REINHARD 



Coxsackie A and B viruses, the ECHO (Enteric Cytopathic Human 

 Origin) viruses, the enteric viruses of animal origin, and the REO 

 (Respiro- enteric) viruses. Why are the enteroviruses important? 

 This is well demonstrated by the kinds of diseases they cause: 

 poliomyelitis, encephalitis, aseptic meningitis, herpangina, pleuro- 

 dynia, pericarditis, myocarditis, exanthematous fevers, gastro- 

 enteritis, and upper respiratory disease. In addition, the entero- 

 viruses cause a variety of systemic diseases which cannot be 

 distinguished as specific syndromes, and which are usually diagnosed 

 clinically as fevers of undetermined etiology (FUE). These agents 

 are responsible for a major proportion of illnesses in children and 

 infants, and are therefore significant in that respect alone. The 

 enteroviruses are ubiquitous, and are frequently recovered from 

 the upper respiratory tract or feces of people who have no overt 

 disease. The following t3rpes of human immunological enteroviruses 

 are recognized: poliovirus, three types; Coxsackie A, twenty- three 

 types; Coxsackie B, six types; ECHO, twenty- six types; and REO, 

 three types (Rosen, 1960; Committee onEnteroviruses, 1962), There 

 are, in addition, a number of types of animal origin, particularly 

 bovine and porcine strains. Of the pathogenetic and infectious 

 characteristics, more will be related later. 



All of our information on viruses emphasizes that these are 

 obligate parasites; physiologically and metabolically incomplete 

 organisms that must utilize other living animal or plant cells in 

 order to persist and propagate. Undoubtedly, virologists will e- 

 ventually produce non- cellular media composed of essential en- 

 zymes and metabolites for cultivating viruses. In the natural 

 realm, however, viruses grow only in living organisms. Their 

 existence outside of the living host is a passive one. For this rea- 

 son, considerations of virus ecology are primarily considerations 

 of host ecology plus physical environmental factors favoring passive 

 persistence or dissemination of the virus between the propagation 

 periods in the host. Accordingly, the effects of cold on virus ecology 

 consist of its effects on availability and suitability of hosts for the 

 viruses, and its effects on persistence of viruses in the physical 

 environment outside the host. 



From the epidemiological standpoint, there is little reason to 

 believe that direct effects of cold on the human host have significant 



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