(From the Canada Medical Record.) 
REPORT ON THE ETIOLOGY, AND THE 
PREVENTIVE VACCINATION 
OF YELLOW FEVER. 
BY DR. L. GERERD. 
y>//y, 1886. 
Late Surgeon to the Interoceanic Canal Company at Pan- 
ama, S. A. 
Translated from the French by Dr. Wolfred Nelson, late of 
Panama, S. A. 
Whence comes yellow fever, how does it propa- 
gate itself, and what is our etiological knowledge of 
its nature? Can that knowledge produce some 
prophylactic means or measures, easy to apply 
and sufficient to give absolute protection against 
this formidable plague ? 
Such were the problems that I had undertaken 
to solve after my arrival on the Isthmus of Pana- 
ma. I shall now briefly give the results of my ex- 
periments and studies : 
I. 
In the month of June, 1882, in a report to the 
Superior Agent of the Interoceanic Canal Company 
resident in the City of Panama, S. A., I had the 
honor to inform him, that I had found in the 
blood of yellow-fever patients, some microscopic 
organisms,—some filiform, others resembling a 
string of beads (chaplets), and, lastly,brilliant little 
bodies. That the organisms were constant in 
appearance, and could thus serve as elements for 
diagnosis. 2 
After some trials and a great many failures I 
succeeded in isolating the microbes, and obtained 
them in great quantity without the human body, 
by artificial cultivation, in liquids suitable for their 
nutrition and reproduction. 
I was then enabled to study the mode of exis- 
tence of the microbes. If one observes the filiform 
bodies attentively for a given time he perceives 
in their transparent and homogeneous substance, 
a series of small corpuscles, that refract light more 
than the other parts of the microbe. Little by 
little these corpuscles arrange themselves around 
a central axis or core, giving the organism the 
appearance of a string of beads, chaplet. (This 
French word signifies the string of beads “ told ” 
by devout Catholics while praying.) Soon other 
changes follow, the string-like formation separates 
and in place thereof nothing remains but a mass 
of brilliant little points. The size of little points is 
about the thousandth of a millimetre. These cor- 
puscle germs have great resistance. They do not 
perish by drying, and can after many years serve 
to propagate the disease, by regeneratifig the fili- 
form bodies, when placed under favorable condi- 
tions. 
But what role can we attribute to the microbes 
in the production of yellow fever ? To elucidate 
this question I have had recourse to experiments 
on animals. At the beginning of my work I ex- 
perimented on a number of rabbits, later with 
dogs, poultry, rats and monkeys, but these animals 
did not show any predisposition to the disease. 
At length a result was obtained by inoculating 
a guinea pig with half a gramme (a gramme is 
equal to 15 1-3 grains) of blood taken from the 
heart of a man an hour after his death from spe- 3 
cific yellow fever. The animal sickened and after 
two days’ fever died in great agony. 
At the autopsy on the little cadaver, I found 
the characteristic lesions of yellow fever, shown 
with sufficient clearness to establish the identity of 
the disease, notwithstanding the difference in the 
organisms. 
These direct inoculation experiments were re- 
peated a great many times, the same results were 
produced in nine cases out of ten. The cadaveric 
lesions were always the same. 
Examinations of blood taken from the ears of a 
guinea pig suffering from the disease invaria- 
bly gave the same results, i.e., the recognition or 
presence of the same microbe met with in man suf- 
fering from specific yellow fever. 
Having thus established that yellow fever was 
transferable by inoculation, or vaccination from 
man to the guinea pig, it became easier to study 
the role of the microbe itself in the production of 
the disease. 
More animals were inoculated with the culture 
liquids peopled with the microbes. They all died 
in the same manner, presenting the same symptoms 
as those infected by the direct inoculation of 
blood. 
The periods of incubation in the various exper- 
iments declared themselves with varying phases in 
from one to nineteen days. Figures that corres- 
pond with those resulting from observation of the 
disease at Panama. 
As a whole, the knowledge acquired by the ex- 
periments just related may be summarized thus : 
ist. Yellow fever is a disease that is always 
characterized by the presence in the blood of the 
patients of a special microbe, which can be multi- 4 
plied outside of the bodies of men or animals, by 
artificial culture. 
2nd. The microbes give birth to germs endowed 
with great resistance to destructive causes, and 
are capable of reproducing the disease. 
3rd. Yellow fever can be transmitted to a guinea 
pig by the inoculation of blood in its sub-cellular 
tissues. 
4th. Finally,the animals inoculated with cultures 
charged with the parasites, contract yellow fever 
and die. Post-mortem, the same lesions are found 
as in those directly inoculated with blood. 
II. 
Vaccination. 
“ In 1880 M. Pasteur discovered the first in- 
“ stance of a disease, produced by a special mi- 
“ crobe, which, by special treatment, could be de- 
“ prived of a part of its virulence, and that fowls 
“ could be inoculated with it without danger. By 
“ using the attenuated virus, the disease could be 
“ communicated to fowls, and after a light attack 
“ they were protected against the fatal disease. 
“ Later, several microbic diseases were recog- 
nized or defined. Their microbes having the 
“ same properties. 
“M. Pasteur, with marvelous sagacity,could not 
“ help but remark that the process which had ena- 
“ bled him to lessen or attenuate the action of the 
“ microbe of chicken cholera, ought to be a pro- 
“ cess of diminishing or attenuating the virulence 
“ of microbes generally that cause other diseases.”* 
Such were the antecedents that encouraged one 
to search out a method for attenuating the microbe 
* Chamberland de la Vacination Charbonneuse. 5 
of yellow fever. In my experiments already re- 
lated I noticed that three of the inoculated ani- 
mals that were dangerously ill recovered. That 
circumstance permitted me to submit to experi- 
mental proof, the important theoretical problem, 
as to whether they were still susceptible to the 
yellow fever poison. The three guinea pigs were 
re-inoculated some time afterwards to demonstrate 
if they were susceptible to the disease de novo. 
They did not present any abnormal symptoms 
after the inoculation, nor the slightest elevation of 
temperature. 
Thus, we should admit in principle that yellow 
fever cannot be taken anew. And in this again 
the experiments were in perfect accord with clini- 
cal observations. 
This fact accepted rendered my later experi- 
ments perfectly legitimate in the alternation of the 
virus of yellow fever poison for the production of 
a vaccine-virus capable of protecting man against 
the terrible effects of the disease. 
The problem, thus stated, to me seemed sus- 
ceptible of receiving a favorable solution by follow- 
ing in the steps traced out with so much perfec- 
tion by M. Pasteur, in his search for the virus of 
charbon or malignant pustule. 
This savant showed that he easily could obtain 
microbes of various degrees of virulence. From 
the deadly virulence, that is to say, that killed 
one hundred times in a hundred the animals ex- 
perimented upon, such as guinea pigs, rabbits and 
sheep, passing thence by a number of intermediate 
steps down to the most inoffensive attenuation of 
the virus. The method of preparing this atten- 
uated or lessened virus thus becomes one of mar- 
velous simplicity. 6 
My conjectures were confirmed by experiment, 
and now, after the usual experiments, trials and 
inevitable reverses, I have obtained the microbe 
of yellow fever in different degrees of attenuation 
which can be reproduced indefinitely by cultiva- 
tion. 
A guinea pig inoculated by this attenuated virus 
not only runs no danger of death from the inocu- 
lation itself but is placed beyond the dangers and 
death that invariably follows the injection of viru- 
lent blood in animals that have not been protected 
by the preventive vaccination, or inoculation. 
The illustrious savant whose methods I have 
followed said : “ We now possess some virus-vac- 
“ cine from charbon, capable of protecting against 
“ that fatal disease without being fatal in itself, a 
“ living vaccine, cultivated at will, transportable 
“ everywhere, without alteration, at length pre- 
tl pared by a method that we may believe suscep. 
“ tible of generalization.” 
I shall now apply his words to yellow fever, and 
it remained for me carry my experiments from the 
animal to man. 
The experiment was made last week on myself. 
Some months ago I was inoculated with an ex- 
tremely attenuated culture. Fifteen days ago by 
a second and stronger culture, and, finally, guided 
by special reasons, I allowed myself to be bitten 
by mosquitoes that had just bitten a man suffering 
from specific yellow fever. He was in the fifth 
day of the disease. 
In view of my experiments it became easy to 
analyse what obtains in the human body, inocu- 
lated, as I was, with a virulence of maximum in- 
tensity, direct from the body of a patient. 
Twenty-four hours after the above direct inocu- 7 
lation I felt sudden pains in the regions of the 
kidneys, a feeling of bruising or soreness in all 
my extremities, a sensation of tearing in my eye- 
balls. Two hours after these first sensations my 
temperature was taken in the mouth and was found 
to be 39°C. (36 9-100 centigrade being equal to 
Fahrenheit). That evening it was 40 0 C. 
The next morning also 40°C. That evening 390 
C. and on the morning of the 3rd day 390. Then 
it kept falling to normal. 
Tongue creamy white, gums bleeding, the 
amount of urine was diminished by one-third. On 
the fourth day I had got back to my normal con- 
dition. 
Thus, the preventive inoculation of yellow fever 
is proven. This was what I had been searching 
for, a virus capable of transmitting a mild type of 
the fever without danger. 
The first step, the most difficult and the most 
laborious, because it was filled with the uncertainty 
of unknown factors, was over. The rest will surely 
follow in time. 
A number of courageous friends having full con- 
fidence in the method, and who fully understood 
the importance of the experiments, and their great 
utility for mankind, have declared themselves 
ready to be vaccinated by me. I shall vaccinate 
them soon, with all the care that such a serious 
matter requires, and with all the precautions ex- 
acted by rigorous experiments. 
In conclusion, I may add that the theoretica 
question of the preventive vaccination of yellow 
fever is thus solved. The practical question has 
now entered on a course of experimentation, and 
promises to be a fact and a safeguard to mankind. (Editorial from the Canada Medical Record.) 
July, 1886. 
YELLOW FEVER AND ITS PREVENTION. 
In this issue our readers will find a timely and 
highly important communication on the etiology 
and prevention of yellow fever by inoculation. We 
are indebted to Dr. Gererd for having prepared it 
as a special contribution to the Record, and to our 
old friend, Dr. Wolfred Nelson, late of Panama, 
South America, for its translation. 
For many years—1826 to date—the city and 
Isthmus of Panama have been recognized hot- 
beds of yellow fever. In 1868 there was a serious 
epidemic in the city of Panama. It appeared 
again as an epidemic in 1880, and h remained en- 
demic and endo-epidemic up to when, 
in May and June, it assumed the proportions of an 
epidemic of the first class, killing forty victims 
daily. This fact was first announced in the New 
\orli Herald, and later by the American papers, 
generally in May. Later the New York Herald 
stated that the mortality of forty per diem under- 
stated the truth. 
The filthy condition of the cities of Panama and 
Colon, in the American Isthmus,may be imagined, 
but the reality is almost incredible. The city of 
Panama—modern Panama—was built in 1688 as 
a strongly-walled, massively-constructed city. 
To-day, speaking of it and its suburbs—now exten- 
sive—it is without water supply or drainage, 
properly so-called. Its water is derived from deep 
wells, built by the early Spaniards, the majority 
on the outskirts of the suburbs. Three of the 10 
largest wells, from which watermen purchase water 
to sell in the city, are at Cocoa Grove. The wells 
are within three hundred feet of a new cemetery, 
they are in a ravine many feet below its surface, 
while they drain a level fully sixty feet below the 
cemetery. The cemetery is, without exception, the 
most flourishing bonanza in the Isthmus. The 
owner of the wells, Senor Don Nicanor Obcarrio, 
has a special concession from the Government of 
the State of Panama to bury the dead. Whether 
they are buried in his cemetery or in the foreign 
Jewish or Chinese cemeteries he exacts his fee. 
Regarding the cemetery, at the edge of the wells, 
between July 15th, 1884 and April 12th, 1886, it 
had actually received 3,884 bodies for interment in 
the ground, apart from several hundreds buried in 
the bovedas or stone vaults. In the month of 
November, 1884, the Canal Company alone buried 
652 officers and men on the Isthmus, principally 
from yellow and malarial fevers, tropical dysentery, 
•See., &c. The Canal hospitals in Panama have 
had as many as seventeen deaths in a single day. 
Such is Panama, well and fitly named the Gate 
to the Pacific, by Captain Bedford Pim, R.N., in 
one of his interesting books. The Isthmus of 
Panama is a constant producer and distributer of 
yellow fever. The Mexican West Coast epidemic 
of 1883 and 1884 was traced to a yellow fever 
corpse landed by a steamer from Panama. 
That death has such a monopoly can easily be 
understood, when the drainage and water-supply, 
so-called, are considered. In both Panama and 
Colon over-crowding has obtained to an incred- 
ible extent, but in Colon the inhabitants have pure 
drinking water, and not cemetery drainage as in 
Panama. In Panama proper the natives throw all 11 
kinds of filth over the sea-walls ; as it is not washed 
away by the tides, there it remains, an insult to the 
eye, a foul, reeking, death-dealing mass. In the sub- 
urbs the inhabitants throw their excretae and filth 
into lanes and vacant lots, this, plus heat and mois- 
ture, generates poisons best left to the understand- 
ing of our confreres. God forbid that it should ever 
reach their nostrils. A few drains within and with- 
out the city are never flushed except by the rains. 
During the dry season, December to May, they 
are simply so many receptacles for excretae. The 
odors that pour forth from them are unbearable. 
It ceases to be a matter of wonder that, under 
such conditions, the Canal hospitals offered a rich 
field for clinical observation for Dr. Gererd and 
his Canal confreres, Drs. Meurrisse, Didier, Ver- 
nialandthe late George W. Nelson. 
Dr. Gererd’s special observations on yellow fever 
and its specific microbe extended over three years* 
He had an able staff of assistants, and the finest of 
appliances that science could suggest, and it was 
his singular good fortune to recognize and iso- 
late and cultivate the special microbe. Its propa- 
gation was brought about by Pasteur’s well-known 
methods and apparatus. 
With Dr. Gererd it was more than a mere mat- 
ter of scientific enquiry pushed to a successful 
issue—with him it was a matter of absolute faith, 
and he abundantly proved it by inoculating him 
self with culture-microbes, and finally resorted to a 
crucial test, in allowing himself to be bitten by 
mosquitoes, that had just fed on a yellow-fever 
patient. Dr. Finlay, of Havana, we believe, was 
the first yellow fever expert to point out the propa- 
gation of yellow fever by mosquitoes. Dr. Gererd’s 
experiments are a highly important contribution to 12 
tropical medicine. His three years of persistent 
labor were crowned with success, and he deserves 
all the praise that science and his Government 
(he is a Parisian) may accord him. 
Yellow fever is one of those fearful scourges in 
whose dread presence physicians feel powerless. 
So little is known of the cause producing it and 
the great variety of treatments are a silent but 
tacit admission that our tropical confreres hither- 
to have been working in darkness, some epide- 
mics killing 75 and 80 per centum,others 8 and io. 
The last great epidemic at New Orleans and vici- 
nity is credited with having swept away 30,000 
victims. 
Yellow fever on the Isthmus of Panama is nearly 
always fatal, that is true specific yellow fever. 
Of twenty-seven admissions to the Canal hospital, 
Panama, fora series of weeks but one recovered. 
The Dingier Expedition to Panama—fully en- 
dorses the above. M. Dingier, Chief of Works ot 
the Panama Canal, accompanied by his wife, and 
family, in all a party of thirty-three, including 
Canal engineers, arrived at Colon on the 29th of 
October, 1883 ; up to January, 1885, or in fourteen 
months, fourteen of the party had had yellow fever 
with but a single recovery, M. Dingier losing his 
whole family, wife, son and daughter. The re- 
coveries truly are the exceptions that prove the 
rule. The malignancy and intensity of the disease 
there destroys the blood. Intense malarial poison- 
ing is supposed to be an important factor, no 
doubt increased by the unsanitary conditions 
already described. 
Dr. Domingo Freire, if we remember rightly, was 
the first observer to recognize a microbe in yellow 
fever and to conduct experiments and publish the 13 
results. One of his first contributions on this sub- 
ject was translated from the Spanish by Dr. Wol- 
fred Nelson, and published in the Record some 
three years ago. Science in a recent issue refers 
to Dr. Domingo Freire’s excellent work at Rio de 
Janeiro, Brazil, and states that in 7,000 inocula- 
tions by him, only eight died of the disease, while 
3,000/inoculated persons living under the same 
"conditions were victims to the disease. 
Dr. Joseph Holt, the very able and inde- 
fatigable President of the New Orleans Board of 
Health, whose quarantine regulations are un- • 
doubtedly the best known, recently has used his 
influence to secure the passage in Congress of a 
Bill to enable an American Commission to visit the 
yellow fever centres and study the disease, and the 
methods of skilled men like Dr. Domingo Friere 
and Dr. L. Gererd. Should the Commission verify 
the experiments of the gentlemen named, pre- 
ventive medicines in the tropics will have entered 
on the grandest discovery of modern times, one 
that will protect millions of people. 
The Record has been promised a series of 
original papers on yellow fever, by physicians of 
recognized standing in Brazil, Mexico, and at 
Panama. They will appear as received, as well as 
a series to be written in Cuba, the hot-bed par 
excellence of the disease.