On the mode of communication of cholera

by John Snow

CHOLERA IN EXETER.

The first cases of cholera in Exeter in 1832, were three in the same day, besides one in St. Thomas’s, a suburb of Exeter, in a gentleman just arrived from London, where the disease was prevailing. The other three were a woman and her two children; the former, with one of her children, had returned from Plymouth the previous day, where she had been nursing a child that had died of the cholera. Within five days from this time, there were seven fresh cases in as many different parts of the town, amongst persons having no intercourse with each other or the first cases. The disease soon became very prevalent, and in three months there were 1,135 cases, and 345 deaths. Exeter is situated on ground which rises from the edge of the river to an elevation of one hundred and fifty feet. In 1832 the inhabitants were chiefly supplied with river water by water-carriers, who conveyed it in carts and pails. Dr. Shapter, from whose work[^[21]] the above particulars are obtained, kindly furnished me with information concerning the sewers, and with maps of their position. The water-carriers, by whom Exeter was very greatly supplied, obtained their water almost exclusively from certain streams of water, diverted from the river in order to turn water-mills; and one of the chief sewers of the town, which receives such sewage as might come from North Street, in which the first cases of cholera occurred, empties itself into the branch from the river which divides into the two mill-streams just mentioned. It must be remarked that the parish of St. Edmund, in which these streams of water were situated, had a lower mortality from cholera than other parts of the town like it, densely populated and on low ground near the river. Dr. Shapter attributes this lower rate of mortality, and I believe rightly, to St. Edmund’s being freely intersected by running streams of water. The people would probably not drink more of the water than in parts of the town where it was less plentiful, and had to be paid for, but they would have much better opportunities for personal cleanliness: so that whilst they would be exposed to only the same number of scattered cases, they would be less likely to have the malady spreading through families, and by personal intercourse. After the cholera of 1832, measures were taken to afford a better supply of water to Exeter; not, so far as I can find by Dr. Shapter’s work, that its impurity was complained of, but because of its scarcity and cost. Waterworks were established on the river Exe, two miles above the town, and more than two miles above the influence of the tide. Exeter has since been very plentifully supplied with this water, and Dr. Shapter informed me that in 1849 there were only about twenty cases of cholera, nearly half of which occurred in strangers coming into the town, and dying within two or three days after their arrival. This last summer there was only one death from cholera in Exeter.

CHOLERA IN HULL.

We will now consider the town of Hull, in which, together with other sanitary measures adopted since 1832, there has been a new and more plentiful supply of water, but with a far different result to that at Exeter. In 1832 Hull was scantily supplied with water conveyed in pipes from springs at Anlaby, three miles from the town. About 1844, new waterworks were established to afford a more plentiful supply. These works were situated on the river Hull, at Stoneferry, two miles and three quarters from the confluence of that river with the Humber. About half the sewage of the town is delivered into the river of the same name, the rest being discharged into the Humber, as appears from information and a map kindly furnished me in 1849 by Dr. Horner of Hull, who was making great efforts to have better water obtained for the town. The tide flows up the river many miles past the waterworks, carrying up with it the filth from the sewers. The supply of water was, to be sure, obtained when the tide was down, but as the banks of the river are clothed with sedges in many parts, and its bottom deep with mud, the water can never be free from sewage. Moreover, there are some parts of the river above Stoneferry much deeper than the rest, and where the deeper water is, according to the testimony of boatmen, nearly stagnant; thus allowing the water carried up by the tide to remain and gradually mix with that afterwards flowing down. There are also boats, with families on board, passing up the river to the extent of five thousand voyages in the year. The water when taken from the river was allowed to settle in the reservoir for twenty-four hours, and was then said to be filtered before being sent to the town. In 1832 the cholera was confined almost exclusively to the poor, and the deaths amounted to three hundred.

In 1849 the deaths in Hull (including the suburb of Sculcoates) were 1834, although 8,000 or 10,000 left the town, it is said, to avoid the ravages of the disease. Dr. Horner informed me that the deaths occurred amongst all classes of the community, and that the town was much better drained in 1849 than in 1832.

CHOLERA IN YORK.

When the cholera made its appearance at York, about the middle of July 1849, it was at first chiefly prevalent in some narrow streets near the river, called the Water Lanes. The inhabitants of this spot had been in the habit, from time immemorial, of fetching their water from the river at a place near which one of the chief sewers of the town empties itself; and recently a public necessary had been built, the contents of which were washed every morning into the river just above the spot at which they got the water. In a short time from twenty to thirty deaths occurred in this locality; but the medical men considering the impure water injurious, the people were supplied from the waterworks, with water obtained from the river at a point some distance above the town, and the cholera soon ceased nearly altogether in this part of the city, but continued to spread in some other parts. The cholera having thus abated in the Water Lanes, the gratuitous supply of water was cut off, and the people went to the river as before. There were still cases of cholera in the town, and it soon broke out again in this locality, and in the first few days of September eight deaths occurred among the persons who used water obtained direct from the river. The tap for general use was again opened, and the river water interdicted, and the cholera again ceased, and did not recur. These circumstances were communicated to me by a friend on whose accuracy I can rely.

The inhabitants of Dumfries drink the water of the river Nith, which flows through the town, and into which the sewers discharge their contents, which float afterwards to and fro with the tide. In 1832 there were 418 deaths from cholera out of a population of 11,606, being at the rate of 360 in 10,000, or 1 in every 28 of the inhabitants. The cholera again visited Dumfries at the close of 1848, and carried off 431 persons, or 1 in every 32, out of a population now numbering 14,000; so that the mortality was excessive on both occasions.

Preston and Oldham, in Lancashire, are supplied with water from surface drainage on the neighbouring hills, and there was scarcely any cholera at either of these places in 1849. The greater part of the town of Paisley is supplied in a similar way; and I was informed that the cases of cholera which occurred there in 1849 were confined to a quarter of the town to which this supply of water does not extend. Nottingham is supplied with filtered water obtained from the river Trent, some distance above the town. In 1832 this supply did not extend to all the inhabitants, and the cholera was somewhat prevalent amongst the poor, of whom it carried off 289; the population of the town being 53,000. After that time the water was extended copiously to all the inhabitants, and there were but thirteen deaths from the epidemic in 1849. The local Sanitary Committee placed the supply of water amongst the chief causes of this immunity from cholera, and I believe justly. There were but seven deaths from cholera in Nottingham last summer.

CHOLERA IN GLASGOW.