When you think about dangerous animals, you might picture fierce predators like lions or sharks. But some animals that seem harmless or even cute can be just as dangerous—or even more so—than you’d expect.
From creatures you might encounter on a hike to those lurking in your own backyard, these animals can be more dangerous than you’d imagine.
1. Mosquitoes – 700,000 People Per Year
Mosquitoes are indeed a major public health concern, largely due to their role in transmitting diseases like malaria.
The statistics from the World Malaria Report show just how big the impact of mosquitoes is: with 249 million malaria cases reported in 2022 and an estimated 608,000 deaths, mosquitoes are responsible for a staggering number of fatalities each year. (ref)
This makes them one of the deadliest animals to humans, despite their seemingly benign appearance.
Timothy C. Winegard’s phrase in his book The Mosquito, “We are at war with the mosquito,”(ref) encapsulates the severity of this issue.
The mosquito’s ability to spread malaria and other diseases such as dengue fever, Zika virus, and chikungunya makes them a persistent and dangerous adversary in global health efforts.
2. Freshwater Snails – 200,000 People Per Year
Freshwater snails carry schistosomiasis, a parasitic disease that causes considerable health problems and fatalities. (ref) Each year, approximately 200,000 deaths are attributed to schistosomiasis. (ref)
Freshwater snails act as intermediate hosts for the parasites that cause schistosomiasis. These snails release larvae (cercariae) into contaminated water, which can penetrate the skin of individuals who come into contact with the water while swimming, bathing, or engaging in other activities.
3. Snakes – 100,000 People Per Year
Snakes are indeed among the deadliest animals to humans, with an estimated 100,000 deaths each year due to snake bites.
This high mortality rate is a result of both the venomous nature of many snakes and the often inadequate medical response to bites in many parts of the world.
Each year, around 5.4 million people are bitten by snakes globally, with between 1.8 to 2.7 million of these bites resulting in envenoming. This venom can have severe and potentially fatal effects, including paralysis, bleeding disorders, kidney failure, and tissue damage. (ref)
4. Ascaris Roundworm – 60,000 People Per Year
Ascaris lumbricoides, the parasitic roundworm, is a major cause of human suffering, with an estimated 60,000 deaths annually due to infections. (ref) This parasite is one of the largest intestinal nematodes and contributes to the burden of neglected tropical diseases (NTDs).
With around one billion people infected worldwide, Ascaris lumbricoides is a leading cause of helminthic infections. It affects individuals in many regions, particularly in areas with poor sanitation and hygiene. (ref)
The roundworms live in the human intestine, where they can grow to lengths of up to 14 inches. The presence of these large worms can lead to various gastrointestinal issues, including abdominal pain, malnutrition, and intestinal obstruction.
5. Dogs – 59,000 People Per Year
Dogs are a part of the global health landscape due to their role in the transmission of rabies. Each year, approximately 59,000 human deaths are attributed to rabies, a viral disease transmitted through the bite of an infected animal, most commonly dogs. (ref)
This makes dogs a notable contributor to human fatalities from zoonotic diseases, despite the availability of effective preventive measures.
Vaccinating dogs is important for controlling rabies, as they are the primary reservoir for the virus. Regular vaccination programs can greatly reduce the incidence of rabies in dogs and, consequently, in humans.
6. Kissing Bugs – 12,000 People Per Year
Kissing bugs, also known as triatomine bugs, are vectors for Chagas disease, a parasitic illness that causes substantial health problems and fatalities. Approximately six to seven million people worldwide are estimated to be infected with T. cruzi, and around 12,000 people die from Chagas disease each year.
Although the disease is found globally, it is most prevalent in 21 Latin American countries where the bugs are endemic. (ref)
If untreated, Chagas disease can lead to serious complications such as heart disease (cardiomyopathy), gastrointestinal problems (megaesophagus or megacolon), and other organ damage.
Severe cases of chronic Chagas disease can lead to death, particularly if complications are not managed effectively.
7. Scorpions – 3,000 People Per Year
Scorpions, with their fearsome appearance, are responsible for a number of human fatalities each year. The annual number of scorpion stings is estimated to exceed 1.2 million globally, with approximately 3,250 deaths attributed to scorpion stings. (ref)
However, it is important to note that only a small fraction of scorpion species—about 25 out of roughly 1,750—pose a real threat to humans. (ref) While not all stings result in severe outcomes, a huge number of cases lead to serious health issues and deaths.
8. Tapeworms – 1,000+ People Per Year
According to the data from Our World in Data, the number of deaths from cysticercosis in 2021 was 1,643. (ref) Cysticercosis is an infection caused by tiny larvae from the pork tapeworm (Taenia solium).
When these larvae get into the nervous system, they can cause serious health problems, including issues with the brain and nerves.
Tapeworms are typically transmitted through consumption of undercooked or contaminated meat, poor hygiene, and contact with contaminated water or soil. Even though tapeworm infections cause fewer deaths than some other diseases, they can still lead to serious long-term health problems and complications.
9. Crocodiles – 1,000 People Per Year
Crocodiles are formidable predators and pose a great risk to humans, with an estimated 1,000 deaths annually due to crocodile attacks. (ref) Their aggressive behavior and opportunistic nature contribute to their dangerous reputation.
The largest and most dangerous crocodile species is the Saltwater Crocodile (Crocodylus porosus), which is known for its ability to attack and kill humans.
The Nile Crocodile (Crocodylus niloticus) is another highly dangerous species responsible for numerous attacks in Africa.
10. Hippopotamus – 500 People Per Year
A study conducted in Burundi found that between 2017 and 2018, hippos accounted for 8% of all animal bites reported in the emergency room, despite representing only a small fraction of overall animal bites. This shows the severe impact hippo attacks have compared to other animals.
According to the study, the mortality rate from hippo attacks is not precisely known but is estimated to be between 500 and 3,000 deaths per year. (ref)
An older study indicated that hippo attacks resulted in fatalities for about 87% of the victims, which is a higher rate compared to attacks by lions or leopards. (ref)
While many of us might associate danger with well-known predators, these creatures remind us that danger can come from the most unlikely sources. Being aware of the risks they pose is crucial for our safety.
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Nancy Maffia
Nancy received a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.
