Rheumatoid arthritis in an Icelandic textbook from 1782

In 1782, Jón Pétursson, a district physician in Northern Iceland, published a textbook on arthritis and its remedies intended for common use. Working within a very simple diagnostic system, essentially comprising osteoarthritis (arthritis fixa) and inflammatory arthritis (arthritis vaga), he describes arthritis vaga as a common, chronic, symmetric, destructive, inflammatory polyarthritis, sometimes with systemic manifestations. It affected people of all ages with a peak incidence around forty, and had a female preponderance. The last observation is of particular interest as he knew he was contradicting all the available literature. Contemporary descriptions of Jón Pétursson suggest that he may have had rheumatoid arthritis himself which would explain his excellent description of this disease.