MIRAGLIA AND BERRY 



is a carrier (asymptomatic), attempts to culture the organism be- 

 come more difficult. This aspect of the problem is not unique for 

 analogies exist in other systems. In rodents, the etiological agent of 

 pseudotuberculosis cannot be isolated from the animal in the normal 

 state, but can be induced to multiply rapidly in individuals under 

 stress or those given large doses of cortisone. 



It is reasonable to assume that the nature of the infected tissue 

 itself may contribute to the difficulty attending efforts to uncover 

 the presence of pathogens. Tissue fluids containing either antibodies 

 or other inhibitors transferred along with the pathogen may prevent 

 its ultimate detection not because of its absence but because its 

 multiplication on suitable substrate is prevented. It becomes 

 necessary under these conditions to remove the effect of the in- 

 hibitory substances either by simple dilution or by more sophisti- 

 cated procedures before the pathogen can be successfully demon- 

 strated. Since uncovering procedures are implem9nted only with 

 considerable difficulty, a more indirect approach might be utilized 

 in attempts at "unmasking"; that is, by stressingthe host to a level 

 where its influence on the parasite becomes minimized. An ex- 

 plosive replication of the pathogen would then permit its presence to 

 be detected by standard procedures. A strategem of this type suc- 

 cessfully executed would do much to broaden our knowledge of 

 agents whose presence otherwise escapes us. 



In recent years, virologists have provided additional evidence 

 that latent viral infections are common to man as well as animals. 

 Data are also accumulating which suggest that latent infections of 

 bacterial etiology may be equally common. Approximately half of 

 the normal population harbor in their nasopharynx coagulase- 

 positive staphylococci, and undoubtedly other agents will be detected 

 when sought with greater effort. 



That such infections exist and are capable under the proper con- 

 ditions of causing overt disease more than justifies any attempts at 

 applying in carefully controlled experiments stressors which will 

 assist in their detection. 



290 



