Complex sentence: His writings are the primary source on this outbreak and modern academics and medical scientists consider epidemic typhus the most likely cause; a 2006 study detected DNA sequences similar to those of the bacterium responsible for typhoid fever.
Split into simpler sentences: His writings are the primary source on this outbreak and modern academics and medical scientists consider epidemic typhus the most likely cause. However, 2006 study detected DNA sequences similar to those of the bacterium responsible for typhoid fever.