"I love my dog. He goes everywhere with me. I take him hunting, he guards my house. We even sleep next to each other."
When humans domesticated animals thousands of years ago they also might have decrease transmission rates of malaria. This process is called zooprophylaxis and involves the diversion of disease carrying insects from humans to animals. The practice of zooprophylaxis is not recent; it was once common practice in Europe for shepherds to sleep in the company of a few sheep who could satisfy hungry mosquitoes. Some experts believe malaria was eradicated from Europe, in part, because of zooprophylaxis. However, additional data indicates that the presence of too many animals can then result in increase malaria transmission to humans. Whether or not the presence of animals among humans helps or harms the situation seems to depend upon animal and human population density. But for many, "man's best friend" might prove to be not just a dog, but a sheep, cow, or even a cat.