Cochin China and China, spreading at the same time to the islands of the Eastern Archipelago. From India it was carried by the coolie ships to Mauritius and Réunion in 1873.

An epidemic which I witnessed in Amoy (1872) illustrated very well a characteristic feature of dengue epidemics— namely, the peculiar suddenness of their rise and extension, and the general prevalence of the disease in an affected community. I am under the mark when I say that in this particular epidemic quite 75 per cent, of natives and foreigners were attacked within a very few weeks. All ages and occupations, both sexes, and people in every condition of life, were alike subject to it. About the first week in August I heard that a peculiar disease had appeared in the town; by the end of the second week the cases were numerous, whole families being prostrated at a time. A week later the cases were still more numerous, and by the end of the month so general was the disease that the business of the town was seriously interfered with. By the end of the following month —that is to say, in about eight weeks from the first appearance of the epidemic all the susceptible apparently had passed through it, and, so far as Amoy residents were concerned, the disease was at an end, cases occurring for a few weeks longer only in visitors from unaffected districts. This course seems to be fairly typical of all dengue epidemics.*^[1]

Etiology.— Germ.— Various bacteria have been described. Graham describes an intracorpuscular amœba, resembling Babesia bigemina, which he states he found in great profusion in the blood of dengue patients in Beyrout, Syria. He maintains

1. ↑
   • It is on my experience in this epidemic that I have based my description of dengue. In the vast majority of the cases the
   characteristic primary and secondary fevers, the initial and terminal skin rashes, and the rheumatic-like pains were well marked. Of course, as with all specific fevers, there was a proportion of atypical cases in which some of the characteristic symptoms were absent or only slightly marked. Remembering my experience of this epidemic, I cannot understand the difficulty some recent Indian observers seem to have in differentiating dengue from seven-days' fever and the like. The skin rashes alone should suffice, especially if taken in conjunction with the double fever and the pains.