These 10 Animals are the Deadliest to Humans, and Most Aren’t Fearsome Beasts

Author Vishay SinghPosted on February 29, 2024Categories Discover Magazine

When you think of killer animals, odds are you picture a lion, a shark, maybe an elephant. But those fearsome beasts are but players in the bigger picture of human demise. The ones that truly take a toll on Homo sapiens are diverse, often surprising, and impressively lethal. The 10 deadliest animals combined kill less than a million humans per year.

While any loss of human life is tragic, humans also have a part to play in the circle of life. We have contributed to habitat loss, and consume hundreds of millions of fish and livestock every day. Technically, humans are the most dangerous species to our own, accounting for nearly half a million annual deaths, according to a 2019 report. But setting aside our own issues, here are the creatures that lead to the most human deaths.

1. Mosquitoes — 700,000 People Per Year

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An unrivaled executioner, the humble mosquito (its name means “little fly” in Spanish) is the only organism that kills more of us than we do. Published estimates for the total number of victims range almost comically, but as a vector for ravaging diseases like malaria (600,000 deaths alone), dengue fever, and yellow fever, there’s no doubt mosquitoes constitute a unique threat to humanity.

Some experts are skeptical of the oft-repeated claim that they’ve killed half of all people who ever lived, but that does little to diminish how deeply they’ve shaped the course of human history. As Timothy C. Winegard puts it in his best-selling book on the subject, “We are at war with the mosquito.”

2. Snakes — 100,000 People Per Year

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Despite coming in nearly an order of magnitude behind the first-place killer, snakes are nevertheless a major problem in many parts of the world. Bites are most common in countries with poor data collection, leading experts to believe they’re drastically underreported.

Accounting for a wide margin of error, the World Health Organization estimates snakes kill between 81,000 and 138,000 people per year (not to mention the hundreds of thousands of survivors who suffer amputations and permanent disabilities).

3. Ascaris roundworm — 60,000 People Per Year

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The body count is startling enough, but the infection rate is astounding: Up to 1.2 billion people (roughly 15 percent of the world’s population) are thought to carry this parasite. Ascaris is the most common cause of soil-transmitted helminthiasis, a class of intestinal infections also transmitted by whipworm and hookworm.

Most people never show symptoms, but in rare cases, the disease can have life-threatening consequences, primarily in children. (Estimates actually vary between 3,000 and 60,000 deaths per year, but we’ll give Ascaris the benefit of the doubt.)

4. Dogs — 59,000 People Per Year

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We may think of them as our best friends, but they’re also one of our greatest menaces. Most deaths by dogs aren’t the direct result of an attack but of the incurable rabies virus they can transmit to humans when they bite.

Rabies vaccines have been around for a century, so this is mainly a problem in countries with inadequate supply or limited medical resources.

5. Freshwater Snails — 12,000 People Per Year

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Once you’ve finished that double take, the first thing to note is that you’re in no danger of a vicious snail mauling. These subtle killers don’t even need to come in contact with their victims. Rather, they carry a parasitic disease called schistosomiasis, which infects some 250 million people in tropical regions of Asia, Africa, and South America.

The snails release schistosomiasis larvae, which can penetrate the skin of any human swimming or bathing in contaminated water and trigger all sorts of nasty health problems (including, rarely but often enough, death).

6. Kissing Bugs — 10,000 People Per Year

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With a name like that, you’d expect a warm welcome, but often these insects bring disaster. The American counterpart to the Tsetse fly, which causes African sleeping sickness, kissing bugs bear a parasite from the same genus (Trypanosoma) in their feces.

They feed on human blood and defecate near the bite, so when the person instinctively rubs the area, the parasites enter their body, causing Chagas disease. It can lie dormant for decades before causing severe damage to the heart and nervous system, sometimes resulting in cardiac failure. Between 6 and 7 million people (mainly in a few Latin American countries) are infected.

7. Scorpions — 3,000 People Per Year

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Of roughly 1,750 scorpion species, just 25 are considered a real threat to humans. Yet those few killers take more lives than almost any other venomous creature (the lone exception awaits further down the list).

All told, scorpions are responsible for more than a million stings per year, mostly in Africa, Asia, and Latin America. In case you encounter one, remember this (scientifically verified) advice from Indiana Jones: “When it comes to scorpions, the bigger the better.”

8. Tapeworms — 1,000 People Per Year

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Next in line is one of the more unsavory creatures on the list. Tapeworm infections, known as cysticercosis, come either from eating undercooked pork or from ingesting traces of infected feces from a human carrier.

The worms then lay eggs in various organs, including parts of the central nervous system, where they can cause epileptic seizures. Though you can pick up this disease anywhere in the world, it’s most common in parts of Asia, Africa, and Latin America, with subpar sanitation and free-ranging pigs.

9. Crocodile — 1,000 People Per Year

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The only other contender from the “big and bad” category, crocodiles, are in constant danger of being pushed out by animals they wouldn’t deign to snap at. And the commonly cited statistic of 1,000 deaths per year, by the admission of its authors, “should not be used too literally.”

Even so, in places where humans live in close proximity to these scaly terrors (especially along the Nile River and in Southeast Asia and Australia), they pose a significant safety hazard.

10. Hippopotamus — 500 People Per Year

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Bringing up the rear is an animal that demands respect despite its rather goofy appearance. It’s difficult to track down an authoritative tally of hippo kills, but this common estimate comes from an Encyclopedia Britannica article.

Throughout their range in sub-Saharan Africa, hippos regularly come into conflict with farmers when they raid crops and sometimes attack small boats (perhaps believing them to be predatory crocodiles). They’re perfectly capable of trampling humans but more often crush them with their powerful jaws.

Vishay Singh