Marcus Antonius Plencic

Background

Marcus Antonius Plencic was born on April 28, 1705, in Gorizia, Austria (now Slovenia).

Education

Plencic received his early education at Gorizia, near his birthplace, then studied medicine at Vienna and at Padua, where Morgagni was one of his teachers. Having taken the degree at the latter university, Plencic returned to Vienna in 1735.

Career

After receiving the degree at the University od Padua, Plencic returned to Vienna in 1735. Plencic established a successful practice and remained there for the rest of his life. In 1770 Maria Theresa ennobled him in recognition of his achievements; he was also accorded the freedom of the city and the province of Gorizia.

As a practitioner, Plencic made careful observations of contagious diseases; applying a rigorous logic to these observations, he reached a remarkable theory of the nature of contagion. He was one of the first to recognize the etiological significance of Leeuwenhoek's animalcules, and his own views were developed a century later by Pasteur, Koch, and their followers. He also noted the incubation period in infectious diseases and discussed the possibility that microorganisms might have periods of latency, after which, conditions having become more suitable, they might resume their pathogenic activity.

Plencic’s theory is set out in his Opera medico-physica of 1762. The work consists of four separate treatises, of which the first contains Plencic’s general theory of disease, while the second and third deal with the specific diseases of smallpox and scarlet fever, presented in illustration of that theory. (The fourth treatise is a digression on the great earthquake of 1755, which destroyed Lisbon.)

Although Plencic’s work was preceded by that of Fracastoro, Kircher, and Lancisi, his theory is the most comprehensive and consistent. His book presents it clearly, and the examples he gives are convincing. Nonetheless, his theory attracted little attention. It was only in 1840 that the germ theory of contagious diseases was again advanced, against considerable opposition, by F. G. J. Henle.

Achievements

• Plencic's major achievement, as a medical practitioner, was in his careful observations of contagious diseases; applying a rigorous logic to these observations. He managed to reach a remarkable theory of the nature of contagion. He was one of the first to recognize the etiological significance of Antonie Philips van Leeuwenhoek's animalcules, and his own views were developed a century later by Pasteur, Koch, and their followers. He also noted the incubation period in infectious diseases and discussed the possibility that microorganisms might have periods of latency, after which, conditions having become more suitable, they might resume their pathogenic activity.

Works

More photos

• book

  • Opera Medico-Physica: de Scarlatina

    (Volume 3)

    1762
  • Opera Medico-physica: De Contagio

    (Volume 1)

    1762
  • Opera Medico Physica, In Quatuor Tractatus Digesta, Quorum Primus Contagii Morborum Ideam Novam Una Cum Additamento De Lue Bovina 1762

Views

Plencic believed contagious diseases to be caused by microorganisms, which he called “animalcula minima,” or “animalcula insensibilia.” These microorganisms, he stated, are both specific and constant - a given animalcule always causes the same disease, and attacks a specific host. They are carried by air; Plencic’s descriptive terms for the means of infection - “materia animata," “miasma animation,” “miasma verminosum”, “seminia animata,” and “principium aliquod seminale verminosum” - emphasizes his conviction concerning the animal nature of the microorganisms. The microorganisms are, in addition, very small (Leeuwenhoek estimated that a drop of water could contain between two and three million) and reproduce extremely rapidly in an appropriate medium, even outside the infected body. The speed of reproduction, Plencic stated, accounts for why a minute amount of an inoculum (as of smallpox) can cause disease.

He was aware of disposition toward a specific disease, immunity (including that resulting from a previous attack), mixed infection, antibiosis, and chemotherapy.

In recommending his theory, Plencic pointed out that it permitted a simple explanation for the prop-agation of diseases and offered an occasion for their rational prevention and treatment. He suggested the use of remedies acting directly upon the microorganisms, among them anthelmintics and antiseptics (mostly compounds of heavy metals). A further advantage of his etiological theory was that it allowed all the contagious diseases of man (including smallpox, plague, and scarlet fever), animals (including cattle plague), and even plants (for example, wheat rust) to be considered on a common basis.

Connections

teacher:

Giovanni Morgagni

associate:

Antonie Leeuwenhoek

References

• Dictionary of Scientific Biography
  1975