[Report 1952] / Medical Officer of Health, Hertfordshire County Council.

  • Hertfordshire (England). County Council. n 50062101.
Date:
1952
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: [Report 1952] / Medical Officer of Health, Hertfordshire County Council. Source: Wellcome Collection.

    102/108 (page 102)
    Unfortunately undulant fever is not a notifiable disease and while it appears that the incidence of the disease is low owing to the fact that few cases come to our knowledge, it is possible that there are many “ missed ” cases in the form of pyrexias of unknown origin which are not diagnosed as being due to the abortus organism. The only answer to brucella infected milk would appear to be universal pasteurization. Brucella Melitensis. During the year there was one case where Brucella Melitensis was isolated from a herd in the county. The infected cow was traced and was slaughtered under the Melitensis Order. No undulant fever cases were reported in people who had consumed the milk, the bulk of which was being sent for pasteurization. (c) The Supervision of Pasteurizing Plants. The County Council, as Food and Drugs Authority, licences and supervises pasteurizing plants in all districts with the exception of Watford Borough and the City of St. Albans, which are separate Food and Drugs Authorities. Pasteurized milk has to comply with the phosphatase test to ensure that it has been subjected to sufficiently high temperature for the specified period of time which will ensure the destruction of pathogenic organisms. A modified methylene blue test is also used to determine the cleanliness or otherwise of pasteurized milk. The following table shows the results of sampling from plants during the year. Table 26. No. in County Phosphatase Test Methylene Blue Test No. Failed 0/ /o No. Failed 0/ /o H.T.S.T. Plants 6 373 5 1-34 357 1 0-28 Batch Holder Pasteurizers 13 627 25 3-99 591 5 0-85 Batch Holder Plants coupled to obtain continuous flow . 1 82 2 2-44 76 — — 20 1,082 32 2-96 1,024 * 6 0-59 * 58 of these samples were not subjected to the methylene blue test owing to atmospheric temperatures being above 65° F. The High Temperature Short Time plant subjects milk to a pasteurizing temperature of not less than 161° F. for a period of not less than fifteen seconds ; the batch holder heats and retains the milk at a temperature between 145° F. for not less than thirty minutes, and a modification of the batch holder subjects the milk to the same time/temperature treatment as the holder plant but the operation is controlled automatically to enable a series of holding compartments to be filled and emptied so that the process is continuous. The County Health Inspector visits each pasteurizing plant at least once a month and special investigations are carried out if failing samples are reported. The County Sampling Officers visited each plant at least once a week and during the year took 981 samples. 225 visits were made by the County Health Inspector to the various plants and a further 144 samples, many of them experimental, were obtained in addition to those taken by the Sampling Officers. It will be seen from the table that once again the lowest percentage of failing phosphatase samples came from the High Temperature Short Time