Initiator of inoculation against smallpox
As a physician Bergius mainly studied the cause and development of contagious deceases and he won a reputation as a skilful doctor both within the country and abroad. He was one of the initiators of inoculation against smallpox and proposed a legislation to speed up vaccination. It was difficult to spread the practice of inoculation because there were few doctors in the country, and it was believed that too many risks would be involved if others performed the inoculations. People's lack of confidence in doctors was also a problem. He wrote about smallpox in his doctoral thesis De variolis curandis (1754), and later in other writings.
Works about deceases and doctors of the time
Among the most significant works in medicine by P.J. Bergius we find Försök til de uti Sverige gångbara sjukdomarnas utrönande [Attempts to uncover the current deceases in Sweden] from the year 1754, and also1755 and 1756, which were carried out at the request of the Collegium medicum. These represent the beginning of a descriptive Swedish epidemiology (a scientific discipline dealing with the spreading, cause and course of deceases.) and today they provide an interesting material in the history of medicine. Here, based on his own observations and information gathered from the country's provincial doctors, he describes the deceases of the time.
Also of great value to posterity is another work by Bergius on the history of medicine: Inträdes-tal om Stockholm för 200 år sedan, och Stockholm nu för tiden [Inaugural address about Stockholm 200 years ago and Stockholm at the present time], which was delivered at the Royal Academy of Sciences on the 20th of August 1750. For the most part it contains information about Swedish doctors ever since the times of King Gustaf Vasa and it is an invaluable source on this subject.
Materia medica - a kind of pharmaceutical handbook of the time
Of great interest to the history of medicine and to botany as well, is Bergiu's Materia medica (1778), a work in two volumes comprising 571 descriptions of Swedish medicinal herbs known at the time.
Here, the plants are described in Latin as follows:
NAMN - quotations of names from older books
FORMA - description of the species
PROPR. - characteristics, properties like smell and taste
VIRTUS - medical and dietetic properties
USUS - use
Plantae capenses, an early flora of the Cape area
Among some thirty works on botany, the most significant is Plantae capenses (Stockholm, 1767). The work portrays the flora of the Cape area (in South Africa) and describes 14 new genera and 130 new species of plants, which were not yet included in the system of Linnaeus. The basic material of this book came from the company director Michael Grubb who provided P.J. Bergius with specimens of Cape plants from his travels with the East India Company. Some of the plants are still preserved in the Bergius herbarium.
Sources: O. Hult "P.J. Bergius och medicinen i Sverige"; SLå XIV, 1931; O. Swartz 1822 "Åminnestal över Petr.J. Bergius"