4 BULLETIN 342, U. S. DEPARTMENT OF AGRICULTURE 
These pathogenic organisms are now considered to be of public- 
health significance since they may cause human disease. Evans (24) 
has also shown that the abortus group contains several different species 
and she later (25) reported on a number of cases of Malta fever due 
to Brucella melitensis. Whittaker and his committee (64) state that 
it has recently been recognized that undulant fever is caused by B. 
abortus (B. melitensis), which is responsible for infectious abortion in 
cattle and swine. This report further states that health authorities 
should recommend to American milk consumers that the general 
market milk supply be pasteurized before it is consumed. Arnold 
(1) found living Brucella after exposure to the temperature of com- 
mercial pasteurization. This was contrary to the findings of Boak and 
Carpenter (14), who concluded that an exposure of 15 minutes at 
140° F. (60° C.) destroyed the human and bovine cultures of B. 
abortus. Gilbert and Coleman (28) report several cases of undulant 
fever and state that a consideration of the data available indicates 
three possible reasons why cases of undulant fever are not reported 
more frequently in districts where unpasteurized milk is used from 
herds in which contagious abortion is prevalent. Many of the severe 
infections of undulant fever have probably been diagnosed as cases of 
typhoid fever, influenza, or even tuberculosis or malaria; mild forms 
may have presented so few symptoms that physicians have not been 
consulted ; and the blood from some cases of undulant fever may not 
have agglutinated cultures of B. melitensis or B. abortus. The labo- 
ratory data and epidemiological findings of Hardy and others (33) 
show that controlled pasteurization is effective against organisms of 
the Brucella group, and Hasseltine (34) states that pasteurization of 
the milk renders it safe and takes care not only of undulant fever 
but of all other communicable diseases transmitted by milk. 
Scamman (51) reports that through 1928, 45 milk-borne outbreaks 
of septic sore throat have been recorded in the United States. In 
some of these epidemics it was found possible to destroy by pasteuriza- 
tion the streptococci isolated from throats of infected people and be- 
lieved to be the infective agents. Pasteurization, properly performed, 
protects against epidemics of this kind. 
The determination of the thermal death point of pathogenic strepto- 
cocci by various investigators together with past experience with the 
use of properly pasteurized milk indicates very clearly that the thermal 
death point of these organisms is relatively low and that they are 
readily destroyed by proper pasteurization. Thus Hamburger (29) 
who studied the epidemic of septic sore throat in Baltimore in 1912, 
traced this epidemic to a certain milk supply. Advice to boil all 
milk was given, and the dairy to which the epidemic was traced, raised 
the temperature of its flash process to 160° F., and then changed to 
the holder process, by which the milk was heated to 145° and held for 
a period of 30 minutes. The cases of sore throat that followed were 
neither as severe nor as numerous and did not follow the milk supply, 
but appeared to have been transmitted from individual to individual. 
Hamburger (30) also found that a streptococcus, isolated from a 
patient having a case of sore throat, was killed by heating m milk 
at 145° for 30 minutes. Davis (19) found that streptococci isolated 
from cases of sore throat were readily killed by heating at 140° F. 
for 30 minutes. He also found that none of 24 strains of pathogenic 
hemolytic streptococci of human origin resisted heating at 140° for 
30 minutes. 
