How much did you pay for some eggs the last time you visited the supermarket? About a year ago in Spain, you would pay around 2€ a dozen. Yesterday, in Austria, I paid 3.49€ for a 10-egg pack. My parents, back in Spain, also paid 3.50€/dozen. Egg prices have skyrocketed in Europe, mainly due to the rebound of bird flu, which has become an increasingly common topic the recent months. What is its relevance?

Bird flu is a zoonosis. Meaning is that it’s an infectious disease that may be transmissible from animals – mainly vertebrates – to humans. Another familiar case to us may be swine fever [1]. Bird flu happens in birds; swine flu affects mainly pigs and boars. Both cases are viruses that affect animals, but if they were to undergo some mutations, they could come to infect humans and become pandemics, depending on transmission potential. Another zoonosis that may ring a bell is COVID-19. But back to the topic, what is the link between bird disease, domestic economy, and environmental health?

Zoonotic diseases are nothing new; we all have studied the black plague in Europe, among others. However, it looks like they are becoming more frequent now. And as it often happens, it is partly due to how we humans have been acting. Zoonosis can happen in both wild fauna and domestic animals. Contact with both of them with humans is what can trigger the outbreaks. Three human-driven phenomena have increased during the last decades: deforestation, (intensive) farming expansion, and urbanization [2].

Deforestation means that wild fauna lose their natural habitats, in which they would not cross paths with humans. Once the habitat is gone, they are forced to move, and they might find domestic cattle or directly human populations, which increases the possibility of transmitting diseases. 

Regarding the increase of intensive farming, great industrial farming complexes have high animal density in a reduced space, and low genetic diversity. This comes with higher vulnerability to diseases, creating a perfect breeding ground for viruses to mutate. 

The rise in urbanization, as well, means that cities grow and grow until they colonize what used to be wild lands, creating more possibilities of contact between humans and infected animals. Summing up, maybe the increase in frequency of zoonotic diseases is not only bad luck, but also an accumulated ecological pressure.

If this was not enough, we also have to consider another factor: climate change. One of the effects of rising temperatures is that viruses can survive longer in the environment. 

Another alteration lies in the changes of birds’ migratory patterns [3]. Preventive measures could be developed by knowing them, considering where birds migrate, their winter and summer resting spots, and the resting spots during their travel. Unfortunately, climate change affects these movements, and they are no longer predictable. On the other hand, physiological stress caused by climate change and global warming makes birds more sensitive to diseases, same way as when we are stressed, our immune system is weaker, and we are more susceptible to colds. Because of all the reasons above, climate change is not only an environmental problem, but also a public health one.