POISONOUS CHEESE.* 
BY PROF. VICTOR C. VAUGHAN, M. D,, PH. D., MEMBER OF THE MICHIGAN" 
STATE BOARD OF HEALTH. 
[Reprinted from the Annual Report of the Michigan State Board of Health, for the year 1885.] 
[Reprint No. 190.] 
It is well known that cases of severe illness follow the eating of some 
cheese. Indeed, such instances have been observed in various parts of the 
world for the past three hundred years. They are* of frequent occurrence 
in the north German countries and in the United States. In England, they 
are less frequently observed, while in France, where much cheese is used, 
we find no record of any such cases. 
The number of instances of cheese-poisoning in this country per year 
must be several hundred, if it does not extend above one thousand. In 
many reports of the different State Boards of Health we find notices of the 
effects of poisonous cheese. During the years 1884 and 1885, there were 
reports made to the Michigan State Board of Health of nearly three hun- 
dred persons who became suddenly and violently ill after eating of cheese. 
It will be seen from the above statements that this subject is of sufficient 
importance to demand the attention of those interested in public health. 
The writer has, therefore, spent a large part of the past two years in the 
study of this subject, and the object of this paper is to present the results 
obtained. 
The symptoms produced by “ sick ” cheese, as reported by German and 
American physicians, agree quite closely and are as follows: Dryness of 
the throat, nausea, vomiting, diarrhoea, nervous prostration, headache, and 
sometimes double vision. In short the symptoms resemble very closely 
these of a gastro-intestinal irritant, with marked effects upon the nervous 
system. In individual cases, some of the above mentioned symptoms may 
not appear at all, or, on account of the greater prominence of some of the 
others, may not be observed. Notwithstanding these alarming symptoms, 
recovery generally follows. 
I stated in my preliminary report of this investigation to the American 
Public Health Association in St. Louis, October, 1884, that I had failed to 
find any record of a case terminating fatally; although I then inferred from 
the language of Hiller, whom I quoted, that a fatal termination was not un- 
known. Since that time I have found that Huseraann, in his work on 
toxicology, refers to some fatal cases. Dr. Henry B. Baker states that a 
* For history of outbreaks of cheese-poisoning in Michigan, and of the beginning of the investi- 
gations in regard to the cause, see pages 132-138 of the Annual Report of this Board for 1884. 222 
STATE BOARD OF HEALTH,—REPORT OF SECRETARY, 1885. 
fatal case occurred in Lansing a few years ago. Death results from prostra- 
tion, and in the observed cases did not appear until from eight to ten days 
after the eating of the cheese. There were no deaths reported from the 
cases in this State in 1884 and 1885. From one of the reports made by a 
physician to the secretary of the Board, I take the following quotation con- 
cerning the symptoms: “ Every person who ate of the cheese was taken 
violently sick. They were attacked with vomiting of thin, watery substance 
at first; later the vomited matter became thicker and reddish. At the 
same time there was diarrhcea, the evacuations being thin and watery. 
There was not much pain, except in the stomach. The tongue at first had 
a white coat, but later became red and dr}r. The pulse was very weak and 
irregular, the face pale and cyanotic. One little boy who ate freely of the 
cheese came very near dying. His body was covered with blue spots.” 
The symptoms of cheese-poisoning and those of sausage and fish-poisoning 
are very similar, though death from eating poisonous sausage and fish fre- 
quently occurs in Germany and Russia, Bohm reports the mortality from 
sausage-poisoning in Germany as from 23.2 to 54.2 per cent.; while Muller 
reports only six deaths in 343 cases occurring in Holland in 1874 ; a mortality 
of less than 2 per cent. It is altogether probable that many of the earlier 
cases reported were in reality produced by trichinaß, The mortality from 
fish-poisoning among the inhabitants along the Volga is reported as high, 
although exact figures are wanting. 
From the studies of Sengbusch, Owsjannikoff, and Berkowsky, it is evi- 
dent that the toxic agent in the fish arises from partial decomposition. The 
fish consist of three species of the genus Acipenser, A. sturio, A. huso, and 
A. ruthemes. For the purpose of preservation, they are cut into pieces, 
salted and buried in wooden casks in the earth. As needed they are taken 
up and eaten raw. Likewise, Kerner, Paulus, Schlosser, Hiedner, and 
Muller, from special studies on sausage-poisoning, conclude that the toxic 
agent is due to partial decomposition, I mention these facts in regard to 
poisonous sausage and fish for the reason that they may throw some liglrt 
upon our study of poisonous cheese. 
Bohm and several others state that cheese which has proved harmful to 
man may be eaten by the lower animals with impunity. In order to test 
this, I kept a cat in confinement for seven days, and furnished it only water 
and cheese from a cake which had poisoned some 30 or more persons. The 
cat fed upon the cheese freely, and at the expiration of the time appeared 
in excellent health. The animal was then killed, and a careful post mortem 
examination failed to reveal any lesion. There was not even the slightest 
evidence of irritation of the stomach. However, from what I now know of 
the toxic substance, I am satisfied that the reason why the lower animals 
were not affected by the cheese was that they did not get the poison in suffi- 
cient quantity. 
All the cases occurring in this State in 1884 and 1885 were due to twelve 
cheeses. Of these, nine were made at one factory, and one each at three 
other factories. I was furnished with a smaller or larger amount of each 
cheese. Of ten of them I secured only small amounts. Of each of the 
other two I received about 38 pounds. 
The maker of the greater number of the poisonous cheeses has been 
engaged in the manufacture of cheese for a great many years, and has quite 
a reputation, justly earned. He owns three large factories. I visited one 
of these and was furnished every facility for studying the methods of manu- POISONOUS CHEESE. 
223 
facture, the agents used and the vats. The milk is brought in every morn- 
ing by the farmers of the neighborhood, is poured into a large tin receiver, 
and thence is emptied into the vats. The milk brought by different persons 
is mixed, and then used for filling each of the vats, three in number. Many 
of the rennets are also prepared by the farmers. This is done by emptying 
the stomachs, scraping off the fleshy parts, filling with salt and drying. The 
rennets thus prepared and found on hand at the time of my visit were exam- 
ined and found to be free from any sign of decomposition. The same ren- 
net was used in each of the three vats. If it be true, as the manufacturer 
thinks, that all the poisonous cheese came from one vat, the rennet cannot 
be the carrier of the toxic substance. The cheese is colored with annotto, 
which was examined and found to be free from harmful adulteration. 
Moreover, the same stock of this coloring agent was used in making the 
cheese which had proved poisonous and that which remained good. From 
these facts it is evident that we cannot charge the deleterious effects of cer- 
tain cakes of the cheese to this ingredient. Coloring cheese with annotto 
has been so long practiced, and the public demand for this color in cheese is 
so well established, that it may be regarded, I suppose, as a justifiable adul- 
teration. The vats were lined with tin and seemed to be kept scrupulously 
clean. They were heated by steam pipes placed underneath. Each vat 
furnished curd for seven or eight cheeses. The curd is cut, placed in cheese- 
cloth, and subjected to pressure in iron hoops, the expressed fluid finding 
free exit beneath. The curing room was found to be large and well venti- 
lated. In this the cheeses are placed on shelves and left for fourteen days or 
longer, when they are placed on the market. The manufacturer states that 
all the cakes which proved poisonous were made between April 26 and 
May 6, 1884. 
Nearly every cheese manufacturer has his theory.as to the cause of poison- 
ous cheese. The majority of them think that it is due to some poisonous plant 
which the cow eats. I have received a large number of letters from cheese 
makers on this subject. While many of them think that it is some plant, 
no two of those writing to me agree as to the special plant. One says that 
it must be some plant which appears early in the spring, because all the 
poisonous cheese made in his factory has been the‘product of early spring 
work. For a similar reason, another thinks that the plant must appear in 
midsummer, while a third is equally certain that the plant is eaten by the 
cows only late in the fall. One, Mr. 0. B. Lambert, argues that the poison 
arises from the whey, and that poisonous cheese will be made in factories 
from which the milkmen carry home whey in their cans. But poisonous 
cheese has been made in factories where this practice is altogether unknown. 
All the samples of poisonous cheese examined by me were found to be 
similar in many respects. From the freshly-cut surface, there exuded drops 
of a watery, slightly opalescent fluid, which was found to redden blue litmus 
paper instantly and intensely. If a small piece was dried thoroughly by 
prolonged exposure to the air, ajid then moistened with distilled water, the 
water would give the same intense and immediate acid reaction. I have 
tested with litmus many samples of good cheese, and have found that while 
all new or green cheeses feebly and slowly redden blue litmus paper, only the 
poisonous cakes give the intense and instantaneous reaction. I think that 
it can be stated that any cheese, which will instantly and intensely redden 
blue litmus paper should be regarded with suspicion. Whether or not all 
poisonous cheeses have this reaction, remains to be determined by the exam- 224 
STATE BOARD OF HEALTH—REPORT OF SECRETARY, 1885. 
illation of a larger number than it has fallen to my lot to study. However, 
this test is easy of application, and every grocer should make it on cutting 
a fresh cheese. If the sample is dry, a bit of it should be moistened with 
water, and the paper then applied. The old, foul-smelling cheeses, such as 
Limburger and Schweitzer, are alkaline in reaction, and poisoning does not 
result from their use. 
Microscopical examination of the opalescent drops appearing on the fresh- 
ly-cut surface of the cheese revealed constantly small spherical bodies, which 
have been determined by Dr. Sternberg to be micrococci. 
My first step in searching for the poisonous principle of the cheese con- 
sisted in treating some of it cut into fine bits, with 90 per cent alcohol, 
filtering and evaporating the alcoholic extract to dryness at a low tempera- 
ture, This residue consisted of a fatty mass. Of this I ate a small bit. It 
had a bitter, acrid taste, and produced within a few minutes marked dryness of 
the mouth and fauces and constriction of the throat, much the same as that 
produced by a large dose of beiladonna, or its active principle, atropia. 
Later, there was considerable nausea, and I could readily imagine that a 
larger amount would have produced vomiting. This experiment was 
repeated a number of times with the same result, and from it I concluded 
that the poison, whatever it might be, was contained in the alcoholic extract. 
This would indicate a chemical poison and not abacteric one. However, this 
chemical poison might be generated by the growth of bacteria. For some 
months I tried to isolate the poison from this alcoholic extract, but was 
unable to do so; for whatever I tried to dissolve the poison in would either 
dissolve the fat as well, or would fail to take out the poisonous principle. 
Besides, the compact, fatty mass extracted with the alcohol was not suitable 
for further extractions. After many attempts in this direction, I gave it up 
and made a water extract .of the cheese. This I also found, by an experi- 
ment upon myself, contained the poison. The watery extract containing only 
traces of fat was much more suitable for study than the alcoholic one. I 
then evaporated the watery solution to dryness, at a temperature not exceed- 
ing 110° C., but was disappointed to find that the residue was not poisonous. 
The active principle had been volatilized or decomposed by the heat employed. 
Next, I tried distilling the aqueous solution. By doing this, I found that 
the first few drops collected in the receiver had the odor of old cheese, and 
when taken into the mouth produced the characteristic dryness and con- 
striction. But the amount of the poison obtained in this way was small; 
and, besides, I thought it altogether pro cable that partial decomposition of 
the substance might be produced in making the distillation. Then, I took 
the aqueous extract of the cheese, shook it with ether, removed the ether with 
a pipette, placed it in a porcelain dish and allowed it to evaporate spon- 
taneously. The residue contained traces of the poison. Another attempt 
was made by rendering the aqueous extract of the cheese alkaline with 
potassium hydrate, then extracting with ether. This process gave the poison 
in greatest amount, and was followed in all the subsequent work. By re-dis- 
solving the etherial residue in water and again extracting the residue, the 
poison was obtained in a state of sufficient purity, so that after allowing a 
concentrated, aqueous solution to stand in vacuo over sulphuric acid, the 
poison formed in needle-shaped crystals. A small bit of one of these crys- 
tals, which, as obtained from one cheese, were large enough to be plainly 
seen with the unaided eye, placed on the end of the tongue, caused a very 
sharp, burning sensation, which was soon followed by dryness and constric- POISONOUS CHEESE. 
225 
tion of the throat, and nausea. The taste was especially sickening. A drop 
of the fluid in which the crystals formed, placed on the tongue, produced, 
in addition to the symptoms mentioned above, griping pains in the bowels, 
followed by one or more diarrhoeal discharges. This was tried several times, 
not only upon myself, but upon some of my students, who kindly offered 
themselves for experimentation. 
For this substance, I have proposed the name tyrotoxicon,—cheese poison. 
With potassium ferricyanide and ferric chloride, tyrotoxicon produces Prus- 
sian blue. It also reduces iodic acid readily. With the general alkaloidal 
precipitants, it fails to react. It is freely soluble in water, alcohol, ether, 
and chloroform. Chloroform was also used in a few trial experiments to sep- 
arate the poison from the aqueous extract of the cheese, but the amount 
obtained with this agent was not so great as that secured with ether. Besides 
the more rapid spontaneous evaporation of the ether rendered it the more 
suitable. The amount obtained from the cheese was exceedingly small. 
From one cake, which was nearly entire, not more than two pounds having 
been removed by the grocer, I secured an amount which I estimated at not 
more than eight grains; but, from the same quantity of another cheese, I 
did not obtain more than two grains. Ido not suppose, however, that all 
of the poison was extracted from the cheese. In future experiments I shall 
endeavor to discover some better method of separation. 
The crystals have a pungent odor resembling that of old cheese, and it 
may be stated here that this odor hds been observed in poisonous sausage, 
according to Husemann and Bohm, It is probable that tyrotoxicon or a 
similar substance will be found in poisonous sausage. If the crystals be left 
exposed to the air at the ordinary temperature of a room they decompose, 
some organic acid, whose composition was not determined, being formed. 
I regret very much that I did not obtain the poison in quantity sufficient 
to enable me to make an ultimate analysis. The question as to the origin of 
this poison is one of great practical interest, and one which I am not yet able 
to solve with satisfaction. Tyrotoxicon belongs to a class of poisons known 
to the chemist under the name of ptomaines. They originate in organic sub- 
stances which are undergoing putrefactive changes. Only a very small num- 
ber of ptomaines have been separated. The majority of them have been recog- 
nized simply by their poisonous effects. They are, undoubtedly, quite widely 
distributed, and vary much among themselves in their toxic and other prop- 
erties. In one sample of ether I found a ptomaine, a small bit of which, 
injected under the skin of a frog, caused death in a few minutes. Therefore, 
in using ether to extract tyrotoxicon from cheese, it became necessary to test 
the ether first. This was done by allowing one pound of ether to evaporate 
spontaneously in a porcelain dish, and examining the residue, if there was 
any. At first I was inclined to the theory that the tyrotoxicon originated in 
imperfectly cured rennets, but I have found it in milk to which no rennet 
had been added. A student brought me a four ounce bottle which was about 
half full of milk. The bottle and its contents had stood in the laboratory 
for more than six months. I removed the glass stopper with which the bot- 
tle had been closed, and observed the same odor as that given off from the 
crystals of tyrotoxicon. The decomposed milk was strongly acid in reaction. 
It was filtered, the filtrate rendered alkaline, and then extracted with ether; 
the etheral solution, on evaporation, deposited a small but distinct amount 
of tyrotoxicon. I then placed one gallon of good milk in a bottle, stopping 226 
STATE BOARD OF HEALTH—REPORT OF SECRETARY, 1885. 
it tightly, and another gallon in a jar which was covered only with a thin 
cloth to keep out the dust. After two months these were examined and 
tyrotoxicon found in the milk from the stoppered bottle, but none in that from 
the jar. However, the milk in the jar contained other ptomaines, only one of 
which, trimethylamine, have I succeeded in separating up to this writing. 
Evidently, then, tyrotoxicon may originate in milk on long standing in 
closed vessels. As the putrefactive changes in the milk are due to the growth 
of minute organisms, the introduction of these organisms into the milk may 
hasten its putrefaction, and, consequently, the formation of the ptomaine. 
The germs may be present in portions of milk which adhere to the sides of 
vessels which are not cleansed as often or as thoroughly as they should be. 
I would suggest that cheese manufacturers frequently inspect the cans in 
which milk is brought to them. When cows are kept in filthy stalls, the milk 
is likely to undergo speedy putrefaction. 
I shall continue these investigations, and hope to ascertain with more 
exactness the conditions under which this poison is formed.