Part 50

Funck finds this sporidium vaccinale constantly in the vaccine lymph and surrounding tissue, as a refractile, amœboid, spherical organism (spore) 1 to 3μ in diameter, and, less abundantly, a round or ovoid spore cyst 25μ. These cysts are either smooth or uneven like a raspberry, and have a single or double contoured membrane. They are easily stained with Sudan III. Examined in hanging drops they are seen just under the cover glass, not on the surface of the drops. Larger flattened bodies found in the lymph, with many included spores are manifestly epithelial cells. Copiman cultivated the organism in glycerinated collodion capsules in the peritoneal cavity of rabbits and dogs, producing zoöglœea masses staining peripherically with methylene blue, and which caused typical vaccinia in calves. He found the same elements in variola of man.

HORSE POX. VARIOLA EQUINÆ.

This was recognized toward the end of the 18th century, in the valley of the Severn, England, by Jenner, who believed it to be the origin of cowpox, but failed apparently to distinguish it from ordinary “grease”. To-day, when we must trace each case to a preëxistent one in some animal, and ignore the question of primary origin, we must still recognize that it passes readily from horse to cow, and from cow to horse, through the hands of milkers and stable-men, but that it also has the source of vaccinated persons in the families of those handling the horses. Whether it was also often derived from the very prevalent small pox in past times is doubtful, yet it appears to have been much more common about the year 1800 than it is to-day. When once started in a stable it passes readily from horse to horse, through the hands of shoeing-smiths and grooms, including of course their aprons, brushes, sponges and rubbers, and also through blankets, bandages, litter and other things on which the virus has been received. The susceptibility of the skin in the hollow of the pastern depends mainly on the frequency of chaps and abrasions, and to a certain extent on contact with the road-mud infected by other passing animals. At times the suffering animal licks the affected part, and determines the eruption on the mouth, lips and nose (see contagious pustular stomatitis). Megnin saw cases affecting the external generative organs and transmitted between the sexes by coition. (See vesicular eruption on the genitals). All such cases should be identified by inoculation.

Hertwig, as early as 1830 recorded the existence of horsepox in Berlin, where it has been seen frequently since, and noted its transmission to man. Bouley gave evidence of its special prevalence at Paris, and of the production of typical vaccine vesicles in man by its inoculation. More recently it has been frequently observed and studied by inoculation and otherwise.

Symptoms. These, whether seen in horse, cow or man, do not differ from those of cow pox, with which it may be held to be identical. The observations of Chauveau, Warlomont, and Pfeiffer that experimental infection, intravenous, subcutaneous, intratracheal (inhalation), or by feeding almost always failed to give the general eruption which characterizes small pox and sheep pox. It remains strictly local except when inoculated on other parts of the skin or mucosa. It must be added, however, that small pox or sheep pox, when inoculated successfully on the horse, as a rule remains confined to the seat of inoculation. The constitution of the horse, like that of the cow, tends to resist its virulence.

The affected horse may show preliminary febrile symptoms, but these are usually too slight to be noticed. They are followed by heat, tenderness and swelling of some part of the skin, usually in the hollow of the pastern and perhaps the back part of the metatarsal region, with more or less (sometimes extreme) lameness. On the swollen skin may be detected nodules, which may pass early into vesicles and pustules. The eruption varies, however, as developed on the comparatively hairless lips or nose, or on the densely pilous pastern.

On the lips, or other part lightly covered with hair, one can easily follow the successive formation of the round nodule, the distinct (sometimes umbilicated) vesicle, with its clear translucent straw-colored contents, and the pustule, which bursts, forming a sore, or dries up forming a dense scab, like that of cowpox.

On the heels, or on any part thickly covered with hair, the vesicle or pustule is rarely recognized, the exudate on the contrary takes place mainly on the surface, which becomes encrusted with an abundant yellowish concretion, matting the hairs together, and sometimes literally covering them. This may be very misleading to the practitioner who expects to see the succession of fully developed vesicle and pustule, and overlooking the true nature of the malady he may allow it to spread widely in a stable.

Describing his inoculation cases, Chauveau gives the following successive phenomena:—

“From the fifth to the eighth day the points of inoculation become distinctly papular. As far as about the tenth day, the papules encrease, and become more prominent, taking the form of an extremely wide cone, with a base of ⅓ to ½ inch. During this period these large conical papules are resistant and painful on pressure, but show no elevation nor change in the epidermis, save a slightly reddish reflection in animals with white skins. Afterward supervenes a new stage which may be called the period of secretion. This commences from the ninth to the twelfth day. The epidermis, slightly raised upon all the papule, sweats out numerous drops of a limpid, very slightly yellow serosity. These drops soon concrete into yellowish, transparent crusts covering the whole surface of the pustule:—a species of characteristic crystallization, very different from the crusts that succeed the vaccine pustules in mare and cow. The secretion, which continues several days, is terminated from the thirteenth to the seventeenth day after inoculation. If then the crust is raised there is exposed a humid, pink, granular surface not projecting beyond the surrounding skin. This surface is hollowed out by a very deep central cavity, a sort of umbilicus, in which is inserted, like a nail, a projection from the deep surface of the crust.”

I would add that after recovery the hair in the seats of the nodules has a lighter color and, on the shanks and higher, remains dappled for the season.

No treatment is demanded. The application of a solution of sodium bisulphite once or twice a day, or continuously on a bandage, will greatly modify the intensity of the inflammation, and ward off complex infections. If the skin is left tender or with a disposition to crack, treat it as advised under chapped heels.

COWPOX. VARIOLA VACCINÆ.

This is manifestly the same disease, and due to the same microbe as horse pox. The disease of the one genus is easily transmitted to the other and the lesions and symptoms are the same, as if the virus were derived from an animal of the same species. Differences in the local manifestations appear to be due rather to the varying conditions of the skin and hair follicles, than to any material distinction in the virus.

Causes. Aside from the germ (Sporidium vaccinale) the conditions which favor infection are: the milking of susceptible cows with imperfectly washed hands, after dressing legs, the seat of horse pox eruption; the milking of healthy cows after those affected with cowpox; and the milking with hands contaminated with the exudate in cases of vaccination of man. That susceptible cows may also be inoculated successfully from smallpox patients, under given conditions appears to be true, but in Western Europe and America this is very uncommon, and would be much more so if vaccination were universally carried out. Among those who claim the identity of small pox and cow pox may be named Ceely, Reiter, Babcock, Thiele, Voigt and Klein.

Ceely alleges the infection of five cows and one heifer, in 1839, in England, from chewing the flock of a bed on which a small pox patient had died. In 12 or 14 days they had tender congested udders, with hard pimples imbedded in the skin, followed by blisters, and brownish scabs. The milk diminished, saliva drivelled from the mouth, the cheeks were inflated and retracted, the coat stared, their feet were drawn together, and the back was arched. The disease was communicated to the owner. This was clearly an outbreak of aphthous fever, which invaded England in that year, and was still an unknown disease to medical men. The implication of the heifer which would not have been inoculated with variola through the hands of the milker, and the salivation which is unknown in cow pox, but points directly to the buccal vesicles of foot and mouth disease, are conclusive on this point.

Ceely later, after many fruitless attempts to convey smallpox to the cow, at last met with results which indicated cowpox, and which he thereafter passed from cow to cow with the characteristic cowpox eruption.

Fletcher further reports the transmission of smallpox through the horse to the cow, and thence to the child in the form of cowpox.

In 1836, Thiele, Kasan, S. Russia inoculated some cows on the udder with smallpox lymph, and conveyed the lymph of the resulting vesicles back to man, and from man to man for seventy-five generations of the virus without finding any variation from the type of the true vaccine disease. He repeated the experiment with equal success in 1838.

Such experiments, made before the days of careful antiseptic, or aseptic, laboratory methods, by men who were daily engaged in making vaccinations, cannot be very implicitly relied on, yet the success of Thiele in Central Asia, the early home of variola, may indicate the possibility of a transition, under given eastern conditions, which, to say the least, is exceedingly rare in Western Europe or America.

The experiments of Klein, conducted under modern methods, are more conclusive, and seem to imply the possibility of smallpox passing into cowpox, in the bovine system, under some not yet clearly defined conditions. Until such conditions are sufficiently well known, so that they can be controlled at will, no one can be justified in attempting to produce lymph for vaccination by simply passing smallpox virus through the system of the cow.

It seems important to note one or two instances of the evident transmission of smallpox from man to man through the bovine system.

In 1860, Martin inoculated variolous matter, from a man who had just died of smallpox, on a cow’s udder, and subsequently inoculated about fifty persons from the eruption caused in the cow. Most of those so inoculated had unmistakable smallpox and three died.

Reiter had a very similar experience.

Chauveau (French Commission) inoculated twelve susceptible cattle with smallpox virus and produced, in all but one, small conical (smallpox) papules and vesicles, and in ten of these, on subsequent inoculation with cowpox, six proved immune, three had rudimentary pustules, and one had a distinct cowpox eruption.

A milch cow and two heifers were inoculated with smallpox and cowpox on two sides of the vulva, with the result that each disease appeared in the seat of its inoculation, with its characteristic vesicles, and the two developed side by side. The smallpox vesicles were by inoculation conveyed from ox to ox with steadily decreasing activity. Inoculated from the cow on a child, it caused great hyperthermia, vomiting, one large vesicle like vaccinia and a general eruption like varioloid. Inoculation from this child upon another produced a mixed eruption of cowpox and varioloid. Inoculation from the second child on a bull and heifer produced papular eruption only.

Smallpox virus, inoculated on a horse produced a papular eruption, but failed to affect another horse that had been previously vaccinated. Cowpox virus inoculated on the first horse which had had the papular eruption, caused a second papular eruption (not cowpox). The virus from a vesicle in the first horse caused a similar eruption in another horse, on which it was inoculated. The lymph from the papular eruption led to a similar eruption in cattle, on which it was inoculated, but did not protect against cowpox, subsequently inoculated.

The lymph from the papular eruption in the horse, inoculated on two children, produced fever, vomiting, a general papular (smallpox) eruption, in which a few of the pustules only showed a tendency to umbilication. A child and its mother in the same ward contracted varioloid. A child inoculated from one of the first named children, had six large umbilicated vesicles like cowpox and a general papular (smallpox) eruption. Another child inoculated from the last had six large umbilicated vesicles, and a general papular (smallpox) eruption. From the papular eruption of one of these children a horse and seven cattle were inoculated and in all a varioloid eruption resulted.