A perfect world is what Adam and Eve enjoyed. They walked with and fellowshiped with God. They couldn't get sick, they couldn't die, there were no tornados, hurricanes, earthquakes, no famine, no poverty. They couldn't murder because people couldn't die, nor would they want to. They couldn't commit adultery, they couldn't covet because they owned everything, but... they had free will. Without free will they could not truly have been created in the image of God. They could do anything they wanted, but in order to exercise their free will there had to be a test of it. God gave them one thing they could not do, eat of the tree of the knowledge of good and evil. The serpent (under the influence of Satan) tempted them and they succumbed. They were no longer covered by the Glory of God and they felt naked and ashamed. The first sin was disobedience to God. They immediately died spiritually. They separated themselves from the God who created and loved them. With the first bite they brought death and devastation into our lives. They caused all mankind to become separated from our loving Creator and Heavenly Father. He was put in the position of having to judge and take vengeance against the sin which he loathes because of the harm it creates. A son of Adam and Eve, Cain, murdered his brother Abel, eventually Adam and Eve died physically, now we all face sin, sickness, poverty, disasters (both natural and otherwise), and death. But the worst part of the curse of sin is our separation from God.
Sin brought with it a curse on us and our world, and the results are what we suffer from today. When something dreadful happens you often hear someone say "How could a good God allow this to happen?", but it was mankind, not God that brought suffering and devastation into the world. Proverbs 19:3 (NIV) reads "A man's own folly ruins his life, yet his heart rages against the Lord."
Satan also attacks us with disasters and diseases. Satan was permitted to test Job by the death of his family, destruction, poverty, and sickness. Job actually put himself in the position to be able to be tested, in his agony he revealed the truth (Job 3:25 "For the thing which I greatly feared is come upon me, and that which I was afraid of is come unto me.") Job 1 reveals that he constantly offered burnt offerings for his children to sanctify them because he was afraid they might have done something wrong. He was allowing fear, rather than faith in God, prevalence in his life. Luke 13 recounts the story of a woman bound by a "spirit" of infirmity for 18 years and was bowed together, Jesus healed her, and when the ruler of the synagogue complained that it was done on the Sabbath day Jesus replied that a daughter of Abraham, who was bound by Satan for 18 years ought to be loosed.
1 Peter 5:8 admonishes us "Be sober, be vigilant; because your adversary the Devil, as a roaring lion walketh about, seeking whom he may devour.
Most of what we endure is a result of the curse that sin brought on us, that is not to say that sometimes God will not use disease, disaster, or even humans as judgment against certain human actions and lifestyles. It was God that brought the judgment of leprosy on Moses' sister, Miriam (Numbers 12:9), when she spoke against Moses (but He also healed her after seven days because Moses asked Him to), and on King Uzziah for transgression in the temple of the Lord (2 Chronicles 26:19). It was God that commanded Saul to slay every man, woman, and child of the Amalekites and their animals, because they ambushed the children of Israel when they came out of Egypt. God brought the flood that destroyed everyone except Noah and his family and select animals, God destroyed Sodom and Gomorrah, and Lot's wife for looking back to her destroyed city. Romans 1:27 states that people with a deviant lifestyle "received in themselves that recompense of their error which was meet," in other words they are justly paid back for the sins they commit. The just God that created Hell for Satan, fallen angels, and demonic spirits, but will also allow the people who refuse to reconcile themselves to Him to be confined there for eternity is also able to use sickness and disasters as judgments against sin. Absolutely God is Love, his perfect will is to reconcile us to Himself and be our Father and our protector, not our judge.
This is a link to a site where you can look up scripture references in many different versions of the bible: http://www.biblegateway.com/