Lincoln's smallpox?

I think it must be difficult to study infectious disease without having some kind of interest in history. The field is so rich in stories from decades and centuries past, and infectious disease has played an enormous role in shaping our societies today. As with many fields, I believe our understanding of the present can be improved if we view it through the lens of the past--realizing as much as we can the historical influences and legacies that have brought us to where we are today.

I mentioned a few weeks back that, despite its eradication in the natural world, the smallpox virus still casts a long shadow, influencing military policy in this age of fears about biowarfare. It's an understandable fear. Untreated smallpox can has a mortality rate in the range of 30%, and as routine vaccination ceased decades ago, many of us are completely susceptible to infection by the virus. If it were to be unleashed today, the results certainly could be devastating if not caught very early.

Of course, although smallpox isn't a scourge any longer, it was quite a different story in 19th century America. Though vaccination using cowpox virus had been introduced and served to protect many people, there were significant problems with the process. For one, other blood-borne diseases could be transfered in the process, since infectious material was often transferred from person to person. Sometimes the vaccine didn't take, and the recipient contracted smallpox anyway, or was sickened from the cowpox. Maintaining the vaccine strain was also difficult. Infectious material could be transferred over distances, but it didn't always remain infectious upon receipt. Alternatively, one could go straight to the source and look for an outbreak of vaccinia in cows, but this was unpredictable and, as one can imagine, inconvenient. Additionally, despite much success with vaccination, many objected to the delivery of material derived from cows into humans, and antivaccination posters at the time depicted cattle-human hybrids resulting from inoculation with cowpox. Therefore, while vaccination against smallpox was popular and somewhat common in a few areas and social circles, it certainly wasn't universal yet in the mid-1800s.

Smallpox has altered the course of history in innumerable ways. The destruction of the native American population by smallpox and measles has been written about extensively, and the disease also struck world leaders and members of royal families. It also appears to have nearly made Abraham Lincoln miss his famous Gettysburg Address. Lincoln's smallpox is addressed in a new manuscript in the Journal of Medical Biography; more below.

The paper summary states:

When Abraham Lincoln delivered the Gettysburg Address, he was weak and dizzy; his face had a ghastly color. That evening on the train to Washington, DC, he was febrile and weak, and suffered severe headaches. The symptoms continued; back pains developed. On the fourth day of illness, a widespread scarlet rash appeared that soon became vesicular. By the tenth day, the lesions itched and peeled. The illness lasted three weeks. The final diagnosis, a touch of varioloid, was an old name for smallpox that was later used in the 20th century to denote mild smallpox in a partially immune individual. It is unclear whether Lincoln had been immunized against smallpox. In that regard, this review suggests that Lincoln had unmodified smallpox and that Lincoln's physicians tried to reassure the public that Lincoln was not seriously ill. Indeed, the successful conclusion of the Civil War and the reunification of the country were dependent upon Lincoln's presidency.

Therefore, the question at the heart of the paper isn't so much "did Lincoln have smallpox?" as it is, "did Lincoln's smallpox infection suggest that he was previously vaccinated?" From the data they present, however, I think that's a bit presumptive. They suggest the illness could have been a few other entities: varicella (chickenpox), disseminated herpes infection, or rickettsialpox, but then rule those out. However, they don't describe other rash-inducing diseases and say why they ruled them out, or if they considered them at all, which is my biggest quibble with the paper.

Information on Lincoln's post-Gettysburg Address illness is scant, and collected from a number of secondary sources rather than Lincoln himself or any family members, or any direct notes from physicians who treated him. Apparently, the disease was first diagnosed as scarlet fever, but modified to smallpox when the rash began to blister. However, a complete description of the nature of the blisters hasn't been found. Lincoln was ill for the better part of a month, during which there was widespread speculation about his health (which his physicians and others, unsurprisingly, tried to play down).

The authors note that if Lincoln had smallpox, it had to have come from another individual. They mention that his son Tad had been ill with a fever and rash just before Lincoln left for Gettysburg. Again, no good account exists of Tad's illness, though it was mentioned that he was "febrile, weak and anorexic, and had a 'scarlet' eruption." Was this smallpox? If Lincoln indeed had smallpox, did he contract it elsewhere? Did he infect others? Answers aren't known, and it's not known whether Lincoln or his son Tad were ever immunized against smallpox.

The rest of the paper concentrates on whether Lincoln's smallpox was immune-modulated (i.e., a mild infection due to pre-existing immunity) or unmodified variola infection. They argue that the symptoms described and the length of illness (greater than three weeks) suggests infection with variola major, the worst strain of smallpox virus, and that the reports of mild smallpox were probably propaganda:

"Lincoln's physicians attempted to reassure him that his disease was a mild form of smallpox, but that may have been to prevent the public from fearing that Lincoln was dying," said Dr. Armond Goldman, emeritus professor of pediatrics at the University of Texas Medical Branch in Galveston.

Ah, the history of spin...

Reference

Goldman and Schmalstieg, 2007. Abraham Lincoln's Gettysburg Illness. Journal of Medical Biography. 15:104-110. Link.

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