Avian flu: What is the risk of disease to spread throughout Brazil?

The Ministry of Agriculture and Livestock (Mapa) confirmed on Friday (16/5) the detection of the avian flu virus in a commercial farm.

The outbreak was identified in an establishment of matrices – which produces fertile eggs for chicken production – located in the city of Montenegro, Rio Grande do Sul.

The outbreak was confirmed by laboratory tests on Thursday (15/5) after the death of about 35 birds.

There is also a suspicion of another outbreak in a zoo in the city of Sapucaia do Sul, which is close to Montenegro, where dozens of birds kept in captivity died.

This is the first time the pathogen appears among the country’s commercial birds – previously it had been found in migratory wild birds and subsistence birds.

This virus is classified as high pathogenicity avianza (IAAP) and has been spreading around the world for almost two decades.

On its website, the map stressed that “the disease is not transmitted by the consumption of poultry or eggs.”

“The Brazilian and worldwide population can remain quiet about the safety of inspected products, with no restriction on their consumption.”

“The risk of infections in humans through the avian flu virus is low and mostly occurs between keepers or professionals with intense contact with infected birds (vivid or dead),” the text points out.

The detection had an immediate impact on Brazilian chicken exports. China, for example, suspended the purchase of this product for the next 60 days.

“I worry about knowing that in the past, even in countries with a very technological poultry, such as the United States and parts of Europe, this virus ended up spreading. This is very alarming,” says Virologist Fernando Spilki, a professor at Feevale University in Rio Grande do Sul.

Check out everything that is known about Avian flu – and the impacts it can have from a commercial and public health point of view.

Avian flu is an infectious disease caused by influenza H5N1 virus which, as its name implies, mainly affects birds.

Virologist Helena Lage Ferreira, professor at the University of São Paulo (USP), says that this pathogen was first identified in 1996 in Guangdong, China, and began to draw attention in Hong Kong.

After being initially contained, new outbreaks began to appear in 2003.

“From 2005, he began to spread around the world, outside Southeast Asia,” says the researcher, who is also former president of the Brazilian Society of Virology.

H5N1 natural reservoirs are aquatic wild birds.

“What happens is that some of these animals migrate, so the virus disperses to other countries and continents,” explains Ferreira.

Since the end of 2022, this kind of influenza has once again been headlines around the world.

From the coastal cities of Dagestão, Russia, to the coast of Peru, passing through Vison farms in Spain and farms in the United States, there were several recorded episodes of millions of animals that died (or were sacrificed) after contact with this infectious agent.

He was first identified in Brazil in May 2023 among wild and subsistence birds.

Now, exactly two years later, the first detection between commercial birds, from farm.

For Ferreira it was expected that this would eventually happen.

“What catches the eye is the outbreak in matrices, which are reproductive birds with more rigorous biosecurity,” she notes.

“Usually, cases of aviary flu are less frequent in these places,” adds the expert.

Remember the history of contaminated migratory birds cited in the previous paragraphs?

Because they are the key to understanding how the proliferation of this infectious agent happens.

Spilki explains that the H5N1 has a “violent transmission” and a “high pathogenicity virulence.”

“Apparently, the arrival of this virus in Brazil repeats what happened in South America. Most likely migratory birds that came from the northern hemisphere, more particularly from North America, brought the virus here,” he says.

“You can see right as H5N1 was introduced, first in northwestern South America, through Ecuador, Chile, Argentina, Uruguay and the Brazilian coast.”

Spilki details that the virus transmission between birds occurs through the environment and that of contaminated water.

“From birds to mammals, the infection occurs through direct contact with excrement or even the body of the animal, since marine mammals predict many of the birds,” explains the virologist.

Between mammals, experts believe that the passage of H5N1 will take place through the airways, through saliva droplets that go out by nose and mouth.

Finally, from birds or mammals to humans, documented transmission so far occurs through the respiratory pathway and by manipulating the carcasses of these animals.

“The infection has nothing to do with food itself,” says Spilki.

The greatest danger is for those who have direct contact with infected or dead birds.

This is the case of farm workers or health surveillance professionals.

“The avian flu virus belongs to the same group of seasonal flu, so the symptoms are very similar: conjunctivitis, runny nose, cough, sneeze, pneumonia…”, list Ferreira.

“In more serious cases, the picture can get worse and end up in death,” she adds.

But the virologist reinforces that there is no evidence of transmission of this H5N1 influenza from one person to another.

“This is an animal adapted virus,” she points out.

In other words, this pathogen would need to go through a series of mutations to be able to adapt to the human organism and be transmitted between our species as well.

Researchers follow the evolution of H5N1 closely, because deaths have recently been recorded of tens of thousands of mammals living near migratory birds such as marine lions and seals.

“Outbreaks with this virus, such as what has just been identified in a commercial farm, are treated by federal and state veterinary services that have a very specialized training to be able to control the focus,” says Ferreira.

In the case of Rio Grande do Sul, Carlos Fávaro, who heads the map, confirmed that the protocol was followed and all Granja birds were shot down to avoid the risk of contagion and transmission.

“In addition, as new introductions of the virus can happen by constant contact with wild birds, it is important that all farms reinforce biosafety measures,” says Ferreira.

A report published by the World Health Organization (WHO) on May 9 accounts for four cases and three deaths of people by aviary flu in 2025.

Since 2003, 265 infections and 145 deaths have been recorded on the planet.

“With the ability to be transmitted from one person to another, H5N1 may be one of the most serious problems that humanity has ever faced,” Virologist Edison Luiz Durigon, professor at the Institute of Biomedical Sciences of the University of São Paulo (ICB-USP), to BBC News Brazil in March 2023.

The good news is that, contrary to what happened at COVID-19, health governments and services already have definite plans for what to do if an advancement of H5N1 becomes reality-some vaccines are even ready or developing now.

One of the first repercussions of the detection of Avian flu in a commercial farm of Montenegro was the suspension of imports of this meat through China for the next 60 days.

In a press conference held on the morning of Friday (16/5), Fávaro said that the measure is part of previously established agreements.

“Brazil was the last country among major chicken meat producers in the world to have contamination in commercial farms. Our system is very robust, very efficient,” he defended.

“In May 2023, we had the first case of Avian flu in Brazil among wild birds. Still, we held two years the entry of this virus in commercial farms. Nowhere in the world got it,” he added.

The Minister of Agriculture and Livestock explained that Brazil has been updating its commercial chicken export agreements to reflect the reality of H5N1 spreading and the update of health surveillance systems that the country has.

During the press conference, he cited the case of Japan, a country whose chicken import comes 70% of Brazil.

These new agreements allow, in case of outbreak, the export restriction is restricted to the state and then the city where the virus was detected.

In practical terms, Japan will continue to receive chicken meat produced in Brazil – there will only be a temporary restriction for gaucho farms and, later, establishments located in Montenegro.

“We decreed a state of health emergency for 60 days. With the robustness of the Brazilian system, I’m sure we will quickly return to normality status,” said Fávaro.

Fávaro also reported that the map was already able to track the farms that received eggs from Montenegro where the outbreak was located, so that an even more rigid surveillance can be done in these places.

The minister also recalled that Brazil has trade protocols on chicken exports with almost 200 nations – and works to gradually update the agreements to what is done today with Japan and other countries, such as United Arab Emirates and Saudi Arabia.

However, China – which is one of the largest Brazilian chicken buyers, with more than 10% of total exports – still has an old agreement, one that blocks the entire importation of the country in the case of confirmation of an avian flu outbreak.

Fávaro says map technicians are still calculating how much the damage will be with the stoppage of sales for the next 60 days, but says it is confident in a rapid resumption of export for this Asian country.

Spilki understands that virus detection generates an alarm.

“What we have seen in other countries is that there is a great potential for virus dissemination in a wild environment, and we had the recent experience of an outbreak in the United States, which revealed how difficult it is to placate this spread,” he says.

“A significant part of American production has been affected in recent months, because this is a very difficult virus to control.”

“So this situation causes a lot of concern,” he adds.

For the virologist, now it remains “to hope that the measures taken quickly by the sanitary authorities will work.”

“We also need to intensify the effort of the active search for new cases to identify the circulation of the virus,” he says.

The researcher also calls for a “proper attention” and “specific care” with the people who handle these birds.

“We even need to think about the families involved in production, even from an economic point of view,” suggests the researcher, remembering how the southern region is strategic for national poultry.

The Brazilian Animal Protein Association estimates that Brazil produced 14.9 million tons of chicken in 2024.

Of this volume, about one third (or 5.3 million tons) were sent abroad.

The largest buyer was China (562 tons), followed by United Arab Emirates (455 thousand tons), Japan (443,000), Saudi Arabia (370 thousand) and South Africa (325 thousand).