As already stated, official inquiries were directed to be made into the causes of this extraordinary mortality, from which it appears:—
That there was nothing peculiar in the disease itself. The medical and other officers of the ship, as well as the medical and other officers at Boa Vista, that is, all competent witnesses who actually saw the disease, concur in stating that it was nothing more than an aggravated form of the common endemic fever of the African coast; a view which is decisively confirmed by the original description of the disease in the medical journal of the ship, and by post-mortem examination.
In opposition to this generally-received opinion, however, Sir William Pym promulgated a statement that, in addition to the common African fever, the celebrated nova pestis of Dr Chisholm had been introduced into the vessel by a passenger taken on board at Sierra Leone; this disease being, as he represents, a fever sui generis, known by the name of the African, Bulam, Yellow, or Black Vomit Fever, attacking the human frame but once, and differing from the common remittent fever in being highly contagious.
That the doctrine on which Sir William Pym’s assertion rests met with little countenance from medical authorities is apparent from the statement of Sir William Burnett, who says:—
“The whole of this, as regards the peculiar properties of the disease, called by Sir William Pym, Bulam, &c., is a gratuitous assumption on his part, and, in my opinion, has no foundation in fact; and in my view of this part of the subject I am supported by nineteen-twentieths of the medical officers of both services, who are of opinion with myself that the more ardent form of Yellow Fever is a mere modification of the bilious remittent so extensively known all over the tropical regions.”
He adds: “The fever which prevailed in the ‘Eclair’ was unquestionably a remittent fever, originating in marsh miasmata, and the exposure of the men in boats during rainy weather.”
Dr King and Dr Stewart, in official Reports upon this case, state their concurrence with Sir William Burnett. Dr McWilliam, on the other hand, is of opinion that the disease, though primarily an endemic remittent of the African coast, became, from a series of causes, exalted into a concentrated remittent or Yellow Fever, and in that manner acquired new and peculiar properties, not primarily and essentially belonging to it.
With reference to this latter opinion, it may be observed that the Governor-General of the Cape de Verd Islands affirms, that not one of those who with a view to escape the pestilence emigrated to the different islands of the Archipelago, had the disease, or communicated it to others. According to the view of Dr McWilliam, therefore, this disease must have been of a very singular character, for in its origin at Shebar, it was not contagious, at Boa Vista it became contagious, while in the other islands of the Archipelago, wherever the sick or the uninfected fled, it again laid aside its contagious character, and did not spread to a single individual.
All the inquirers and reporters agree in stating that among the causes which concurred in communicating to this disease so extraordinary a degree of prevalence and mortality, the more important were the following:—
The employment of the crew uninterruptedly for an unusual length of time, including the sickly season, in a peculiarly unhealthy situation, and dangerous local duty.