VACCINATION WITH VIRUS q/D IN THE CONTROL OF
    JUNGLE YELLOW FEVER IN BRAZIL

b) Fred L. Soper and H. H. Smith, International Health
Division of the Rockefeller Foundation, Rio de Janeiro  33

Reprinted from the Transactions of the Third International Congress
of Tropical Medicine and Malaria, 1938, Vol. I, pp. 295-313

PRINTED IN HOLLAND BY C. A. SPIN & ZOON N.V.


VACCINATION WITH VIRUS 17D IN THE CONTROL OF
     JUNGLE YELLOW FEVER IN BRAZIL1
by Fred L. Soper and H. H. Smith, International Health
  Division of the Rockefeller Foundation, Rio de Janeiro

Vaccination in Jungle Yellow Fever

The first attempt to protect an exposed population against
jungle yellow fever by vaccination was made in Parani, Brazil, early
in r 9 36 (I), using hyperimmune goat and monkey sera and a virus
nlodjfied by culture in mouse embryo tissue (I 7E) (2). The difficulties
encountered were such as to cause the discontinuation of this method
in the field, and during the yellow fever season (January to May)
of 1937, no attempt was made to protect exposed populations.

Work with another modified virus (I 7D) developed in the
laboratories of the International Health Division of The Rockefeller
Foundation in New York, began in Brazil in February, I 93 7 (3).
By June, these studies had progressed far enough to justify field
vaccination, and the county of Varginha, Minas Geraes, in a region
where jungle yellow fever had been found a few weeks previously,
was chosen for the first field application of the new vaccine virus.
During the next three months, 2,746 persons were vaccinated in
the field, with satisfactory results, and, in September, routine field
vaccination began, which increased the total field vaccinations for
the year 1937 to 36,104.

The 193 8 yellow fever season in South Brazil began early in
January, with an outbreak of jungle yellow fever at Presidente
Wenceslau, S3o Paul0 (4), and shortly thereafter the disease was
found at Mathias Barboza, Minas Geraes. Vaccination units were
moved into both these districts, and an attempt was made throughout
the following months to vaccinate threatened populations wherever
yellow fever was found. The I y 3 8 yellow fever season was an active
one, with outbreaks in some of the richest and most heavily populated
agricultural districts of Brazil, in the states of Minas Geraes, Rio de
Janeiro, SZo Paulo and Santa Catharina. The need for vaccine greatly
exceeded the initial production capacity of the laboratory and the

1 This report is based on work of many colleagues of the Cooperative Yellow Fever
Service, iointlv maintained bv the Ministrv of Education and Health of Brazil
and tde `Inte&ational Health' Division of' The Rockefeller Foundation. Special
credit for the rapid expansion of vaccination in 1938 must go to the Brazilian
Government, which furnished the necessary additional funds.

295


FRED L. SOPER AND H. H. SMITH

ability of the field service to apply it. The Brazilian Government
opened a special credit of 2,000 cantos, or approximately $ 100,000
UScy., to cover the cost of a program for the vaccination of at least
one million persons during the year I 93 8.

From January first to July 3 ~st, a total of x57,86 I persons were
vaccinated, and the final figures for the year will almost certainly
exceed the preliminary estimate of one million.

Table I gives the number of persons vaccinated per month in
Brazil, from September, I 937, to July, I 93 8, by states. Table II
gives the distribution of the same persons by population groups.

Origin of Vaccine Virus 17D

In December, 1933, Lloyd transferred the Asibi strain to tissue
culture containing mouse embryo tissue and monkey serum ; after
I 8 subcultures, a second transfer was made to a medium containing
whole chick embryo tissue, from which, after 56 passages, it was
transplanted to tissue culture containing chick embryo, from which
the central nervous system had been removed. After 39 passages in
this medium, without central nervous system tissue, this strain of
virus, now known as I'D, was tested and found to have lost much
of its viscera- and neurotropism, while still retaining the property
of stimulating the production of antibodies (5). Virus I'D was first
used for human inoculation on November 30, I 936, in New York
(6), with material transferred 227 times in tissue culture since its
last previous passage in an animal host. Subcultures used as source
of vaccine in Brazil have ranged from the 205th to the 3 I 7th.

      Results Obtained with Virus 17D
  The points on which a method of vaccination for general use
as a public health measure should be judged, may be grouped under
the following headings :
    a.  Ease of manufacture of standard product.
b. Ease of application under field conditions.
    C.  Safety and comfort of persons vaccinated.
d. Safety of persons not vaccinated.
e. Antibody production.

      A.  Ease of Manufacture of the Standard Product
  The titer of virus in tissue culture material is much below that
obtained by grokth in the' developing chick embryo. The vaccine

296


VACCINATION WITH VIRUS r7D IN JUNGLE YELLOW FEVER

virus is maintained in tissue culture free of central nervous system
tissues, to avoid any possible reversion to type, but for the preparation
of iaccine, tissue culture is inoculated in the allantoic sac of the
sir-day old chick embryo. After further incubation for four days,
,u a temperature of 37' C., the embryo is removed, triturated, and
suspended (I o %) in inactivated human serum diluted with equal
anlounts of distilled water. The filtrate of this suspension, which is
the vaccine material, is distributed in ampoules, frozen, dried in
v;Icuum, sealed and stored at about 2' C. In addition to the usual bac-
teriological controls for sterility, each lot of vaccine is titrated for
virus content by intracerebral inoculation in serial dilutions in
white mice, and is inoculated intracerebrally into a rhesus monkey,
to test for possible increase in either viscera- or neurotropism.

Altough laboratory studies indicate (3) that a much smaller
dose may be sufficient, between 350 and 800 MLD 1 for mice are
now being allowed for each person vaccinated in Brazil. On this
basis the Rio de Janeiro Laboratory `is producing some I 20,000 doses
of vaccine per month, at a total cost, including overhead, excepting
rent, of less than $ 3,odo UScy., or 2;: cents UScy., per dose.

  B. Ease of Application under Field Conditions
Virus I 7D, even when dried and sealed, is susceptible to

ordinary temperatures and to direct sunlight ; the vaccine leaves
the Rio laboratory, packed with ice and salt, in wide-mouthed
thermos flasks, and is thus kept chilled until the moment of rehy-
dration. Even after rehydration with distilled water the ampoule
is kept on ice, and the vaccine is finally diluted in physiological
saline solution in the syringe itself immediately preceding inoculation.
To determine the viability of the virus used, mice are inoculated
intracerebrally with the remaining vaccine after the last person has
been inoculated.

Experience shows that a vaccination unit, consisting of three
persons, a doctor, a technical assistant and a secretary-chauffeur, can,
under optimum conditions, register and inoculate from I ,000 to
2,000 persons a day a. The actual cost of applying vaccine in Brazil

I The end point of titration in mice is considered as that dilution which, when
injected in 0.03 C.C. amounts intracerebrally in mice, will produce a mortality.
of lo% (7).

s The use of three Forsbeck needle-racks by each unit is advisable, to avoid unne-
cessary delays in waiting for needles to cool after boiling. It is believed that certain
irregular results of postvaccination protection tests are due to failure to cool needles
after boiling, with consequent inactivation of the vaccine virus.

297


FRED L. SOPER AND H. H. SMITH

in I 9 3 8 has not exceeded, including initial cost of automobiles and
equipment, 7 cents UScy., per capita. The actual field operating
expense has dropped from 5% cents UScy., per capita, in January, to
3 cents UScy., in June. However, the per capita cost of application
must increase rapidly in sparsely populated regions and in areas
where transportation is difficult.

    C. Safey and Comfort of Persons Vaccinated
Since the beginning of work with virus I'D in February,
I 93 7, a conscientious search has been made among vaccinated
groups for evidence of:

I. Severe reaction at site of inoculation ;
2. Sensitization to foreign protein ;
3. Serum sickness ;
4. Virus reaction, visceral and neural ;
5. Delayed jaundice, and

  6. Infection with other viruses.     .
  Special attention should be called to the distribution of vacci-
nated persons by population groups (Table II). `Employees of the
Yellow Fever Service, of the airlines, the population of large coffee
fazendas, inmates of schools, laborers and highway construction
gangs and members of military units, all form very useful groups for
observation. Even where it has not been possible for physicians of
the Yellow Fever Service to make personal observation, fazenda
owners, military medical officers, school directors and other respon-
sible persons have given information as to the severity of postvacci-
nation reactions.

The sum total of observations on vaccinated groups may be
stated briefly as follows :

For the eighteen months' period, during which almost 600,ooo
persons were vaccinated, there is no evidence of severe reaction
at the site of inoculation, of sensitization to foreign protein 1, of
serum sickness, of delayed jaundice (8), (y), nor of infection with
other viruses.

The type of relatively mild reaction which is observed seems
to be a general, not neural, reaction to the virus itself, after an
       -

l A number of cases have received second and third inoculations of r7D, without
any evidence of sensitization to chick protein.

298


VACCINATION WITH VIRUS I'D IN JUNGLE YELLOW FEVER

incubation period of generally from five to eight days. 1
The symptoms most frequently noted are : headache, backache,
body pains, weakness and malaise, lasting from a few hours to a
couple of days. The reaction to virus I'D is not severe enough to
have any influence against its general acceptance by the people.
Fazenda owners, and others responsible for large groups, generally
report from 5 to 8 y0 of reactions, with not more than I to 2 yO of
reactions severe enough to cause loss of time from work. A person-
to-person canvas, however, will result in 20, 40 or even 50% of
individuals questioned reporting at least a slight headache, but the
number of severe reactions does not increase correspondingly. The
most severe reactions reported are those related to each other by
members of the foreign colony in the capital city of Rio de Janeiro !
Considering the number vaccinated, it seems truly remarkable
that many more conditions occurring after vaccination have not been
credited to the inoculation. Experience has failed to reveal any
contraindications to the use of virus I 7D, early restrictions have been
entirely removed, and children of all ages and women in all stages
of pregnancy are routinely inoculated.

      D. Safe9 of Persons Not Vaccinated
In using a living virus for vaccination, the possibility of such
living virus being picked up from the blood stream by some insect
vector, and sooner or later reverting to its original virulence, must
be considered. Such return to virulence of a yellow fever vaccine
would have to depend upon the following factors :
    I. Circulation of virus in the blood stream in quantities sufficient
   to infect the insect vector ;

2. Ability of the infected vector to transmit the vaccine virus,
and

3. Ability of the vaccine virus to revert to a virulent state.
Experimental work indicates that sufficient virus does not
circulate to infect the traditional vector, AZdes aegypii, and that even
when this mosquito has been infected by special methods it does

1 So far, only one case has been reported, in which symptoms of involvement of the
central nervous system were attributed by the attending physicians to inoculation
with virus 17D. Case E. R. C., observed by Drs. Raul Azevedo and Deolindo
Couto, Rio de Janeiro, to whom we owe thanks for details of this case, developed
signs of meningeal involvement one month after vaccination with Lot 136 of
virus r7D, the estimated virus used beiig zao MLD for mice. Complete recovery
occurred, and studies are now in progress to determine, if possible, the nature of
the infection..

299


FRED L. SOPER AND H. H. SMITH

not readily transmit the r7D virus, even after prolonged incubation
(IO). Attempts to infect AZdes aesypti by postvaccination feeding on
humans and on rhesus monkeys, which have been shown to circulate
more virus than do humans, were failures, no virus being demon-
strated in the mosquito by either feeding'on monkeys or inoculation
into mice. The immersion of AZdes aegypti larvae in high concentration
of virus did result in the production of infected mosquitoes, as
demonstrated by mouse inoculation ; such infected aegypt' failed
completely to transmit virus to susceptible animals, even after
prolonged incubation periods.

The difficulty of getting virus I'D to circulate in appreciable
quantities with regularity, has, so far, prevented conclusive experi-
ments with the jungle vectors of yellow fever, only a few of which
have very recently been definitely incriminated (I I). The same
difficulty has prevented the carrying out of a large series of animal
passages, to determine the ability of virus I 7D to revert to its
original type ; the relative stability of the virus in tissue culture,
embryo passage and in mouse brain passage, suggests that such
reversion to virulence, if it did occur at all, would be slow in appear-
ing. This opinion is strengthened by the results of other workers,
who have not been able to transmit a tissue culture virus with A&les
aegypti' (I 2), nor to reconvert it to virulence by direct liver-to-liver
passage (I 3).

E. Anti body Production

The rhesus monkey, which is more highly susceptible to yellow
fever than is man, becomes fully resistant to virulent strains, such
as Asibi, following inoculation with virus I'D. Similar tests on
humans have not been made, but the wide use of virus 17D this
year, among exposed populations, during active outbreaks of jungle
yellow fever, has resulted in a mass of field observation almost as
conclusive as laboratory experiments. Local physicians and other
observers report a sudden reduction in observed cases in infected
districts shortly after mass vaccination, and cite instances in which
individuals, who failed to be inoculated, later contracted the disease
in infected forests, while vaccinated members of the same labor
gangs escaped. Field experience suggests that the protective effect
of vaccination begins not later than a week after inoculation, although
laboratory tests fail to show demonstrable antibodies at this time (3).
While it is probable that a much larger number of cases of yellow


VACCINATION WITH VIRUS r7D IN JUNGLE YELLOW FEVER

fever must have occurred among persons infected before vaccination,
only eight of these have been reported, four in Minas Geraes, three
in Santa Catharina and one in SZo Paulo. Onset in two was on the
same day as vaccination, in the other four, between the first and
fourth days following. Two of the three fatal cases in this group were
confirmed by viscerotomy, and a virus, quite different from the
vaccine virus, was isolated from one of the non-fatal cases.
Two additional cases of postvaccinationyellow fever have been

found, one mild case with onset thirty days, and one fatal case with
onset six weeks after vaccination. These cases had received virus
from lots 95 and I I 7, both of which gave irregular results, as measured
by the protection test (Table IV). It is possible that neither received
active virus.

The mouse protection test (14) has been used since I 93 I,
for determining the presence of yellow fever antibodies in the blood
serum of persons and animals. It is customary to inoculate six mice
with highly neurotropic virus and with the serum to be tested.
Results are read as a fraction showing the proportion of mice living
on the fourth day (d enominator), which survive to the tenth day
(numerator) after inoculation.

  Seven readings are possible, of which only two, 6/6 and 516,
are, in analyzing critical immunity surveys, considered definite
evidence of previous infection with yellow fever ; 4/6 and 3/6
results are considered inconclusive, and 216, 116 and o/6 as negatives.
It has been noted in immunity surveys that bloods from regions
where yellow fever has never been present give remarkably clearcut
negative readings, whereas bloods from endemic regions give an
appreciable number of inconclusives, as well as positives and nega-
tives. The majority of these inconclusives are probably from indivi-
duals who have at some time been exposed to yellow fever infection,
and are, almost certainly, not apt to ever again develop clinical
yellow fever. It seems'reasonable at the present time to read mouse
protection test results as indicating full protection, partial protection
and no protection, without attempting to interpret too rigidly these
readings in terms of reaction to yellow fever infection, further than
to assume that those showing full protection are, at the moment
tested, adequately protected against fully virulent virus. Postvacci-
nation results, when compared with prevaccination results (Table III),
suggest that virus I'D does produce some measurable antibody
formation in almost IOO y0 of persons receiving 50 MLD or more


FRED L. SOPER AND H. H. SMITH

of living virus. It has been noted that in many postvaccination pro-
tection tests, in which the final reading is : 216, 116, or even o/6,
the average length of survival of inoculated animals is from one to
two days longer than for similar negative tests in vaccinated groups.
This suggests that sufficient antibody is present to definitely delay
the action of virus inoculated in animals.

Table III gives the results of pre- and postvaccination tests on
the same individuals, including both laboratory and field groups 1,
during the preliminary phase of observation, before routine field
vaccination began. Attention must be called to the fact that on one
occasion, the virus was apparently inactive before inoculation began,
since all of the persons tested failed to give evidence of antibody
development, and the inoculation of the remaining vaccine into mice
failed to cause any deaths.

Table IV covers a special investigation to determine the results
obtained with different dosages of virus, and to evaluate the viability
test as an indication of efficiency of the preceding vaccination. The
groups bled for this special study were selected as probably represen-
tative of the poorest work of the season, and included groups receiving
the lowest doses of virus used during the height of the yellow fever
outbreak, working with newly trained personnel, far from head-
quarters. The results indicate that doses as low as so, 85 and IOO
MLD per person are adequate to give satisfactory results. They also
indicate that the viability test, in and of itself, is not a safe indication
of the efficiency of the vaccination. For example, lot I I 7 of virus
I'D was used and tested in five groups, of which only one gave
satisfactory results, the viability tests for which, o/s, 115 and 1/4,
were poor. Postvaccination mouse protection tests on a number
of persons from vaccinated groups are proving a better method of
checking the work of field units than is the test for viability of the
remaining vaccine.

Table V gives a general summary of all postvaccination protection
test results for work with virus I'D in Brazil.
  A study of Tables III, IV and V and other available information
suggest that the differences in the results of vaccination depend in
great part upon the delivery of relatively small amounts of active
virus below the skin of the individual vaccinated. The results show

1 Vaccination of these groups was carried out under the direct supervision of
Dr. H. H. Smith, who, with Drs. Henrique Penna and Adhemar PaolieUo (3),
has published a report covering observations on the first 60,000 vaccinations in Brazil.

302


VACCINATION WITH VIRUS r7D IN JUNGLE YELLOW FEWER

that with standardized methods of vaccine production and with
adequate supervision of the administration of virus in the field,
highly satisfactory results can be obtained.

Anticipated Epidemiological Results of Vaccination
Admitting that the individual can be protected by vaccination,

the epidemiological results of vaccination must vary with the con-
ditions under which infection,occurs. Where man is an essential
element in the cycle of infection, responsible for maintaining the
virus, as in urban oegypti-transmitted yellow fever, artificial immuni-
zation of the bulk of the population should effectively protect the
remaining non-immunes. It is probable that occasional mass vacci-
nation will be found more economical and practicable in certain
regions, for breaking the cycle of infection, man-aetlypti-man, than
is the traditional maintenance of antimosquito services for the
prevention of aegypti breeding.

In considering jungle yellow fever, however, in which man is,
apparently, not an important factor in maintaining the virus, vacci-
nation should alter the epidemiological picture, mostly by preventing
the infection of vaccinated persons, and, only in a very minor
degree, by reduction of the source of virus for forest vectors.
Vaccination promises to be a great aid in preventing the transfer

of yellow fever infection from one place to another by the human
host ; the long-distance transfer of virus, by modem methods of
rapid transportation, can be prevented by vaccination, as can also
the introduction of virus from jungle to urban areas. Since the jungle
infection, apparently, exists independent of the human population,
and spreads from place to place by other than human carriers,
vaccination cannot be expected to completely eradicate yellow fever.

Summary.

During the period, September I 937 to July I 93 8, over half a
million persons were inoculated with the modified yellow fever
virus r7D. Vaccination with this virus was widely used throughout
the I 93 8 epidemic of jungle yellow fever in South Brazil. Field obser-
vations indicate that vaccination becomes effective within a week
after inoculation. Reaction to vaccination is relatively mild, and no
contraindications have been found. The results of approximately
3,000 mouse protection tests are presented, showing that a high
percentage of persons vaccinated develop demonstrable antibodies.

303


I.

2.

3.

4.

5.

6.

7.

8.

9.

IO.

II.

12.

13.

`4.

304

FRED L. SOPER AND H. H. SMITH

Bibliography

Soper, F. L. Vacina+o contra a febre amarella no Brasil, de
1930 a 1937. Arch. de Hie. Rio de Janeiro. 1937. 7: 379-390.
Lloyd, Wray, Theiler, M., and Ricci, N. I. Modification of the
virulence of yellow fever virus by cultivation in tissue in vitro.
Tran. Roy. Sot. Trop. Med. Hyg. 1936. 29: 481-529.
Smith, H. H., Penna, H. A., and Paoliello, A. Yellow fever
vaccination with cultured virus (I 7D) without immune serum.
Am. Jr. Trop. Med. 1938. In Press.
AragZo, H. de B. Observa@es a respeito de urn foco limitado de
febre amarella sylvestre no Estado de SZo Paulo. Brasil Medico.
Rio de Janeiro. 1938. 52 : 401-412.
Theiler, M., and Smith, H. H. The effect of prolonged culti-
vation in vitro upon the pathogenicity of yellow fever virus.
/I. Exp. Med. 1937. 65: 767-786.
Sawyer, W. A. Experience in vaccinating against yellow fever
with immune human serum and virus fixed for mice. Am. Jl.
Hyg. 1937. 25: 221-231.
Reed, L. J., and Muench, H. A simple method of estimating
fifty per cent endpoints. Am. Jl. Hyg. 1938. 27: 493-497.
Findlay, G. M., and MacCallum, F. 0. Note on acute hepatitis
and yellow fever immunization., Trans. Roy. Sot. Trop. Med. Hyg.
1937. 31 : 297-308.
Soper, F. L., and Smith, H. H. Yellow fever vaccination with
cultivated virus and immune and hyperimmune serum. Am. /I.
Trop. Med. 1938. 18 : II r-134.
Whitman, L. Failure of ACdes aeavpti to transmit yellow fever
cultured virus (I 7D). I 93 8. In Press.
Shannon, R. C., Whitman, L., and Franca, M. Yellow fever
virus in jungle mosquitoes. Science. 1938. 88 : (No. 2274)
I IO-I I I.
Roubaud, E., Stefanopoulo, .G. J., and Findlay, G. M. Essais
de transmission par les stegomyies du virus amaril de cultures
en tissu embryonnaire. Bull. Sot. Path. Exot. 1937. 30 : 581-583.
Findlay, G. M., and MacCallum, .F. 0. Vaccination contre la
fievre jaune au moyen du virus pantrope att&mk employ6 seul.
Bull. O$. lnternat. d'Hyg. Publ. 1937. 29 : 1145-II.+g.
Sawyer, W. A., and Lloyd, Wray. The use of mice in tests of
immunity against yellow fever. jl. Exp. Med. 1931. 54 : 533-555.


VACCINATION WITH VIRUS 17D IN JUNGLE YELLOW FEVER

TABLE I

Persons in Brazil vaccinated with virus 17D from September 1937
     to July 31st 1938, away from the. laboratory

Months

September ......

October ........

November ......

December  ......

January  ........

February  .......

March ..........

April ...........

May  ...........

June ............

July  ...........

Total ......

Federal
district

46

3.337

13.411

IO.313

6.181

7.224

6.444

11.c-J   77.713  24.768  .09.342  34.368    28   i91.219

Rio de   S"a0    Minas   Santa   Mato
Janeiro   Paul0   Geraes  Catarina  Grosso
State   State    state    State    State

1.861

18.234

17.238

12.894

16.760

10.726

8.103

1.406

11.259

3.719

10.580

7.473

11.540

12.701

31.517

64.118

41.084

66.340

72.393

83.317

22.363

12.005

6

II

II

Total

3.719

10.580

7.473

11.546

20.850

36.766

96.247

94.998

97.431

99.783

r11.786


FRED L. SOPER AND H. H. SMITH

TABLE II

Distribution by population groups of persons
        vaccinated in Brazil

           September 1937 to July 3rst 1938
v-x$7 ) \yz;i ( Total

Farms and hamlets ......

hlilitary units ...........

Schools ................

Labor gangs  ...........

Cities and towns ........

Miscellaneous ...........

Total . . . . . . . . . . . . . . . .

16.530      397.809        414.339

I.105         23.730       24.831

994       34.348        3i.342

368       39.183        39.11'

14.361         13.337      61.698

-           9.414         9.454

33.318      557.861        19'.==9

306


TABLE III  Immunitv to vellow fever followine vaccination with Virus 17D measured hv nwtwc protection tw+t
                _ _

Where used

-

7

1

1

Viability ) Per-

test

sons
inocu-

1 lated
  results         t

Post-vaccination
26126 1 71
Pm-vaccination
Post-vaccination
Pre-22natiok 77
Post-vaccination
23/23 1
Pre-vaccination
Post-vaccination
Pre-~%ratic!n "I
Post-vaccination
23123   I 79
Pre-vaccination
Post-vaccination
27/27J/2 / 589
Pre-vaccination
Post-vaccination
pr$$~/,7,tioi, `72
Post-vaccination

TOTAL   1149
Pre-vaccination
Post-vaccination

:e is calculated on tE

Lot   Dilu-

No.   tion

hlousc protection test resulta"     I

Dose

rl.L.D'
Mouse)

ajoto
7.100

a~.000

25.000

2~.000

11.000

25.000

2.500

2.500

314
;`I'

414
515
I6

of I
lice
iur-
ving

I
4

0
11

I
II

2
28

IO
89

a
82

0
22

I
20

I
2

z

7;

26
96

2     2     I
42   18   81

0
29

0
14

0
0

I
24

8:

I
34

2
2

IO
185

4
76

II
`3

I     I
114   164

6
78

CC-
ion
in-
iex4

ber

ested

o/4
015
d6

`14
I/J
.I6

45
16

! 3

7-

214
16

3lr
16

I
I
L I

I (
-

39

I : I)
t : 2)

[ : I)
t : 2)

1:2

Laboratory

18

`4
0

2
0

0
0

0.6
5.4

40

Laboratory

12

43
I

6     0
0     0

41

Field

66

14
0

9
0

I
3

0
7

0
18

41

I : 2)
and)

1:z

Laboratory

IO

4
0

4
0

0
0

42

52

12

12

Field

I32

109
0

16
0

3
0

1:1

I : IO

1: IO

Field

69

14
0

`3
0

Field

`19

122
4

26
I

Field

21

I7
15

0
0

0
25

0
II
4:

0
0

527

417
20

13
I

0
0

0
5

0
3

0
0

0
7

I
I

2
18

0
0

3
34

r The endpoint for titration of virus in n

nortal

My

w  * The fraction indicates the number of mice dyitg of specijic encephalitis (numerator) in comparison with number alive four days after inoculation
0
-4    (denominator).
  3 The fraction indicates the number of mice Juryiving lo the tenth uhy (numerator) in comparison with number alive four days after inoculation
    (denominator).

* Average number of mice surviving calculated on basis of six mouse groups.


                TABLE IV
Immunity to yellow fever following vaccination with Virus 17D

measured b

xotection test

be 1
T

Num

ber

testec

IO
I7
20
21
23
21
20
21
20
I2
IO
21
22
20
20
II
20
20
20
21
21
21
19
21
s
II
21
20
20
21
14
42
36
42
39

L
Per-

sons

nocll
lated

47
338
I43
329
310
364
241
237
476

72
I08
`95
94
353
III
II
399
414
269
313
417
634

`19
109
405
192
356

243
60
384
1201

`307

954

-
1 i

Viability

test

results

Mouse protection test results3

-

t
i ;

T

41
$5

2/4
316

311
I/G

1

-

314
4/5
116

Pro-
tec-
tion
in-
dex'

::i
5.8
I*'
I.0
4.7
3.8
2.0
5.3
5.8
5.4
5.4
5.6
5.3
5.2
5.4
5.4
1.6
4.7
2.4
4.9
1.4
4.7
4.9
5.8
1.1
1.2
3.8
4-I
3.6
4.2
4.3
4.4
3.8
5.0

%
of
mice
sur-
riving

88
81
96
84
a2
z:
i;
97
89
89
96
88
87
90
89
93
77
41
88
89
78
a2
96
84
86
64
68
60
70
71
ii:
83

Dose

M.L.D'   Where used

Mouse:

ISW
85
85
130
130
SO
*::
850
85
87
170
270
210
140
270
100
100
85
85
110
110
110
110
85
85
85
85
170
81
85
200
200
200
280

Farms & Hamlets
Cit. & Towns
Milit. Units
Farms & Hamlets
Farms & Hamlets
Cit. & Towns
Cit. & Towns
Farms & Hamlets
Farms & Hamlets
Schools
Farms & Hamlets
Farms & Hamlets
Cit. & Towns
Farms & Hamlets
Farms h Hamlets
Cit. & Towns
Farms & Hamlets
Farms & Hamlets
Farms & Hamlets
Cit. & Towns
Farms & Hamlets
Schools
Farms & Hamlets
Farms & Hamlets
Farms & Hamlets
Farms & Hamlets
Cit. & Towns
Cit. & Towns
Farms & Hamlets
Farms & Hamlets
Farms & Hamlets
Farms & Hamlets
Farms & Hamlets
Farms & Hamlets
Cit. & Towns

Lot   Dilu-

No.   tion

4/4
s/s
i/6

014
O/S
`16

I     0     0     I
0     0     I     3
0     0     0     0
0     I     0     I
0     I     I     2
0     0     0     2
0     0     I     0
3     2     0     I
0     0     I     I
0     0     0     I
0     0     0     I
0     0     0     S
0     0     0     2
0     0     I     3
0     0     1     3
0     I     0     0
0     0     0     4
0     0     0     I
0     0     0     I
I     I     I     0
0     0     3     I
0     0     0     3
0     0     I     I
I     I     I     0
d     0     0     0
I     0     0     0
0     0     0     3
I     0     0     2
2     0     0     2
I     0     I     0
3     f     7     6
I     3     0     I
I     I     0     3
0     2     0     5
I     0     I     3

-

L

I
3
4
7
iI
S
0
3
0
4
3
4
S
I
3
i
7
:
7
7
S
I
S
I
i
7
I2
I2
7
IO
17

z
16
II
II
IO
a
5
14
II
5
`3
16
II
14
7
II
`3
9
4
IO
II
a
I2
4
I
I2
7
2
Ia
I8
Ia
14
IS

69
79

a0

85

91

101

102

`03

106

'15

117

126

016
116
616
z;:
216
6/6
116
414

0
2
0
I
I
t
IO
I
0
0
0
0
0
I
0
0
0
3
IO
I
0
2
I
0
0
I
5
z
3
G7
II
I

4s
616

I*)**
  316
  w
16116
  616
2;;
  416
  4/s
  014
  014
  s/s
  S/I
  o/s
  I/J
  616
  616
  I/S
  116
/6,1+2, s/j

4

314 (
015
I/S  J
4/4

The endpoint for titration of virus in mice is calculated on the basis of 10 % mortality.
The fraction indicates the number of micz dying of specifi etrcepbalifis (numerator) in comparison with number alive four days after inoculation
(denominator).

The fraction indicates the number of price suryiving fo the tenth uky (numerator) in comparison with number alive four days after inoculation
(denominator).

Average number of mice surviving calculated on basis of six mouse groups.

308


                 TABLE V
Immunity to yellow fever following vaccination with Virus 17D
       measured by mouse protection test

Lot

NO.

39

40

41
41
42
12
12
I*
14
14
IS
s6
17
s*
19
60
61
62
63
64
65
67
68
69
:t
77
78
79
80
83
84
81
88
91
101
102
103
106
112
11s
7'7
123
126
136
137

T

Dilu-

tion

T

Dose
M.L.D'
:Mouse)

810 to
7.100
8 5 .ooo

2J.000
2J.000
I I .ooo
2 5 .ooo
2.500
2.JOO
?

6.800
540
?
230
?
I .700
760
I.700
?
140
340
540
170
r.yoo
170
810
8.50
400
85
130
230
8.50
  SO
*SO
*SO
170
210
100
8.5
230
110
170
200
200
220
280

Where used

Laboratory

63165

20

I8

0

Laboratory     201/202      71    $2     I

Field and
Laboratory
Field
Field
Field
Field
Field and
Laboratory
Field
Field
Field
Laboratory
School & Field
Field
School & Field
Army & Field
City Br Field
Field
City & Field
Laboratory
Field
Field
Army & Field
Field
City & Field
Field
Army & Field
Field
City
Field
City
Fiidj & Lab.
School & Field
City & Field
Field
City
Laboratory
School & Field
Citv & Field
Field
City & Field
Laboratory
Field

IS/I8
27129
34134
23123
28129
I/18
79186
1981203
I21/12~
1341138
49188
*07/*40
68/84
100/107
196/*v
205/218
134/w
78/78
81184
171/188
41171
17170
so/Ios
184/190
3001377
1391149
40/51
**I37
*70/*79
37147
47154
I 861202
145J163
212/232
264/282
ror/106
20123
85194
27142
I 50/208
118/176
59185
*40/*5 3
87189
TOTAL

77.
141'

840

1245'

ISSO
1868
co4
126
1680
1943
22
2284
1866
1743
73
1293
714
2152
4414
5933
2807
1486
1781
3'91
41x4
2182
4752
6233
6822
7995
3867
624
  21
3614
`0414
10259
6166
9233
7400
3089;

66
IO
132
69
159
21
I43
76
108
80
2
:i
99
129
s=
56
73
24
18
IO
47
93
128
84
37
44
100
3'
43
62
41
46
70
40
41
14
80
113
  I
120
3;:
2944

0
0
0
0
4
`I
3
0
0
2
11
I
4
I
5
I
3
I
0
4
t
6
2
3
3
2
2
0
9
I
11
0
I
0
13
0
4
IS
0
23
0
I
170

Viability
test
results

Pef-

sons
nocu-
lated

km-
her
ested

I-

O/4   I/4
O/S   I/S
,I6   16

Mouse protection test results 3

*Is
L/G

214
516

0

--
311
4

314
415
i/6
--

0

0

0
0
0
0
I
4
4
0
2
0
2
0
0
I
3
I
0
I
I
0
0
0
4
I
I
0
0
0
4
0
0
I
3
0
0
0
I
0
I
0
3
0
1
48

I t

41.
s/s
i/6

%
of
mice
sur-
riving

Pm-
tec-
tioo
in-
kx4

0

3     4    II   89    1.4

0     I     7    II    28     82    S.1

3
0
0
0
2
0
4
0
2
0
0
0
0
I
I
I
2
0
2
0
0
0
0
I
I
I
0
2
2
0
0
2
2
I
I
0
I
0
I
I
0
6
0
0
48

3
0
7
I
18
0
20
3
IO
2
iz
2
7
I2
I
2
3
4
0
I
0
I
I
II
3
I
I
s
0
I
I
I
0
2
0
I
1
s
9
0
1
1
1
162

18
0
3-5
`I
46
0
33
8
28
Y
I
I2
6
13
16
14
6
II
10
7
I
I
4
21
22
IO
3
3
7
3
z
2
7
7
I
I
2
s
`3
0
9
2
3
427

22
2
42
29
14
0
44
28
32
22
4
20
17
31
32
36
21
16
29
7
3
I
9
24
30
29
7
14
3'
12
II
`9
3
7
II
II
II
I
2s
41
I
30
3
`7
85'3

I

20
8
s*
24
34
*i
35
37
34
49
I
29
26
24
tt
`9
22
26
IO
s
7
23
39
:1:
23
22
49
16
20
24
`9
31
48
24
`3
6
39
19
4
48
3
`I
231

78
96
85
84
76
13
ii
78
89
41
83
82
::
83
81
78
81
::
88
73
i!
8.5
`35
83
82
90
71
82
59
9=
92
9=
58
8s
83
72
96
69
81
83
80

4.8
S-8
S-1
I.1
4.1
0.8
4-4
1.3
4.7
1.4
2.4
s.0
4.9
4.8
4.6
s-0
I.0
4.8
4.9
::i
I.1
4.4
4.8
4.9
s.0
S-1
s-0
s.0
1.4
4-3
4.6
3.6
1.5
1.4
S*S
3.5
S.1
s-0
4.2
S-8
4.x
4.9
0
::*

1 The endpoint for titration of virus in mice is calculated on the basis of 50 % mortality.
                                                      
2 The fraction indicates the number of mice dying of Jpeci'c encepbafitiis (numerator) m comparison with number alive four days after inoculation
(denominator).

3 The fraction indicates the number of mice s~ruiving to the tenth day (numerator) in comparison with number alive four days after inoculation
(denominator).

4 Average number of mice survivin,? calculated on basis of six-mouse groups.
5 Revaccination immunes.


FRED L. SOPER AND H. H. SMITH

IMMUNITY TO YELLOW FEVER BEFORE AND AaFTER UACCINATION WITH VIRUS 170.


VACCINATION WITH VIRUS x7D IN JUNGLE YELLOW FEVER

MONTHLY PROGRESSOF ROUTINE FIELD VACCINATION
  IN BRAZIL, SEPTEMBER 1937 TO JULY 1938

l10.00~

100.001

9o.ooc

8O.OOC

7OOOf

   6O.OOC
2
s
3  5o.ooc

2
2  4oooc

  30.000

20 000

10.000

o-

3-

,,

I-

I-

I-

)-

I-

  A


FRED L. SOPER AND H. H. SMITH

POST VACCINATION MOUSE PROTECTION TEST RES'ULTS
ON 2944 PERSONS INOCUL4TED WITH VIRUS 17D

1.300

1.200

1.100

1.000

900

600

700

600

500

400

300

200

100

0

1

I


VACCINATION WITH VIRUS r?D IN JUNGLE YELLOW FEVER

Disptltutio.

  W. A. P. Schiiffner (Holland) :  Mit besonderer Genugtuung
horte ich die Vorschlage Sopers. die er beziigl. des Ablesens des
mouse-protection-tests machte. Sie stimmen mit den von uns in
Amsterdam gegebenen erfreulich iiberein. Die Anspriiche, die man
an den Mause-Versuch stellen muss, haben sich mit der Zeit ge-
andert . Urspriinglich von Theiler und von Sawyer ausgearbeitet,
wurden die Methoden von franzosischer und portugiesischer Seite
(im Office intemationa1 d'hygi&ne) als nicht spezifisch angegriffen.
Um diesen Vorwurf zu entkriften, vermehrte Sawyer die Menge
des Virus ; statt einer 10% Emulsion nahm er eine 20% ; damit
konnten unspezifische Reaktionen (die iibrigens kaum vorkommen)
nlit noch grijsserer Sicherheit ausgeschaltet werden. Aber natiirlich
gingen damit schwache spezifische Reaktionen verloren. Heute aber,
wo an der Spezifitat des Miuse-Versuchs nicht mehr gezweifelt
werden kann, verlangt die Erforschung der Epidemiologie des Gelb-
Iiebers such das Erfassen einer schwachen Immunitat. Wir haben
daher einmal die schwgchere Emulsion (I o yO, und davon 0,`2 cc. mit
0,q zu priifendem Serum intraperitoneal gegeben) beibehalten und
zweitens, ebenso wie heute nun such Soper, vorgeschlagen, die Resul-
tate, die jetzt noch als zweifelhaft oder gar als negativ gelten, mit zu
beriicksichtigen. Ich stimme Soper vollkommen bei, wenn er daran
erinnert, dass selbst ein volkommen negativ abgelaufener Mausever-
such (6/6) noch nicht eine Rest-ImmunitEt ausschliesst. Zu dieser
Auffassung wurden Snijders und ich friiher bereits bei unsern Dengue-
Untersuchungen gedrungen, spgter hatten wir sie fiir das Verstindnis
der Verhsltnisse in Suriname, wo der Eingeborene auffallend resistent
bei Gelbfieberepidemien war, notig.

313