Leptospirosis is an infection caused by the Leptospira bacterium, named so because of it’s corkscrew shape. Symptoms of the infection can be extremely mild (such as headache and fever) but can also be extremely severe (meningitis or bleeding on the lungs). The same infection is called Weil’s disease when it causes an infected person to turn yellow and suffers from kidney failure. The disease is most commonly observed in tropical areas, but can occur anywhere. Although mortality rates attributed to infection are largely unknown, it is estimated that up to ten million new infections take place each year worldwide.