VII. Present Concepts of the Common Cold

Abstract

Understanding the common cold includes knowledge about the causation, the clinical symptoms, etiology of the cold, the role of seasonal environment and host responsiveness to infection. The common cold is primarily a subjective illness, with upper respiratory and some constitutional symptoms. Physical signs have been generally unreliable or non specific. There is no single cause of the common cold. Recently discovered agents that grow only on human and/or monkey kidney at reduced temperature and pH have been associated with colds. Also older well known viruses such as influenza cause the common cold. The number of viral causes may exceed 100. Mere isolation of a virus from respiratory secretions does not establish its causitive role in illness. Also infection may be symptomatic or not. The dose of virus and its state of attenuation are related to symptoms. No evidence has been developed to show that physical cold causes or increases susceptibility to the common cold. Persons with an unusually high or low frequency of common colds under natural conditions are equally susceptible to infection by other measures. In the former group symptoms also occur from noninfectious stimuli whereas the latter sometimes have asymptomatic infection. Following a viral common cold, specific immunity can be shown.