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ON ENDEMIC AND EPIDEMIC INFLUENCES IN .

By ARCHIBALD SMITH, M.D. [Read 6th July, 1868.]

The coast of Peru, from 3 deg. 30 min. to 21 deg. 30 min. S. lat., is naturally a continuous, arid, and sandy desert, which is here and there intersected by rivers, or consider- able streams of watgr, that descend through rocky clefts from the Andes. By these channels, which are partially dried up in the dry season on the mountains or Sierra, the maritime valleys are partly irrigated and fertilised. In olden times the land of the Incas was extensively watered, through the medium of a most laborious and widely spread system of aqueducts, leading from the hills to the coast, which was closely peopled, as numberless ruins of large towns and adoratories bear witness. The most northern province of this coast range is called Piura, of which Payta in lat. 5 deg. 5 min. 30 sec. S., long. 81 deg. 8 min. 30 sec. W. is the well known seaport. Twenty-eight leagues inland from Payta, is the headland of this coast district, and it is occupied by three large estates, namely, Yupatera, Moropon, and Mono de las Padres. The aspect of this spot is indescribably beau- tiful. The surrounding hills are clothed in a lovely verdure of flowery luxuriance, and ample fields produce arrow-root, yucas, Indian corn, sugar cane, and all sorts of savoury and refreshing fruit matured under a uniformly clear and serene sky. When it rains in the province, the river Chiri over- flows its banks, and spreads out into stagnant marshes at the three estates just mentioned; whilst lower down, the stream is almost altogether absorbed, and swallowed up in its sandy channel. From 6 a.m. to 6 p.m. you have all the region bathed in glowing sunshine ; and, at sundown, an icy wind from the Cordillera blows over the heated plains underneath, so that no clothes can protect one from its chilling midnight effects. Dur- ing the season of inundations near the foot of the Andes of Yu- patera, the malaria on this property is so intensely active, that EPIDEMIC INFLUENCES IN PERU. 251 it produces the most malignant remittent and intermittent fevers, which often prove fatal in the first, second, and third accession. In other instances, the endemic fever of this locality assumes the continued type, with a duration of two or three weeks ; much of which time the lies " during patient atabardillado," or in an insensible state of fever with de- lirium. I have known an English overseer who was thus affected, and when he awoke into a state of consciousness, he found himself the only surviving inmate of his once happy home, his wife and children having been all suddenly cut off by the fever, whilst he lay insensible to the sorrows that sur- rounded him. The white inhabitants of the district who survive the endemic fevers, become subject to chronic disease and enlargement of the spleen and liver, while the negro race are the only human beings that thrive in it. The ques- tion of the special influences of race on the origin and spread of particular diseases, is a subject which deserves more atten- tion than it has yet received. On the coast of Peru the negro resists the evil effects of malarial exposure far better than the Indian or European, and he also suffered compara- tively little in the hsemagastric pestilence which recently committed great havoc among the other races. Cold notably modified the type of the recent epidemics, and though the temperature of Piura by day is dry and hot, yet it is a curious problem for the epidemiologist, what may be the effect of nocturnal cold on the type of malarial fevers in such a climate as that of Mono de los Padres, Moropon, and Yupatera? Has the gelid nocturnal breeze from the Cordillera the power of so modifying the miasm of the plains, as that it should in any instance be able to generate the continued, instead of the intermittent or remittent form of fever?and so run its entire course, as I have already observed, in the typhous shape? In the city of Lima, lat. 12 deg. 2 min. S.,long. 76 deg. 58 min. W., six miles from the sea, and about 500 feet above the level, with a population of about 100,000 in- habitants, malarial and pythogenetic causes combined, are in co-operation, and therefore it is quite usual to see the in- termittent fever pass into the typhoid; but the latter often occurs independently, and is one of the prevailing diseases of the capital, though pure typhus is rarely seen there. In the eminently dry province of Piura, the epidemic yellow fever of 1852 and 1853, did not reach'the fatal climax of black vomit; and the'deaths produced by it in certain Indian towns and villages, were chiefly owing to overcrowding in the ill-ven- tilated dwelling places of the poor. It was observed like- 252 EPIDEMIC INFLUENCES IN PERU. wise, in southern Peru, that this epidemic did not, in 1855, diffuse itself within the dry and volcanic oasis of Arequipa ; and though hundreds of cases were imported into the city of that name (lat. 16 deg. 20 min. S., long. 71 deg. 32 sec. W., at the foot of the;snow-capped Misti), no new cases are known to have sprung from them. But beyond and above the richly cultivated and fertile oasis, and suburbs of Arequipa, as at Pocsi and Chihunta,for example, at the elevation of from nine to ten thousand feet above the sea level, and in a cool bracing climate, this pestilence established itself, and extended epi- demically to the southern and inland departments of Puno and Cuzco; and proved most fatal in the city of Cuzco, which is situated at the elevation of about 11,300 English feet. At Cajamarca, lat. 70 deg. 7 sec. S., long. 78 deg. 31 sec. W., and at an elevation above the -Pacific of 9,000 feet, the seasons were observed greatly to influence the force and spread of the epidemic yellow fever, in the years 1855 and 1857. Here the disease abated in the dry season, from May to October, and increased rapidly on the first ap- pearance of gentle showers in the latter end of October. One morning, after some refreshing falls of rain on the pre- ceding evening, almost all the cottages or native huts scat- tered over the extensive plain of Cajamarca, were revisited by the pestilence in the most sudden manner?and in front of every door there lay a corpse of livid or yellow hue, which but a few hours before, was the active living form of a human being: and in course of one month, we are told that Cajamarca lost 3,000 of its inhabitants from the ravages of this formid- able disease. In other parts of inland Peru, however, as on the intercordillera table-land of Cerro Pasco, Janja, and Ayacucho, &c., the epidemic of 1855, much modified in its forms, had widely and rapidly spread abroad in the dry season of the Andes ; and no success has, as yet, attended the attempts made to trace the source of this pestilence to any ascertained peculiarity of atmospheric condition. It is only certain that successive outbreaks of the same epidemic, on different sections of the Andes, were continued from 1853 to 1857-8, as a sequel to the grippe, which in 1851 com- menced simultaneously all over the coast in the month of July, and thence traversed the whole Republic, highlands as well as lowlands, before the middle of September of the same year. This influenza, or grippe, was evidently dependent on some general atmospheric disorder, though too recondite to be made manifest to our ordinary senses; and I am not aware that any scientific meteorological observations were EPIDEMIC INFLUENCES IN PERU. 253 made, in regard to the atmospheric or epidemic constitution of that year.* It was from Lima and the seaports, that the various epi- demics radiated to the interior in north south and central Peru. So that it must be always remembered that while the epidemic had retained sufficient vitality to climb the snowy Cordillera, strewing the mule road and footpaths, with the dead and the dying, it was not in the colder elevations it originated, but in the warm and humid climate of the coast, and in the heat of summer. And it is certainly noteworthy, that wherever a new focus of infection originated (even in cases of ascertained con- tagion) the first symptoms of the malady were confounded with those of an ordinary catarrhal affection, so as to have very generally misled the doctors in the treatment, and especially as to the use of blood-letting, which was followed by rapid prostration of the vital forces. Independently, however, of all considerations respecting the origin of these and other Peruvian epidemics of older date, the diffusion and propagation of them, must have exhibited in their course, various climatic modifications, at the different well- marked zones of elevation above the sea, and particular variations of temperature connected with the epidemic region. As regards the eastern and western side of the same moun- tain chain, Humboldt remarked long ago, that people of a

* I may here allude to what I have fully related elsewhere (see Transac- tions of the Epidemiological Society of London, " On the Epidemics of 1719 20, and 1759, in Peru," part i, vol. 2) regarding the participation of animals, donkeys and dogs, etc., in some of the Peruvian epidemics. One of these fatal epidemics commenced in Buenos Ayres and extended inland to Peru, and was attended with strong hsemorrhagic symptoms ; and the other overran the whole viceroyalty from Potosi to Quito, in an incredibly short period of time. The black cattle of the Sierra of Peru, if driven to the pastures on the coast in summer weather, are very generally attacked by fever, become stu- pified, and die with amazing rapidity of liver and intestinal disease, rendering the dead animal useless for the butcher. It is, therefore, a rule with cattle- dealers, to convey the Sierra cattle to the coast, daring the colder months on the sea board. Dr. Unanue of Lima, used in his Lectures, as I am in- formed, to give an interesting account of an epidemic among the huanacs, or huano birds at the Chincha Islands, where they were seen to rise into the air and drop suddenly dead in flocks at a time. To give an idea of the mul- titude of the birds and the quantity of ordure they are capable of yielding on a given surface in one year, I may just mention the following fact on ;tbe authority of my friend, Dr. Guestas, who was living in Lima when I was last there in 1859 and 18(10. He was a gentleman of great respectability, and owner of a small islet on the coast of South Peru, of about one hundred in or had commenced yards square. Before the foreign trade huano, guano, in Peru, this little property yielded annually 5000 i'anegas, or bushels, of fresh huano manure, worth from four to five Spanish dollars per fanega. But during late years huanacs being much disturbed and diminished in num- bers, the produce of this islet is reduced to less than 3000 yearly. 254 EPIDEMIC INFLUENCES IN PERU.

colder climate, when conveyed into the torrid zone, are readily affected by a hot and vitiated atmosphere, of which the natives scarcely experience the bad effects, and in illus- tration of this remark, he says that the great epidemics of Panama and , used to be signalized by the arrival of ships from Chili, one of the healthiest countries in the world. (See Essai Politique, tome iv, ch. xii, p. 503.) To the same effect, a modern writer observes, that the climate of Lima, which has been always celebrated for its benignity, is not so in the present day. He thinks that the frequent and rapid communication with Panama by steamers, the immense ingress of Chinese and other foreigners, have impaired the local atmosphere of the capital; and consequently, since the year 1851, the population of the capital has been chastised by the frightful epidemic yellow fever, which as a rule, is a disease proper to hot and marshy climates, but which did not spare the sierra of Peru, but almost depopulated the pro- vince of Conchucos (of which the capital, Siguas, is in lat. 8 deg. 50 sees. S., long. 77 deg. 55 min. W.), and other pro- vinces in the .* On the banks of the great inland rivers, Apurimac, and Pachachaca, in the south, and Maranon in the north, this epidemic assumed its gravest forms, and so tracing the march of yellow fever from the Port of Islay, on the Pacific, lat. 16 deg. 32 min. S., long. 72 deg. 43 min. W., across the pass of Santa Rosa to Sicuani, and the city of Cuzco, and thence to the sugar-cane growing valley of Abancay, lat. 13 deg. 37 min. S., long. 72 deg. 30 min. W., the Opuss over a track of ever-varying elevation and temperature of from four to five hundred miles in ex- tent. Since the preceding paragraphs were written yellow fever has again after an interval of twelve years, reappeared in a virulent epidemic form in the capital of Peru and its seaport Callao. In the Lima newspaper, Cumercio, of 13th April, 1868, now before me, I find the following summary of deaths from the reigning yellow fever. In the whole month of March 460 persons died in Callao of this pestilence, of whom 214 were natives, and 246 strangers, and among the latter, there were 110 Chilians, 38 Italians, 22 French, 17 English, 14 Germans, 8 Chinese, 7 Austrians, 5 Portuguese, 5 Mexicans, 5 Dutch, 5 North

" ? See book entitled Geographia del Peru." by Dr. Don Mateo Paz Soldan, and edited by his brother, Don Mariano Felipe Paz Soldan. Vol. i, p. 281, and p. 4.'17. Paris, 1862. EPIDEMIC INFLUENCES IN PERU. 255

Americans, 4 Spaniards, 3 Ecuatorians, 3 Bolivians, 3 Greeks, 1 Swede, 1 Norwegian, and 1 Danish. In this enumeration Protestants, who were 50 in number, are not included. In all the month of March (1868) in the general cemetery of Lima (the capital) 161 who died of yellow fever were buried; and from the 1st to the 10th of April (when the list of deaths ends) 260 victims fell in Callao, and in Lima 150. The population of Callao is about a tenth of that of Lima, but in proportion the number of foreigners will be probably considerably more than in the capital, which may be estimated at about one hundred thousand, exclusive of trans- itory visitors ; the epidemic broke out at Callao, and thence spread to Lima, where it is probable that the daily mortality would be for some time on the increase, until the winter set in about the end of May or middle of June. The epidemic has already spread some way to north and south of the capital; and the most striking feature connected with its diffusion is that while in the neighbourhood of Lima which is in 12deg. 2 min. S. lat., the prevailing epidemic is yellow fever, in the province of Trujillo in 8 deg. 6 min. N., the epidemic is typhoid, as shown by the government despatches as follow :? Lima, February 5th, 1868.?The government having knowledge that the Hospital of Trujillo is incapable for want of funds to render assistance to the poor, and consider- ing that in this population an epidemic of typhoid fevers (" fiebres tifoideas") has broke out, which renders the im- mediate provision of the said establishment necessary, it is determined that the minister of state may give out the re- quisite instructions, to the effect that the Departamental treasury, remit immediately to the treasury of Trujillo 2,500 sols, with destination to the supply of the said hos- pital, &c., &c. Signed, Munos. There is also another order of the same date and tenor from the same minister, Munos, addressed to the deacon of the medical faculty, on the appointment of a salaried medical to forthwith to the bordering province of gentleman proceed " Chachapoyas beyond the Cordillera, to combat the epi- demic that has broken, out there." And further, with date March 3rd, 1868, there is issued by the same authority a order in favour of Dr. Adolpho Olachea, with a com- money " mission to combat the epidemic of yellow fever, la epi- demia de fiebre icteroides," which has developed itself, or broken out at the post of Tumbes, just on the frontier between Peru arid Ecuador. ?56 EPIDEMIC INFLUENCES IN PERU.

From these government commissions to various parts of the republic, we find that now, as in 1853, two modifications of fever?the typhoid and typhus icteroides?prevail in dif- ferent sections of Peru ; and in the present case we can hardly doubt that the same epidemic constitution reigns from Callao to Tumbes in 3 deg. 30 min. Between Lima and Trujillo there are over four degrees of latitude of coast, with a gradual diminution of atmospherical humidity as we proceed northward, and between the province of Trujillo and Piura there is the arid desert called Sechura of ever-shifting sand without water, and about one hundred miles in extent; and the banks of the river Tumbes, as we approach the bay of Guayaquil, is for ever verdant with the never-failing moisture of the Equator. In the dry central district of Trujillo, and in the remote transandine region of Chacha- poyas, in a mild and equable climate, typhoid seems to reign ; while on the Tumbes we have yellow fever, and the rainless and hot province of Piura to the south of the Tumbes, ap- pears to be equally free of both forms of the epidemic, though the intercommunication must be constant. I wish I had the means of accurately collating the facts of these diverse climatic influences, with the precise modifications of fever prevailing in each, in order to be able to trace the phenomenal line of communication and natural connection between them. I hope to receive some further light on this subject yet from Peru. But in the mean time it may be sufficient to observe that on this as on former occasions, yellow fever came in the train of revolution and military commotion in different parts of the country, and ultimate massing of bodies of men in the capital, to which all converged from the outer provinces. The elements of infection probably abounded in the local atmosphere of Callao, the centre of shipping from all parts of the world, and met there suitable material of diffusion among non-acclimated, both natives and foreigners. The connexion between typhoid and yellow fever seems as prominent in the Peruvian epidemics of 1868, as in those of 1853-7 ; and in the epidemic aboard the Jason, on the West* India and Halifax station, described in Dr. Slayter's valuable paper, read at a meeting of the Epidemiological Society of London, 2nd June, J 862, the connexion between yellow fever and various forms of typhus and typhoid fever seems indis- putable.