Last week, a number of websites (including Vox) circulated a chart from Bill Gates purporting to show that mosquitoes are deadlier than any other animal — even humans.
The logic? Humans kill around 475,000 other humans each year through murder, wars, etc. But, the chart noted, mosquitoes now kill 725,000 people each year by transmitting diseases like malaria, dengue fever, and so forth.
There's one problem: this comparison isn't quite right.
Jonathan Eisen, a biologist at the University of California, Davis has a good post pointing out the flaw in the reasoning. If we're going to count all the diseases that mosquitoes transmit, then we should include all the diseases that humans pass on to other humans, too. That includes HIV/AIDs, which kills 1.78 million per year. It also includes tuberculosis, which kills 1.34 million people per year. And so on. Humans are easily the winners here.
If we wanted, we could take this even further. The World Health Organization estimates that air pollution kills about 7 million people per year — making it one of the leading causes of deaths on the planet. There's at least an argument for adding this to the "deaths caused by humans" tally (although this gets tricky since the energy use that leads to pollution also boosts human well-being).
Anyway, the broader thrust of Bill Gates' post was still correct — and vitally important. Diseases transmitted by mosquitoes are a major public-health crisis that don't get nearly enough attention. (Shark attacks, by contrast, often dominate headlines but only kill about 10 people per year.) Gates is doing invaluable work calling attention to the situation. And my colleague Dylan Matthews has a great list of cheap, cost-effective ways to tamp down on mosquito-borne diseases.
But deadlier than humans? Not quite.