DISTRIBUTION OF DISEASE GERMS 99 



113. Bacteria upon carelessly handled bread. A special 

 student of bacteriology recently made a careful study of 

 loaves of bread to ascertain how many bacteria there are 

 upon the surfaces of the loaves. He secured bread from vari- 

 ous parts of the city and from people who handled and sold 

 it in many ways. He found that unwrapped bread had more 

 bacteria upon it than wrapped bread. From 31 loaves col- 

 lected from dirty shops the average number of bacteria upon 

 each loaf was 64,970. Of the unwrapped samples 39 per 

 cent had an average of 14,000 bacteria upon each loaf, 39 

 per cent had an average of 4000 bacteria upon each loaf, 

 and the remaining 22 per cent had an average of 2500 bac- 

 teria upon each loaf. Of the specimens of wrapped bread 

 45 per cent averaged 848 bacteria to the loaf, and 55 per 

 cent averaged 371. Obviously, if the fresh bread is wrapped 

 in clean paper it will be a much less important carrier 

 of bacteria. 



Few of the bacteria upon the samples of bread were found 

 to be disease-producing, but unclean bread is not especially 

 attractive, even if its load of bacteria does contain but 

 few that produce disease. It is a notable fact that since the 

 first publication of such studies as that just described, the 

 practice of wrapping bread has become much more common. 

 A careful study of other common food substances which are 

 handled by many persons or not carefully handled might 

 produce equally striking evidence regarding the distribution 

 of bacteria. 



114. Protecting ourselves and others. The diseases most 

 commonly transmitted from person to person are those which 

 enter the lungs or alimentary canal through the mouth or 

 nose, such as grippe, diphtheria, colds, tuberculosis, and 

 typhoid fever. Since persons who are well are contaminated 

 through these sources, it is obvious that persons who have the 

 disease must be the source of the trouble. Too much dili- 

 gence is not possible for the protection of yourself and others. 



