The Conduct of the Yellow Fever Campaign in Vera Cruz and the Second Yellow Fever Zone, 1921-1922, by Bert W. Caldwell, July 30, 1922

    THE CONDUCT OF THE YELLOW FEVER CAMPAIGN IN VERA CRUZ
AND THE SECOND YELLOW FEVER ZONE,- 1921 - 1922.

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    The campaign for the control of the epidemic of yellow fever that
spread over the area comprised in the Second Yellow Fever Zone, of which
the city of Vera Cruz is the center, began in June 1920. During this
year a total of 505 cases of yellow fever were reported in the whole of
Mexico of which number two-thirds were reported from the city of Vera
Cruz and the territory within a radius of 200 kilometers of that city.
During the year 1921 a total of 123 cases were reported for the whole of
Mexico of which number 75 were reported from Vera Cruz and contiguous
territory. During the present year- 1922- but five cases have been
reported in the Republic of which one was reported from the territory
comprised in the Second Zone.

    The campaign for control, which the Departamento de Salubridad
Publica had conducted from June to December 1920, had produced excellent
results and when the Comision Especial began its work in the city of
Vera Cruz in the month of January 1921, the epidemic was being rapidly
placed under control, due to the efficient service performed by Doctor
Juan Graham Cassasus and his associates.

    Outside of Vera Cruz the whole area was badly infected. To the
North Papantla and Tuxpam, which at that time were included in this Zone,
were experiencing formidable epidemics, and a few cases had been previ-
ously reported in the city of Tampico. To the West the small cities and
towns along the lines of the Interoceanic and Mexican Railroads were
reporting cases, while practically every town and hacienda along the
Papaloapam Valley from the Oaxacan mountains to the Gulf Coast was badly
infected. Puerto Mexico and the towns along the Tehuantepec Railroad
were supposedly free from the disease although previously one or two
cases had been reported from Puerto Mexico.

    The entire area was carefully surveyed and the program for the
campaign was decided upon. That program, with but few minor changes,
has been consistently adhered to in this Second Zone. It was decided to
throw a line of brigades across the Isthmus of Tehuantepec located in

    In the Papantla-Tuxpam-Gutierrez Zamora area to the north the
problem was more difficult. Here an extensive and a commercially im-
portant area was heavily infected and epidemics of sizable proportions
were raging in Papantla and Tuxpam, and the towns and haciendas along
the Tuxpam and Gutierrez Zamora Rivers were reporting cases. Alamo, San
Isidro and San Rafael with other small settlements reported positive
cases as late as November 1921.

    In this area permanent brigades were established in Papantla,
Tuxpam, Gutierrez Zamora and Alamo, while Brigadas Volantes swept through
the smaller places and haciendas and the epidemic was brought under con-
trol. By the end of May both Tuxpam and Papantla were free from the
disease, but in the territory between these places cases occurred as
late as November 1921.

    In July Doctor Emmet I. Vaughn took charge of this area with head-
quarters at Tuxpam, and until September 1st 1921, conducted an intensive
campaign, leaving for Belize during the first week in September. By the
first of December the entire area had been freed from the disease and
since January 1st of the present year, when Doctor M. E. Connor took
charge of the First Zone, to which this territory had been attached,
the effective campaign which he has conducted has prevented any recur-
rence of the disease.

    In Tampico the Associated Oil Managers, under the able direction
of Doctor Tomas Cuaron and Mr. Le Prince, the distinguished Sanitary En-
gineer, had instituted a decidedly effective campaign. The work which
these two sanitarians, in conjunction with Doctor A.R. Stubbs, accom-

    In July 1921 the Associated Oil Managers retired from active par-
ticipation in the campaign and the territory was attached to the Vera
Cruz Division, with Dr. Cuaron in charge of Tampico and Dr. Monroe as
his assistant in charge of work in the field. From January 1st this
territory, north of the 20th degree of latitude, was comprised in the
First Yellow Fever Zone and Dr. M. E. Connor assumed direction. The
results of his work during the first half of the present year in the
Tampico area justified him in turning the area over to the representa-
tives of the Departamento de Salubridad Publica on July 1st 1922.

     Protested in this manner by a line of outpost brigades 75 kilome-
ters south of any reported infection, and with an area free from the di-
sease to the north of the 20th degree of latitude, the problem centered
around the city of Vera Cruz. Intensive work was instituted in January
1921 in the city and in the adjacent territory and no halt has been per-
mitted since that time. Continuing the successful campaign which my
efficient predecessor, Doctor Juan Graham Cassasus, had conducted, the
mosquito incidence was rapidly reduced and further spread of the infec-
tion in the city was inhibited. On March 16th 1921 the last case of yel-
low fever originating in Vera Cruz was reported and since that time there
never has been a stegomyia incidence sufficiently high to permit secon-
dary infection in the city. The mosquito incidence has been maintained
remarkedly low for the past twelve months, with the stegomyia incidence
practically nil. Cases originating outside of the city have been brought
to Vera Cruz during the year 1921 for hospital care and medical treat-
ment, and some of these cases have been reported and charged to Vera
Cruz. The last case of this kind was the Doctor Cross case reported
December 23rd of last year.

    With Vera Cruz free, our next problem and decidedly more import-

    This area is along the fertile valley of the Papaloapam River
extending from the Oaxacan mountains to the Gulf, a distance of 220
kilometers, and includes the contiguous territory from Tierra to Tuxte-
pec, thence to Cosamaloapam. It is along this river that the large sugar
haciendas of the State, the immense banana plantations and the important
tobacco and cotton haciendas of the Valle Nacional and the adjacent val-
leys are located. Commercially and agriculturally it is the most im-
portant section of the State of Vera Cruz. These large industries
annually import thousands of laborers from the States of Oaxaca, Puebla,
Michoacan, San Luis Potosi and other States of the Central Plateau who
sweep through the cities of Tuxtepec, Cosamaloapam, Tierra Blanca, Tla-
cotalpam, Alvarado and other cities or come by rail through Vera Cruz,
they and their women and children, every one of whom is non-immune to
yellow fever. They roam from ingenio to ingenio, from hacienda to ha-
cienda, and in prosperous times this movement of non-immune labor is
sufficiently large to keep the area constantly infected and to establish
and maintain its endemicity.

    Along the course of this important valley for a distance of 250
kilometers a population of 200,000 exists and important commercial and
population centers are within easy communication. For a large part of
the distance the homes of "colonos" line either side of the river bank
and the villages are frequently continuous.

    In July 1921 the first case from this area was reported at Cosa-
maloapam, a city of some ten thousand people. The patient lived in a
house adjacent to the "cuartel" and the soldiers became infected. From
this focus the soldiers carried the disease from house to house and from
Cosamaloapam to nearby cities and by the end of July Tierra Blanca, Chan-
guiltanguis, Tlacotalpam, Otatitlan and Alvarado were reporting cases.
From Tierra Blanca the infection spread north and cases were introduced
into Cordoba, Orizaba, Nogales and Paso del Macho. Due to the measures

    Our campaign at once took a very wide range. It became necessary
to limit the disease within the already wide area which had been invaded.
It was determined to clean up the Papaloapam Valley in a manner that
would prevent a reappearance of the disease after we had once wiped it
out. Brigades were established in each of the important population cen-
ters and in addition Brigadas Volantes were sweeping both banks of the
river, house by house, from Alvarado on the coast to El Hule, 200 kilo-
meters inland.

    It was at this period of the campaign that a serious error of
omission was made, in that the valley of the Papaloapam River above El
Hule and on through Tuxtepec was not covered in our campaign. The Vocal
of the Commission in charge of the campaign in this area had made a sur-
vey and had recommended that intensive work be done from Tuxtepec to the
upper reaches of the river covering the haciendas and municipalities to
the west of that city, and had included in his "presupuesto" the esti-
mate for the brigades to be located for this purpose. But as no cases
had been reported from this part of the Zone above El Hule it was final-
ly determined not to institute work there until later.

    Retribution for this error followed fast. In August the captain
in command of the garrison at Ojitlan, a distance of 45 kilometers west
of Tuxtepec was called to Tierra Blanca, which place had already been in-
fected from Cosamaloapam. He returned to Ojitlan after a two days stay
in Tierra Blanca, and on August 22nd came down with yellow fever and
died on the 27th.

    The municipality of Ojitlan is composed of some 8,000 people, of
which 2,000 live in the village of Ojitlan. They are for the greater
part Oaxacan Indians, who never leave their mountain homes except to go
down to the haciendas to labor. With but very few exceptions they are
non-immune to yellow fever and seemed to be particularly susceptible to
attack. Among them, the disease once introduced, spread rapidly. In
October the epidemic was reported through the Governor of the State of
Oaxaca to the Departamento de Salubridad Publica and the Vocal in Charge

    From Ojitlan the disease spread down the valley through Laguna
infecting the haciendas and finally reached Tuxtepec, where in December
Dr. Cross contracted the disease, was brought to Vera Cruz for hospital
care and died December 28th 1921.

    Our work was now extended to cover the entire valley. The epi-
demic was well under control. All known foci of infection were intensive
ly worked and all potential foci were given careful attention by Brigadas
Volantes. Permanent brigades continued their work in all of the more
important places and in every city of consequence with the exception of
two, San Andres de Tuxtla and Tehuantepec, our campaign was conducted
vigorously.

    Each of these places contain approximately 17,000 inhabitants.
Work was not instituted in San Andres for the reason that the altitude
protects the city from a high stegomyia incidence, nor in the city of
Tehuantepec where in the opinion of the Director of the Commission no
work was necessary at this time for the reason that the city had expe-
rienced an epidemic of large proportions in 1917 and that the inhabitants
were immune to the disease. In Salina Cruz the stegomyia incidence is
at no time of the year sufficiently high to permit secondary infection.

    The entire area was well under control by January 1st of the pre-
sent year, but on March 20th a well-defined case of yellow fever develop-
ed at the Ingenio San Cristobal, seven kilometers from Cosamaloapam, and
the seat of the most intensive infection during August and September of
last year. This case has been the only case reported on the Gulf Coast
during 1922.

    In addition to the anti-stegomyia work, our brigades have inci-
dentally done anti-malarial work. All anti-larval measures are anti-

    In Tierra Blanca, El Hule, Santa Lucrecia and other places the
Comision secured the co-operation of Superintendent Vera of the Vera
Cruz and Istmo Railroad, and Superintendent Enriquez of the Tehuantepec
Railroad, who have in every possible way supported the work of the Co-
mision Especial. In conjunction with these gentlemen and the municipal
authorities of these places the Comision has covered the cost of con-
struction of drainage ditches and other necessary work with decided be-
nefit to the citizens of these cities and to the traveling public. In
none of these places is the house index of mosquitos above five percent
and the malaria rate has been reduced materially.

    In the methods of stegomyia breeding control the Vocal in Charge
of the Second Zone has depended upon the following measures, listed in
the order of their importance to the work.

    First: The emptying and cleaning of all man made water deposits

    Second: Next in importance and always to be insisted upon where
the deposits contain sufficient water to support fish life, is the plant-
ing of fish. No particular variety need be insisted upon; all varieties
of minnows are the natural enemies of larval life and they devour both
larva and pupa as well as the eggs rapaciously. The top feeder, the
bottom feeder and the fish that range all through the water in search of
food supply are used. Personally I prefer the free ranging fish to any
of the other varieties. He protects himself better, eats the larvae as
he finds them and will go to the top in search of eggs and other food.
In addition he stays in his natural element, the water, and is not con-
tinuously jumping out of the barrel or uncovered tank or trying to get
out of the container when the rain fills it to overflowing. He is usual-
ly hardier, lives longer and is more resistant to the rough usage occa-
sioned by emptying and filling the deposit. Great loss always attends
the use of "jumping" fish. The success of the use of fish depends upon
the constancy with which they remain in the container and do the work
assigned them. For this reason I prefer the fish that remains well with-
in the container and ranges freely in search of his food supply.

    Third: Next in importance, and it would be of first importance if
the measure could be made one of universal adoption , is the permanent
covering of each water container. This is the most efficient, most eco-
nomical and by all means the most satisfactory measure, and if univer-
sally adopted would do away with fish planting, oiling and other less

    Fourth: The use of oil is next in importance. Oil can be used
in the drains in the patios, in the cineza-water containers and in other
containers which cannot be emptied and cleansed and which may be too
small to support fish life. It is an expensive measure and its use is
generally objected to on the part of the people of the community.

    Fifth: Last and of minor importance, for the reason that its use
is but seldom indicated, is fumigation. We have used it for the purpose
of destroying adult mosquitos which we had reason to believe were infect-
ed, and in those occasional cases where there was a heavy mosquito in-
festation in schools, theaters, cuartels and other places of public
congregation located in infected or suspicious areas.

    A survey of the Second Zone recently completed shows a satisfactory
condition existing in every city save one. That is the city of Tlacotal-
pam. Here the incidence of mosquitos is high. The prevailing species
are culicidae, with some anophelines and stegomyia. Throughout the Zone
the results of our work have been satisfactory beyond our expectations.
Yellow fever has been reduced to the vanishing point. Both the United
States and Cuba have removed the yellow fever quarantine against Mexican
Gulf ports. It seems that the campaign has secured definite control.
The work that has been done should be continued until all danger is past
and with as great an intensity as it has been previously conducted. I am
referring to the area comprised in the Second Yellow Fever Zone. I am
most reluctant to disagree with the distinguished Director of the Comi-
sion Especial, Dr. Jos. H. White, or with my able and experienced col-
league, Dr. M. E. Connor, as to the maintenance of the active work in

    I am not unmindful that less than one year ago all of this area
within 150 kilometers of Vera Cruz was reporting yellow fever cases.
That in October of last year a violent epidemic was raging through the
"tierra caliente" portion of Oaxaca and was extending down through
Tuxtepec. That at the end of last December, a trifle over eight months
ago, Dr. Cross became infected with yellow fever and died of the disease,
and that on March 20th of this year, a little more than four months ago,
a non-immune from Mexico City contracted the disease in San Cristobal,
near Cosamaloapam , in an area of known yellow fever infection six
months previous. In my best judgment the campaign should be continued
through the present rainy season and beyond that period if there is
the slightest element of doubt as to the future safety of the area from
infection. To discontinue or to abridge the work at this time, when
mosquito incidence under normal conditions is at its peak, and when any
diminution of anti-stegomyia work would result in the usual high ste-
gomyia incidence within a short time, would lay the foundation for the
invasion of the port of Vera Cruz by yellow fever from any focus that
may have been overlooked and would constitute an error potential with
most unsatisfactory results.

    The work of the Comision Especial and of the Consejo Superior
before the Comision Especial was created, and for a time after, has
been conducted at great expense. The results obtained have fully
justified the expenditure incurred. To continue this work until its
efficacy has been fully demonstrated will cost but little more, and
that cost would be small in comparison with the cost that would be
made necessary if a single case of yellow fever should originate in
or near any Gulf port. The campaign would have to be reopened with
all its vigor. Quarantine, which has so revently been withdrawn, would
be immediately instituted, and more than all the lasting good which

    Whatever action that the Comision may take as to other Zones,
I most urgently recommend that it continue the campaign in the Second
Zone until the end of the present rainy season and longer if conditions
at that time should make desirable.

BERT W. CALDWELL, M. D.
Vocal in Charge of
the Second Yellow Fever Zone
. Vera Cruz, Mexico,
July 30th 1922.