Of all of the symptoms of plague, the ‘plague spots’ are the most problematic. For some reason historians (and others) have grabbed on to plague spots as a distinguishing characteristic to recognize images of the plague even though they are not an obligate symptom of plague.
The image to the left is one of the most often misrepresented. This illustration of leprosy was discussed in the recent Medieval Globe issue by Green, Walker-Meikle, and Muller (2014). Lori Jones’ talk last month in Kalamazoo highlighted how metastatic these improperly identified images (including the one to the left) have become and how hard it is to correct them (or wipe them off the internet).
Skin spots vary among plague patients because they are a symptom of sepsis, an infection of the bloodstream, often advancing to full septic shock and death. The infectious agent doesn’t have to be plague, and in most cases it isn’t plague. It can be caused by any agent causing sepsis (and some conditions that are not infections at all). These spots can be variously described as hemorrhagic spots, disseminated intravascular coagulation (DIC), or purpura. A recently published case study of three lethal pneumonic plague cases from China in 2014 describes the spots like this:
“Because the basic lesion of plague is vascular endothelial cell injury, acute hemorrhagic and necrotic lesions, haemorrhage spots can be found all over the body in patient 1 at the final period of the disease, at the chest and abdomen in patient 2, but not in patient 3.”(Li et al, 2016)
Among the signs and symptoms listed in the case report for pneumonic plague patients 1 and patient 2 included DIC, haemorhaggic spots and septic shock. As we would expect given the initial distribution of plague in the mammalian body, they also had “acute liver injury” and “acute kidney damage” along with, of course, pneumonia. Patient 1 had very low platelets and both had delayed clotting time as expected in cases of blood leakage and clotting in the tissues causing the DIC and hemorrhagic spots.
The most important thing to remember about plague spots is that they are highly variable. Not everyone develops spots at all. When they do develop spots, they are most likely already in septic shock and are unlikely to be mobile, as the people in the above illustration obviously are.
These spots should not be confused with acral necrosis, also called gangrene, which is the blackening and tissue death at the tips of the extremities (usually fingers and toes). This occurs when blood flow has been cut off from tissue in the extremities. In plague patients this would be due to clotting and/or vascular collapse in the extremities. Amputation is a common treatment for this condition. As with DIC, it happens in many medical conditions, perhaps most commonly today in diabetes mellitus. Since this type of blackening of the fingers and especially toes would have been fairly common in cases of sepsis or even local infection in the extremities, it is unlikely to be the reason the second pandemic came to be called the Black Death much later.
Green, M., Walker-Meikle, K., & Muller, W. P. (2014). Diagnosis of a “Plague” Image: A Digital Cautionary Tale. The Medieval Globe, 1(1), 309–326.
Jones, L. (2016) “Is that Plague Image Really an Image of the Plague? Tackling the Digital Disconnect between Medieval Witnesses and Twenty-First Century Understandings of Epidemic Diseases in the Middle Ages” 51st International Congress on Medieval Studies, Kalamazoo, MI. Session 297.
Li, Y.-F., Li, D.-B., Shao, H.-S., Li, H.-J., & Han, Y.-D. (2016). Plague in China 2014—All sporadic case report of pneumonic plague. BMC Infectious Diseases, 16(1), 1–8. http://doi.org/10.1186/s12879-016-1403-8
National Library of Medicine, Disseminated intravascular coagulation (DIC), Medline Plus.
National Library of Medicine, Purpura, Medline Plus.
National Library of Medicine, Gangrene, Medline Plus.