importance. While these investigators have not proven that the mosquito is the essential factor in disseminating yellow fever, still they offer as a result of their studies very strong indications in favor of this view, and leave little room to doubt the direction that future studies of this subject should take. If the position taken by Reed and his associates be correct, and if subsequent investigations prove beyond doubt that yellow fever, like malaria, is carried from the sick to the well by mosquitoes, or that the mosquito serves as a host for the development of a parasite obtained from other sources and capable of causing yellow fever in persons bitten by the insect, it is evident that we shall, as in the case of malaria, have not only a satisfactory standpoint from which to interpret many phases of the subject that are not yet clear, but we shall be moreover in possession of information that will obviously necessitate radical changes in many of our methods for the prevention of this disease.'

Prophylaxis.-The most important measure against the introduction of yellow fever into a locality is good general sanitation, including clean and well-drained streets, proper disposal of garbage and excreta, prevention of overcrowding, an abundant supply of pure water for domestic purposes, and a competent system of quarantine.

With the occurrence of the disease all cases should be isolated. Their discharges, including those from the bladder, bowels, and vomited matters, also all the soiled body- and bed-clothing, should be carefully disinfected. The sick chamber should be clean and well aired. In case of death the body should be wrapped in a sheet soaked in a reliable disinfectant, placed in a close coffin, and buried or cremated at once. If buried, it should be in a place from which there would be no danger of the pollution of neighboring watersupplies.

The results of the studies of Reed and his associates, noted above, point so directly to the mosquito as the prob

1 Later news from Reed and his colleagues still further strengthens their opinion as to the part played by mosquitoes in spreading this disease. See Journal of the Am. Med. Assoc., 1901, No. 7, Feb. 16.

able mode of dissemination, that until it is proved innocent of this rôle no effort for its extermination should be spared. What has been said on this point under Malaria will serve equally well here.

Under the headings "Disinfection of Apartments" and "Disinfection of Ships" will be found the steps necessary to render quarters occupied by those patients free from danger.

DENGUE.

Definition. A specific, epidemic, febrile disease of tropical and subtropical countries, that is characterized by suddenness of onset, severe pains in the muscles and articulations, the appearance of an initial and terminal rash, and by a tendency to terminate favorably in from three to four days.

It is also variously known as “breakbone fever,” “dandy fever," "three days' fever," etc. It is certainly infectious, though no micro-organism has as yet been proved to stand in causal relation to it.

Its outbreak is favored by high temperature and by geographical location more than by any other known factors. It is most apt to occur, even in the tropics, during the warmest months. In higher latitudes, that are still within its epidemic zone, the greatest number of outbreaks have occurred during summer and early autumn. It rarely develops at a temperature below 64° F. (Hirsch), and its progress is, as a rule, suddenly checked by the onset of cold weather and the occurrence of frost.

It is a disease of low-lying localities along the coast, especially of overcrowded, unsanitary towns and cities. It rarely extends into the country, and only very exceptionally has it been observed at high altitudes.

Neither physical conditions of the soil, nor such meteorological influences as atmospheric moisture, rain, and wind,

have any apparent influence upon the course and occurrence of the disease so long as the temperature remains favorable.

Neither race, age, sex, nor social condition is regarded as a conspicuous factor in either predisposing to or protecting from dengue.

The march of the disease through a community is often so rapid that from 60 to 75 per cent. of all the inhabitants will be affected within a few days of its primary appearance.

By certain authors dengue is said to simulate yellow fever in some respects. By others it is regarded as predisposing to subsequent infection by yellow fever, cholera, typhoid, or malaria. By some a single attack is thought to afford protection, by others this is denied.

In marked contrast to the severity of the symptoms of this disease stands the rarity with which it proves fatal. It is apparently dangerous for only the very young and those of the aged who are already affected with grave organic lesions. Many epidemics pass away with no deaths at all, and even in the severest the number of deaths has "not yet reached as high as 0.5 per cent. of those affected" (Scheube). It is said to occur among animals (horses, cows, dogs, and cats).

Dengue has been recognized as a distinct disease since 1824, though descriptions of an identical affection occurring in Egypt, Spain, Java, and India were given in the latter part of the eighteenth century. During the present century it has appeared on a number of occasions in India, Africa, the West Indies, and southern United States. The first recognized epidemic in this country occurred in Savannah, Ga., in the fall of 1826. During the two following years it spread throughout the southern States, the West Indies, and the northern coast of South America. Between 1848 and 1850 and in 1854, widespread epidemics occurred along the Mississippi valley and in the southern Atlantic seaboard States. The last epidemic occurred in 1873 in Alabama, Mississippi, and Louisiana. The "bilious remitting fever" described by Rush in 1780, as occurring in Philadelphia, is regarded by Hirsch as dengue fever. The zone of epidemicity of this dis

ease is embraced between lat. 32° 47' north (Charleston, S. C.) and 23° 23' south (St. Paulo, Brazil) (Hirsch).

Dissemination.-It is questionable if dengue is contagious. At first sight, its rapid spread throughout a community may be attributed to a very high degree of contagiousness. On further inquiry, however, this seems to be erroneous. Like influenza, with which it is held by some to be closely allied, by others to be identical, it has been observed to spring up suddenly at various points in the same locality among persons who have had no communication with one another. Its rapid spread is therefore regarded as due more to the simultaneous infection of large numbers of individuals from a common focus or source, rather than from the transmission of the morbific material from person to person. Again like influenza, it is believed to be carried from place to place along lines of travel by land and sea. After the subsidence of an epidemic it occasionally happens that, in places of suitable temperature, dengue remains endemic for a time.

Prophylaxis.-As a rule, special preventive measures against dengue have not been practised, probably because of the comparative rarity with which the disease proves fatal; and indeed, until we possess some knowledge of its exciting cause and of its mode of dissemination, it will be difficult to institute a rational system of prophylaxis. The fact of its sudden and simultaneous occurrence among groups of individuals in the same locality, who have in no known way been exposed to contagion, and of the coincidence of epidemics in different places, illustrates the insidious nature of its dissemination and the, for the time being, ubiquity of the poison. Isolation of the sick, with disinfection of excreta, clothing, and apartments, might be practised, but it is doubtful if this would prove of any marked influence in checking the march of the epidemic.

TYPHUS FEVER.

Definition. A specific, contagious fever characterized by a maculated rash, extreme depression of the vital powers, nervous derangements, and a tendency for non-fatal cases to terminate by crisis in about two weeks.

It is also variously known as "spotted fever," "jail fever,” camp fever," "ship fever," and "hospital fever." Its specific exciting cause is not known, though doubtless such a factor exists. It is universally admitted that the most important influences that predispose to its epidemic occurrence are widespread destitution and misery, with their usual concomitants-viz., overcrowding, filth, poor and insufficient food, intemperance, and inadequate clothing and shelter.

In former years epidemics of typhus fever occurred with. comparative frequency, both in Europe and in this country; but latterly-i. c., during the past twenty-five years-by reason of the sanitary improvement that conditions of life have everywhere undergone, its visitations have become fewer until it has practically disappeared, as a dreaded pest, from among civilized peoples.

Distribution. The occurrence of typhus fever is not markedly influenced by geographical location, though it is usually regarded as more likely to occur in temperate and cold than in the warmer climates, possibly because of the conditions favorable to open-air life that the latter afford.

Its epidemic outbreak is, as a rule, referable to the predisposing influence of the social condition of the people among whom it occurs. The history of the disease, during the time when it was more frequent than it is to-day, points directly, as stated above, to widespread destitution and misery, with all that they entail, as the important factors in determining the development of an epidemic. Up to about the middle of the present century it had occurred epidemically in many parts of both the eastern and western hemispheres.

Australia, New Zealand, Japan, a large part of Africa, and parts of southern Europe have been comparatively free from the disease. According to Hirsch, endemic centers have be