"National Hotel disease" was the name given in the press to an outbreak of virulent dysentery that afflicted guests staying at Washington D.C.'s National Hotel on the eve of James Buchanan's inauguration as president of the United States in February of 1857.
Among the afflicted were Buchanan himself and several of his closest friends and associates, leading conspiracy theorists at the time to suggest that perhaps the "disease" was actually poison slipped into the hotel's food supply by abolitionists bitter over the election of the pro-slavery Buchanan. However, it seems that in actuality the frigid winter that year had caused the hotel plumbing to freeze, leading to a sewage backup that overflowed into and contaminated the hotel's kitchen.
Whatever strain or strains of bacteria were involved must have been particularly virulent, because many of the guests remained sick for months or even years after, and several died from the disease. Buchanan himself was bed-ridden for the first six weeks of his presidency and among the people who ultimately died of the illness were Mississippi congressman John Quitman and Pennsylvania congressman John Montgomery.