CO129-562-12 Dysentry epidemic- recommendation to enforce compulsory pasteurization of milk 7-6-1937 - 17-8-1937 — Page 21

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adolescents and adults with a history of glandular tuberculosis in childhood completely disprove the hypothesis that a slight infection with bovine bacilli in early life preserves one from phthisis later. A person infected in childhood with bovine tubercle bacilli may in adult life develop phthisis due to these same bacilli and may possibly spread bovine tuberculosis to other human beings and to animals through the agency of the sputum. We cannot, in view of these facts, accept the suggestion that a few bovine bacilli may be permitted in milk on account of their immunising value; the evidence that sub- clinical infections afford permanent protection against tuberculosis is quite inadequate and, as already pointed out, the risk outweighs the hypothetical advantage.

57. There is thus ample evidence that a large number of cases of bovine tuberculosis occur in man, and that the milk supply is seriously infected with bovine tubercle bacilli. The relation between the degree of infection of milk and the incidence of disease in man is complicated and is discussed in a subsequent part of our report (paragraph 133). Here we confine ourselves to the remark that serious cases of disease are few in comparison with the opportunities of infection. We also postpone the discussion of the means by which the degree of infection in milk may be limited.

(ii) Undulant fever.

58. Undulant fever is closely allied to Malta fever, an infection derived from the consumption of the milk or the flesh of goats, due to Brucella melitensis. It is, however, due not to that organisin but to Brucella abortus of bovine origin or to Brucella abortus suis. It is contracted from the consumption either of cow's milk or of the flesh of swine, or possibly from contact with infected animals. In Great Britain contagious abortion of swine is comparatively rare, and it is believed that milk is the principal source of human infection.

59. The extent to which milk is infected is not definitely known, but it is established that cows infected with contagious abortion pass infected milk in a large proportion of cases, though perhaps inter- mittently. Such tests of mixed milk as have been taken indicate that herd samples are more frequently infected with Brucella abortus than with the bovine tubercle bacillus. In spite of this, undulant fever in man is very rare. The numbers of cases recorded in England and Wales in recent years have been as follows:-

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1929

1930

1931

1932

5

17

28

40

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It is possible that the disease often passes unrecognised, for a considerably heavier incidence is reported in other countries,

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