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attacked by the malady; but in this event, no cases, or at least very few, 
appear during the next following year, the epidemic entering the neigh- 
boring hamlets. If, on the other hand, dysentery, during the first year, 
appears only in the late autumn or early winter and if only a small 
number of people are attacked, then in the coming season a large epi- 
demic, which, as a rule, will entirely disappear in the third year, must be 
expected. Reinfection, by which the disease is contracted in two suc- 
cessive years, is, according to my experience, of very rare occurrence. 
Among 10,000 patients sick with dysentery I have only observed such 
a recurrence in three or four instances and in these the first attack had 
been a very mild one. I have never observed a reinfection with patients 
in whom the course of the disease had been very severe. 
The main factors in the spread of dysentery are the hosts (i. e., the 
individuals who convey the bacillus in the intestinal tract) ; and of these, 
three classes are to be considered: First, healthy persons; second, those 
who have mild cases of dysentery or of diarrhoea respectively; third, 
convalescent dysentery patients. 
As is the case in typhoid, cholera, or diphtheria, perfectly healthy indi- 
viduals may serve as hosts for the bacillus without manifesting a single 
symptom of dysentery, but to bring the proof of the presence of the bacil- 
lus in healthy stools is extremely difficult; however, Conradi succeeded 
in so doing in three cases which he encountered in a small epidemic of 
dysentery at Metz. During an outbreak of dysentery we often encounter 
patients affected with this disease or with diarrha@a, who clinically only 
show the symptoms of a simple intestinal catarrh but in whom dysentery 
can with certainty be demonstrated by bacteriologic methods and such 
cases appear not only in times of epidemics but also during the cold sea- 
sons. So-called winter diarrhoea often belongs to this category and in 
this way the bacillus is conveyed from person to person. I do not believe 
the organism can live for any length of time outside the human body. It 
maintains its existence therein throughout the winter and if it reaches 
the outside world during a favorable time in the early summer it may 
then cause a great epidemic. We were able to demonstrate the presence 
of the dysentery bacillus in stools which macroscopically had a perfectly 
normal appearance and which had been taken from patients one or two 
weeks after their convalescence. The fact that dysentery patients who 
were dismissed from the hospital as entirely cured would at times suffer 
a relapse after several weeks, or that the disease appeared in their respec- 
tive families, would seem to prove that the bacillus can be present in the 
stools of convalescents for even a longer time than that given above: 
however, the question as to whether the specific organism can remain in 
the stools of convalescents for years, as is the case with typhoid, is still 
an open one. 
Forster has lately emphasized the fact that the bacillus of typhoid finds 
a permanent habitat in the gall bladder, from which, from time to time, 
