We usually think humans catch diseases from other humans — think the flu — but scientists have just published an awesome graphic that shows just how intertwined our germs are with the animals that surround us.
Many germs that infect animals can be dangerous to humans.
Scientists think that Ebola is carried by fruit-eating bats then transmitted to chimps, gorillas, monkeys, and humans. Rabies infects mammals like raccoons, skunks, bats, and foxes, and can be transferred to humans through a bite.
The new study, published in the journal Scientific Data, mapped the relationships between microorganisms — bacteria, viruses, and fungi — and the animals (including people) they can infect.
Each dot represents a species of animal (specifically those with backbones, including mammals like dogs and cats, amphibians like frogs and salamanders, and birds — called “aves” in the map — like chickens and parrots). You can see humans have only one dot — we are the only species, but other groups, like the bright-pink mammals group to the right in the image, include many species.
The bigger the dot, the more unique pathogens infect it. The largest dot is clearly the human species, but that’s likely because scientists spend much more time studying germs that infect us than they do studying, say, frog infections.
Lines connecting dots represent at least one microorganism — the thicker the line, the more germs infect both species. The researchers also included infections that are transmitted to multiple species — for example, rabies can infect and be transmitted between different mammals like raccoons, cats, dogs and humans.
There is one noteable exception: The brighter blue portion of the map lumps together “domestic” animals — those that live in our houses or are grown for food — including dogs, cats, pigs, and cattle.
Infections that these animals get can pretty dangerous if they can also infect humans, because we come into contact with them so frequently — either because they are kept as pets or because we eat them.
Interestingly, you can see below that amphibians remain pretty isolated from the rest of the animals when it come to sharing their diseases.
The scientists based this graphic on data published between 1950 to 2012, and focused on 15,219 animals.
It’s a beautiful illustration, but it might distract from how dangerous zoonotic diseases, or diseases that can be transmitted from animals to humans, can be.
A 2012 study found that 2.2 million deaths are caused by diseases transmitted from animals, according to Live Science. That includes deaths from food-borne illnesses, zoonotic tuberculosis, rabies, toxoplasmosis, hepatitis E, and even anthrax. Sadly, many of these diseases riddle the poorest countries around the world.
That being said, it’s good to keep in mind that not all of these infections are dangerous. Some of the infections in the map are actually beneficial to one or both species.
Although it’s probably best to not feed or touch that adorable squirrel at the park, just in case.
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