2 3 o INFECTION AND IMMUNITY 



(broncho-pneumonia, diphtheria) is shown by the fact 

 that the greatest mortality occurs during the months 

 of February, March, April, and May, and the least 

 during the summer and autumn months, also by the 

 very low mortality of the Pacific Coast region. 



The combined influence of an unfavourable climate 

 and density of population is shown by the statistics 

 relating to the State of Rhode Island, which has the 

 highest death-rate from this disease of any of the 

 registration States (47.6). The lowest rate in the re- 

 gistration States was in Vermont (6.1). 



Patients having measles may communicate the dis- 

 ease from the very outset of the attack and it is prob- 

 able that the germ is present in the abundant 

 secretion from the bronchial and nasal mucous mem- 

 branes, as well as in the desquamated epithelium from 

 the surface of the body after the eruption has de- 

 veloped. When convalesence has been established, 

 if the patient's body and clothing have been disinfected 

 he can no longer communicate the disease. The 

 period during which isolation should be insisted upon, 

 to prevent the extension of the disease, is about three 

 weeks from the date of the first appearance of the 

 eruption. The infectious material is not so tenacious 

 of vitality as in smallpox and scarlet fever and the 

 disease is not so likely to be conveyed by means of 

 infected clothing and other articles exposed in the 



