There are up to 150 diseases that pets can transmit to humans, some of which are extremely dangerous and even life-threatening. The medical community refers to these animal-borne diseases collectively as zoonoses.
Most zoonoses are mild, but some can be very serious. In 1918, the world was horrified by the rapid and deadly outbreak of the Spanish flu. This epidemic originated from pigs and caused widespread death around the globe, with approximately 40 million fatalities reported.
Recently, dangerous zoonoses have become hot topics in the media, such as Bovine Spongiform Encephalopathy (Mad Cow Disease), Ebola virus fever, and Marburg virus, which are transmitted through the consumption of monkey meat in Africa. AIDS is also believed to have originated from a variant of an African monkey that infected humans.
In 1994, the Hendra virus emerged in Australia. This virus, originating from bats, infected horses and subsequently humans; symptoms resemble those of the flu, and there have been several fatalities. By 1999, a new virus called Nipah also emerged from bats, infecting pigs and then humans. The disease begins with flu-like symptoms such as body aches and high fever, and can lead to severe complications like encephalitis. Nipah caused 105 deaths in Malaysia in 1999.
Some pathogens that were previously only found in tropical regions have begun to appear in North America, such as the West Nile virus, first identified in New York in 1999. This disease affects certain bird species, particularly crows, and is transmitted to humans by mosquitoes. Symptoms are similar to the flu; while it rarely results in death, it can cause serious complications in older adults.
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Hendra Virus |
In 2003, the SARS outbreak originating from mainland China resulted in nearly 800 deaths worldwide, including in Vietnam. The causative agent was a particularly mutated coronavirus, possibly originating from a wild animal, such as the civet cat.
In early 2004, the H5N1 avian influenza outbreak spread rapidly across Asia, later reaching Europe and threatening the African continent. The transmission sources were domestic birds raised by humans.
In addition to the aforementioned “hot” outbreaks, common zoonotic diseases encountered in everyday life include typhoid (found in the feces of livestock, chickens, ducks, birds, turtles, and snakes), Hanta virus infections (from rodent droppings), rabies, cat scratch fever, and leptospirosis (transmitted from rodents, dogs, cats, pigs, and cattle)…
How do zoonoses cause disease?
Blood, saliva, feces, urine, skin, fur, meat, milk, and eggs from animals can all be sources of infection for humans. Weather, climate, and natural conditions significantly influence the emergence of zoonoses. Some diseases are only harmful in hot and humid tropical regions, while others occur exclusively in temperate zones. Insects, bugs, flies, mosquitoes, ticks, fleas, and birds can all serve as intermediaries to transmit pathogens from animals to humans.
High densities of animals in a specific area, deforestation, and easy transportation are all factors that facilitate the rapid emergence of zoonoses. Additionally, human lifestyle choices, such as living closely with livestock and dietary habits like consuming raw or undercooked meat, can also contribute significantly to the emergence of diseases.
Fortunately, most animal diseases rarely infect humans. However, recent developments concerning certain animal-specific viruses have raised significant concerns among scientists, as they are difficult to eradicate and can easily mutate and adapt to new environments, potentially crossing species barriers to infect humans. Industrial farming practices, with excessive animal density over small areas, have created conditions conducive to disease spread. Deforestation has forced wildlife to encroach on populated areas in search of food, consequently transmitting diseases to humans. Today, along with the growth and expansion of the transportation industry, pathogens can quickly and easily travel around the world with tourists and goods. Thus, some believe that the emergence of zoonoses is the price humanity pays for the scientific advancements we currently enjoy.
