The Milroy lectures on epidemic influences : on the epidemiological aspects of yellow fever : on the epidemiological aspects of cholera / by Robert Lawson.

  • Lawson, Robert, 1892-1957.
Date:
1888
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Licence: Public Domain Mark

Credit: The Milroy lectures on epidemic influences : on the epidemiological aspects of yellow fever : on the epidemiological aspects of cholera / by Robert Lawson. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    years was 129,527; of these 14,752, or 11*4 per cent., sailed in tlie above noticed thirtj-two vessels, and of these 18 L died of cholera, or 12'8 per ],000 of those embarked in them. Ships leaving Calcutta for places south of the Equator, or round the Cape, proceed south as near as they can to the meridian of 90° east until they reach the south-east trade wind, and from this point their track is very nearly the same, whether their destination be Mauritius, Natal, or the Cape. Taking the mean of several cases, the approximate latitude of a sailing ship, from Calcutta, on the sixth day at sea is about 15° north, on the fifteenth day about 7° north, and on the twentieth day about 1° north, with a varia- tion, in individual instances, of about three degrees in the last. It thus appears that sailing vessels during the first of the three periods mentioned must have been between the land and 16° north, in the second from 15° north to about 2° north, and during the last from about 1° north southwards, and the factors which determined these outbreaks must have become active in these positions respec- tively. The deaths up to the sixth day, being all due to cases arising within the recognised incubative period, may be referred to exposure to the cause previous to embarkation. Six ships had such cases in 1872-74, and three only in the other seven years of the decade. During the second period fourteen ships were affected in 1872-74, while there were only six in the other seven years. In the third period twelve ships were affected in 1872-74, and four only in the other seven years. One of the ships in 1874, the Blenheim, was a steamer. She embarked her emigrants on 13th June, and landed them at Natal on 8th July, the twenty-sixth day after. The vessel had five deaths in all, after the twentieth day, consequently she must have been south of Mauritius when the outbreak commenced. Another vessel, the Enmore, was a steamer; she sailed for Demerara on 4th July, 1873. There were two deaths in this ship by the fifth day, three from the eleventh to the twentieth, and five more after the twentieth day. On the assumption that her progress southward did not differ materially from that of the Blenheim, the Enmore must have been south of Mauritius also by the twentieth day. While these manifestations were taking place at sea, there seems to have been an outbreak of cholera in the Isla.nd of Timor in 1872. In 1873 it was epidemic at Sincapore, in the Kingdom of Siam, and along the valley of the Irawaddy from Rangoon to Bhamo; and the Dutch troops at Acheen, at the north end of Sumatra, were attacked in December, and during 1874 they suffered severely.