If you were to die in an animal attack, what do you think would kill you? Would it be a lion, a tiger or a bear (oh my!)?Maybe, but none of those are at the top of the list for animals that kill humans.The deadliest animal?Mosquitoes cause the most animal deaths every year. (Times archives)1. It's found in your backyard — the mosquito.The World Health Organization reports that 500 million cases of mosquito-borne diseases occur every year and cause 2.7 million deaths. Dengue is the world's most important mosquito-borne virus disease, with more than 200 million people worldwide at risk of infection and 20 million cases a year in more than 100 countries. Though, 90 percent of the mosquito-borne diseases occur in Africa.Dogs account for 55,000 deaths a year because unvaccinated dogs can carry rabies. [Octavio Jones, Times Staff Photographer]2. Rabid dogs.About half the world's population ― which is more than 3 billion people ― live in areas where dog rabies still exists. The World Health Organization estimates that at least 55,000 human rabies deaths occur yearly in Africa and Asia following contact with rabid dogs.[Flickr Creative Commons ]3. The tsetse fly.Though the tsetse fly looks like a regular housefly, it's much more deadly. BBC News said the tsetse fly uses a large proboscis to bite vertebrate animals, including humans, and suck their blood.The fly carries a sleeping sickness that can cause fevers, headaches and joint pain, followed by vomiting, swelling of the brain, and trouble sleeping. About 20,000 to 30,000 people are thought to be infected with the sickness every year, the vast majority in sub-Saharan Africa. An estimated 10,000 die from the disease.[Scott Keeler | Times ]4. Crocodiles.BBC News estimates that about 1,000 humans are killed per year from crocodiles. Several hundred attacks occur each year in Africa and about a third of them are fatal.Kristen Yaldor, 37, was attacked by a hippo on her birthday when canoeing in Zimbabwe on Dec. 1. She and her husband were on vacation at Victoria Falls. [Photo courtesy of Kristen Yaldor]5. The hippopotamus.Recently, a Florida couple planned a dream vacation to Zimbabwe but was then attacked by a hippo. The wife sustained a fractured femur and is still hospitalized in intensive care.BBC News reports that the hippo is the world's largest land mammal killer. It's estimated that the aggressive animal with sharp teeth kills 500 people a year in Africa. Hippos can crush a human to death with their weight ranging anywhere from 3,000 to 9,000 pounds.