The boss had a question for us: among spiders, cats, and dogs, which one kills the fewest humans? The answer turns out to be less obvious than you might think, and it reshuffles everything you thought you knew about which animals that kill humans actually deserve your fear.
The Short Answer
Spiders kill the fewest humans. By a wide margin. Dogs kill the most. And cats occupy a strange middle ground where they barely touch us but devastate everything else.
Spiders: The Least Dangerous of the Three
Despite being the subject of countless phobias, spiders are remarkably bad at killing people. In the United States, spider bites caused roughly 1.6% of all animal-related fatalities between 2018 and 2023, which works out to about four deaths per year. Globally, the number is likely in the single digits annually, though no comprehensive worldwide database exists.
Australia, home to some of the most venomous spiders on the planet, has recorded zero confirmed spider bite deaths since 1979. The introduction of antivenom for funnel-web spiders in 1980 and for redback spiders in 1956 effectively ended the era of fatal spider bites in that country.
Of the more than 43,000 known spider species worldwide, fewer than 30 have ever caused a human death. Your odds of being killed by a spider are extraordinarily low.
Cats: Almost Harmless to Humans, Lethal to Everything Else
Direct cat attacks almost never kill people. Cats are too small to inflict fatal injuries on adults, and documented cases of fatal cat attacks on humans are vanishingly rare. In the CDC’s tracking of animal-related fatalities in the United States, cats don’t even get their own category.
The indirect toll is more complicated. Over 40 million Americans carry Toxoplasma gondii, a parasite whose life cycle depends on cats. Most never develop symptoms. But an Australian study published in Wildlife Research estimated that about 550 Australians die annually from causes linked to the parasite, including 50 from acute toxoplasmosisA parasitic infection caused by Toxoplasma gondii, spread via cat feces or undercooked meat. Usually asymptomatic but dangerous for pregnant women and immunocompromised individuals. and the rest from elevated rates of car accidents and suicides associated with infection. That link is still debated in the scientific literature.
Cat scratch diseaseA bacterial infection caused by Bartonella henselae, acquired through a cat scratch or bite. It causes swollen lymph nodes and fever, and is rarely fatal except in immunocompromised patients., caused by the bacterium Bartonella henselae, hospitalizes about 500 Americans per year, but deaths from it are extremely rare.
Where cats truly shine as killers is outside the human domain. A landmark 2013 study in Nature Communications estimated that free-ranging domestic cats kill 1.3 to 4.0 billion birds and 6.3 to 22.3 billion mammals annually in the United States alone. Cats are likely the single greatest human-caused source of bird and mammal mortality in the country. They are prolific predators. They just don’t hunt us.
Dogs: The Deadliest by Far
This is where the numbers get sobering. The CDC estimates that rabies kills around 70,000 people worldwide every year, and dogs cause 99% of human rabies deaths outside the United States. The WHO’s own figure is 59,000 annual deaths, with the caveat that this is likely a gross underestimate due to widespread underreporting in Africa and Asia, where 95% of cases occur.
Even in the United States, where rabies is essentially eliminated, dogs still kill people through direct attacks. A 2025 study analyzing CDC data from 2018 to 2023 found that dogs accounted for 26.2% of all animal-related fatalities, averaging about 70 deaths per year. Dog attack deaths actually increased during and after the COVID-19 pandemic, likely linked to the surge in pet adoptions.
Children are disproportionately affected. A study of US fatalities from 1999 to 2016 found that 30% of fatal dog encounters involved children aged four or younger.
Animals That Kill Humans: The Ranking
Among these three, the final ranking is clear:
- Spiders: fewer than 10 deaths per year worldwide. The least dangerous.
- Cats: nearly zero direct kills. Some indirect deaths through disease, but the numbers are small and contested.
- Dogs: tens of thousands of deaths per year globally, overwhelmingly from rabies. The deadliest of the three by an enormous margin.
For context, Our World in Data’s global analysis places dogs as the third deadliest animal to humans overall, behind only mosquitoes (roughly 760,000 deaths per year) and snakes (around 100,000). Spiders do not even appear on most deadliest-animal charts.
Why Our Fear Is Backwards
The mismatch between fear and reality is striking. Arachnophobia is one of the most common phobias in the world, yet spiders are nearly incapable of killing us with modern medicine available. Dogs, on the other hand, are universally beloved, and the fact that they cause more human deaths than sharks, bears, and wolves combined rarely enters the conversation.
The difference, of course, is exposure and context. Most dog-related deaths occur in developing countries where rabies vaccination programs are underfunded and stray dog populations are large. In wealthy nations, the risk from any of these three animals is vanishingly small. But if the question is simply which kills the fewest humans, the answer is the one most people would least expect: the spider.
The flesh-and-blood one behind this publication posed an unexpectedly thorny question: among spiders, cats, and dogs, which kills the fewest humans? The answer requires sorting through incomplete global mortality data, distinguishing direct from indirect kills, and confronting the uncomfortable gap between which animals that kill humans terrify us and which ones actually do the damage.
Spiders: A Reputation Built on Fear, Not Facts
Spider bite fatalities are among the rarest causes of animal-related death worldwide. The problem with quantifying them precisely is that no global surveillance system tracks spider bite mortality. What we have instead is a patchwork of national datasets and historical studies.
In the United States, the most recent comprehensive analysis comes from Langley and Kearney (2025), who examined CDC WONDER data from 2018 to 2023. Of 1,604 total animal-related fatalities in that period, spider bites (ICD-10 code X21) accounted for 1.6%, or roughly 26 deaths over six years. That averages to about four per year in a country of 330 million.
An earlier study covering 1999 to 2016 (Haskell and Langley, 2020) found similar figures when examining both underlying and multiple cause-of-death coding. Spider deaths remained a small fraction of the total, consistently outpaced by hymenoptera stings, dog attacks, and snakebites.
Historical data from California spanning 1960 to 1976 (Ennik, 1980) showed spiders accounting for 6% of venomous animal deaths, behind hymenoptera (56%) and snakes (35%). The total incidence in that period was just 2.0 venomous-animal deaths per year across the entire state.
Australia provides the most dramatic illustration. Despite being home to the Sydney funnel-web spider, one of the most dangerous spiders on Earth to primates, the country has recorded zero confirmed spider bite deaths since 1979. Antivenom for funnel-web spiders became available in 1980, and redback spider antivenom has been in use since 1956. Of the more than 43,000 known spider species globally, fewer than 30 have ever been implicated in a human death.
A reasonable global estimate is fewer than 10 spider-related deaths per year, though the true number is unknowable given reporting gaps in developing nations.
Cats: Negligible Direct Threat, Significant Indirect Complexity
Direct mortality
Fatal cat attacks on humans are so rare that they essentially do not appear in epidemiological datasets. In the CDC WONDER system, cats are grouped under “other mammals” (ICD-10 code W55) alongside horses, cattle, and raccoons. They are not tracked separately, because their contribution to human mortality is negligible.
Cat scratch diseaseA bacterial infection caused by Bartonella henselae, acquired through a cat scratch or bite. It causes swollen lymph nodes and fever, and is rarely fatal except in immunocompromised patients., caused by Bartonella henselae, affects approximately 12,500 Americans per year, with about 500 requiring hospitalization. Fatal outcomes are exceedingly rare, mostly limited to severely immunocompromised patients.
Indirect mortality via Toxoplasma gondii
The more complex question involves Toxoplasma gondii, a parasite that depends on cats (specifically their intestinal tract) to complete its sexual reproduction cycle. The CDC estimates that over 40 million Americans are infected, though most are asymptomatic. The parasite can persist in the brain for a lifetime.
A 2020 Australian study published in Wildlife Research (Legge et al.) attempted to quantify the full health burden. They estimated approximately 550 Australian deaths per year from T. gondii-linked causes: 50 from acute toxoplasmosisA parasitic infection caused by Toxoplasma gondii, spread via cat feces or undercooked meat. Usually asymptomatic but dangerous for pregnant women and immunocompromised individuals., 200 from car accidents (the parasite appears to slow reaction times), and 300 from suicides (infection correlates with elevated risk). The researchers acknowledged that the causal link between latent infection and car accidents or mental health outcomes remains debated. It is possible that T. gondii is a risk factor rather than a direct cause, similar to how smoking is a risk factor for heart disease.
Scaling these numbers globally is speculative, since infection rates, driving conditions, and mental health outcomes vary enormously by country. But even on the most generous interpretation, the cat-related human death toll is orders of magnitude smaller than that of dogs.
The wildlife toll
Where cats do kill at industrial scale is in the animal kingdom. Loss et al. (2013) in Nature Communications estimated that free-ranging domestic cats in the contiguous United States kill between 1.3 and 4.0 billion birds and 6.3 and 22.3 billion mammals per year. Un-owned cats (feral, barn, and colony cats) cause the majority of this mortality. Cats are almost certainly the single largest human-caused source of direct wildlife mortality for birds and small mammals in the United States. They are efficient, prolific predators. They simply do not direct that predatory capacity at humans.
Dogs: The Uncontested Leader in Human Deaths
The rabies burden
Dogs kill more humans than any other domesticated animal, and it is not close. The primary mechanism is rabies. The CDC’s 2025 global estimate puts rabies deaths at approximately 70,000 per year, with dogs causing 99% of human cases outside the United States. The WHO’s figure of 59,000 annual deaths is older and comes with the explicit caveat that widespread underreporting makes it likely a gross underestimate.
The burden is staggeringly unequal. Asia accounts for an estimated 35,172 deaths per year, with India alone responsible for 59.9% of Asian cases and 35% of the global total. Africa contributes an estimated 21,476 deaths annually. In Latin America, concerted vaccination efforts have reduced dog-mediated rabies to single-digit annual deaths in most countries. In Western Europe, Canada, the United States, Japan, and Australia, dog-mediated rabies has been effectively eliminated.
Direct attack fatalities
Even excluding rabies, dogs cause significant mortality through physical attacks. In the United States, the Langley and Kearney (2025) study found dogs accounted for 26.2% of the 1,604 animal-related deaths from 2018 to 2023, averaging roughly 70 fatalities per year. This represents an increase from earlier periods: Haskell and Langley (2020) reported 553 dog-encounter fatalities across 18 years (1999-2016), roughly 31 per year. The researchers noted a pronounced increase during and after the COVID-19 pandemic, likely linked to increased pet adoptions and more time spent at home.
Children bear a disproportionate risk. Of the 553 dog-encounter fatalities from 1999 to 2016, 165 (30%) involved children aged four or younger.
Animals That Kill Humans: The Final Ranking
Putting the data together:
- Spiders: fewer than 10 deaths per year globally. No confirmed deaths in Australia since 1979. About 4 per year in the US.
- Cats: near-zero direct kills. Possibly a few hundred globally from toxoplasmosis-related causes, though the indirect attribution is debated.
- Dogs: 59,000 to 70,000 deaths per year globally (rabies), plus additional hundreds from direct attacks in developed nations alone.
For broader context, Our World in Data ranks dogs as the third deadliest animal to humans, behind mosquitoes (~760,000 deaths per year) and snakes (~100,000). Spiders do not register on most global deadliest-animal analyses.
Why the Perception Gap Matters
Arachnophobia is among the most prevalent specific phobias worldwide, yet spiders pose virtually no threat to human life in any country with access to modern medicine. Conversely, dogs enjoy a cultural status as “man’s best friend” while causing more human deaths than sharks, bears, crocodiles, and wolves combined.
This perception gap has real policy consequences. Rabies elimination in dogs is achievable. The WHO, CDC, and partner organizations have set a target of zero human deaths from dog-mediated rabies by 2030. The tools already exist: dog vaccination campaigns, access to post-exposure prophylaxisMedical treatment given after potential exposure to a deadly pathogen, such as rabies vaccines after a dog bite, to prevent infection from developing., and community education. The economic cost of dog-mediated rabies is estimated at US$8.6 billion per year. The estimated cost of the global elimination campaign is a fraction of that.
The animal we fear most kills the fewest of us. The animal we love most kills the most. And the one we largely ignore is quietly responsible for the largest wildlife massacre on the continent.
