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SCARLET FEVER AND SEPTIC SORE THROAT.
Attention was first directed against milk as a vehicle for spreading scarlet fever by Taylor (1870), but
this report was overlooked, and it was not until a series of extensive epidemics occurred around about 1912, that general attent. ion was focussed upon milk. One of these outbreaks, described by Capps and Miller (1912), involvedmore than 10,000 cases, but a full review of the epidEmiology of scarlet fever during this phase is given by Armstrong and Parr an ( 192?). At this stage it was almost universally believed that some human carrier of streptococci invariably contaminated the milk, but even at this early stage Savage (1911) advanced the hypothesis that scarlet fever streptococci might invade the cows udder, whilst Davis (1912) and Smith and Brown (1915) also favoured this view. The idea was reiterated by Savage in (1931), and again by Minett (1932a), but it was very generally rejected at this stage. The accurate streptococcal typing methods introduced by Lancefield paved the way for the final proving of the hypothesis in a joint report by Bendixen and Minett (1938) describing an outbreak in Denmark, and another at Doncaster in England, in which the scarlet fever epidemics were definitely caused by cows suffering from Strep. PY£g~ mastitis.
In most of the earlier investigations very extensive efforts were made to find some human carrier, who had had direct or indirect contact with the milk. Vlhen it is remembered that the streptococcal carrier-rate can rise to as high as 25% of the population (vide Topley and Wilson 1936), it will be appreciated that a carrier can generally be found somewhere. In Table 11 is given a list of some of the main epidemics that have been reported fairly fully, the references being classified according to
whether or not any serious effort was made to look for a cow carrying scarlet f~ver streptococci in the udder. From this table it is fairly clear that in the majority of extensive epidemics a cow will be found to be a carrier, if an immediate and ,a careful search is made.
STAPHYLOCOCCAL FO OQ.:EQ ISONING.
Since the first report made by ~aber (1914), information has gradually been accumulated to show that certain staphylococci which are sometimes to be found in the cow’s udder canmproduce a toxin which gives rise in man to symptoms of nausea, vomiting, diarrhoea, pyrexia, and prostration. The toxin is sometimes to be found in milk itself, but more often it is produced in cream, or cream derivatives, such as cak~ and pastry fillings. The toxogenic staphylococci may come from milk, or from other sources, such as the finger-nails of some « carrier »·, outbreaks definitely traced to milk being recorded by Crabtree & Litterer (1934) ;&Shaughnessy & Grubb (1936 & 1937).
Minett (1938) made a careful survey of reputed human toxogenic strains, and compared them with strains causing st aphylococcal masti ti.s, and he conol ud ed that certain mastitis strains do produce sufficient toxin to cause food-poisoning epidemics. Hackler (1939) described an outbreak caused by milk, where the infection was introduced by a human carrier during bottle capping operations. He based this opinion chiefly upon the fact that the milk was pasteurised, but such evidence must be treated with reserve, because staphylococcal entero-toxin is relatively heat-resistant, and would not be entirely destroyed by pasteurisation.
SALWIONELLA FOOD-POISONING.
The species gen6rally involved in milk-borne outbreaks of Salmonella food-poisoning are s. dubli~ enteritidis, and Typhi-murium, though other members pathogenic for man would behave similarly after gaining access to milk, Sources of Infection.
Contamination of milk may come directly from the cow, as a result of tlle existence of a septicaemic condition, with organisms filtering through the udder tissue into the milk; or, alternatively, the milk may become contaminated from urine., or faecal splashings from a carrier cow. Secondly, rodents, flies, or polluted water maycause the contamination, and finally it may come from the hands of a human carrier.
Chapter 1. Cows that may be dangerous and Bovine diseases that are economically important.
A. Foodo and Drugs that contaminate milk B. Important diseasl3s of dairy cattle.
( 1) Bovine tuberculosis.
( 2) I! co ntae; ious abortion.
( 3) I! mastitis.
( 4) II paratyphoid fever.
( 5) Other diseases of less importance.
Chapter 2 Important milk-borne diseases of man.
A. The COIN as thG reservoir and spreader
of infect ion.
(1) Tuberculosis.
(2) Undulant fever.
(3) Scarlet fever and septic sore throat.
(4) Staphylococcal food-poisoni:r~.
(5) Salmonella food -poisoning.
(6) Diptheria.
B. Man as the reservoir and spreader of infection.
(l) Typhoid & paratyphoid fever.
(2) Bacillary dysentery.
(3) Scarlet fever & septic sore throat.
( 4) Dipther la.
c. ~he control of milk-borne epidemics in
SC »J.t h Afr ic 3.
Chapter 3. Clean and Dirty Milk.
A. The production of clean milk.
( 1) Materials.
(2) Methods.
(a) Cleanliness.
(b) Temperature & Storage time.
B. The grading of milk.
Chapter 4. The production of milk of rea so nab le chemical quality.
Chapter 5 The provision and maintenance of a safe milk supply.
A. Definition of pasteurisation.
B. Pasteurising plants.
(1) The holder method.
(2) Short-time-high-temperature pasteurisation,
c. The efficiency of pasteurisation.
(1) The design of’ the plant.
(2) The principles of installation and operation.
(a) Rapid heating.
(b) The correct pressure relationships.
(c) Eliminating post-pasteurisation storage.
(d) Eliminating post-pasteurisation recontamination.
D. Maintaining control of pa~teurising plants
(1) Visual inspection.
(2) V=tboratory control.
Chapter 6. Proposed reorganisation of the South African Milk Industry.
( l) Intro due tion.
(2) Nature of proposed Milk Control
Organisation.
(3) Function of the Milk Corporation.
(4) Outline of the Constitution of
the Corporation.
(5) Financial Aspects.
(6) Objections to a Milk Corporation.
BIBLIOGRAP:SX.
