December 7 - Trypanosoma cruzi

Years after returning from the long voyage of the Beagle, Charles Darwin started to feel not-so-well - dizziness, muscle spasms, fatigue and other symptoms. Some speculate that the naturalist may have acquired Chagas Disease while he was traveling in South America. This malady is caused by a single-celled parasite known as Trypanosoma cruzi. These parasites are transmitted by triatomine bugs such as Rhodnius prolixus, commonly called "assassin bugs" or "kissing bugs", the latter because of their tendency to take blood meals around the mouth. The parasites are passed out in the bug's feces and enter the bite wound where they travel through the blood and can take up residence in numerous organs. The acute form may go unnoticed and the chronic form can take decades to set in. Infected people often die of heart failure, due to the damage done to this organ. Animals such as opossums, bats, and livestock serve as reservoirs for the parasites. In 2009, a paper documented transfer of genes from the trypanosome to humans followed by inheritance in the children of these Chagas Disease patients!