Experiments on Animals

II Anthrax

In animals, anthrax is also called charbon, splenic fever, or splenic apoplexy: in man, the name of malignant pustule is given to the sore at the point of accidental inoculation, and the name of woolsorter’s disease is given to those cases of anthrax where the lungs are infected by inhalation of the spores of the bacillus anthracis. The disease occurs among hide-dressers, woolsorters, brushmakers, and rag-pickers: among animals, it occurs in sheep, cattle, horses, and swine:—

“Many of the outbreaks of anthrax in England have been in the neighbourhood of Bradford, and have been traced to the use of infected wool-refuse as manure. A map published by the Board of Agriculture shows that the outbreaks of anthrax are most frequent in those counties of Great Britain where dry foreign wools, hairs, hides, and skins are manufactured into goods. In 1892, there were forty-two outbreaks of anthrax in the West Riding of Yorkshire, as against two in the North Riding, and one in the East Riding. An undoubted fact in connection with anthrax is its tendency to recur on certain farms. During 1895, the disease reappeared on twenty-three farms or other premises in England, and six in Scotland, where it had been reported in the previous year.” (Dr. Poore’s Milroy Lectures, On the Earth in relation to Contagia, 1899.)

An admirable account of the disease, as it occurs in man, is given by Dr. Hamer and Dr. Bell, in the valuable series of monographs edited by Dr. Oliver of Newcastle, under the title Dangerous Trades (London, John Murray, 1902). Happily, the disease is very rare among men, even among those most exposed to it. For its treatment in man, an antitoxin has been used with some success: but the cases are too few to be of much importance.15

The bacillus anthracis was first seen more than fifty years ago: “Anthrax has the distinction of being the first infectious disease the bacterial nature of which was definitely proven.”16 Pollender in 1844, Roger and Davaine in 1850, noted the petits bâtonnets in the blood of sheep dead of the disease, and thought they were some sort of microscopic blood-crystals: it was not till 1863, after Pasteur’s study of lactic-acid fermentation, that Davaine realised they were living organisms. Afterward, Koch succeeded in making cultures of them, and reproduced the disease by inoculating animals with these cultures; yet it was said, so late as 1876, that the bacillus anthracis was not the cause of anthrax, but only the sign of it: “Along with the bacilli, there are blood-cells and blood-plasma, and these contain the true amorphous virus of anthrax.” Then came Pasteur’s work, and reached its end in the experiments at Chartres, and the famous test-inoculations (1881) at Pouilly-le-Fort.

In the Agenda du Chimiste (1896) M. Roux gives the following account of this work, which he watched from first to last:—

“Vaccination against charbon has now been put to the test of practice for fourteen years. Wherever it is adopted, there the losses from charbon have become insignificant. It was followed by vaccination against swine-measles, rouget des porcs, the special study of our poor friend Thuillier. But the immediate result of Pasteur’s vaccinations is their least merit: they have given men absolute faith in a science that could show such good works, they have started a movement that is irresistible; above all, they have set going the whole study of immunity, which is bringing us at last to a right way of treating infective diseases.

“Virulence is a quality that microbes can lose, or can acquire. Suppose we came across the anthrax-bacillus so far attenuated, in the way of Nature, that it had lost all power to kill—of course we should fail to recognise it; we should take it for an ordinary bacillus of putrefaction: you must watch it through each phase of its attenuation, to know that the harmless organism is the descendant of the fatal virus. But you can give back to it the virulence that it has lost, if you put it, to begin with, under the skin of a very delicate subject, a mouse only one day old. With the blood of this mouse inoculate another, a little older, and it will die. Passing by this method from younger to older mice, we come to kill adult mice, guinea-pigs, then rabbits, then sheep, etc. Thus, by transmission, the virus gains strength as it goes. Doubtless this increase of virulence, that we bring about by experiment, occurs also in Nature; and it is easy to see how a microbe, usually harmless to this or that species of animals, might become deadly to it. Is not this the way that infective diseases have appeared on the earth from age to age?

“See how far we have come, from the old metaphysical ideas about virulence, to these microbes that we can turn this way or that way—stuff so plastic that a man can work on it, and fashion it as he likes.”

Pasteur’s note on the attenuation of anthrax was presented to the Académie des Sciences on 28th February 1881; and the test-inoculations at Pouilly-le-Fort were made in May of that year. It was hardly to be expected that every country, in every year, should obtain such results as France now takes as a matter of course; and at one time, about twenty-one years ago, there was in Hungary a “conscientious objection” to the inoculation of herds against the disease. But in Italy, from 1st May 1897 to 30th April 1898, the issue of anti-charbon vaccine from one institute alone, the Sero-Therapeutic Institute at Milan, was 165,000 tubes, enough to inoculate 33,734 cattle and 98,792 sheep. And in France, between 1882 and 1893, more than three million sheep, and nearly half a million cattle, were inoculated.

The work done in France was published by M. Chamberland, in the Annales de L’Institut Pasteur, March 1894. The following translation of his memoir—Résultats pratiques des Vaccinations contre le Charbon et le Rouget en France—shows something of the national influence of the Pasteur Institute:—

1. Charbon

“After the famous experiments at Pouilly-le-Fort, MM. Pasteur and Roux entrusted to me the whole method and practice of the vaccinations against charbon. Twelve years have passed, and it is now time to put together the results, and to make a final estimate of the value of these preventive inoculations.

“Every year we ask the veterinary surgeons to report—

1. The number of animals they have vaccinated.

2. The number that have died after the first vaccination.

3. The number that have died after the second vaccination, within the twelve days following it.

4. The number that have died during the rest of the year.

5. The average annual mortality before the practice of vaccination.

“The sum total of all the reports is given in the following tables:—

Vaccination against Charbon (France).
Sheep.

Years.	Total Number of Animals Vaccinated.	Number of Reports.	Animals Vaccinated according to Reports received.	Mortality.			Total.	Total loss per 100.	Average loss before Vacci- nation.
				After First Vacci- nation.	After Second Vacci- nation.	During the rest of the Year.
1882	270,040	112	243,199	756	847	1,037	2,640	1.08	10%
1883	268,505	103	193,119	436	272	784	1,492	0.77	″
1884	316,553	109	231,693	770	444	1,033	2,247	0.97	″
1885	342,040	144	280,107	884	735	990	2,609	0.93	″
1886	313,288	88	202,064	652	303	514	1,469	0.72	″
1887	293,572	107	187,811	718	737	968	2,423	1.29	″
1888	269,574	50	101,834	149	181	300	630	0.62	″
1889	239,974	43	88,483	238	285	501	1,024	1.16	″
1890	223,611	69	69,865	331	261	244	836	1.20	″
1891	218,629	65	53,640	181	102	77	360	0.67	″
1892	259,696	70	63,125	319	183	126	628	0.99	″
1893	281,333	30	73,939	234	56	224	514	0.69	″
Total	3,296,815	990	1,788,879	5,668	4,406	6,798	16,872	0.94	10%

Vaccination against Charbon (France).
Cattle.

Years.	Total Number of Animals Vaccinated.	Number of Reports.	Animals Vaccinated according to Reports received.	Mortality.			Total.	Total loss per 100.	Average loss before Vacci- nation.
				After First Vacci- nation.	After Second Vacci- nation.	During the rest of the Year.
1882	35,564	127	22,916	22	12	48	82	0.35	5%
1883	26,453	130	20,501	17	1	46	64	0.31	″
1884	33,900	139	22,616	20	13	52	85	0.37	″
1885	34,000	192	21,073	32	8	67	107	0.50	″
1886	39,154	135	22,113	18	7	39	64	0.29	″
1887	48,484	148	28,083	23	18	68	109	0.39	″
1888	34,464	61	10,920	8	4	35	47	0.43	″
1889	32,251	68	11,610	14	7	31	52	0.45	″
1890	33,965	71	11,057	5	4	14	23	0.21	″
1891	40,736	68	10,476	6	4	4	14	0.13	″
1892	41,609	71	9,757	8	3	15	26	0.26	″
1893	38,154	45	9,840	4	1	13	18	0.18	″
Total	438,824	1,255	200,962	177	82	432	691	0.34	5%

“Comparing the figures in the fourth column with those in the second, we see that a certain number of veterinary surgeons neglect to send their reports at the end of the year. The number of reports that come to us even tends to get less each year. The fact is, that many veterinary surgeons who do vaccinations every year content themselves with writing, ‘The results are always very good; it is useless to send you reports that are always the same.’

“We have every reason to believe, as a matter of fact, that those who send no reports are satisfied; for if anything goes wrong with the herds, they do not fail to let us know it at once by special letters.

“Anyhow, thanks chiefly to new veterinary surgeons who do send reports, we see that in the twelve years, up to 1st January of this year, we have had exact returns as to 1,788,879 sheep and 200,962 cattle—about half of all those that were vaccinated.

“The mortality among sheep and cattle is slightly higher after the first vaccination than after the second. This fact seems to us easy to explain. The animals reported dead include both those that died as the result of the vaccinations, and those that, being already infected at the time, died of the actual disease. But, at the time of second vaccination, the animals are already more or less protected: hence a lower mortality from the actual disease, and a lower sum total.

“The whole loss of sheep is about 1 per cent.: the average for the twelve years is 0.94. So we may say that the whole average loss of vaccinated sheep, whether from vaccination or from the disease itself is about 1 per cent. The loss of vaccinated cattle is still less: for the period of twelve years, it is 0.34, or about 1/3 per cent.

“These results are extremely satisfactory. It is to be noted especially that the average annual death-rate from charbon, before vaccination—the average given in these reports—is estimated at 10 per cent. among sheep, and 5 per cent. among cattle. But even if we put it at 6 per cent. for sheep, and 3-1/3 per cent. for cattle, and say that the worth of a sheep is 30 francs, and of an ox or a cow 150 francs—which is well below their real value—even then it is obvious that the advantage of these vaccinations to French agriculture is about five million francs in sheep, and two million in cattle. And these figures are rather too low than too high.

2. Rouget

“Some years after the discovery of vaccination against charbon, M. Pasteur discovered the vaccine for a disease of swine known under the name of rouget. From 1886, these vaccines were prepared and sent out under the same conditions as the vaccines against charbon. The following table gives the reports that have come to us of this disease:17 —

Vaccination against Rouget (France).

Years.	Total Number of Animals Vaccinated.		Number of Reports.	Animals Vaccinated according to Reports received.	Mortality.			Total.	Total loss per 100.	Average loss before Vacci- nation.
					After First Vacci- nation.	After Second Vacci- nation.	During the rest of the Year.
	{
		For these two years
1886		France	49	7,087	91	24	56	171	2.41	20%
		and other countries
1887		are put	49	7,467	57	10	23	90	1.21	″
		together.
1888		15,958	31	6,968	31	25	38	94	1.35	″
1889		19,338	41	11,257	92	12	40	144	1.28	″
1890		17,658	41	14,992	118	64	73	254	1.70	″
1891		20,583	47	17,556	102	34	70	206	1.17	″
1892		37,900	38	10,128	43	19	46	108	1.07	″
Total		111,437	296	75,455	534	188	345	1,067	1.45	20%

“The total average of losses during the past seven years is 1.45 per cent., or about 1-1/2 per cent.

“This average is appreciably higher than the average for charbon. But it must be noted that the mortality from rouget among swine, before vaccination, was much higher than that from charbon among sheep. It was about 20 per cent.; a certain number of reports speak of losses of 60 and even 80 per cent.: so that almost all the veterinary surgeons are loud in their praises of the new vaccination.”

The rest of M. Chamberland’s paper is concerned with the defects, such as they are, of the vaccinations, and the need of absolute cleanliness in the making of them: which is somewhat difficult for this vast number of vaccinations of animals all over France, and in other parts of the world. The whole story of the discovery is told in M. Valléry-Radot’s Life of Pasteur: and the whole story of rouget, in the same most fascinating book, vol. ii., p. 180.