Deaths during construction of the Panama Canal were overwhelmingly from tropical diseases, notably yellow fever and malaria:
https://en.wikipedia.org/wiki/Health_measures_during_the_con...>
The transmission of yellow fever by mosquitos was established by Maj. Walter Reed, US Army, the physician for whom Walter Reed Hospital is named:
https://en.wikipedia.org/wiki/Walter_Reed>
The shear lethality of tropical diseases to Europeans prior to the 20th century really cannot be overstated. I'd run across a statistic that the life expectancy of a British soldier stationed to Africa was on the order of six months:
In 1824 half the 600 soldiers garrisoned in the Gold Coast died within a few months, and the House of Commons was told in 1826, that of 1,567 troops sent out in the previous two years, 905 had died. Europeans died mainly from malaria and yellow fever - or from the “cures” which were nearly as dangerous as the ailments. Blood-letting was common. Leeches were standard colonial surgical equipment, being placed on the patients shaved head to “suck out” the fever. Great blisters were raised with steaming cloths or mustard packs and then broken to drain away the fever. On the same principle, salivating was induced by calomel, often at the expense of the victim’s teeth, or by quicksilver and mercury, an even more drastic “treatment” that inflamed the mouth and sometimes caused the sick man to suffocate on his own swollen tongue.
https://web.archive.org/web/20070106173014/myweb.tiscali.co....>
Drawing a distinction between death by disease and by accident may be somewhat arbitrary, but still seems a distinction worth noting.