414 THE BACTERIAL ASPECTS OF PASTEURIZATION 



ton. From this work it is now clear that septic sore throat in man is of human origin, 

 even when the disease is contracted through milk infected in the udder, for it was 

 found that while the human streptococcus is but slightly pathogenic for cows, this or- 

 ganism may become implanted in the udder. This may take place through milking, 

 wiping with infected cloths, through passing quills up the milk ducts, and in similar 

 ways. When this takes place garget does not ensue, but the streptococcus becomes 

 seeded in the udder and may remain for six weeks or longer. In other words, the 

 cow may become a passive carrier of the human streptococcus, thus explaining why 

 milk-borne outbreaks of septic sore throat are sometimes long drawn out. 



The hemolytic streptococci found in milk show distinct cultural and biological 

 differences from St. epidemicus. No single test, however, can be relied upon to differen- 

 tiate them. Brown, Frost, and Shaw found hemolytic streptococci in considerable 

 numbers in the certified milk of five dairy herds. These streptococci belonged to 

 several distinct cultural and serological groups. There is no evidence that any of 

 them, whether from gargety cows or from mixed milk, are pathogenic for man. There- 

 fore, to justify condemnation of the milk supply upon bacteriological grounds alone, 

 the streptococcus found should correspond in all respects with the characters of St. 

 epidemicus. 



Milk- sickness. — Milk-sickness is an acute non-febrile disease due to the ingestion 

 of milk, milk products, or the flesh of animals suffering from a disease known as 

 "trembles." The disease is characterized by great depression, persistent vomiting, 

 obstinate constipation, and high mortality. The picture is that of a poisoning rather 

 than an infection. 



Milk-sickness is primarily a disease of cattle, secondarily of man. In cattle it is 

 called "slows" or "trembles," and formerly was prevalent in the central part of the 

 United States. The pioneers suffered severely in winning the West. Nancy Hanks, 

 the mother of Lincoln, died from the disease in 1818 after an illness of a week. As 

 forests are cleared and pastures fenced the disease becomes less frequent. It is still 

 met with in the valley of the Pecos River, New Mexico, in parts of Tennessee and 

 North Carolina. The cause of the disease has been obscure. Alkali drinking water 

 has been accused; pathogenic micro-organisms have been described; and poisonous 

 plants have been suspected. 



Marsh' studied the rayless goldenrod, Aplopappus heterophylliis, and concludes 

 that milk-sickness is a poisoning due to this plant. He produced trembles or alkali dis- 

 ease in horses, cattle, and sheep by feeding sufficient quantities of the rayless golden- 

 rod. The toxic principle is excreted in the milk, and calves and lambs may be poi- 

 soned in this manner. Stock eat this weed only where there is little good forage. The 

 obvious remedy is to see that the animals are well fed. It is entirely practical to dig 

 out the weed in fenced pastures. 



Malta fever. — Malta fever is a disease primarily of goats, secondarily of man. 

 The infection is transmitted from goats to man through raw milk containing Brucella 

 melitensis. There is an extraordinary relationship between Bruc. melitensis, the cause 

 of Malta fever, and Bacillus abortus, the cause of contagious abortion of cattle. The 

 latter often contaminates milk. Thus, Schroeder and Colton found this bacillus in 



' Marsh, C. D.: Bull. Cur. Anim. IndusL, U.S. Dipt. Agric. May, 1925. 



