Dr. R. J. Reece's report to the local government board on the epidemic of enteric fever in the city of Lincoln, 1904-5.

  • Reece, Richard J.
Date:
1906
Catalogue details

Licence: In copyright

Credit: Dr. R. J. Reece's report to the local government board on the epidemic of enteric fever in the city of Lincoln, 1904-5. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    {B. coli), proof of the destruction of the latter affords convincing evidence of the death of the former. Consequently, we have based our belief in the innocuous character of the water passing into consumption upon the destruction of B. coli, which is always present in the raw waters ; and we may add that we have not been content with affording proof of its absence from one cubic centimetre or even 10 cubic centimetres, but have always submitted as much as 100 cubic centimetres of water to cultural tests. It is apparent, in the light of the foregoing statements, that the absence of B. coli from 100 cubic centimetres of water affords the most convincing evidence of the absence of the typhoid bacillus. Indeed, the absence of B. coli from 10 cubic centimetres of water may perhaps be ■considered sufficient proof of its wholesomeness. Many bacteriologists do not condemn a water unless it contains B. coli in one cubic centimetre. In what follows we deal with a period of two months, namely, from February 11th to April 11th, 1905 :— Treatment of the Raw Waters at the Works. Having regard to our experience of the germicidal action of sodium hypochlorite and to the proportions which we have thought fit to use at the works, we doubt whether any typhoid bacilli, if present in the raw waters, could reasonably be considered to have escaped destruction from February 11th to the time of writing this report. [On February 24th the treatment was interrupted for about three hours owing to an accident to one of the pumps. Without entering into technical details, we may say that, as soon as we were informed of the accident, we took immediate and, as we believe, successful steps to prevent any ill effects which might conceivably have arisen from this.] As regards the destruction of any typhoid bacilli, which previous to the treatment may have been present in the deeper layers of the sand filters, or in the water mains, we •cannot absolutely fix a date ; but, as an extra precaution upon this point, between February 18th and 21st we treated each filter bed in turn with a strong dose of sodium hypochlorite, allowed the germicide to permeate the whole bed, and then closed the outlet valve. After a suitable interval the valve was opened, but so slightly that when the out-flowing water from the bed mixed with the rest of the filtered water from the •other beds, the probability of the mixed water passing into consumption was not affected to any material extent. t To conclude, we think that if any typhoid bacilli entered with the raw water after February 11th they could not have escaped our treatment; and, further, that if any were present in the water system subsequent to that date they could not at the outside have survived beyond February 22nd, when the sectional treatment of the filter beds was completed. In this connection it may be noted that some exhaustive tests quite recently made in America seem to show that the typhoid bacillus cannot live for more than a few ■days in water. Without entering into unnecessary detail, the following facts may serve to illustrate the success (bacteriologicallv) of the treatment :— Thirty-three samples of the water, after treatment and filtration, collected between February 12th and April 12th from a main tap at the waterworks, yielded results as follows :— 9 per cent, of the samples contained B. coli in 10 cubic centimetres of water ; 24 per cent, of the samples contained B. coli in 100 cubic centimetres of water ; 67 per cent, of the samples contained no B. coli in 100 cubic centimetres of water. Over 100 samples collected between February 23rd and April 12th from numerous main taps within the area of water supply, yielded results as follows :— 5 per cent, of the samples contained B. coli in 10 cubic centimetres of water ; -iW 17 per cent, of the samples contained B. coli in 100 cubic centimetres; 79 per cent, of the samples contained no B. coli in 100 cubic centimetres of water. These results were obtained notwithstanding the absence of impounding reservoirs. If the raw water had been stored before filtration our task would have been much easier, and the dose of germicidal agent might have been reduced to about one-fifth or one-tenth of what was actually employed. From a chemical point of view the treated water is probably slightly less pure organically than was the filtered water previous to the treatment with chloros. The latter substance appears to exert a slight solvent action upon the organic matter in the water and in the filter beds (just as it does upon the organic matter of a soil); but, taken in con- junction with the remarkable destruction of intestinal microbes which it effects, this circumstance is of small moment. There is no appreciable change in the water, either as regards chemical composition in general, total solids, chlorine (free or combined), or hardness.