The construction of the railroad, however, proved extraordinarily challenging due to inadequate financing compounded by the rugged terrain, thick jungle, torrential rains, and prevalence of malaria, yellow fever, dysentery, and other tropical diseases. As many as four thousand people, including Keith's three brothers, died during the construction of the first 25 miles of track. Having subsequent trouble recruiting Costa Rican laborers, Keith eventually brought in blacks from the Caribbean islands (mainly Jamaica), Chinese, and even Italians, to complete the project. The Jamaicans that Keith brought in were English speakers and to this day maintain their heritage.