Which group gained the most from the opening of the panama canal in 1914

To combat the threat of tropical diseases such as malaria and yellow fever, the United States decided to use new measures to eradicate the disease before the construction of the Panama Canal.  Under the leadership of Colonel William Crawford Gorgas, many changes were made.  When it was discovered that mosquitoes were the source of the disease, Gorgas who was appointed as the head of hospital and sanitation, he made sure that containers with stagnant water were removed because mosquitoes lay their eggs there.  He also built domestic water systems to eliminate the need to collect rain water.  Prophylactic Quinine was supplied to the people in the area and fumigation and oiling of streams were launched.  Those who were sick were quarantined and workers would sleep in screened structures so that mosquitoes would not be able to bite them.  These programs resulted in the successful elimination of tropical diseases in the area and the health of workers improved.