how come animals get sick and die they didn't eat the forbiden fruit?

The curse applied to all of the creation, I believe. Here are a couple passages:

Genesis 3:17

And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life;

Romans 8:19-22

19 For the earnest expectation of the creature waiteth for the manifestation of the sons of God.

20 For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope,

21 Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God.

22 For we know that the whole creation groaneth and travaileth in pain together until now.

Here is a quote from "The Relationship Between Sin and Death in Genesis: Death Before Sin?" By James S. Stambaugh:

The passage in Romans 8:19-21 confirms the thought of Genesis. In fact, these verses are Paul's commentary on Genesis 3:17,18. Here Paul tells us that the whole of creation has been subjected to "vanity" by God because of man's sin. The word "vanity" refers to that which fails to attain its basic goal. This means "that the non-human creation has been subjected to the frustration of not being able to properly fulfill the purpose of its existence." (Ref. 8) The entire creation experienced the same fate that man did when he fell. Now, since man is the initiator of the curse on the earth, he must also somehow be the initiator of the restoration of the creation, and this is exactly what Paul is trying to tell us. God was to be glorified by the smooth running of nature. When man fell, his act brought sin and death. Therefore, if death prohibits the smooth running of nature, then death must not have been a part of God's original plan.

It is because God purposed for man to live forever, but not the animals. The Creator provided each with the kind of brain needed: man’s to serve forever; the animal’s to serve a short lifetime. The Creator gave life to both humans and animals. But scientists report that humans seem to have the potential of endless life, so that investigators are perplexed as to why man dies.

The Bible gives the reason. It says that the Creator gave the first humans the opportunity of living forever. Death came only because they rebelled. (Gen. 2:17; 3:17-19; Rom. 5:12) Animals, though are not capable of conscious rebellion against God; yet they live only for a length of time and then die. For them death was natural.—2 Pet. 2:12. The status of the beast has remained unchanged since its creation—it lives out its life span and dies. At no time has it had set before it the prospect of eternal life.

Because the bible is a book of stories, stories that serve as a messages to make us better people and shouldn't be taken at face value. If you actually believe in a talking snake and garden of eden get help!

Death affects all animals because as all first graders know, death is the full cessation of vital functions in the biological life.

You and I didn't eat it any more than the animals did.

Adam and eve made the choice that put the earth into the state, where we could choose good or evil, grow and develop, suffer and die. The consequences of their choice was not all bad for us or animals. My dog sure enjoys that steak bone.

In DC Comics, it says that Superman will never kill anyone, but I'm sure he has stepped on an ant here or there, and he has killed germs there is no avoiding it. There are flaws in all works of fiction and the bible is no exception. At least with DC Comics, the authors sign the comic books and you can communicate with them even as fan mail.

Because animals were part of the earth and the whole earth was cursed as a result of the fall of man. Read the book, its right there in black and white.

All the subhuman kingdoms are contained within the mind of humanity. Mineral, plant, and animal kingdoms are all inside of me, and so if I die these also die. If I renew my mind, these species will also be renewed unto everlasting life. What dreams may come...

It's only a story. The bible is not nessarily based on fact. Mabe that partuclar bible story is really talking about poison.

because Adam and Eve were given the authority over all the earth and when they handed it over to satan in the garden they caused death to come upon all creation.....that is why Jesus had to come and die for us on the cross for our sins so that the curse of sin and death would be broken once and for all for those who choose to recieve it......

The bible says a lot of things.

The stories are nice, but they have little to do with the reality of the world.