Complex sentence: It is estimated that 102,000 workers had died during the construction of the Panama Railway, and 22,000 during the earlier French effort to build a canal; and many of these deaths were due to disease, particularly yellow fever and malaria.
Split into simpler sentences: It is estimated that 102,000 workers had died during the construction of the Panama Railway, and 22,000 during the earlier French effort to build a canal. Many of these deaths were due to disease, particularly yellow fever and malaria.