with two human infections involving farm workers who developed mild symptoms, including pink eye.

In the new study, published in the New England Journal of Medicine, researchers from the University of Wisconsin-Madison and Texas A&M fed droplets of raw milk from infected cattle to five mice.

The rodents developed signs of illness, including lethargy, and were then euthanized four days later to study their organs.

The researchers found high levels of virus in their nasal passages, trachea and lungs, and moderate-to-low levels of virus in other organs.

“An important consideration is that the consumption of raw, unpasteurized milk is becoming increasingly popular,” said Rowland Kao, a professor of veterinary epidemiology at the University of Edinburgh, who was not involved in the research.

Raw milk laws vary by state in the US, with some permitting its sale in retail stores, others only allowing it to be sold on the farm it was produced, and others still prohibiting it altogether.

An official 2019 survey found that 4.4 percent of adults said they had consumed raw milk in the past year. Such consumers tended to be younger and lived in rural areas.

“While this study shows that mice can become systemically infected due to ingesting infected milk, this does not prove that the same is true for humans, though it does increase the possibility,” added Kao.

In addition to the mice tests, the research confirmed that heating raw milk to high temperatures destroys nearly all virus after a few seconds, and completely destroys the pathogen after several minutes.

A recent nationwide survey of pasteurized milk found all samples were negative for viable virus, though inactivated virus, no longer capable of spreading or infecting a host, was found in about 20 percent of retail samples.

Finally, the researchers tested the effect of storing infected raw milk at fridge temperatures and found that the virus levels declined only slightly after five weeks, indicating that refrigeration alone is not sufficient to make raw milk safe.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

Washington:

A second case of bird flu has been found in a human, US health authorities announced Wednesday, less then two months after the first one as an outbreak of the disease circulates widely among dairy cows.

Both individuals infected with the virus called H5N1 — the first in Texas, the second in Michigan — were dairy farm workers who suffered only minor symptoms and have recovered, according to authorities.

Despite the second infection, the US Centers for Disease Control and Prevention said its risk assessment for the general public remained “low,” but it did suggest it expects more cases.

Given the high levels of the virus “in raw milk from infected cows, and the extent of the spread of this virus in dairy cows, similar additional human cases could be identified,” the CDC said.

However, “sporadic human infections with no ongoing spread will not change the CDC risk assessment for the US general public, which CDC considers to be low.”

The latest case in Michigan was detected in “a worker on a dairy farm where H5N1 virus has been identified in cows,” the CDC said.

According to Michigan Health and Human Services, the worker had only mild symptoms and has recovered.

Two specimens were collected from the worker — one from the nose and the other from the eye — with only the eye specimen testing positive.

Additionally, “similar to the Texas case, the patient only reported eye symptoms,” the CDC said.

– Chickens, cows, humans –

As of Wednesday a total of 52 US herds were infected with bird flu across nine of the 50 states.

“People with close or prolonged, unprotected exposures to infected birds or other animals (including livestock)… are at greater risk of infection,” the CDC said.

Though the current H5N1 strain has killed millions of poultry during the present wave, affected cows have not fallen severely sick.

Cows and goats joined the list of victims in March, surprising experts because the animals were not thought to be susceptible to this type of influenza.

Virus fragments have meanwhile been found in pasteurized milk, but health authorities say milk sold in US stores is safe because pasteurization effectively kills the disease.

There is no evidence of human-to-human transmission at present but health officials fear that if the virus were to eventually spread widely it could mutate into a form that could pass between humans.

Avian influenza A(H5N1) first emerged in 1996 but since 2020, the number of outbreaks in birds has grown exponentially, alongside an increase in the number of infected mammals.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

A turkey stands in a barn, Aug. 10, 2015, on a turkey farm near Manson, Iowa. The U.S. Department of Agriculture reported that avian influenza (bird flu), which is deadly to commercial poultry, was confirmed in a flock of 47,300 turkeys in Jerauld County of South Dakota last Wednesday, Oct. 4, 2023, and at a farm with 141,800 birds in Sanpete County of Utah last Friday, Oct. 6.
| Photo Credit: AP

Scientists in Britain have found they can partially protect chickens from bird flu infections by editing their genes, signalling a new potential strategy to reduce the spread of the deadly virus.

Highly pathogenic avian influenza, known as bird flu, has spread to new corners of the globe since 2022, wiping out millions of poultry birds and sending egg and turkey prices soaring.

Experts warn that mutations could potentially threaten a human pandemic, though the current strain has not caused significant disease in people.

Researchers said they used the gene-editing tool CRISPR to make specific changes to a gene called ANP32 that is essential to support flu viruses inside chickens’ cells. CRISPR is a type of molecular “scissor” technology that scientists can use to edit DNA.

Also Read | Mammalian spread of H5N1 and its pandemic potential 

Flu viruses hijack proteins like ANP32 inside cells to help themselves replicate, and the edits in chickens were designed to stop the growth of bird flu.

Upticks in cases tend to occur during the spring and autumn migration of wild birds that transmit the virus, and the U.S. last week reported its first case in a commercial flock since April.

Experiments showed that almost all of the gene-edited chickens showed resistance to lower doses of a less lethal form of bird flu than the H5N1 strain that has circulated the globe recently, said Wendy Barclay, a flu expert and professor at the Imperial College of London.

When birds were exposed to much higher levels of the virus, though, about half of the gene-edited chickens had breakthrough infections, she said.

Also Read | Most avian flu outbreaks in India reported from post-monsoon to pre-summer season: study

“We can move toward making chickens resistant to the virus but we’re not there yet,” Barclay said. “We would need more edits – more robust edits – to really shut down the virus replication.”

The findings were published in Nature Communications on Tuesday.

Researchers now think that making three specific genetic changes to chickens’ cells will better protect birds. However, they have not bred chickens with three edits yet, said Helen Sang, who previously studied genetically modifying chickens against bird flu at the University of Edinburgh.

Sang said scientists found that genetic modification would not work well enough.

Unlike genetic modification, which introduces foreign genes, gene editing alters existing genes. The technology is considered to be less controversial than genetic modification and is more lightly regulated in some countries.

“The way forwards here is not to rely on single edits but to use a combination of them,” Barclay said.

France this month became the first country in the European Union to vaccinate poultry against the virus.

However, that strategy led the U.S. to impose trade restrictions on French poultry imports, citing a risk of introducing the virus into the country because vaccinated birds may not show signs of infection.