308 BACTERIA AND DISEASE 



the same disease.* Some of the most recent work on the 

 relationship existing between B. eoli and epidemic diarrhoea has 

 been done by Delepine, who examined milk in the outbreak of 

 epidemic diarrhoea which occurred in Manchester in 1894 (see 

 p. 224), and has also examined a large number of town and country 

 milks. His conclusion is that : — 



" Epidemic diarrhoea of the common type occurring in this country 

 is apparently, in the great majority of instances, the result of 

 infection of food by bacilli belonging to the colon group of bacilli, 

 and which are present at times in fsecal matter. It appears that 

 this infection of food does not generally lead to serious consequences, 

 unless the infection is massive from the first, or the food is kept 

 for a sufficient length of time, and under conditions of temperature 

 favouring the multiplication of these bacilli. 



"Milk, which is the most common cause of epidemic diarrhoea 

 in infants, is usually infected at the farm, or (through vessels) in 

 transit. Of the bacilli of the colon group which are capable of 

 rendering the milk infectious, those which do not produce a large 

 amount of acid, and do not coagulate milk, are the most virulent, 

 and are probably the essential cause of epidemic diarrhoea." f 



It is evident that our knowledge of the bacteriology of diarrhoea 

 is not sufficiently established to permit of any very definite con- 

 clusion on the matter. It may be that the whole group of choleraic, 

 enteric, and diarrhoeal diseases are caused by a group of micro- 

 organisms having many similarities and relationships to each other ; 

 or it may be that different forms of diarrhoea have their own specific 

 causal organism ; or, lastly, it may be a question of association of 

 organisms or of toxins which brings about the disease.j In any 

 event, there is abundant evidence that epidemic diarrhoea is a 

 bacterial disease in the same sense as typhoid fever. 



Conditions favourable to Epidemic Diarrhcea. — Theprovisional 

 results of Ballard's inquiry into the causation of epidemic diarrhoea 

 may be stated as follows : — 



"The summer rise of diarrhoeal mortality does not commence 

 until the mean temperature recorded by the 4-foot earth thermometer 

 has attained somewhere about 56° F., no matter what may have been 

 the temperature previously attained by the atmosphere or recorded 

 by the 1-foot earth thermometer. The maximum diarrhoeal mortality 

 of the year is usually observed in the week in which the temperature 

 recorded by the 4-foot earth thermometer attains its mean weekly 

 maximum. The decline of the diarrhoeal mortality is in this con- 



* La Semaine Med., October 1897. 

 t Jour, of Hygiene, 1903, vol. iii., No. 1, p. 90. 



J See also Report of Medical Officer to Local Government Board, 1902, p. 395 

 (Martin), 404 et seq. (Klein). ' 



