These 10 viruses are low-key scarier than horror movies—stick around to see which one still has the world on edge. 
TOP 10. Plague


This brutal bacterium was the mastermind behind the 14th-century Black Death—wiping out roughly a quarter of Europe’s population in just a few short years. Back then, it spread so fast through flea bites and human contact that there weren’t even enough people left to bury the endless stream of dead. This disaster didn’t just kill millions; it flipped Europe’s history on its head, leaving a permanent mark on its culture, religion, and economy for centuries to come.

TOP 9. Smallpox


Smallpox is the ultimate contagious troublemaker—terrorizing humans across every continent for centuries with its gruesome skin lesions and high fatality rate. In the early 1900s, it was killing millions every single year, hitting children the hardest. But here’s the win we all need: thanks to global vaccine rollouts led by organizations like the WHO, smallpox got the boot in 1980. Total W for humanity in the fight against deadly diseases!

TOP 8. Pestilence


Pestilence (courtesy of rats, fleas, and the Black Death bacterium) has one truly terrifying resume in human history. In the 1400s, the Black Death tore through crowded European cities and rural villages alike, taking out around 50 million people in a decade. Jump to the 1900s, and major plague outbreaks hit densely populated parts of Asia— infecting millions more before containment measures took hold.

TOP 7. AIDS (HIV)


This deadly virus has infected over 36 million people worldwide and claimed more than 32 million lives to date. When AIDS popped up in the 1980s, it sent panic spreading like wildfire across the globe, as little was known about its transmission or treatment. These days, we’ve got better meds and life-saving antiretrovirals that let patients live long, healthy lives, but AIDS still wreaks havoc in tons of developing countries with limited healthcare access.

TOP 6. Ebola Virus


Ebola is the definition of deadly—first spotted in remote African villages back in 1976. It spreads super fast through bodily fluids, and anyone infected usually doesn’t make it long, succumbing to severe bleeding and organ failure. The 2014–2016 Ebola outbreak absolutely crushed several West African countries, overwhelming local hospitals and killing thousands of people, including many frontline healthcare workers.

TOP 5. Sarin


Sarin is a lethal nerve agent cooked up by the Soviet Union during the height of the Cold War, designed for maximum destruction. It sneaks into your body through your lungs or skin in seconds—causing paralysis, convulsions, and serious harm, or even killing you outright within minutes. This stuff has been used in terror attacks more than once, most infamously the 1995 Tokyo subway attack: 13 dead, over 5,000 injured, and lifelong trauma for countless survivors. Chilling doesn’t even cover it.

TOP 4. Lassa Fever


Lassa fever is caused by the Lassa virus—first found in West Africa in the 1960s. It jumps from infected rodents (like mice) to humans, often via contaminated food or water, with symptoms like high fever, severe headaches, vomiting, and dangerous internal bleeding. Over the past few decades, outbreaks have hit multiple African countries with weak public health systems, killing tons of people before treatments could be deployed.

TOP 3.Scarlet Fever



Scarlet fever is no joke—this bacterial infection was a total menace back in the day. In the 1860s alone, it killed a whopping 9.72 million people. Throughout the entire 19th century, it swept across Europe, wiping out 25% of the continent’s population. These days, fatal cases are super rare, but make no mistake—it’s still one of the deadliest childhood killers in history.


TOP 2. Avian Influenza (Bird Flu)


Bird flu is hyper-contagious—and it can jump from wild birds to domestic poultry, then to humans in a dangerous crossover. If this virus mutates the wrong way to spread easily between people, it could spark a massive pandemic with tons of deaths worldwide. We haven’t seen a global outbreak yet, but this hidden threat still has experts on edge, with constant monitoring of bird populations to spot risks early.

TOP 1. COVID-19


Let’s be real—almost everyone knows this terror, as it upended daily life for billions. It’s caused unprecedented cases and deaths worldwide, overwhelming hospitals and testing systems. First spotted in China in late 2019, COVID-19 spread across the globe in the blink of an eye, thanks to international travel. With unpredictable symptoms (from mild colds to severe lung damage) and severe cases hitting vulnerable groups hard, it’s infected millions and killed hundreds of thousands. Total chaos that’s still shaping our world today.