Why Animals and Humans Are Infected by the Same Virus [Reading Science]

The Huanan Seafood Market in Wuhan, Hubei Province, China, known as the origin of COVID-19, which has been closed.
[Photo by YouTube screenshot]

[Asia Economy Reporter Kim Jong-hwa] The novel coronavirus infection (COVID-19) is known to have been transmitted from bats to humans. Bats are widely recognized as hosts of major infectious diseases that have recently spread.

The severe acute respiratory syndrome (SARS) outbreak in 2002 was transmitted to humans through civet cats or chickens that had contact with bats, and the Middle East respiratory syndrome (MERS) in 2012 also spread as humans contracted the virus from camels, which had been infected by bats, while riding camels. The 2009 novel flu was transmitted from pigs to humans. Many other infectious diseases have also been transmitted to humans through animals.

Diseases caused by viruses that start in animals and infect humans are called "zoonotic infectious diseases." Viruses are not complete living organisms but exist in an intermediate state between living and non-living entities. Therefore, they require a host to reproduce. Using the host's replication system, viruses replicate their own genome.

In the case of human influenza viruses, transmission occurs through contact with bodily fluids via sneezing or through pets, plants, and food. However, due to significant genetic differences between animals and humans, infection usually does not occur. Simply put, even if the virus mutates, it has tended to mutate in a direction that weakens its pathogenicity.

However, recently, environmental changes have caused mutations in the virus that increase pathogenicity, making the situation more serious. Viral mutations mainly occur during the process of adapting to a new host, and the mutated genetic material produces new cell membrane proteins. In this process, the virus gains infectivity to a different host, and depending on the environment of the infected host, it becomes a new and powerful pathogen.

In other words, zoonotic infectious diseases that start in animals survive by continuously switching hosts from animals to humans, and due to frequent genetic mutations, eradication is difficult. Unlike in the past, nowadays, viruses evolve into more pathogenic forms as they move from animals to humans.

Although 18 years have passed since the SARS outbreak, a definitive vaccine has not yet been developed. Vaccines for MERS and the mosquito-borne Zika virus are still under development. So, why have zoonotic infectious diseases increased so significantly recently?

Scientists point to "global warming" as the primary cause. As the Earth warms, hot and humid environments have increased, leading to the emergence of many new viruses. This is because habitats for mosquitoes and bats, which prefer hot and humid environments, have greatly expanded compared to before.

The increase in experiential cafes that release wild animals and the use of wild animals for food are also loopholes that fail to prevent the rise of infectious diseases. Wild animal experiential cafes and similar facilities allow close contact between wild animals and humans, which is dangerous.

In such facilities, it is common to eat tea and snacks in unsanitary spaces where wild animal feces are scattered or to touch and pet wild animals like raccoons. It is also difficult to verify whether these animals have been properly quarantined and legally imported.

The consumption of wild animals is historically and culturally linked to dietary habits. It is said that Chinese people began eating bats, or more broadly wild animals, due to the impact of a great famine. With no other food available, survival depended on catching and eating wild animals, making this a dietary habit that has continued since that time.

The fastest means of spreading viruses worldwide is airplanes. The development of air logistics accelerates the spread of infectious diseases.
[Photo by YouTube screen capture]

The problem lies in management. If the Chinese government was aware that the distribution of wild animals for food was frequent, strict hygiene management should have been enforced. South Korea is not much different. If unknown wild animals are used for food, thorough hygiene management must be implemented first, just as with other livestock already used for food.

The fastest vector spreading zoonotic infectious diseases worldwide is the airplane. It is the leading cause enabling pandemics. As international travelers increase, the virus's travel time has drastically shortened. The typical incubation period of a virus is up to two weeks, but now it can fly anywhere in the world within 2 to 3 days, allowing infectious diseases to spread rapidly.

Nowadays, many households live with companion animals. There are quite a few diseases that can be transmitted through pets. Companion animals should also receive regular vaccinations. Even after the COVID-19 storm has passed, habitual handwashing and regular vaccinations for pets are essential lifestyle practices to maintain.

This content was produced with the assistance of AI translation services.