10 deadliest animals to humans

Think you might know what the 10 deadliest animals might be? Our expert guide rounds up the animals causing the most number of human deaths per year – and some of them might just surprise you.

Hippopotamus opening jaws in threat display in Kwando River, Namibia.

When you think of deadly and dangerous animals, what springs to mind? It is likely big, carnivorous, apex predators, such as lions, wolves, or sharks. What you will learn from this list however is that size and strength can be deceiving. Sharks, although often unjustly perceived as very deadly, do not even make this list, being responsible for only six human deaths a year on average. Lions? Only 22! Rather, the deadliest animals are often the smallest, and cause death not through strength, but through disease and toxins. Read on to find out more.

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10 examples of animals that are deadly to humans

1. Hippopotamus (Hippopotamus amphibius)

500 deaths per year

Before we get to small and deadly, let’s start with the biggest. When you think of deadly African wildlife, you might perhaps assume lions took the top spot. In actual fact, hippos kill many more people every year.
Causing an estimated 500 deaths annually (as compared to only 22 for lions), hippos are deadly land mammals. This is because they are very aggressive and territorial, and have a habit of charging at boats and capsizing them.
The people on board then either drown or are killed by the animals themselves. Weighing an average of 1,500 kg (males), with large sharp teeth, it’s certainly an animal you wouldn’t want to face up against.

2. Elephants (Elephantidae family)

500 deaths per year

African elephant on the move. © Manoj Shah/Getty
We may perhaps think of elephants as gentle, thoughtful creatures, but they can also be deadly. This is in part due to their sheer size and weight, as the largest living land animals.
Because of habitat loss and encroaching farmlands into elephant home areas, they are coming into contact with humans more and more frequently, and this has led to conflict.
Groups of elephants have been known to raid farms and villages, and will gore or trample any humans that get in the way. One blow from an elephant is enough to kill, and around 500 deaths a year are caused in this way.

3. Saltwater crocodile (Crocodylus porosus)

1,000 deaths per year

Saltwater crocodile, Sundarbans, India. © ePhotocorp/Getty
Another deadly water-dweller you would want to avoid is the saltwater crocodile. Crocodiles as a group are quite deadly, killing around a 1,000 people a year, but they do not generally set out to hunt humans and kills are opportunistic.
The saltwater crocodile however is one of the most likely to see humans as prey. It is also fierce, fast, and intimidating, being the largest living reptile and crocodilian known. Males can grow to a length of 6 metres and weigh 1,300 kg.
When pursuing prey through the water they can also reach speeds of 18mph. All this together means that if a saltwater crocodile has chosen you as his prey, survival is unlikely.

4. Ascaris roundworms (Ascaris genus)

2,500 deaths per year

Ascariasis is a disease caused by the parasitic roundworm Ascaris lumbricoides. © Sinhyu/Getty
The deadly agent here is a parasite. That is, an animal that lives on or in another (a host) and causes it harm.
The roundworm here is the parasite, rather than just the vector, like mosquitos. Ascaris roundworms are transmitted when a person accidentally ingests their eggs, which is unfortunately usually when food or drink is contaminated by human faeces.
The worms take residence in the small intestine and use the human body to stay alive, feed and reproduce. The resulting disease is called Ascariasis, is characterised by fever, abdominal pain and swelling, and shortness of breath, and kills around 2,500 people every year.

5. Scorpions (Scorpiones order)

2,600 deaths per year

Indian red scorpion, Satara, Maharashtra, India. © ePhotocorp/Getty
Some of the most deadly animals are those that deliver venom. Unlike poisonous animals, who secrete toxins, venomous animals directly deliver it using specialised body parts, through a bite or, in this case, a stinger.
Scorpions produce venom for the same reason that many species do, not to kill humans, but to subdue or kill their prey. However, the venom of 25 species of scorpion can be deadly to humans if you are unlucky enough to get in one’s way.
Stings often happen when scorpions are accidentally stepped on with bare feet, or when they are hiding in people’s shoes. They use it as a defence mechanism against getting crushed, rather than as an attack.
Around 2,600 deaths a year are caused by scorpion stings. The most lethal in the world is considered to be the Indian redscorpion (Hottentotta tamulus).
Meerkat family of adult with three pups sheltering under here in desert environment
Paul Souders / Getty Images

6. Assassin bugs (Reduviidae family)

10,000 deaths per year

Some assassin bugs can carry Chagas disease. © Vini Souza/Getty
Another insect that spreads disease and death through its bite is the aptly-named assassin bug. Some species of this Central and South American ‘true bug’ are responsible for spreading Chagas disease, another tropical parasitic disease that kills approximately 10,000 people per year globally.
The species that do this are also often called ‘kissing bugs’, as they tend to bite people’s faces as they sleep. Charming.

7. Saw-scaled viper (Echis carinatus)

138,000 deaths per year

Saw-scaled pit viper, India (Echis carinatus). © Lensalot/Getty
The venomous saw-scaled viper holds the record as the most deadly snake in terms of mortality. Snakes overall are high up on the list of deadly creatures as snake bites are responsible for as many as 138,000 deaths annually.
The saw-scaled viper is a particularly aggressive species, making it more deadly than the snake that is actually the most highly toxic but also shy, the inland taipan (Oxyuranus microlepidotus).
Its aggressive nature, paired with its potent venom and presence in highly populated areas, make the saw-scaled viper a snake to fear.

8. Freshwater snails (Gastropoda class)

200,000 deaths per year

Planorbarius snails are the intermediate host for the trematode parasite of the Schistosoma genus, which is responsible for schistosomiasis. ©Getty
This one may surprise you. More than 200,000 deaths a year can be attributed to freshwater snails. This is because they are hosts to deadly parasites, in particular parasitic flatworms known as flukes.
There are as many as 24,000 species of flukes, and most of them are parasites of vertebrates (like us) and molluscs (like snails).
A particularly nasty one that is transmitted by freshwater snails is called Schistosoma. The flukes live and develop within the snail then are released into the water. Humans get infected from the contaminated freshwater as the flukes penetrate the skin.
This is responsible for a deadly human disease called schistosomiasis, also known as ‘snail fever’.
After malaria this is considered to be the second most “socioeconomically devastating” parasitic disease, and causes as many as 200,000 deaths a year, according to the World Health Organization (WHO) in 2000.

9. Humans (Homo sapiens)

431,000 deaths per year

Soldiers marching in the desert. © Frank Rossoto Stocktrek/Getty
It’s a cliche, but (aside from mosquitos) the most deadly animal is ourselves!
Homicides account for an estimated 431,000 human deaths a year, making us by far the deadliest mammals. Our capacity for advanced tool use above and beyond that of all other animals has in some ways been our downfall, leading as it has to complex weapons that we use to kill each other.
And this is not to mention the destructive impact our activities have had on the natural world, resulting in climate change, which is already estimated to cause over 150,000 deaths annually.
Climate change affects human health and safety in many ways, affecting the cleanliness of our water and air, our food security, and the frequency of natural disasters. It can also increase the frequency of diseases, including ones mentioned in this list, such as malaria.
The WHO estimates that between 2030 and 2050 climate change will cause approximately 250,000 additional deaths per year due to malnutrition and disease.

10. Mosquitos (Culicidae family)

725,000 – 1,000,000 deaths per year

Orient mosquito (Anopheles minimus) engorged with blood, feeding on a human host. © Smith Collection/Gado/Getty
The ultimate example of a very small animal with a very big impact. In terms of the number of humans killed every year, mosquitos by far hold the record, being responsible for between 725,000 and 1,000,000 deaths annually. That is not to say these tiny insects set out to kill, however.
Rather than killing directly, mosquitos are instead very frequent ‘disease vectors’. This means that in the course of their feeding, on human and animal blood, they incidentally transmit infectious pathogens, carrying bacteria, viruses, and parasites from person to person.
The mosquito-borne disease with the highest number of fatalities is malaria, a parasitic infection that is spread by female Anopheles mosquitoes. This disease is so widespread and lethal that it has had a massive impact on human history and even our evolution.

Main image: Hippopotamus opening jaws in threat display in Kwando River, Namibia. © Paul Souders/Getty