What we currently know about the H5N1 bird flu virus
Bird flu continues to cause commotion in Germany. According to the local ministry of agriculture, around 138,000 animals were killed in an outbreak in Schwerin alone last fall and winter. But bird flu is no longer just raging on poultry farms.
1. The H5N1 virus can spread from animals to humans, but not from person to person
Its first victims were chickens. That was in 1959. As a result, the disease caused by the H5N1 virus is still called “bird flu” today. But it is no longer just poultry that are infected with the virus and sometimes become seriously ill. The disease has now also been found in dairy cows in the United States, where it seems to be spreading rapidly. Transmission from cow to cow can occur via milking machines, because the virus mainly affects the animals’ udders.
“Something like this has never happened before, such extremely large outbreaks in cows – all experts are concerned,” said virologist Christian Drosten in an interview with “Editorial Network Germany“.
The virus has also been found in cats and mice and occasionally in pigs, dogs, horses, bears and foxes. There are also known cases of bird flu in humans, in varying degrees of severity. The World Health Organization has recorded 463 deaths from bird flu in the past 21 years, documented in 23 countries.
In contrast to Coronavirus According to current knowledge, H5N1 does not spread from person to person. Those who became infected usually had close contact with sick or dead animals, worked on an affected poultry farm and inhaled contaminated dust or came into contact with the animals’ feces.
Because bird flu affects the respiratory tract, scientists assume that transmission to other people cannot be completely ruled out – for example via exhaled air or mucous membranes when coughing. However, there are no documented cases of people becoming infected with each other.
2. The first symptoms such as fever and cough appear about five days after infection
This explains why it usually takes five days from infection to the first symptoms Robert Koch Institute (RKI)It lists the following as typical complaints:
- Fever
- Cough
- Shortness of breath
- nausea
- Vomit
- Diarrhea
Other classic flu symptoms can also occur, such as sore throat, headache and muscle pain. Conjunctivitis is also a possible consequence.
The receptors to which the pathogen can attach itself in the human body are located in the lower respiratory tract. Therefore, these are affected the most. According to the RKI, the mortality rate, depending on the virus type, is between 20 and 60 percent – and is therefore “relatively high”.
It is therefore extremely important to treat the virus as early as possible, within the first 48 hours. As with the ‘normal flu’, doctors resort to antiviral drugs.
3. Supermarket milk from contaminated cows is unlikely to make you sick
Is it dangerous to eat eggs from sick chickens or milk from sick cows? The Federal Institute for Risk Assessment, or BfR for short, says: “In principle, transmission of the pathogen via infected food cannot be ruled out. However, human infections with the bird flu virus are rare and direct and close contact with infected poultry or other animal species appears to be the main route of transmission to humans. The BfR has not yet received any data indicating that people have been infected with the bird flu virus via food and have become ill.”
There is currently no danger from food in this country. At present, there are only known cases from the US where cattle were infected with bird flu and the virus was subsequently found in supermarket milk. Dairy farms in Germany are not affected. In the US, it may be useful as a precaution to prepare certain foodstuffs before consumption in such a way that the risk of infection is as low as possible. The BfR mentions the following measures for this:
- poultry must reach a core temperature of at least 70 degrees for at least two minutes. When the meat is no longer red or pink in color, it is sufficiently heated.
- Eggs It is best to cook until the whites and yolks are firm. Products with raw eggs (egg whites, tiramisu) are best avoided.
- Bee milk Do not buy raw milk, but pasteurized milk. This milk was heated to 75 degrees. The viruses appear to survive the process—in affected areas of the U.S., bird flu viruses were found in one in five milk cartons on supermarket shelves—but pasteurization “appears to effectively eliminate the risk of transmission of intact viruses,” the BfR reports.
4. The virus is constantly changing and can become more aggressive
Outbreaks of H5N1 had already occurred on two poultry farms in Britain in 1959 and 1991. In 1997 and early 2000s, cases of bird flu occurred in Asia.
Like all influenza viruses, the bird flu virus has the ability to change, adapting to environmental conditions and becoming more aggressive. Current cases of the disease are not only due to H5N1, but also to the related subtype H5N2. In April 2024, a man died from this virus variant Mexico.
Cows are repeatedly infected with influenza viruses, but with influenza D. H5N1 and H5N2 belong to the Influenza A group. Cows are usually not susceptible to it. Current developments in the US show that the virus has mutated and has now acquired the ability to infect cows. With each mutation, the risk of a subtype emerging that becomes dangerous to humans increases. Researchers must therefore keep a close eye on the many subtypes.
What we currently don’t know about the H5N1 bird flu virus
1. How will H5N1 spread?
The rapid spread among dairy cows is currently only known in the United States, but cases of H5N1 are occurring worldwide. And they were able to multiply.
Timm Harder from the Friedrich Loeffler Institute in Greifswald explains 2023 in an interview with “German wave“: “The enormous expansion of poultry production worldwide, but especially in China and Southeast Asia, has led to the dramatic spread of the current highly pathogenic, i.e. particularly aggressive, pathogen.” Harder is head of the National Reference Laboratory for Avian Influenza.
Migratory birds carry the virus all over the world, he explains: “Because of the special husbandry methods in Asia, for example when ducks are herded into harvested rice fields, there are always large interfaces between wild bird populations and infected livestock birds. This caused the virus to spread to wild animals, which were then spread by migratory birds.”
In the past, bird flu was mostly limited to the fall and winter, arriving with migratory birds from the northeast and disappearing again when the animals flew back in the spring. These seasonal influences no longer exist. “This virus has adapted very well to wild bird populations that live in water and is now found there all year round. That is now the case in North America, and it will continue to develop in South America,” Harder explains.
2. What is needed to prevent H5N1 from causing the next pandemic?
How, whether and when bird flu will have pandemic potential is difficult to predict, Timo Ulrichs explains online in an interview with FOCUS. He is a virologist and specialist in microbiology and infectious disease epidemiologist. For Ulrichs, however, one thing is certain: “If the bird flu virus spreads to humans and causes a pandemic, the corona pandemic will seem like a piece of cake.” The lethality of bird flu is much higher than that of corona. By this, Ulrichs means the ratio between the number of deaths and the number of sick people.
WHO member states are currently learning the lessons of the coronavirus pandemic – and want to be better prepared for a global health crisis next time. Common rules and measures are needed to combat a pandemic more effectively. But the agreement, which was supposed to be concluded in May 2024, initially failed. A new attempt will follow.
Full testing is proving important in the fight against H5N1 – just like with Corona. Only in this way can you get a realistic picture of the spread, trace infection routes and prevent future infections. There is currently no mandatory testing in the United States, where the virus is spreading among dairy cows. Not for people and animals in the affected farms and certainly not for family members who have come into contact with infected people.
There is already a vaccine against H5N1. The EU has now ordered 665,000 doses of vaccine against the transmission of bird flu from animals to humans. They are intended for people at particularly high risk, such as poultry workers or veterinarians. “The aim is to prevent the spread or possible outbreaks of bird flu in Europe and to protect citizens and their livelihoods,” the European Commission said. Germany has not yet secured any vaccine doses.