FLAGELLATE DIARRHCEA 



1797 



On the other hand, of late years a number of observers — e.g., Wenyon and 

 O'Connor — do not believe in the pathogenic action of these germs. It is 

 quite true that flagellates may be aerial contaminations of faeces, and that 

 others may perhaps be non-pathogenic. Still, in our opinion, when these 

 parasites are very numerous there can be no doubt that they can and do 

 cause irritation of the bowel and diarrhoea. It is equally true that they can 

 live in considerable numbers in man's intestine without causing diarrhoea, 

 ' but such a person, in our belief, is a carrier. 



Fig. 759. — Cercomonas longicauda Davaine. 



(After Wenyon and O'Connor, from the publications of the Wellcome Bureau 

 of Scientific Research.) 



Climatology. — The flagellates and their associated diarrhoeas are to be found 

 in temperate and tropical climes. They are common in Ceylon, the Anglo- 

 Egyptian Sudan, the Balkans, and Brazil, but have been reported from many 

 parts of Africa, Asia, and America. 



etiology. — It is difficult to prove that the flagellate is the cause of the 

 diarrhoea, but if one of these organisms is present in very large numbers in 

 a case, if bacteriological research fails to demonstrate any pathogenic bacteria, 

 and no other cause can be found, it may be provisionally admitted that they 

 are causal. If the causal organism 



is killed off and the diarrhoea ceases 

 pari passu with this process, and 

 does not return, and the flagellate 

 is cither absent or only present in 

 small numbers, the first assumption 

 receives support, but beyond this we 

 cannot at present go. 



The difficulty is that the numbers 

 of the parasites wax and wane in 

 the carrier without producing sym- 

 ptoms, but when present in large 

 numbers they are generally associ- 

 ated with diarrhoea. Infection may 

 be by t' e cysts passing into the 

 alimentary canal of flies, and so to 

 human food, but perhaps it may take 

 place more directly at times. We 

 have never seen them cause true 

 dysenteric symptoms. 



From certain experiments carried 

 out by Miss Porter, it would seem 

 that cockroaches may play a role as 

 transmitters of flagellate diarrhoeas 

 of man. This observer succeeded 

 in transmitting Giardia, Tricho- 

 monas and Chilomastix of human 

 origin to clean white rats by allow- 

 ing their food to be contaminated with the excrement of cockroaches [Peri- 

 planeta amencana and P. orient alis) which had fed on infected stools. 



Fig. 759A. — Cyst of Giardia inies- 

 tifialis IN Fresh Condition in 

 Human F^-^eces. 



(Photomicrograph, X 70 diameters.) 



