Mallorca 1820 plague study suggests more lethal disease type

A new study published in the journal PNAS suggests that the 1820 plague outbreak in Mallorca was not a classic bubonic plague caused by Yersinia pestis, but rather a more lethal form of the disease. Researchers Joana Maria Pujadas-Mora and Pere Puig indicate that the high mortality rate, which reached 78%, is better explained by pneumonic and septicemic forms of the plague.

Historical evidence suggests the outbreak likely originated in Tangier and arrived in the Son Servera region via crew members from an infected ship. Because goods were unloaded via small rowing boats rather than large ports, researchers believe rats were unlikely to be the primary reservoir. Instead, the disease was likely spread through human ectoparasites, such as lice and fleas, or direct person-to-person contact.

To combat the spread, authorities at the time implemented containment measures similar to modern quarantine protocols, including house confinements and the closure of establishments. They also practiced ‘friegas de aceite’ (oil rubs) in the streets as a method of environmental disinfection.