Milk-borne infections in Great Britain.

As long ago as 1857 Dr. Taylor of Penrith showed that an outbreak of typhoid fever was spread by milk. Since that date the literature has been strewn with reports on milk-spread outbreaks of infectious disease, but even so numerous outbreaks remain unrecorded. The importance of milk as a vehicle for the trans mission of disease is due to three factors. The cow may suffer from infections which are common also to man; milk is a suitable medium for the multiplica tion of most pathogenic organisms and ingestion is an important factor in infection; milk is much handled between cow and consumer, so facilitating its infection. There are three sources of human milk-spread infections. (1) Bovine infection of the cow may cause tuberculosis, brucellosis, some salmonella infections, and, very rarely, foot and mouth disease and anthrax. (2) Through the cow, but in the animal due to human bacterial strains implanted from human sources, some scarlet fever and other streptococcal infections and certain staphylococcal infections are so disseminated. (3) Specific contam ination of the milk after it leaves the cow may be the cause of the enteric infections, i.e. typhoid fever, paratyphoid fever and dysentery, diphtheria, some scarlet fever and other streptococcal infections, most staphylococcal infections, and some salmonella outbreaks. Although it is possible to estimate with consider able accuracy the extent to which tuberculosis in man is of bovine origin and to make an estimate of human brucellosis, we are without reliable statistics of the extent of other infections. The Ministry of Health list of milk-borne out breaks of infection reported in Great Britain between 1900 and 1933 and tabulated by the Committee on Cattle Diseases includes 97 outbreaks, analysed as enteric fever 30, paratyphoid fever 7, typhoid and dysentery 4, diphtheria 14, scarlet fever 28, sore throat 5, gastro-enteritis 3, salmonella 3, sickness and diarrhoea 3. G. S. Wilson in The Pasteurization of Milk mentions 69 outbreaks in the years 1912-37 comprising scarlet fever and septic sore throat 40, diphtheria 20, the three enteric diseases 39, gastro enteritis 14; total 113. Both authorities stress the marked incompleteness of the records. The com parative prevalence today of these infections can be judged from the following list of 25 outbreaks over the last seven years collected by the author without any detailed study of the literature. They are (excluding tuberculosis) undulant fever 2, scarlet fever 2, diphtheria 1, typhoid fever 2, paratyphoid fever 4, dysentery 11 (Sonne type 9, other types 2), salmonella Dublin 2, staphylococcus food poisoning 1. Many outbreaks are never recorded in the literature or only obtain brief mention in not readily accessible annual reports of medical officers of health. It is probably a decided understatement to write that well over 50 per cent, of definite outbreaks are never recorded in available literature.