Klingon augment virus

The Klingon augment virus was created when a group of Klingon scientists attempt to bioengineer genetically enhanced warriors using DNA from genetically modified Human embryos left over from Earth's Eugenic Wars. The genetic manipulations ultimately failed, but not before a carrier of the Levodian flu was augmented. The Human DNA combined with the flu to form a virus that caused an epidemic to spread through the Klingon population.

The virus caused the infected Klingons to gain strength and intelligence initially, but because Human and Klingon DNA is incompatible, this was quickly followed by personality changes and the loss of the characteristic Klingon forehead ridges. The ultimate result was a breakdown in neural pathways and death.

Eventually, the virus was stabilized in a way that the initial symptoms still occured, but the virus was stopped before the neural pathways could break down. Because the virus affected the DNA, the higher strength, intelligence, and lack of forehead ridges was passed down some generations until the forehead ridges once again became the dominant trait.