viruses

Zoonotic spillover explained: how viruses like SARS-CoV-2, HIV, Ebola, and MERS crossed from animals to humans — and why it keeps happening.

Viruses are the most numerous lifeforms on Earth, but they're simple — just RNA or DNA wrapped in protein. They replicate by hijacking cells. If viruses evolved intelligence, they could become the apex predators of the biological world, infecting and controlling complex organisms with surgical precision.

Some viruses kill almost everyone they infect. Others spread so fast they ignite global pandemics. Here are the most dangerous viruses on Earth and the science behind their lethality.

Viruses and bacteria both cause infections and both are too small to see, yet they differ in size, structure, reproduction, and treatment. Here is how to tell them apart.