Complex sentence: The investigation arrived at the discovery of the new bacteria because the research showed that 4 of the patients were infected by a new bacteria; their symptoms in 2009 including fevers, headaches, fatigue, nausea, and vomiting.
Split into simpler sentences: The investigation arrived at the discovery of the new bacteria because the research showed that 4 of the patients were infected by a new bacteria. The symptoms in 2009 included fevers, headaches, fatigue, nausea, and vomiting.