in the early history of this disease [yellow fever], I did suppose it to be infectious … until the fever at Alexandria brought facts under my own eye, as it were, proving it could not be communicated but in a local atmosphere … we know only that it is generated near the water side, in close built cities, under warm climates … where one sufficient cause for an effect is known, it is not within the economy of nature to employ two. if local atmosphere suffices to produce the fever, miasmata [foul discharge] from a human subject are not necessary, and probably do not enter into the cause.
Thomas Jefferson to John Page, August 16, 1804
In the face of coronavirus, I’m excerpting correspondence about diseases that ravaged the nation in Thomas Jefferson’s time.
Patrick Lee’s Explanation
Wise leaders are willing to change their minds.
In the previous post from this letter to Virginia’s Governor Page, the President raised the question: Was the yellow fever contagious, passed from person to person, or was it endemic, its cause being associated with a particular place? Experts disagreed, but Jefferson thought the former.
Facts (Jefferson loved facts!) from the outbreak in Alexandria, VA, caused him to change his mind. The fever ran rampant only in warm weather and in densely populated cities close to the water. Reason told him (he really loved reason!) if one cause was identified, a second cause was unnecessary. Thus, the disease was “probably” not infectious but caused by unique, local conditions.
Jefferson was correct in identifying warm weather and a waterfront as contributors. He may have been correct about densely populated cities, but he disliked those, anyway. Everyone would be wrong about the real cause for the next 100 years: the lowly mosquito, active in warm weather, needing water to reproduce, and appearing more of a menace in urban areas.