CHAPTER IX. Geographical Limits of Yellow Fever

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.