INSECTS AND DISEASE Fig. 21. WALTER REED Fig. 23. JAMES CARROLL Fig. 24. ARISTIDES AGRAMONTE
AMERICAN MUSEUM GUIDE LEAFLETS Two years blter. early mm the year 1900. 2 commission of army officers was appomted to study the disease im Havana as 2 resultofa number of cases which had occurred among the American troops — statiomed there. The Chairman of the Commission was Dr. Walter Reed. and his associates were Dr. James Carroll, Dr. Jesse W. Lazear, and Dr. Aristides Agramonte. At the very beginning, the investigztors turmed their attention to the mosquito as 2 possible agent im the transmission of the disease. Dr. Carlos ] Finlay of Havana had suggested the mosquito theory of yellow fever very convincingly im 1881. though without experimental proof, and the discoveries of Manson and Ross and Grassi and Bijnami had recently demonstrated 2 similar origin for malaria. Reed and his colleagues were fortunate im thus beginning almost at once with a correct hypothesis.
The lower animals do not suffer from yellow fever, so that experiments upon human subjects were essential. In the words of Dr. Kelly's Ife of Major Reed. “after careful consideration, the Commission reached the conclusion that the results, if positive, would be of sufficient service to humanity to justify the procedure, provided, of course, that each individual subjected to experiment was fully informed of the risks he ran, and gave his free consent- The members of the Commision, however, agreed that it was their duty to run the risk involved themselves, before submitting anyone else to i.~ The first successful experiment was made with Dr. Carroll, who allowed himself to be bitten on August 27 by 2 mosquito which had previously bitten four yellow fever patients. Four days later he was taken sick and for three days his life hung in the balance. Both he and Private W. H. Dean, the second case produced experimentally in the same way, recovered. Dr. Lazear, however, who came down with the disease, not 2s 2 result of the experimental inoculations to which he also had submitted, but from an accidental bite, was less fortunate than his colleagues, for a week later he died, after several days of delirium with black vomit.
An experimental station, named “Camp Lazear” after this first martyred member of the party, was established in the open country; and to the lasting honor of the United States Army, volunteer subjects for the experiments from among the troops were always in excess of the demand. Private John R. Kissinger and John J. oa
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AMERICAN MUSEUM GUIDE LEAFLETS spread of yellow fever—it was all an unfathomable mystery—but today the curtain has been drawn’’; and later on New Year’s Eve— “only ten minutes more of the old century remain. Here have I been sitting reading that most wonderful book, ‘La Roche on Yellow Fever, written in 1853. Forty-seven years later it has been permitted to me and my assistants to lift the impenetrable veil that has surrounded the causation of this most wonderful, dreadful pest of humanity and to put it on a rational and scientific basis. I thank God that this has been accomplished during the latter days of the old century. May its cure be brought out in the early days of the new.
The practical result of this discovery was immediate and striking. In the half century or so for which we have records, yellow fever had killed an average of 750 persons a year in the City of Havana. The sanitary reforms introduced by the American army of occupation which produced good results in reducing typhoid and smallpox had been powerless against yellow fever because its cause was as yet a mystery. Following immediately on the experiments at Camp Lazear, on February 15, 1901, a campaign was begun on the new lines indicated, by screening the rooms occupied by yellow fever patients and destroying all mosquitoes in the neighborhood. Asa result there were six deaths in the City of Havana during the year 1901 as against 305 in the preceding year, and although sporadic cases have been introduced from other localities, yellow fever has never again established itself in Havana. The scourge of centuries was wiped out in a single year.
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773 INSECTS AND DISEASE THE SUCTORIA OR FLEAS The Suctoria or fleas are small, wingless, jumping insects which are strongly compressed sideways. They are all parasitic, when adult, on warm-blooded animals; but the footless, worm-like larve are not. Adults of both sexes have piercing mouth-parts and suck blood. The larve, however, have chewing mouth-parts and feed on more solid organic material. The larve live in dust and refuse on the floor or ground and pupate there, usually in thin silken cocoons.
The Dermatophilidz, one of the principal families of Suctoria, have the segments of the thorax much shortened and constricted, but the side-plates of the metathorax extend over two or three abdominal segments; the third antennal joint has no completely separated false joints; and the fully developed female, living beneath the skin of her host during her final development, has a greatly dilated abdomen. The most familiar example is Dermatophilus penetrans, the “‘chigoe,” “‘chique,’’ “chigger,”’ “‘jigger,’’ or “‘sandflea.’ The fertilized female burrows under the skin, especially about the toes, and causes a nasty ulcer. The eggs which she lays in the ulcer, or the larve which hatch from them, drop to the ground for further developmert. The female may be picked or squeezed out of the ulcer and the wound should then be carefully treated to clear away the pus. Asa method of control—even if not for other reasons!—the habitations of men and domesticated animals should be cleaned to destroy the larva. This species is found in the warmer parts of America and in Africa. Members of the family Pulicide, on the other hand, do not have the thoracic segments much constricted and shortened but the side plates of the metathorax extend over only one abdominal segment; the third antennal joint has nine more or less distinctly separated false joints; the spines on the hind tibiz are in pairs, are few in number, and are not in a very close-set row; and none of the species burrow under the host’s skin. In the senus Ctenocephalus both the head and the pronotum (front section of the thorax) have stout, spine-like bristles (ctenidia); the last tarsal joint has four pairs of lateral spines and, in distinction from /Veopsy/la, the eyes are distinct. In Ceratophyllus the head has no ctenidia but the pronotum does; the last tarsal joint has five pairs of lateral spines. In Pulex and Xenopsylla neither the head nor the pronotum has ctenidia. The distinction between these two genera is chiefly based 49
AMERICAN MUSEUM GUIDE LEAFLETS on internal anatomy. Ceratophyllus fasciatus is the rat and plague flea of temperate regions. It feeds on rats, mice, skunks, and man. In America, it seems to be confined to California; but it also occurs abundantly in Europe. Xenopsylla cheopis is the tropical rat and plague flea. Although it largely confines its attentions to rats, it also, unfortunately, attacks man. The cosmopolitan human flea (Pulex irritans) is most abundant in warm regions, and attacks rats, skunks, and domestic animals as well as its normal prey, man. The cat and dog fleas, Ctenocephalus canis (female’s head less than twice as long as high) respectively, are common parasites. Fig. 26. MODEL OF THE FLEA (Pulex irritans) American Museum of Natural History 50
INSECTS AND DISEASE THE BLACK DEATH AND ITS CONTROL Of all the insect-borne diseases, the one that has proved in the past most deadly to mankind is bubonic plague, a malady closely bound up with the activities of the insect pests which have just been discussed. We have records of the ravages of this disease from very early times. The countries of the Levant have been centers of plague infection for 3,000 years as a result of their unique position as gateways between the East and the West. Plague among the Philistines is described in the First Book of Samuel, the golden images of tumors and of mice, prepared as sacrificial offerings, referring clearly to one of the characteristic symptoms of the disease and to its prevalence among rodents.
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Sheree Fig. 27. THE PLAGUE AT EPIRUS. P.MIGNARD (1610-1695) The first fully recorded pandemic of plague broke out at Pelusium in Egypt in 542 A. D. and spread by way of the principal trade routes of the time into Palestine and then to the rest of the known world. Procopius says of this outbreak, of which he was a witness “‘It spared neither island nor cave nor mountain top where man dwelt. ... Many houses were left empty and it came to pass that many from want of relatives and servants lay unburied for several days.” 51
AMERICAN MUSEUM GUIDE LEAFLETS The second pandemic of plague, the Black Death of the Middle Ages, originated in Mesopotamia about the middle of the eleventh century. In the track of travel and commerce, particularly on the route of the returning crusaders, it quickly spread to the West and North. It is said that 25,000,000 people, one fourth of the population of Europe, perished of plague during the fourteenth century. A third pandemic of plague which is still going on at the present time (1918) broke out at Yunnan Fu in China in 1871 and attracted seneral notice when it reached Hongkong in 1894. From this point Fig. 28. MODEL OF CORNER OF RAT-INFESTED DWELLING American Museum of Natural History the disease made its way to India where it raged unchecked for ten years and carried off 6,000,000 people. This time, however, the world invasion of the Black Death was to be met by a new defensive mechanism, the organized force of scientific research. A Japanese bacteriologist, Yersin, discovered the bacillus of plague in 1894 and it was soon proved that the disease from which rats were simultaneously suffering (as they had done in the days of Samuel) was the same as the human plague. The infection may be more or less chronic among the rodents, persisting among them for years as 52