GEOGRAPHICAL LIMITS OF YELLOW FEVER
The geographical limits of yellow fever, when first encountered by
the white man, were not very wide. They were contained within a zone
limited on the north by the twentieth parallel of latitude, on the
south by the eighth, on the east by the sixtieth meridian, and on
the west by the one hundredth. Practically, the disease was confined
to the shores of the Caribbean and the southern shores of the Gulf
of Mexico. Within these regions it was practically endemic at the
time Columbus discovered America. The arrival of the white man with
his sailing ships made the disease much easier of transmission from
place to place, because man traveled much more frequently and much
farther, and also because sailing ships, with their fresh-water
tanks, bred the stegomyia extensively. Under these influences the
endemic area began slowly to spread. Toward the north the endemic
area never extended far beyond the limits it occupied when Columbus
made his first voyage. Havana, in latitude 23°, is the northern
endemic limit in the western hemisphere. This is rather strange, as
the city is located so near the original endemic focus. The arrival
of a considerable number of non-immunes in a locality is necessary
for yellow fever to become endemic, and this supply has to be fairly
constant. During the first hundred years after the founding of
Havana, in 1511, the city was considered very healthy. In 1620, an
epidemic of yellow fever occurred, the disease having been introduced
from Panama (Porto Bello) by the treasure fleet on its way to Spain.
In 1649 another epidemic occurred, which was extremely severe and
spread to many other towns of Cuba. This epidemic lasted more or
less until 1655. For a hundred years after this, nothing in the
nature of an epidemic occurred. In 1762, at the time of the capture
of Havana by the English colonial troops from the North American
colonies, the disease again became epidemic, and after that time
remained constantly in Havana as an endemic disease. At this time it
was recognized as being introduced from Vera Cruz, Mexico, under the
name of “black vomit.” It became endemic, and did not disappear as
on former occasions, on account of the large and constant supply of
non-immune persons, due to the presence of the English troops, and
after their departure, to the fact that the port was thrown open to
general commerce, and to a continuous supply of immigrants from Spain.
It would seem, then, that Havana, after remaining in the epidemic
area for some two hundred and fifty years, finally, about the year
1762, passed permanently into the endemic area.
Havana is the most northern point to which the endemic area ever
extended. Toward the south the endemic area spread much farther from
the original endemic focus than on the north. While in distance from
the original endemic area the disease spread further south than
north, it did not in point of latitude. Rio Janeiro and Santos, the
furthest points south to which the endemic area spread, are about
latitude 23°, much the same as Havana on the north. Para, Manaos,
Pernambuco and Bahia gradually came within the endemic area, until
finally, in 1849, yellow fever took up its permanent habitat in Rio
and Santos. During the year 1850, forty-one hundred and sixty persons
died of yellow fever in Rio.
These cities, like Havana, were subject to epidemics of yellow fever
years before they became endemic centers. Endemicity did not spread
regularly over this area from north to south. The disease became
endemic in Rio thirty or forty years before it did in Manaos. Other
factors proved more potent than location as to latitude. The large
emigration to Brazil, which set in about the middle of the nineteenth
century, gave a constant and large supply of non-immunes to Rio,
while Manaos did not get this supply until railroad construction
commenced in the interior, about the beginning of the present century.
Strictly speaking, Pernambuco, on the eastern coast of Brazil, about
longitude 35° west, is the point farthest east where yellow fever
really became endemic, in the sense of remaining continuously in one
city for a number of years. But on the west coast of Africa, from
St. Paul de Loanda on the south to the Canary Islands on the north,
yellow fever has been present all the time at some point or points,
ever since its introduction in 1494, though on this coast it has
never manifested itself continuously in the same town or city for any
considerable number of years. But it is endemic on the coast in the
sense that it no longer has to be re-introduced from the outside, but
is always present at some point. We have a pretty accurate account of
its first introduction into the Canary Islands in 1494 by Spaniards
returning from Hispanola.
The farthest point west at which it has ever become endemic is its
original home, Vera Cruz, Mexico. It has been endemic at both Panama
and Guayaquil, on the west coast of America. While these points are
on the west coast, and Vera Cruz is on the east coast, still, Vera
Cruz is some sixteen degrees of latitude west of either Panama or
Guayaquil.
The endemic limits of yellow fever at its period of greatest extent
would be defined by a line drawn from Havana, commencing on the
north, to the Canary Islands, down the west coast of Africa to
Loanda, from Loanda west to Rio Janeiro, Brazil, from Rio Janeiro to
Guayaquil, Ecuador, from Guayaquil to Panama, from Panama to Vera
Cruz, Mexico, and from Vera Cruz back to Havana, a very restricted
area compared with other infectious diseases.
But it is as an epidemic disease that it has caused most alarm and
loss. The United States, Spain, and the West Indies have suffered
most severely in this respect. It has been epidemic as far north as
Quebec in North America. In 1805, some fifty-five cases occurred
among the English troops stationed there. In Europe, it has been
epidemic as far north as Swansea, Wales. In the year 1865, the
sailing ship _Hecla_ from Cuba, introduced yellow fever into Swansea,
and twenty-two cases developed in the town in persons who had no
communication with the vessel.
France has never had a yellow-fever epidemic of any consequence,
though it has been demonstrated that under favorable conditions,
the disease might become epidemic. At St. Nazaire, in the year 1861,
yellow fever was introduced by the sailing ship _Anne-Marie_, and
forty cases resulted, with twenty-three deaths.
Yellow fever has appeared in epidemic form several times in Italy,
but has never extended further east. Leghorn is the most eastern
point to which yellow fever has ever reached. There in 1804 a severe
epidemic occurred in which some two thousand persons died.
On the west coast of Africa epidemics have occurred as far south as
St. Paul de Loanda. The island of Ascension, about the same latitude
as St. Paul but in the mid-Atlantic, has suffered very severely.
In 1823, the British sloop _Bann_ brought yellow fever from Sierra
Leon to Ascension. Ninety-nine cases occurred on the _Bann_, with
thirty-four deaths, and on the island itself twenty-eight cases
occurred with fifteen deaths.
Yellow fever has been epidemic on the east coast of South America
as far south as Montevideo, and on the west coast as far south as
Valparaiso, and on this same coast as far north as Guaymas, Mexico.
The epidemic area of yellow fever has been very much more extensive
than the endemic area. This epidemic area would then be bounded by a
line commencing on the north at Quebec, Canada, extending east to
Swansea, Wales; from Swansea south to St. Nazaire, France; from St.
Nazaire southeast to Leghorn, Italy; from Leghorn south to Loanda, on
the west coast of Africa; from Loanda west across the Atlantic to the
island of Ascension; from Ascension still west across the Atlantic
to Montevideo; from Montevideo still west across South America to
Valparaiso, Chili; from Valparaiso northwest to Guaymas, and from
Guaymas northeast back to Quebec.
By lines of latitude and longitude the epidemic area would be bounded
on the north by the forty-fifth degree, north latitude; on the south
by the thirty-fifth degree, south latitude; on the east by the tenth
degree, east from Greenwich, and on the west by the one hundred and
tenth degree, west from Greenwich.
In point of area its period of greatest extent was during the first
half of the nineteenth century. Since the middle of the nineteenth
century its area has been decreasing rapidly, until at the present
time this disease is confined to a half dozen centers in South
America.
Within the epidemic area the loss of human life from this disease has
been very great, the United States and Spain, being the most populous
countries affected.
South America lies generally well east of North America, and its
northern coast is about opposite the southern part of North America,
so that the neck of land which connects the two runs east and west
and is known as the Isthmus of Panama. Most of this isthmus is
embraced in the present Republic of Panama.
Columbus was the first white man to visit Panama. On his third
expedition he entered the Bay of Bocas del Toro, and spent some
time there. On this same expedition he also visited Limon Bay, into
which the northern end of the Panama Canal at present empties. He
also visited Porto Bello, which afterwards became rich, famous, and
populous, and which is located on the northern extremity of the
royal paved highway running north from the old city of Panama. He
left more than one hundred men under his brother, Diego, at Belen,
some fifty miles west of the present town of Colon. After several
years of sickness, hardships and deprivations, this colony was
finally destroyed by the Indians. Spain afterwards ennobled Columbus’
grandson, Luis, under the title of Duke of Veragua, and granted to
him a large tract of land in the neighborhood of this old colony, to
which was given the name “Dukedom of Veragua.” One of the provinces
of the Republic of Panama which covers about the same area as did the
tract referred to, is known as the Province of Veragua. The old royal
highway just referred to, running between Panama and Porto Bello,
lies from five to fifteen miles east of the Canal. Columbus’ third
voyage was made in 1498. A few years later, Balboa, with a party
of Spanish adventurers, under the authority of the Captain-General
from Santo Domingo, arrived in the eastern part of Panama and made
permanent settlements, at first on the north coast, and discovered
the Pacific.
A few years later, in 1519, the city of old Panama was founded.
Balboa was the best type of the Spanish conquistador. He was brave,
hardy and determined, qualities very common to the early Spanish
adventurers, but Balboa was more able and had much broader views of
government and colonization than either Pizarro or Cortez. He was
displaced as governor of Panama by Pedrarias, a man inferior to him
in every respect. Balboa was beheaded by Pedrarias in 1517. He had
heard of the Inca empire to the south, and was getting together a
fleet on the south coast with the intention of invading this empire.
Pedrarias became jealous of his power, and feared he was getting
together a force for the purpose of overthrowing his government. As
far as historical data show, there was no reason for this jealousy.
Tradition has it that the cause of the enmity between Balboa and
Pedrarias was due to the fact that Balboa, being betrothed to the
daughter of Pedrarias, became involved in an affair with the daughter
of an Indian chief while absent on the south coast building the fleet
with which he hoped to conquer the Inca empire. Pedrarias’ daughter,
hearing rumors of this affair, became very jealous, and influenced
her father’s mind against Balboa, even to the extent of having him
beheaded. This is, however, probably pure romance.
The facts seem to be that Pedrarias, being a narrow-minded man and
jealous in disposition, gradually became hostile to Balboa on account
of the latter’s popularity with the Spanish colonists, as well as
with the Indians. Balboa, for a conquistador, was humane in his
attitude toward the Indians. For this reason Pedrarias began to make
charges against and quarrel with Balboa. Pedrarias, being governor,
had absolute power in the Province of Panama, and Balboa, to be
successful in fitting out his expedition, knew that he had to have
the support of Pedrarias. In his endeavor to placate him and insure
his support, Balboa married Pedrarias’ daughter, a child of six years
of age. The marriage ceremony was performed by proxy, Pedrarias’
daughter being absent in Spain. Balboa never saw his wife.
Pizarro was one of the lieutenants of Balboa, though as an officer
of Pedrarias’ government he was actually in charge of the party
that arrested Balboa. Balboa’s death was a great loss to Spain
and to Panama. He would in all probability have made a much more
humane conqueror of Peru than did Pizarro, and certainly would have
made a much abler ruler of that country. He was beheaded at Acla,
the capital of Panama at that time, situated on the north coast on
Caledonia Bay. All trace of this town has now disappeared.
Panama when first known to the Spaniards, in the early part of
the sixteenth century, was a thickly inhabited country, peopled
by a mild-mannered Indian population, who lived principally by
agriculture. Las Casas makes the statement that during the twenty
years in which Pedrarias governed Panama he caused the death of
three million Indians. I am inclined to think this a very great
exaggeration, but it is evident from the accounts one reads of
Balboa’s expeditions that there was a considerable population in the
country. As day after day he makes marches from town to town, Balboa
describes getting supplies from these towns, and that he was able
to procure from five hundred to a thousand porters for carrying the
baggage of the expedition. In every town he secured some gold, and
none but a very populous country could have furnished the supplies of
men and amounts of gold which he describes.
The Republic of Panama is something over half the size of the state
of Alabama, containing some 31,571 square miles of territory, and
is divided into two parts near its center by the Panama Canal. The
western half contains at present all the population of the Republic.
The eastern half has no population at all, with the exception of a
few wild Indians. In Balboa’s time this eastern half was thickly
populated, and contained most of the inhabitants. Columbus looked
upon Panama as the richest portion of his American discoveries,
particularly from a gold-producing standpoint, and the Spaniards
generally shared this opinion. This was such a widespread belief that
the country was known as Castilla del Oro.
The importance of Panama was vastly increased by the discovery and
conquest of the Inca empire about 1530. Vast quantities of gold and
silver bullion passed through Panama on its way to Europe. It seems
to be an historical fact, mentioned by Prescott and other writers,
that Pizarro exacted from the Inca emperor, Atahuallpa, for his
ransom, a room full of gold, the dimensions of which are stated as
being twenty-two feet long, seventeen feet wide and nine feet high.
An adjoining room of somewhat smaller dimensions Atahuallpa agreed
to fill twice over with silver. Such quantities of bullion were
introduced into Europe as had never before been dreamed of, and
prices rose to what was then considered an extraordinary figure.
The city of Panama became the commercial metropolis of the western
hemisphere. The highway between Porto Bello and old Panama became a
road over which there was a constant stream of people traveling. All
the merchants, officials and colonists going to Peru, western Mexico,
and the Spanish possessions in the East Indies used this route, and
there was a steady and constant stream of such people going between
the colonies and mother country.
About the beginning of the seventeenth century Panama was the chief
port for the Spanish trade of the Pacific. This large travel and
large business was fortunate for her from a commercial point of
view, but it was the cause of her evil reputation as to health. Her
location was in the tropics, where the stegomyia mosquito could breed
freely all the year round. Yellow fever was early introduced by
the Spanish conquistador. Then the constant stream of unacclimated
Europeans passing for four hundred years through her borders made
conditions ideal for the development and maintenance of yellow fever.
And for four hundred years this region has been known as the most
unhealthy in America.
As Panama grew in wealth and importance, and it became known what
great amounts of treasure were passing through her borders, she
became attractive to the English soldiers of fortune. Drake was
one of the earliest of these, and his name and fame are intimately
associated with the early history of Panama. He first came to the
north coast in 1572, and remained in the country nearly two years.
He secreted his ships in remote places among the beautiful San Blas
Islands, and it was not discovered by the Spaniards just where he
was. From this point he made frequent expeditions against the various
Spanish possessions.
From Drake’s accounts there was still a considerable Indian
population in the country, though not by any means as numerous as
in Balboa’s day. This Indian population was bitterly hostile to the
Spaniards, who, whenever they could get hold of them, were their
harsh and cruel taskmasters. Consequently, the Indians were friendly
to the English whom they knew to be the enemies of Spain.