What life form has the best kill-death ratio against humans.

Source.

I read somewhere that snakes kill more humans then any other animal because they are every where

Viruses, no cure for a lot of them so it really helps their odds :(

Other humans are number one but number two are Mosquitoes. They may be one of the smallest on this list, but they are among the deadliest. These insects are carriers of fatal diseases such as malaria and dengue, which kill around 660,000 to 1,000,000 people every year.

Number 3The Tsetse fly is responsible for spreading the African sleeping sickness, which affects as many as 500,000 people, 80 percent of whom eventually die.

Number 4If you fear snakes, your fear is not unmerited. Snakes kill an average of 50,000 people around the world every year. Most deaths are said to come from snakes that are threatened by mere human presence and activity.

5.Known as one of the oldest creatures to ever live on earth, scorpions evolved from sea-dwelling creatures to land menaces about 340 million years ago. Around 1,300 to 2,000 species of scorpions exist in the world but only 25 of them have poison that is dangerous enough to kill humans. Nevertheless, anywhere between 1,000 to 5,000 people are killed by scorpions annually.

I agree with am87. Micro organisms; Viruses and bacteria n such. And allthough some insects do cause deaths, (like mosquitos) its because of what they may carry, not the bug itself.

Take the black plague as an example. It was belived to have came from rats or fleas.i forget. And how often do they kill ppl?never.though the bubonic plague killed over 1/3of europes population.thats 20million ppl!

And thats just in a 5year span.it killed roughly80mill total. If i remember corect ^_^ lol