Discovery of Sarcoptes Scabie (Scabies) 1687 – Its Cause Was Not a Sacred Curse

Working with pharmacist Diacinto Cestoni, Italian researcher Giovanni Cosimo Bonomo discovered the cause of a skin infection called scabies. He proposed that it spread through the mating of male and female mites and observed a mite laying eggs. From their observations, they concluded that the disease was transmitted to people and between people through dirty clothes. He also speculated about scabies treatments such as sulfur. Dermatology professor Marcia Ramos-e-Silva writes: "Although not immediately recognized, their work marked the first recognition of the parasitic theory of infectious diseases, demonstrating for the first time that a microscopic organism could cause a disease. It can even be said without doubt that Bonomo and Cestoni's discovery ushered in a new era in medicine."

Although the microscopic mite Sarcoptes scabiei (the scabies parasite, which is very difficult to see with the naked eye) had been observed before Bonomo's detailed description in a 1687 letter to physician and naturalist Francesco Redi, this parasite was not regarded as the cause of scabies; instead, the disease was generally thought to be related to Galen's bodily humors (see the "Galenic Writings" entry). "I extracted a very small white sphere (from the skin) that was barely discernible. Examining it under a microscope, I found a very tiny living creature resembling a whitish turtle (the larva), somewhat dark on its back, with some fine, long hairs, moving nimbly, with six legs and a pointed head bearing two small horns at the tip of its nose." Bonomo wrote.

Immediately after the publication of Bonomo's letter, the pope's chief physician Giovanni Lancisi rejected the parasite as the sole cause of scabies. Bonomo decided to avoid an argument when Lancisi proposed a humoral origin and referred to the Holy Scriptures.

Scabies manifests as a very itchy skin rash. In people with a weakened immune system, it can sometimes become very severe. Later researchers discovered that parasitic mites caused other skin diseases, such as mange in domestic animals, and that mites could infest plants and honeybees.

Description of the article image: In 1687, mites were difficult to study because of their small size. Today, however, scientists at the US Agricultural Research Service freeze mites and use a scanning electron microscope to observe them. Shown here is Lorryia formosa, a yellow mite among fungi.

Historical figures mentioned in the article: Francesco Redi (1626–1697), Diacinto (or Giacinto) Cestoni (1637–1718), Giovanni Maria Lancisi (1654–1720), Giovanni Cosimo Bonomo (1663–1696)

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