302 The Philippine Journal of Science ma 



twenty days ; on the other hand, on account of the latency char- 

 acteristic of this disease, it is probable that the incubation period 

 may often be much longer than ninety-five days. 



The large percentage of latent infections (78 per cent) among 

 these experimentally parasitized men was somewhat unexpected. 

 However, the frequent occurrence of latent infections in enta- 

 mcebic dysentery has been noted by a number of authors,!^ ^nd 

 is well known to every clinician and pathologist working in the 

 Tropics. 



Vincent (1909) has reported cases of entamoebic dysentery 

 in soldiers returned from French Indo China, of whom some had 

 never suffered from dysentery and others had recovered from 

 attacks while in the Tropics. After their return to France, 

 where infection was considered impossible, these men showed 

 not the slightest intestinal symptoms for three, six, and, in 1 

 case, eleven months, and then developed attacks of entamoebic 

 dysentery. In such cases Vincent observed that the attacks 

 followed certain adjuvant causes, such as indigestion, alcoholic 

 excess, chill, or excessive and prolonged fatigue. 



Musgrave published in 1910 a study of 50 cases of intestinal 

 entamoebiasis without diarrhoea which came to necropsy. Two 

 of these cases showed a perforation of the appendix from enta- 

 moebic ulcerations, 5 had perforations of entamoebic ulcers of the 

 large intestine, and 4 had entamoebic liver abscesses. The ne- 

 cropsies of the other 39 cases showed more or less extensive enta- 

 moebic ulcerations of the large intestine. None of these cases 

 had bloody mucous stools or even diarrhoea ; indeed, constipation 

 was a characteristic feature of several of them up to the time 

 of death. 



Moreover, individuals who are infected with the pathogenic 

 microorganism, but who show no clinical manifestations of the 

 specific disease, are well known in most, if not all, infectious 

 diseases. As an example of the prevalence of such "contact 

 carriers," which is comparable with the condition found in enta- 

 moebic dysentery, the results of the investigation carried out 

 under the auspices of the Medical Commission for the Investiga- 

 tion of Acute Respiratory Diseases of the Department of Health 

 of the City of New York " may be cited. This investigation 

 disclosed the fact that pneumococci could be isolated from the 



"Dock (1891), Councilman and Lafleur (1892), Musgrave (1905), 

 Martini (1908), Vincent (1909), Musgrave (1910). 



" Park and Williams (1905), Longcope and Fox (1905), Duval and Lewis 

 (1905), Buerger (1905). 



