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Journal of Experimental Medicine

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ETIOLOGYVIII.

OF YELLOW

FEVER.

PRESENCE 0~" A LEPTOSPIRA IN WILD ANIMALS IN GUAYAQUIL
A N D ITS RELATION TO LEPTOSPIRA ICTEROH2EMORRIIAGIABA N D LEPTOSPIIZA ICTEEOIDES.
BY H I D E Y O NOGUCHI, M.D.

(From the Laboratories of The Rockefeller Institute for Medical Research.)(Received for publication, May 16, 1919.)

Leptospira icterohcemorrhagi¢ was demonstrated in the kidneys of wild rats
first by Ido and his associates in Japan, 1 then by Stokes, Ryle, and Tytler, 2
Courmont and Durand, 3 Martin and Pettit, 4 Renaux, 5 Coles, 6 Monti, ~ Grasso, 8
and Dalmau 9 in Europe; and by Noguchi 1° and Jobling and Eggstein u in North
America; by Nicolle and Lebailly 12 in Tunis, and by Lh6ritier 13 in Algeria. Thatthe leptospira found in wild rats is in all probability identical .with that which
produces infectious jaundice in man was the conclusion of Ido and his associates t
and later of the writer 1° from the reciprocal immunity reactions between thehuman and rat strains. Just how the rat strain enters the human body is still a
I Ido, Y., Hoki, R., Ito, H., and Wani, H., J. Exp. Med., 1917, xxvi, 341.
2 Stokes, A., Ryle, J. A., and Tytler, W. H., Lancet, 1917, i, 142.
Courmont, J., and Durand, P., Bull. et m~m. Soc. m~d. h3p. Paris, 1917,
xli, 115.
4 Martin, L., and Pettit, A., Compt. rend. Soc. biol., 1917, Ixxx, 10, 574; 1918,
lxxxi, 697.
Renaux, E., Compt. rend. Soc. biol., 1917, lxxx, 405.
s Coles, A. C., Lancet, 1918, i, 468.
Monti, A., Boll. Soc. med.-chir. Pavia, 1917, cited by Martin, L., and Pettit,
A., Spiroch~tose ict6roh~morrhagique, Monographies de l'Institute Pasteur,
Paris. 1919.
s Grasso, G., Pathologica, 1918, x, 8.
9 Dalmau, M., Treballs Soc. Barcelone, 1918, cited by Martin, L,. and Pettit,
A,. Spiroch~tose ict6roh~morrhagique, Monographies de l'Institute Pasteur, Paris,
1919.
10 Noguchi, H., J. Exp. Med., 1917, xxv, 755.
11 Jobling, J. W., and Eggstein, A. A., at. Am. Med. Assn., 1917, lxix, 1787.
12 Nicolle, C., and Lebailly, C., Compt. rend. Soc. biol,, 1918, lxxxi, 349.
13 Lh6ritier, A., Bull. Soc. path, exot., 1918, xi, 357.
95

96

ETIOLOGY OF Y E L L O W~PEVER.

VIII

matter of conjecture, based on circumstantial evidence. It is not yet entirely
clear how the leptospira happens to be carried by rats. It is probable that theinfection is an accidental one, occasioned by the direct transmission of the leptospira to man through exposure of some part of the body to the water of a cesspool or to moistened ground on which the urine of an infected rat has been deposited within a few hours previously. In a longer period the organisms would
be destroyed by other saprophytic bacteria. 14 The incidence of infection ismuch greater in countries where the body is exposed, especially the feet andhands, to ground or water infested by wild rats. The occupation of the people
also plays an important part in the frequency of infection. Once a rat becomes
infected it supplies the infective agent for an indefinite length of time, possibly
until its death. Transmission of the leptospira from rat to rat is accomplishedby infected food or drink and is particularly easy in view of their cannibalism.
T h e question of the presence of a leptospira in tropical countries,
especially where endemic foci of yellow fever exist, has not heretofore
been studied, b u t with the isolation of a pathogenic leptospira fromcertain cases of yellow fever in Guayaquil the relation between theh u m a n and animal strains demands a thorough investigation. A
general survey has therefore been made to detect the presence ofthe leptospira among the wild animals encountered in Guayaquil.
T h e mode of s t u d y consisted in inoculating intraperitoneally 1 to 2
cc. of a Ringer solution emulsion of both kidneys of two animals
into three guinea pigs. T h e emulsions were prepared, in the proportion of 1 gm. of the k i d n e y to 10 cc. of Ringer solution, b y finely
grinding up the kidneys in a m o r t a r with sterile sand. Rats, mice,bats, and an opossum were examined for the presence of the leptospira. These animals are a b u n d a n t in and about the houses andbuildings in Guayaquil, and t h e y were caught and sent in alive b y
the B o a r d of I-Iealth 15 of the city. Table I shows the results of theinvestigation.
T h e experiments show t h a t eight out of twelve groups of rats
carried in their kidneys a leptospira capable of producing in guinea
pigs pathological changes similar to those produced b y Leptospira
icteoh¢emorrrhagice. Only two groups of rats were absolutely free
14Noguchi, H., J. Exp. Med.; 1918, xxvii, 593.
151 am greatly indebted to Dr. Le6n Becerra of the Board of Health, for hiscooperation in the course of the work which was carried on in Guayaquil. For
some specimens of bats I am also indebted to Dr. Gonzales-Rubio, Jr.

97

HIDE¥O NOGUCHITABLE I.
Experiments with Rats.

Groups of rats.

Results.

Remarks,

1 (doubtful).

Temperature 40.2°C. on 5th day.
Survived.
Temperature 39.8°C. on 5th day.
Survived.
Apparently no reaction.

Perhaps an abortive
infection.

2 (positive).

Temperature 40.4°C. on 6th day.
Epistaxis and icterus on 7th day.
Killed. Lungs and stomach hemorrhagic. Liver icteric and enlarged. Acute parenchymatous
nephritis. Other organs unchanged.
No leptospira found by dark-field
examination.
Apparently no febrile reaction. Animal became icteric with temperature of 36.2°C. on 8th day.
Killed. Findings typical; difficult to find leptospira in blood ororgans.
Died over night.

3~

Only slight temperature rise, but
typically jaundiced on 8th day
and was killed. Typical changesof the organs. Leptospira difficult to find.
Died in 9 days without typicalchanges.
Died over night.

4"

Became jaundiced on 5th day.
Died in 9 days. Typical findings.
Leptospira not demonstrated.
Temperature 40.2 ° on 10th day;
40°C. on l l t h day, but animal
never came down with typicalsymptoms.
Temperature 40.5°C. on 8th day and37.4 ° on 10th day, with extreme
jaundice. Typical findings withleptospira in the tissues.

Negative.
Transfer to Guinea
Pig 377 A (blood 2
cc.).
Temperature
40°C. on 5th day.
Killed " 8th "Typical, but no leptospira found by
dark-field examinatl~on.
In a later passage theleptospira was demonstrated.

98

ETIOLOGY OF YELLOW FEVER.

VIII

TABLE I--Continued.
Groups of rats.

Guineaig No.

Results.

5 (negative).

383

D i e d of intercurrent infection in
10 days.
No reaction.
Temporary rise in temperature forseveral days. Survived.

384
385

"

386
Died in 2 days. Negative.
386 A Temperature 40.3°C. on 7th day,but with ultimate recovery.
387
No reaction.

7' (doubtful).

388
Nothing typical.
388 A Temperature 40.2°C. on 4th day,but recovered.
389
Died in 14 hours. Negative.

6

8 (positive).

390

Temperature 40.2 ° on 5th day,
38.6°C. on 7th, with marked jaundice. Killed. Typical findingsin the organs; leptospira not demonstrated by dark-field examination.

390 A Highest temperature 39°C. on 5thday. Died in 9 days. Typicallesions.
391
Slight febrile reaction. Recovered.
9

~C

392

Highest temperature 39.4°C. on 5thday. Died on 7th day with typical lesions.
392 A Highest temperature 39.6°C. on 8thday. Died on 10th day with ictems and hemorrhages.
393
Temperature 40.1°C. on 6th day,
39.9 ° on 7th day. Transient icterus on 10th day. Recovered.

Remarks.

Perhaps an abortiv,
infection.

Transfer to two guine~
pigs (blood 2 cc.)
Both became typically yellow amwere killed on 10tl
day. Typical findings, with leptospir~in liver, but nora
in kidney or bloodof one animal; sec
ond animal showe(
no leptospira.

HIDEYO NOGUCItI99

TABLE I - - C o n c l u d e d .
Groupsof rats.

! Guinea
pigNo.

10 (positive).

394

Results.

No high fever. Icterus in 8 days.
Killed in 11 days. Lesions typical. Leptospira difficult to find.
394 A Temperature 39.4°C. on 5th day.
Icterus following day. Killed on
8th day. Typical lesions at autopsy. Leptospira found.
Remained well.
395

11

"

396

12

"

398
399
400

Remarks.

Transfer to two guinea
pigs. Both died indays with typical le.
sions and jaundice.

Temperature' 39.7°C. on 4th, 40° Transfer to two guinea
on 5th, 36.6° on 7th day. Intensepigs (blood 2 cc
ly jaundiced. Killed in 6 days.
each). One died inand the other in c
Typical changes. Leptospira difficult to find.
days--both intensely jaundiced. Typi
cal lesions. Melemand black vomit ir
latter.
396 A Had very little fever, but died withjaundice in 9 days. Autopsy
typical.
397
Temperature 39.6--39.8°C. on 6th, This animal was con
7th, and 8th days. Suspicion ofvalescing after a mik
icterus. Killed for examination in
infection.
15 days. Lungs showed old hemorrhagic areas; other organs notchanged.
Remained well.
""

Died in 13 days, with typical jaundice and lesions.

from the organism, while two others showed a suspicious reaction
w i t h o u t t e r m i n a t i n g in f a t a l i n f e c t i o n . I n o t h e r w o r d s , a b o u t 67 p e r
c e n t of t h e r a t s s t u d i e d h a r b o r e d t h e l e p t o s p i r a in t h e i r k i d n e y s .
I n t e s t i n g m i c e for t h e s a m e o r g a n i s m i t w a s f o u n d t h a t o u t of
t h r e e g r o u p s of s e v e n m i c e each, o n e p r o d u c e d e x t r e m e j a u n d i c e a n d"the o t h e r t y p i c a l c h a n g e s i n t w o o u t of t h r e e g u i n e a pigs, o n e d y i n g
i n 8 a n d t h e o t h e r in 9 d a y s a f t e r t h e i n o c u l a t i o n of t h e k i d n e y e m u l sion. T h e r e w a s h e m o r r h a g e b e f o r e d e a t h f r o m t h e r e c t u m in o n e

I00

ETIOLOGY

OF Y E L L O W~EVER.

VIII

and from the nose in the other. The leptospira was difficult to findin the blood, liver, and kidney, but was found in subsequent passages.
No positive results were obtained with the kidney emulsions ofeight bats and one opossum. It may be noted that Nicolle andLebailly 12 obtained negative results with bats caught in Tunis.
The experiments show that the emulsions which produced a fatal
infection in guinea pigs did not always kill all the guinea pigs inoculated with the same quantities of the same material and under thesame conditions. Some died, while others had a mild abortive infection or escaped infection altogether. This seems to indicate that
there exists among individual guinea pigs a considerable variationin their susceptibility to the same strain of the organism and explains
why it is important to use as many guinea pigs as convenient for the
purpose of transmitting the organism to this animal. There is a
close analogy with the frequent abortive infections which were obtained in the attempts to transmit Leptospira icteroides to guinea
pigs.
The relation between the rodent strains and the strains of Leptospira icteroides on the one hand and those of Leptospira icteroh¢morrhagix on the other was next studied from the standpoint of pathogenicity and immunity. For this purpose two strains of leptospiraisolated from rats and one from mice were used. The three strains,designated Groups 8, i 1, and 30, have morphological features identicalwith those of the strains isolated from wild rats caught in the vicinityof New York, 1° and are consequently indistinguishable from theicterohemorrhagic strains derived from the Japanese and European
sources. They are slightly coarser than the strains of Leptospiraicteroides.
With regard to the pathogenicity of the Guayaquil rat leptospira,it is difficult to point out any essential difference between the symptoms and lesions that occur in guinea pigs infected with it and thosein animals inoculated with the icterohemorrhagic strains of temperate
climates. They all produce jaundice and hemorrhages, althoughwith some strains hemorrhage is the outstanding feature.

mDEYO NOGUCm

101

Identification of the Organism by Means of Immunity Reactions.
In order to determine whether the leptospira isolated from wildrodents in Guayaquil is identical with the strains of Leptospiraiaerohcemorrhagia~ from other sources, and what relation it may haveto Leptospira icteroides from yellow fever patients in the same city,
their immunity reactions were taken into consideration in a seriesof experiments.
Immune Sera.--Two rabbits were immunized with each of thethree strains of Guayaquil rodent leptospira by injecting intravenously 2 to 4 cc. of rich living cultures of the organisms several
times at 7 to 12 day intervals. The animals were bled on the 9th
day after the last injection and the effects of their sera tested not
only upon the same and other strains of Guayaquil origin, but also
upon the Japanese, European, and New York strains of Leptospiraicterohcemorrhagia~. The relation of this group of organisms to thatof Leptosp#a icteroides was likewise studied and will be discussed at
greater length in connection with the relation between yellow fever
and infectious jaundice.
The first experiments were designed for observation of the actionof each of these sera upon the organism in vitro. To 0.5 cc. of arich suspension of culture in saline solution was added 0.2 cc. of theimmune serum with or without the simultaneous addition of 0.2 cc.
of fresh normal guinea pig serum as complement. The mixture
was placed in a water bath at 37°C. for 2 hours and then examined
under the dark-field microscope. The entire procedure was carriedout with strict aseptic precautions, and each experiment was accompanied b y a control with normal rabbit serum. The tubes were
kept at room temperature for 96 hours and their contents examinedagain. Except for a greater amount of precipitation in some tubes
the results were about the same as those observed at the end of 2hours at 37°C. The control tubes with normal rabbit serum showednumerous active organisms after 4 days.
Pfeiffer's phenomenon was also studied by the usual procedure;that is, examination of the peritoneal fluid of guinea pigs after inoculation with a given serum and the strain in question. In this instance
0.5 cc. of rich culture was mixed with 1 cc. of the immune serum and102

ETIOLOGY O F YELLOW FEVER.

VIII

injected intraperitoneally, examination being m.ade after 30 minutes
and 2 hours.
As another means of identification the protective p r o p e r t y of eachi m m u n e serum (1 cc.) was tested on guinea pigs against approximately
10 m i n i m u m lethal doses of the different strains. U n f o r t u n a t e l y
TABLE II.
Immunological Relation of the Guayaquil Rat Leptospira to Leptospiraicterohcemorrhagice.

Immune Serum 906, produced with Group 8 strain, injected on Jan. 15, 22,
Feb. 3, 15, 1919.
Culturestested.
Group 8
"

11

"

30

Effectsin d t r o .

Pfeiffer Protectivepropertyagainstinphenomenon,
tectionin guineapigs.

Marked precipitation, ag- Positive.
glutination, and disintegration.
Effects similar to the foregoing but less in degree.
Marked agglutination andlater disintegration.

Similar to the foregoing
but less marked.
American No. 1 Rather marked agglutination.
"" 3 Effects similar to the foregoing.
French.

1 cc. protected guinea pigs
against about 10 minimum lethal doses.

Japanese.

Could not be tested becauseof loss of virulence.
1 cc. protected guinea pigs
against about 10 minimum lethal doses.

the virulence of the American and British strains of L e p t o s p i r a icteroh¢emorrhagice was considerably a t t e n u a t e d during m y absence of 6months and could n o t be tested with reliable results. This, however, was not a serious obstacle to determining the affinity of thesestrains for t h e Guayaquil strains, because an i m m u n e serum produced in rabbits with the avirulent American strain was t e s t e dagainst the pathogenic Guayaquil strains. A brief s u m m a r y of theforegoing experiments is given in Tables I I to VI.

TABLE HI.

Immunological Relation of tke Guayaquil Rat Leptospira to Leptospiraicler o~ m o r r ka gia~.
I m m u n e Serum 914, produced with Group 11 strain, injected on Dec. 30,
1918, Jan. 6, 14, 21, I919.
Cultures tested.

Effects ~ ~itro.

Pfeitfe~"phenomenon,

P r o t e c t i v e p r o p e r t y a g a i n s t infection in g u i n e a pigs.

Group 8Moderate agglutination
but no degeneration.

Positive.

1 cc. protected guinea pigs
against about 10 minimum lethal doses.

"

Marked precipitation andagglutination; later degeneration.
Effects similar to the foregoing but less marked.

11"30Japanese.
American No. 1

a¢

at

3

ta

cc

at

tt

tt

,,

,t

Could not be tested because of loss' of virulence.
~t

Marked agglutination anddegeneration.
,cFrench.

~t

t¢

tt

1 cc. protected guinea pigs
against about I0 minimum lethal doses.
TABLE IV.

Immunological Relation of the Guayaquil Rat Leptospira to Leptospiraider oIu~raorrka gi~e.
I m m u n e Serum 904, produced with Group 30 strain, injected on Dec. 30
1918, Jan. 6, 14, 22, Feb. 3, 15, 1919.
Effects in vitro.

Cultures tested.

Marked agglutination andsubsequent disintegration.
Slight agglutination, but
no degeneration.
Marked precipitation, aggintination, lysis, anddegeneration.

Group 8

"

11

,,

30

Japanese.
American No. I

,t

~t

3

t¢

t~

tt

tc

Pieiffer
phenomenon.

P r o t e c t i v e p r o p e r t y a g a i n s t infection in g m o e a pigs,

Positive.

1 cc. protected guinea pigs
against about I0 minimum lethal doses.
gt

t¢

,t

tt

Could not be tested on account of loss of virulence.

Slight agglutination; no
degeneration.

British.
103

tt

,t

104

ETIOLOGY

OF Y E L L O W]?EVER.

Vlll

TABLE V.

Immunological Relation of the Guayaquil Rat Leptospira to Leptospiraicterohcemorrhagice.
Immune Serum 952, produced with American Strain 1, injected on Dec. 30,
1918, Jan. 6, 14, 22, Feb. 3, 15, 1919.
Cultures tested.

Effects in vitro.

Pfeiffer
phenomenon,

Protective property against infection in guinea pigs.

Group 8Moderate agglutination;slight degeneration.

Positive.

"

11

"

30

Very marked agglutination and degeneration.
Slight agglutination anddegeneration.

1 cc. protected guinea pigs
against about 10 minimum lethal doses.
Not tested.
1 cc. protected guinea pigs
against about 10 minimum lethal doses.
Not tested.

Moderate agglutinationand degeneration.
American No. 1 Marked agglutination anddegeneration.
Slight agglutination andBritish.
degeneration.
Japanese.

TABLE VI.

Immunological Relation of the Guayaquil Rat Leptospira to Leptospiraicterohcemorrhagi,6e.
Immune Serum 911, produced with the Japanese strain, injected on Dec. 30,
1918, Jan. 6, 12, 22, Feb. 3, 15, 1919.
Cultures tested.

Group 8

Effects in dire.

Pfeiffer
phenomenon,

Protective property against infection in guinea pigs,

Moderate agglutinationand degeneration.

Positive.

1 cc. protected guinea pigs
against about 10 minimum lethal doses.

Slight agglutination; no
degeneration.
Marked agglutination and" 30
disintegration.
Very marked agglutinaJapanese.
tion and lysis.
American No. 1 Moderate agglutinationand degeneration.

"

II

British.

Slight agglutination anddegeneration.
,

Lg

Could not be tested because of loss of virulence.

HIDEYO

105

NOGUCHIThe tables show that while there exist undeniable variations in
the intensity of the immunity reactions as manifested in vitro in theform of agglutination and subsequent disintegration of the organism,
as well as in vivo in Pfeiffer's phenomenon and protection against
infection with one or the other strains, the variations are neverthelessof so slight a nature as to lead one to assume that the strains isolated
TABLE VII.

Immunological Relation of the Guayaquil Rat Leptospira to Leptospira icteroides.
I m m u n e Serum 906, produced with Group 8 strain, injected on Jan. 15, 22,
Feb. 3, 15, 1919.
Leptospira
ict*roides

Effects"i n v i t r o .

strain,A.A.
E. Ch.
A. Ce.

Slight agglutination; no degeneration.
No effect.
""Pfeiffer
phenomenon,

Protective property
againstinfectionin
guineapigs.

Negative.

No protection.

"

"

"

"

"

"

TABLE VIII.

Immunological Relation of the Guayaquil Rat Leptospira to Leptospira icteroides.
I m m u n e Serum 914, prepa,red with Group 11 strain, injected on Dec. 30,
1918, Jan. 6, 14, 21, 1919.

L~p~o~r~jiaero~desEffectsi n v i t r o .

strain.

A°A.

E. Ch.
A. Ce.
M.G.

No effect.

Pfeiffer
phenomenon.

Protective property
against infection inguinea pigs.

Negative.

No protection.

cg

Definite agglutination, but no immobilization.

Doubtful.

cg~c

1 cc. did not prevent the infection, but the animal survived.

from rats and mice in Guayaquil belong to the group of Leptospiraicteroh(emorrha, gi6e now known to be widely distributed among theserodents inhabiting the temperate zone.
The results of a parallel series of experiments performed with the
immune sera on different strains of Leptospira icteroides are given
in Tables VII to IX.

106

ETIOLOGY OF YELLOW FEVER.

VIII

Prophylactic Inoculation.--February 6, 1919. A number of guinea
pigs were inoculated subcutaneously with 0.5 and 2 cc. of killedculture (heated to 60°C. for 10 minutes in the waetr bath) of the
Guayaquil rat strains of leptospira, Groups 8, 11, and 30. These
animals were inoculated after 15 days (February 21) with virulent
cultures of the same and of other strains. At the same time some ofthe vaccinated guinea pigs were inoculated also with the icterohemorrhagic strains, including the American No. 1)6 the Japanese, and the
TABLE IX.
I m m u n o l o g i c a l R e l a t i o n o f the G u a y a q u i l M o u s e L e p t o s p i r a to L e p t o s p i r a icteroides.

I m m u n e Serum 904, produced w i t h G r o u p 30 strain, i n j e c t e d on Dec. 20,
1918, Jan. 6, 14, 22, Feb. 3, 15, 1919.
Leptospiraicteroide4

Effects in vitro.

Pfeiffer
phenomenon,

E. Ch.
A. Ce.
M.G.

Slight agglutination without immobilization.
No effect.
""

Doubtful.
Negative.
"

A.A.

"

strain,""Protective property
against infectionin
guinea pigs.
No protection.
"

"

"

"

"

"

French. The guinea pigs previously inoculated with the killed cultures of the Guayaquil strains proved resistant to a subsequent infection, not only with homologous but also with the heterologous
strains derived from Japanese, European, and American sources.
This experiment indicates that the Guayaquil rodent strains of leptospira are identical with Leptospira icterohcemorrhagice.
SUMMARY.

By the inoculation of guinea pigs intraperitoneally with the emulsions of kidneys from wild rats and mice captured in Guayaquil, it
was found that 67 per cent of the wild rats tested harbored in theirkidneys a leptospira which produced in guinea pigs symptoms andlesions identical with those produced by Leptospira icteroh6emorrhagice
derived either from patients suffering from infectious jaundice inJapan or Europe, or from wild rats caught in New York.
16 This strain was so a t t e n u a t e d t h a t some of the guinea pigs escaped a f a t a l
infection a n d could n o t be used in further experiments.

HIDEYO NOGUCHI107

Immune sera were prepared in rabbits by injecting different strainsof the Guayaquil leptospira. These sera had a marked agglutinating
and disintegrating influence upon the homologous strains, and also,
but often to a less pronounced degree, upon the strains of Leptospiraicterohcemorrhagice from other sources. Pfeiffer's phenomenon was
also found to be positive, and protection was demonstrated against
infection with virulent cultures of strains of Leptospira icterohcemor-

rhagiae.
The same sera had no effect, or at most a very slight one, upon

Leptospira icteroides. Guinea pigs inoculated with icteroides strains
were not noticeably protected by the use of the immune sera prepared with the Guayaquil rat strains.
Guinea pigs inoculated with killed cultures of the Guayaquil strainsof leptospira proved to be resistant to a subsequent infection withheterologous as well as homologous strains of Leptospira icterohcemor-

rhagice.
It is concluded, therefore, that the leptospira isolated from thekidneys of wild rats and mice in Guayaquil belongs to the group of
Leptospira icterohcemorrhagi¢e, and differs from Leptospira icteroides
in its immunity reactions.
No positive transmission was obtained with kidney material frombats and an opossum.