Viruses Are Diverse
Viruses differ from each other in many ways. The differences affect how they make you sick and how you can stop them. Choose an option below and see how these 12 viruses line up!
Sort by
Human papillomavirus
Cause of COVID-19
Cause of AIDS
Cytomegalovirus
Viruses are very tiny. So tiny, they’re measured in nanometers (there are 10 million nanometers in one centimeter). At that scale, does size matter? As it turns out—yes!
All viruses need to be much smaller than the cells they infect. Size also affects how viruses can spread. For example, some move through the air inside droplets of liquid. Smaller viruses, like influenza A, SARS-CoV-2, and rhinovirus, can fit into the smallest droplets without weighing them down. An inhale draws them past hair and sticky mucus in a person's nose and then deep into the airways.
Others, like Ebola, are too big to spread this way. A sick person can release Ebola in a cough. But it can only fit in a heavy glob that falls quickly to the ground.
For Example
Rhinovirus
Rhinovirus is among the smallest viruses that infect people.
Though small, it’s quite infamous. You’ve probably had one. It’s one of several viruses that cause the common cold.
Ebola
Ebola is huge with a unique shape. But it’s still much smaller than a cell.
green = protein
yellow = envelope
blue = genetic material
main cause of the common cold
green = protein
yellow = envelope
blue = genetic material
Commonly known as “stomach flu” or “food poisoning”
green = protein
yellow = envelope
blue = genetic material
Mosquito-borne, causes birth defects like microcephaly (stunted head growth)
green = protein
yellow = envelope
blue = genetic material
Human papillomavirus
The most common sexually transmitted infection. Usually has no symptoms but can cause genital warts or increase risk for cervical cancer.
green = protein
yellow = envelope
blue = genetic material
Curable but often not detected. Causes liver damage that builds up over many years.
green = protein
yellow = envelope
blue = genetic material
One cause of the seasonal respiratory illness known as the “flu”.
green = protein
yellow = envelope
blue = genetic material
Cause of COVID-19
Cause of the respiratory illness COVID-19
green = protein
yellow = envelope
blue = genetic material
Spreads through saliva of infected animals. Affects the nervous system (brain and spinal cord)
green = protein
yellow = envelope
blue = genetic material
Cause of AIDS
Damages the immune system making it harder to fight infections.
green = protein
yellow = envelope
blue = genetic material
Extremely contagious, causes a rash and respiratory illness.
green = protein
yellow = envelope
blue = genetic material
Cytomegalovirus
(the same family as the viruses that cause genital herpes and chicken pox). Adults usually have no symptoms. Babies born with CMV can have long-term problems like hearing loss.
green = protein
yellow = envelope
blue = genetic material
Causes fever, body aches, pain, diarrhea, and bleeding inside the body.
Viruses are even more diverse than this!
This page focuses on viruses that infect people and make us sick. Keep in mind that there are many more viruses that can infect people without making us sick. Beyond human viruses, there are viruses that infect just about every living thing.
Researchers are discovering new viruses all the time. Some are so weird and different from the ones we know about that we understand little about them.
Viruses are essential
Viruses make up a huge amount of the earth’s organic matter. And they hold more than half of its genetic diversity.
Some may be important for keeping us healthy. And many have jobs that we don’t even know about yet.
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