Zoonosis a term that only entered the consciousness of a wider public with the corona pandemic. Zoonoses, i.e. infectious diseases that are transmitted from animals to humans, or vice versa, have always existed. But in an increasingly connected world, they are becoming more and more common. Large-scale deforestation, penetration into previously untouched natural areas, wildlife markets, expansive animal breeding, population growth and mobility pose a threat to pandemics. All this brings more and more people into delicate contact with wild animal species. Pandemics have a lot to do with globalization because it has fundamentally changed ecosystems and made natural virus barriers disappear.
“Unusually many bird flu viruses”
Recently, the report has attracted attention, according to which in Russia for the first time a transmission of avian flu of the subtype H5N8 from animals to humans has been detected. Several employees of a poultry farm in southern Russia are ill. The H5N8 virus is currently the predominant bird flu virus in Europe. “The development in Europe remains dynamic. In addition, new cases of wild birds and poultry from many European countries are reported every day,” writes the Swiss Federal Office for Food Safety and Veterinary Affairs (BLV) in its Radar Bulletin of February 2021; this bulletin is published together with the Friedrich Löffler Institute (FLI), the German Federal Research Institute for Animal Health. “There are currently an unusually large number of different strains of avian influenza viruses circulating,” the bulletin continues. In addition, migratory birds would come back in the next weeks. Therefore, the risk of further spread of avian flu in wild birds, poultry farms and bird populations in zoos is high.
Human-to-human infection possible
The Federal Office therefore warns the population against touching dead wild birds. Since the proven contagion of animals on humans in Russia, this probably applies all the more. The Robert Koch Institute (RKI) in Berlin considers it even possible to transfer from person to person in individual cases. However, the World Health Organization (WHO) estimates that the risk of a sustainable spread of the virus by humans is low.
Immune system not prepared
Nevertheless, the science editor of the Bayerischer Rundfunk (BR) concludes in a detailed documentation: “The crossing of the species barrier, i.e. the contagion of a person with an adapted influenza subtype by wild birds or breeding poultry, could provoke a new influenza pandemic, i.e. the worldwide occurrence of an infectious disease. Since this new pathogen did not occur in the population before, the immune system of humans is not prepared and therefore not protected. The virus could well spread from person to person.“Thomas Mettenleiter, President of the Friedrich Löffler Institute, says:“With bird flu, you have to be prepared for everything.”
Massive expansion of animal husbandry
That doesn’t sound really reassuring. Especially if one once again realizes to what extent so-called farm animals are “produced” and carted around in the world. Animal husbandry is being expanded worldwide, and annual meat consumption has increased significantly in recent decades. While the average global annual consumption was 33.5 kilograms per capita in 1990, it was 42.9 kilograms in 2018. The latest figures from the United Nations Food and Agriculture Organization (FAO) for 2021 show impressively how much demand for meat and other animal products has skyrocketed for virtually all animal species.
EU as live animal export world champion
Chickens are at the top of the most commonly kept animal species worldwide: in 2019 there were around 25.9 billion animals, 80 percent more than in 2000. But the stock of almost all other” farm animal species " has also grown significantly in the last 20 years: cattle (plus 14.5 percent), sheep (plus 16.2 percent), ducks (plus 26.3 percent) and goats (plus 44.2 percent). Only pig farming experienced a decline of 5.4 percent. The latest FAO figures also show that no region in the world exports more live animals than the European Union: 1.6 billion crossed the borders of an EU state in 2019-the majority of them were poultry.
“Ordered the second potion”?
The German weekly Der Freitag uses a sarcastic metaphor: “Well then-during a pandemic! - to happily continue to cart poultry through world history is a bit like ordering the second potion without having drunk the first one to the end.“Of course, no one can say if and when a next pandemic will break out. However, researchers have been warning for years about a super-virus that would not only be easier to transmit from person to person, but also much more deadly than what we are currently experiencing. The probability of this happening is higher today than in “normal” times, because we have persistently high numbers of infections and a high number of circulating viruses.
Problem at the root of
However, the fight against a pandemic alone is not enough, the problem must be tackled at the root. In a major study last year, British researchers once again demonstrated how significantly human intervention in ecosystems can promote the development of zoonoses. They analyzed approximately 7,000 Ecosystems and 376 species of potential host animals. The result: the use of habitats and thus ecosystems by humans has " global and systematic effects on local zoonotic host communities. (…) There are more species and a greater number of known zoonotic hosts in man-managed ecosystems than in nearby undisturbed habitats.” In other words, most zoonoses are also man-made.
Mix of animal species has changed
According to the scientists, the transformation of forests, grasslands and deserts into cities, suburbs and agricultural land has led to a serious change in the mix of animal species. “Environmental specialists” such as rhinos or ostriches, who have very specific food or habitat requirements, have been pushed back and thus the losers of human spread. “Generalists “such as rats, which are small and numerous and lead a” fast”, short-lived life, could have won and spread further and further. It is precisely these animals that carry a great abundance of pathogens.
Not the wilderness is the problem
With the study, the researchers also contradict the conventional view that the wilderness is the largest source of zoonoses. “The popular-cultural depictions of jungles teeming with microbial threats is a misjudgment,” they write. They also found that human land use not only increases the number of host animals, but also hosts a greater number of pathogen species.
Grosse Märkte, tiefe Hygienestandards
The nature conservation organisation WWF draws attention to another problem in an analysis of wildlife trade in the Southeast Asian Mekong region. Out of an estimated 500 markets in larger cities where wildlife is often traded, more than half are in regions with a potentially high risk of zoonosis. According to WWF analysis, many rural communities still rely on wildlife for food security, especially in remote areas with high levels of child malnutrition. Increasingly, however, wildlife is also being hunted for sale in urban markets.
“Large markets with low hygiene standards on which wild meat is sold are particularly risky for the transmission of zoonoses,” warns Stefan Ziegler, expert on species conservation and Asia at WWF Germany. At live animal markets such as exist in large parts of China and Southeast Asia, wild and farm animals are sold and slaughtered side by side. But it is not only the markets that pose a risk, according to Ziegler: “The corona outbreaks in European mink farms show that such plants are ticking virus bombs. And wildlife farms are also estimated to number hundreds in Southeast Asia.”
WWF calls for risk classes
Every year, tens of millions of wild animals are traded in the region for food or for use in traditional medicine, writes the WWF. In addition to wild boars and deer, these are often rodents and bats, which are considered a reservoir for a variety of pathogenic pathogens. The WWF therefore calls for the trade in wild animals and their products to be classified according to risk classes: control or even trade bans from higher risk classes are then indispensable – especially in urban areas with a high population density. There must also be increased efforts to combat the illegal trade in species. “What happens in secret and remains in darkness is risky. The smuggling of wild animals beyond all controls and regulations can be an ideal breeding ground for virus leaps from animal to human,” warns WWF expert Ziegler.