MEASLES, SCARLET FEVER, MUMPS, DENGUE FEVER, ETC. 929 



the throat. It remains contagious throughout the disease and far 

 into the convalescent period. In ordinary uncomplicated cases the 

 infectiousness probably ends three or four weeks after disappearance 

 of the rash, but when suppurating ears or other open secondary 

 lesions persist, contagiousness may last throughout the period of 

 the existence of the secondary lesion. Place 20 has particularly 

 studied such cases, and reports isolated observations in which con- 

 tagiousness has lasted for twenty weeks after convalescence. 



The so-called "return" cases are due to this long period of 

 contagiousness, and Rosenau states that in the Boston City Hospital 

 it has been observed that about 1.5 per cent of discharged scarlatina 

 convalescents give rise to " return" cases, although the patients are 

 kept in the Hospital for fifty days. From our own observations 

 in army sanitation, there is very little doubt in our minds about 

 the existence of scarlet fever carriers and this is in keeping with 

 the observations of others. 



We have, thus, as dangers for scarlet fever transmission, the 

 typical cases themselves from the beginning of the throat infection 

 until long after convalescence, the cases in which persistent 

 secondary suppurative lesions continue after convalescence, the mild 

 unrecognized cases and, possibly, carriers. 



In addition to this, transmission by milk has not been uncommon. 

 Trask 21 has collected thirty-five scarlet fever epidemics indirectly 

 traceable to milk, and Rosenau speaks of a milk epidemic in Boston 

 which gave rise to 500 cases. This epidemic was suppressed by 

 pasteurization of the milk. 



In prevention of the disease attention must, therefore, be chiefly 

 centered upon early recognition and proper quarantine. In schools, 

 asylums and other closely associated units, great care must be exer- 

 cised to detect the first symptoms of sore throat when scarlet fever 

 has occurred in any member of the community, and daily inspection 

 is as necessary here as in measles. Children from households in 

 which scarlet fever has occurred should be excluded from school 

 and isolated until the incubation period of seven days is over. The 

 incubation in this disease is usually shorter than this, rarely longer. 

 The isolation of cases should be continued for from fifty to sixty 



20 Place, cited from Rosenau 's Preventive Medicine and Hygiene, D. Appleton 

 & Co., New York and London, 1921. 



21 Trask, U. S. Pub. Health Bulletin, No. 41. 



