World literature is rich in fables and stories featuring animals like birds, mice, and cats, often imparting moral lessons to humanity. Art frequently draws upon nature to teach life lessons. Oscar Wilde, in his work "The Decline of Lies," suggests that life mimics art more than the reverse. However, we might challenge this assertion by urging a closer examination of real-life events, which often serve as the unfinished narrative of nature.

Nature, while a source of challenges, also provides valuable insights. Humans are merely one species among many in the natural world. Mother Nature sends us recurring signals, indicating that life could be more harmonious for all living beings. Sadly, these warnings are frequently ignored.

We witness various pressing issues daily: climate change, natural disasters, ozone depletion, plastic pollution, excessive water consumption, unsafe construction practices (as seen in Turkey and Syria), poaching, and rampant deforestation in places like the Brazilian Amazon. Among these calamities are zoonotic diseases—ancient yet currently relevant phenomena.

Zoonotic diseases, including epidemics and epizootics, are ever-present. The SARS-CoV-2 pandemic is a recent and significant example of a zoonosis—originating from bats—that has severely impacted human populations, with over 673 million infections and nearly 7 million deaths reported.

Animal infections that cross into human populations are of particular interest. Zoonoses account for approximately 75% of all infections affecting humans, highlighting the deep interconnectedness between humans and animals within the global ecosystem. The prevalence of zoonotic diseases often correlates with overall public health: more zoonoses typically indicate poorer health outcomes.

Both common and avian flu represent just a segment of a broader issue. The major influenza pandemics of the 20th century (1918, 1957, and 1968) left an indelible mark on the collective consciousness of scientists and the public alike. These pandemics resulted in significant morbidity and mortality, with seasonal flu mortality rates hovering around 1% and certain pandemics, such as the 1918 outbreak, claiming up to 40 million lives.

International organizations like the WHO have expressed concern over emerging threats such as the SARS coronavirus epidemic (2002), the H1N1 pandemic (2009), and the MERS outbreak (2012). While these events did not escalate to catastrophic levels, they heightened global vigilance.

Coronaviruses have entered the epidemiological landscape, compounding anxieties already instigated by previous influenza outbreaks. Additionally, less severe but notable outbreaks (Ebola, Marburg, Crimea-Congo) also contribute to global health concerns. A particularly alarming form of influenza is avian flu.

While one might be tempted to oversimplify and attribute the issue solely to birds, the reality is that the host range for influenza viruses extends beyond them. Avian flu can affect various species, including humans—often referred to as "featherless bipeds" in philosophical discussions.

Avian flu is more than a minor ailment affecting mallard ducks. In its highly pathogenic form, it can lead to nearly 100% mortality in various wild and domestic bird species, causing widespread fear and uncertainty. For instance, The Atlantic recently reported on the dire state of bird populations due to avian flu.

The first scientific documentation of avian flu in chickens and ducks dates back to 1878 in Lombardy, Italy, where it was mistaken for avian typhus. Since then, numerous outbreaks have occurred globally, particularly in Asia and the United States, with significant incidents in Hong Kong during the late 1980s and late 1990s.

Historically, bird flu outbreaks have been most prominent in China, but they can also arise in distant regions, attributed to the extensive migratory patterns of birds. For example, wild ducks nesting in Canada can serve as asymptomatic carriers of the virus.

The close interactions between migratory and domestic birds, as well as mammals in shared environments, facilitate the virus's transmission. Infected birds' respiratory secretions and droppings can accumulate in places like lagoons and farms, leading to widespread infection. Influenza viruses are resilient and can survive for extended periods in various environments.

The situation is further complicated by the fact that avian viruses, particularly subtypes like A/H5N1, are increasingly targeting mammals. Just as the current pandemic coronavirus has adapted to various mammalian hosts, so too do some influenza viruses demonstrate a propensity for mammalian infection.

Recent outbreaks, such as those seen in minks, underscore the growing concern regarding mammals as potential hosts for avian flu viruses. Numerous species of mammals have tested positive for the virus, raising alarms about their role in the virus's transmission.

The potential for avian flu viruses to mutate and adapt to mammals is particularly alarming. In certain carnivorous mammals, such as red foxes and otters, the A/H5N1 subtype has demonstrated neurological effects. This raises concerns about the possibilities of human transmission from these species.

Every zoonotic epidemic serves as a reminder from nature of our interconnectedness and vulnerability. The Covid-19 pandemic, alongside various influenza outbreaks, emphasizes the global nature of our world and the shared threats we face from infectious diseases.

This commentary stems from a compelling article by a European research group examining an animal disease currently not known to affect humans. However, given the unpredictable nature of viruses, it's crucial to remain vigilant.

Rubiviruses, a lesser-known family of viruses, present another area of interest. The Matonaviridae family, which includes rubella, comprises single-stranded RNA viruses. As of now, three rubivirus species have been identified, with only one affecting humans.

While rubella is typically mild in children, it poses significant risks to pregnant women. No human cases have been documented for the other rubivirus species, underscoring the need for ongoing research.

In summary, the landscape of zoonotic diseases is vast and complex, with emerging infections posing continual challenges. The interplay between animals and humans, coupled with environmental changes, creates fertile ground for new diseases to arise. With advancements in laboratory technology, including genomic sequencing, we may uncover more about these infectious agents.

In light of the ongoing evolution of zoonotic threats, it is vital to remain aware of the connections between various species and the potential for new infections to emerge, ensuring that we heed nature's warnings to mitigate future risks.