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(b. Solkan, Austria [now Yugoslavia], 28 April 1705; d. Vienna, Austria, 25 November 1786)


Plenčič 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, Plenčič returned to Vienna in 1735. He 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, Plenčič 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. Plenčič’s theory is set out in his Opera medico-physica of 1762. The work consists of four separate treatises, of which the first contains Plenčič 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.)

Plenčič 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 the air; Plenčič’s descriptive terms for the means of infection—“materia animata,” “miasma animatum,” “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, Plenčič stated, accounts for why a minute amount of an inoculum (as of smallpox) can cause disease. 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. 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, Plenčič pointed out that it permitted a simple explanation for the propagation 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.

Although Plenčič’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. As late as 1828 K. Sprengel wrote, in the fifth volume of his history of medicine, that “His rich experience with scarlet fever did not prevent Plenčič from proposing a flighty hypothesis of seminiis animatis.” It was only in 1840 that the germ theory of contagious diseases was again advanced, against considerable opposition, by F. G. J. Henle.


I. Original Works. Plenčič’s principal work was published as Opera medico-physica in IV tractatus digesta… (Vienna, 1762). The third treatise was translated into German by J. P. G. Pflug as Abhandlung vom Scharlachfieber (Copenhagen, 1779); it was emended by Plenčič and published separately as Tractatus de scarlatina … (Vienna, 1780). Another work is Dissertatio physicoeconomica sive nova ratio frumenta aliaque legumina quam plurimis annis integra salvaque conservandi (Vienna, 1764), also published in French and German.

II. Secondary Literature. See I. Fischer, “M. A. Plenčičz, ein Wiener Vorläufer der modernen Bakteriologen,” in Wiener klinische Wochenschrift, 26 (1913), 1804–1807; and “Marc Anton Plenciz,” in Wiener medizinische Wochenschrift, 77 (1927), 735–736. A more recent treatment is A. Berg, “Marc Anton Plencicz und seine Lehre von den belebten Krankheitserregern (1762),” in Medizinische Welt (1962), 2425–2428, 2480–2483. See also Branko and Ivan Marušič, Solkanski rojak dr. Marko Anton pl. Plenčič (1705–1786) (Solkan, 1967); S. Peller, “Marc Anton von Plenciz,” in Pirquet Bulletin of Clinical Medicine, 10 (1963), 2, 11–12; and I. Pintar, “Marko Anton Plenčič in ujegov nauk o’Contagium vivum,” in Zdravstveni vestnik, 16 (1947), 64–71.

Vladislav Kruta

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