Paravaccina

PARAVACCINA (paravaccina), a unique cowpox-like disease of cattle, characterized by a specific rash on the udder and teats and capable of being transmitted to humans (zoonosis). About 30 years ago, French authors described under the name "vaccine rouge" (red vaccination) a specific skin rash observed in some cases in humans after smallpox vaccinations, in the form of cherry-red nodules the size of half a pea. In Russia, this variety was described by Hubert as early as 1887 under the name vaccina rubra (8 cases in primary vaccinations and 2 cases in revaccinations). At the site of the injection or incision, a red firm elevation already appears on the 2nd-3rd day, increasing in size over several days. The size of this efflorescence is about that of a pea. Neither pressure (delle) nor a ring around it occurs. No scars remain. Control vaccinations with detritus after vac. rubra are successful. Vac. rubra occurs rarely. The course is chronic, in some cases vac. rubra remains unchanged for up to 5 months, leaving behind a small pigmented spot. With such a slow course, vac. rubra was sometimes confused with vaccinal keloid. Pirquet in 1915 came to the conclusion that "vaccine rouge" represents a disease sui generis, caused by a special microbe found in the smallpox detritus along with the true causative agent of vaccination; this is purely a local skin lesion, which, unlike vaccination, occurs without general phenomena; Pirquet proposed for it the name "paravaccina" (paravaccine). The question of the etiology of P. and its relationship to cowpox was taken up (in 1915) by Lipschütz. On histological sections from the nodules of P., in the protoplasm as well as in the nuclei of the prickle cells of the epithelium of the affected skin areas, Lipschütz found peculiar, eosinophilic inclusions the size of a nucleus, round, oval or slightly irregular in shape. In one cell, 1-2 such formations are found. In addition, in the superficial layers of the prickle cells affected by P., Lipschütz discovered "elementary bodies" morphologically and in staining very similar to the bodies of Paschen (see Smallpox-etiology); they represent very small formations, about ¹μ in size, arranged singly in the form of diplococci or in clusters (Strongyloplasma parav. Lipschütz). On well-prepared specimens, they are found in enormous numbers and very much resemble a pure culture of the smallest cocci. Like Pirquet, Lipschütz comes to the conclusion that the causative agent of P. is a special virus, biologically close to the virus of vaccination but not identical to it. Cowpox is characterized by acute inflammation with pustule formation, while the agent of P. causes the development of a limited tumor from newly formed blood vessels, proliferating angioblasts and connective tissue cells. On the cornea and the skin of rabbits, P. does not take, there is no cross-immunity between P. and cowpox, consequently these are two different infections. Justitz in 1917 observed typical P. in 6 persons who had recently had smallpox and were vaccinated with fresh vaccine from the State Smallpox Institute in Vienna. The beginning of the development of the nodule was noted on the 5th day. In control persons, the usual phenomena characteristic of revaccination developed. On the basis of this, Justitz joins Pirquet's opinion that the viruses of vaccination and P. sometimes occur together in the detritus, but P. is not found only in smallpox vaccinations because its development is suppressed by the vaccine. However, with insufficient content of vaccine germs in the detritus in the vaccinated (especially in revaccinated), P. develops, which may give rise to the erroneous conclusion of the success of revaccination. In recent decades, in foreign, mainly German, dermatological literature, a peculiar occupational disease of rural owners, milkers, veterinary personnel and other persons who come into frequent contact with cows has been described repeatedly. This is a specific nodular skin lesion, mostly localized on the hands and fingers, the so-called "milker's nodules" (Melkerknoten of German authors). Recently (1931), Morozov and Dolgov in Moscow proved that P. is the most frequent cause of this little-known disease. In addition, they proved that "milker's nodules" are identical in etiology to the "vaccine rouge" of French authors and that the primary source of these diseases in humans is a unique cowpox-like zoonosis in cows, named by them P. (observations in the Moscow region in 1928-31). P. in cattle proceeds as follows (Morozov and Dolgov): after a 3-7 day incubation, reddish spots appear on the udder, on the teats, sometimes on the perineum, on the site of which, after several days, dense cherry-red nodules the size of a hemp seed to a pea form. Merging, they form a wide flat efflorescence with a rough, warty surface of brick-red or dark red color. The surrounding skin remains unaffected. After the dried elements fall off, no scar forms, but a pigmented spot of dirty color remains for a long time. The general condition of the animal does not suffer. P. is contagious for humans, transmitted most often during milking and when caring for sick cows. According to Morozov and Dolgov, P. in humans and cattle can be distinguished from vaccination on the basis of the following clinical signs, etiological data and results of experiments: 1) incubation in P. as a rule is 3-7 days. 2) The nature of the rash can be varied (nodules, flat warty growths in cattle). Typically, there is a slow development of a dense, highly convex nodule of cherry-red color, 4-6mm in diameter. The reverse development of the rash ends within 4-6 weeks by resorption, without scar formation. Atypical forms (in humans) are not uncommon, disappearing already within 3-7 days. 3) P. gives neither allergy nor immunity to cowpox. Skin and corneal vaccinations of P. to rabbits and guinea pigs remain unsuccessful. Autoinoculation in humans, transmission of P. to other persons succeeds, but not in all cases, and apparently only when the P. virus is sufficiently virulent (virus from fresh cases of "milker's nodules"). In all the more than 30 cases of P. in humans and several hundred in cattle observed by them, Morozov found the Strongyloplasma paravaccinae described by Lipschütz. P. in humans ("vaccine rouge") was observed only in France, Austria and North Africa (Lipschütz). In Germany (in humans), it apparently occurs only in the form of "milker's nodules", but not after smallpox vaccinations. Friebos (1914) believes that the cause of "Melkerknoten" is an attenuated virus of cowpox and compares "milker's nodules" with the abortive form of smallpox or "stonepox" (Steinpocken) of sheep. According to Morozov's data, not only the above-mentioned form, but also the so-called "warty smallpox" (Warzenpocken), "chickenpox" (Windpocken, varicella) of cattle, sheep and goats are in their etiology P.