Bird flu is particularly raging this year. What is known about the previous outbreaks and what risks the virus poses.
The current outbreak of bird flu (H5N1) is the largest ever documented. The virus, which is particularly dangerous for animals, is raging worldwide. The USA is particularly affected. But Austria has also already declared its entire national territory a risk area. The pathogen was introduced into five poultry farms there in the past few weeks, and tens of thousands of animals had to be culled. There were also outbreaks of H5N1 in Hungary, the Czech Republic and Bavaria.
Infection is usually fatal for poultry. But the pathogen has long since spread to numerous other species, such as cows, raccoons and cats. How dangerous can the pathogen be to humans? t-online answers the most important questions.
In the USA, it was confirmed for the first time in March that the H5N1 pathogen of clade (variant) 2.3.4.4b was detected in dairy cows. At the end of March, the first farm worker tested positive for the virus. As the news channel CNN reports, citing Texas researchers, the dairy worker went to a doctor after he developed painful, red, swollen, weeping eyes with burst blood vessels. However, he did not have a fever and his lungs were clear, according to the study published by the scientists.
Since then, the virus has spread in several farms. Almost all of those infected had direct contact with dairy cattle or poultry. Direct person-to-person transmission has not been proven, but there are suspected cases.
The American health authority CDC has reported mild cases so far after people became infected on poultry or dairy farms. Apparently many infections remain undetected. Among 115 blood samples taken between June and August in two states, eight cases showed that people had recently been infected with the virus.
The number of unreported cases is likely to be significantly higher than the number of infections known to date - “despite ongoing efforts to monitor dairy workers for illness, test for H5N1 and offer antiviral treatments,” according to the CDC. The reasons are that employees often do not become seriously ill and some companies do not want to take part in the testing.
However, both the US and European health authorities and the Robert Koch Institute (RKI) currently consider the risk for the general population to be low.
So far, the illnesses following an infection in humans have been mild to moderate, explained the US health authority CDC. The usual flu symptoms appear such as fever, sore throat, shortness of breath and cough. Conjunctivitis, nose or gum bleeding, diarrhea, vomiting and abdominal pain are also reported. Neurological symptoms (seizures) and encephalitis may also be associated with bird flu infection.
According to the Federal Institute for Risk Assessment, a residual risk remains. Therefore, chicken meat in particular should be cooked well (at least 70 degrees core temperature), and eggs should not be eaten raw. The virus was also detected in milk in the USA, but it was no longer infectious.
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Can H5N1 cause a new pandemic?
The coronavirus has already shown that viruses can constantly change and adapt to their environment. If the bird flu virus mutates, experts say H5N1 has the potential to trigger a new pandemic. It could also be a start to the next pandemic, warned Christian Drosten from the Berlin Charité, for example.
Evolutionary biologist Michael Worobey also warned: “We are in uncharted territory here, as an H5N1 virus adapted to mammals is spreading for the first time in land mammals with which hundreds of thousands of people come into contact every day,” he said, referring to the situation in the USA. The next pandemic virus will come from a situation very similar to this one. No one can say with certainty whether it will be H5N1 or not.
How can farmers effectively implement biosecurity measures to prevent the spread of H5N1?
Interview between Time.news Editor and Dr. Jane Smith, Avian Virus Expert
Time.news Editor (TNE): Good day, Dr. Smith, and thank you for joining us to discuss the ongoing bird flu outbreak, especially the H5N1 strain. This year’s outbreak seems particularly extensive. Can you shed light on what makes this outbreak different from previous ones?
Dr. Jane Smith (JS): Absolutely, and thank you for having me. This year’s H5N1 outbreak is indeed the largest documented thus far. It has been notably severe, affecting multiple countries at an alarming rate. In places like the USA and Austria, the virus has led to significant culling of poultry and has even been detected in other species like cows and raccoons. Previous outbreaks were often more localized, but this year’s spread underscores the interconnectedness of our ecosystems and the challenges in managing such a contagious virus.
TNE: That’s concerning. The implications for poultry, as well as other livestock and wildlife, must be significant. How does H5N1 primarily affect these animals?
JS: H5N1 is notoriously lethal for poultry; infection often results in death. In addition to poultry, we’ve seen transmission to other species in recent weeks, which complicates containment efforts. For example, we’ve had confirmed cases in dairy cows in the US, raising alarms about potential cross-species transmission.
TNE: Speaking of humans, there was a recent report of a dairy worker in the US testing positive for H5N1. Can you clarify the risk posed to people who may come into contact with infected animals?
JS: Yes, that case highlighted a potentially concerning development. While the initial worker’s symptoms were relatively mild—red eyes and no respiratory issues—it’s important to note that direct transmission between people has not been conclusively proven. Most infections in humans have emerged from handling infected animals, particularly in farming environments. Nonetheless, with almost 115 blood samples showing signs of recent infection, it indicates that there may be more cases than we realize.
TNE: That’s certainly troubling. You mentioned that health authorities currently view the risk to the general population as low. How is that assessment determined?
JS: That assessment comes from the fact that to date, there are no confirmed instances of sustained human-to-human transmission of H5N1. The CDC has reported mostly mild to moderate cases in individuals with direct contact with infected poultry or livestock. While there’s a residual risk, especially for farmworkers, the general population is not at high risk provided they practise necessary precautions.
TNE: Speaking of precautions, what measures should people take regarding bird flu, especially in terms of food safety?
JS: Great question! It’s critical to cook poultry products thoroughly—chicken should be cooked to at least 70 degrees Celsius (158 degrees Fahrenheit). Eggs should also be cooked well, and raw consumption should be avoided. While the virus has been found in milk in the US, studies show it isn’t infectious when pasteurized. Always practicing good hygiene in food handling is key.
TNE: Given the scale of this outbreak, what recommendations do you have for those working in the agriculture sector?
JS: Farmworkers should certainly stay vigilant. Monitoring health for flu-like symptoms, adhering to strict biosecurity measures, and participating in any offered testing programs are all essential. It’s also important for farms to report unusual health issues in their livestock to prevent further spread and to seek antiviral treatments if exposed.
TNE: Thank you, Dr. Smith, for sharing your insights. The situation is complex but awareness and preparedness can help mitigate risks.
JS: Thank you for having me. It’s crucial that we remain informed and proactive in this evolving situation.