Why Are Some Viruses More Lethal Than Others?
There are as many viruses on Earth as there are stars in the sky, but not all viruses are created equal. Some are simply better equipped to kill than others. Like the Daily Show host, Trevor Noah once said, "It's cool if you are THE coronavirus ... getting upgraded from a local disease to a global pandemic." So, of the thousands of viruses out there, why do only a few become an epidemic? Why are some viruses, like COVID-19, more dangerous than others?
For a virus to be deadly enough to become an epidemic, it has to be both lethal and good at finding new victims. It should be able to avoid early detection by the host’s defenses (like white blood cells) and, even if detected, to withstand the damage. Being a virus that is good at all four of these attributes is a tall order.
Ebola, for example, is lethal, but since it travels through body fluids, it relatively lacks in its ability to spread. The flu, on the other hand, is good at spreading fast. Its ability to rapidly mutate helps it defend against vaccines (this is why you need a flu shot every year). However, our body has enough cellular weaponry to detect and kill the virus before it becomes dangerous.
Then there’s the coronavirus. COVID-19’s protein shell can latch on to respiratory droplets and evade detection by the body until it reaches the lungs. There, it goes under mass reproduction, killing healthy tissue and causing the immune system to harm the body in an attempt to rid itself of the virus. However, COVID-19’s greatest weapon is its ability to gestate for weeks without showing symptoms. Often, by the time most patients show diseases, the virus has already done severe damage.
This accelerated contagion and lethality, coupled with the fact that there is no definitive preventative medicine or treatment available encapsulate how the coronavirus managed to shut down the entire world.
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For a virus to be deadly enough to become an epidemic, it has to be both lethal and good at finding new victims. It should be able to avoid early detection by the host’s defenses (like white blood cells) and, even if detected, to withstand the damage. Being a virus that is good at all four of these attributes is a tall order.
Ebola, for example, is lethal, but since it travels through body fluids, it relatively lacks in its ability to spread. The flu, on the other hand, is good at spreading fast. Its ability to rapidly mutate helps it defend against vaccines (this is why you need a flu shot every year). However, our body has enough cellular weaponry to detect and kill the virus before it becomes dangerous.
Then there’s the coronavirus. COVID-19’s protein shell can latch on to respiratory droplets and evade detection by the body until it reaches the lungs. There, it goes under mass reproduction, killing healthy tissue and causing the immune system to harm the body in an attempt to rid itself of the virus. However, COVID-19’s greatest weapon is its ability to gestate for weeks without showing symptoms. Often, by the time most patients show diseases, the virus has already done severe damage.
This accelerated contagion and lethality, coupled with the fact that there is no definitive preventative medicine or treatment available encapsulate how the coronavirus managed to shut down the entire world.
SOURCES:
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