Examining the death of Charles Darwin brings up some interesting observations. He suffered a fatal heart attack on April 19, 1882, after having had suffered a few heart attacks in the prior years. He also had problems with his stomach and often had bouts of nausea, both symptoms related to heart problems.
Although it is usually assumed that Darwin died for a heart attack, some believe that Darwin was suffering from Chagas' disease. This has not actually been proven, seeing as Charles Darwin was never actually tested for the disease.
Chagas' disease is an illness spread by insects particularly in South and Central America. It is believed that Darwin contracted the disease while he was doing research on plant and animal life on one of the islands.
Symptoms of the disease match up to the state that Darwin was in at the end of his life. These symptoms can take up to 20 years to manifest, so he very well might have gotten bit by a bug while he was doing research when he was younger.
Symptoms of Chagas' include:
Allegedly, the last words he spoke were to his wife Emma and they began with "I am not the least afraid to die." Some people will cite this as evidence for his conversion to Christianity at the end of his life, which is a topic of at least moderate controversy.
Although his family initially wanted him to be buried in the family burial grounds, he was actually one of only five non-royal individuals in the United Kingdom to have a state funeral. He was buried in Westminister Abbey with other renowned scientists such as Isaac Newton and John Herschel.