Common Cold

COMMON COLD, cooling of the body or its parts, as a cause of various diseases. Various hypotheses are put forward to explain the connection between a cold and the subsequent disease. In the view of earlier physicians, cooling played a huge, self-sufficient role in the etiology of the most diverse diseases, which were grouped under the general name of cold or rheumatic diseases and catarrhs. However, in connection with the clarification of our knowledge about the infectious nature of the vast majority of 'cold diseases' and about rheumatism, cooling came to be attributed much less or different significance in the etiology of these processes than before. Some are even inclined to completely deny the etiological significance of cooling (Kisel, Khodunsky and others). However, the vast medical experience accumulated over centuries, as well as extensive statistical data, with indisputable evidence speak for the existence of a causal relationship between the occurrence of certain diseases from the group of infectious diseases (especially, for example, catarrhs of the respiratory tract, pneumonias) and the preceding cooling of the body. The statistical materials relating to this prove the fact of a sharp increase in cold diseases in cold weather (see Bronchitis, Pneumonia, Influenza, Rheumatism). Particularly convincing are the latest materials collected by Schade during the world war: in military units located in cold, damp weather in the open air, cold diseases were observed several times more frequently than in units located in protected trenches. However, there are data from the same period in which the role of cooling does not appear so clearly (see War-military pathology). All these data have forced the search through observation on humans and experiment to clarify the question of the essence of the effect of cooling on the occurrence of diseases. Since the latter are in the majority infectious diseases, this question in a number of cases basically reduces to the problem of the effect of cooling on the occurrence and course of infections. However, as we will see below, this problem alone by no means exhausts the question of the occurrence of cold diseases. All experiments conducted to clarify the connection between cooling and infection are in essence a repetition in various modifications of the classic experiments of Pasteur, who showed that chickens, not susceptible to anthrax in general, contract it when subjected to the action of cold. Pasteur explained the result of this experiment by the fact that the normal body temperature of chickens reduces the virulence of anthrax bacilli. In contrast to this, subsequent authors (Lode, Tromsdorff, Lipari, Fischel and others.), who confirmed Pasteur's data also with other bacteria (pneumococci, staphylococci, Friedländer's bacilli, cholera vibrios) and on animals of different species, came to the conclusion that cooling causes a decrease in the body's resistance to infection. In this case, as infectious agents, in the opinion of all authors, pathogenic microorganisms constantly present on the surface of mucous membranes acquire the greatest significance. However, this position has not yet been experimentally confirmed, since almost no one has managed to produce in animals inflammatory changes, for example in the respiratory organs, with simple cooling of the body without simultaneous inoculation of infectious agents. Apparently, the observations on humans that catarrhs of the respiratory tract and pneumonias in polar travelers (Nansen), as well as in mountaineers, are very rare also belong here. The significance of cooling in the occurrence of postoperative pneumonias also cannot be considered fully proven, despite the positive results of Henle's experiments, since in these cases, in addition to cooling, other factors also play a role (anesthesia, infections). The decrease in the body's resistance to infectious agents during cooling some explain mainly by local, as well as reflex action of cold, others - by changes in general immunobiological properties. As local factors arising during cooling and facilitating the introduction of microbes, mainly circulatory disorders (arterial and venous hyperemia) are put forward; but this assumption (Lipari, Kiskalt) met sharp objections (Strasser, Khodunsky) and cannot be considered proven. The effect of cold on the state of cellular colloids, mainly in the sense of reducing their dispersity (Schade), put forward at the present time, also with difficulty can be invoked to explain the effect of cooling in the occurrence of infection. The reflex effect of cooling is mainly reduced to reflex hyperemia; for example, hyperemia of the mucous membranes of the respiratory tract and abdominal viscera occurs when cold acts on the skin (Harcourt, Heintz, Rosbach, Aufrecht, Aron). Sometimes in such animals, even ecchymoses were observed, especially in the pleurae (Zillessen, Reinbot). However, whether all these phenomena have any significance in the sense of the occurrence of infectious processes in the corresponding organs remains unclear, especially because the degree of cooling in all the experiments cited far exceeded that which is usually attributed an etiological role in cold diseases of humans. In general, a number of authors (Strauss, Khodunsky and others) point out that the results of experiments with cooling on animals cannot be used to explain the etiology of cold diseases in humans, because the vascular reactions of humans differ significantly from those of animals and the relationships between them and the microbial flora are much more complex. Changes in the immunobiological properties of the body under the influence of cooling, as the cause of cold diseases, were also tried to be substantiated by experiments on animals (Tromsdorff, Lode, Nagelschmidt, Fischel). In this case, it was found that general cooling leads to a decrease in the production of hemolysins and a weakening of the bactericidal properties of serum. The ability of leukocytes to emigrate and phagocytose is also sharply weakened. However, all these experiments still give little for understanding the etiology of cold diseases in humans and their connection with infection. The coolings used by the authors were always very severe, while observations on humans show that cold diseases often arise after slight and very short-term exposure to cold. Thus, despite numerous experimental works, the question of the connection between cooling and infection remains still unclear. Hence, naturally, attempts arise to explain the etiology of some cold diseases without directly involving infectious factors. In this case, one usually proceeds from the ideas of reflex vascular changes under the influence of cold or the humoral changes caused by it or finally allergic conditions. The direct local effect of cold on tissues also apparently plays a role in the origin of some forms of cold diseases (see Cooling). These mainly include some diseases of the peripheral nerves (trigeminal neuralgia, facial nerve paresis, sciatica), as well as partly the so-called muscular rheumatism. The possibility of paralysis of nerves, especially superficially lying ones, under the action of cold on the corresponding areas of the skin has also been proven experimentally. The reflex hyperemia that arises, for example, in the respiratory tract when cold acts on the skin, without the addition of an infectious factor, according to some authors, in agreement with experimental data (see above), does not cause inflammatory phenomena on the mucous membranes and in the lungs. However, a number of other authors, mainly clinicians, admit this possibility, proceeding mainly from observations of the occurrence of catarrhs of the upper respiratory tract directly following the action of cold (Strassmann, Konstamm). By reflex vascular influences, some, especially clinicians, also explain the disorders of kidney function that occur when the skin is cooled (Strasser), others admit damage to the epithelium of the renal tubules at this time, and base themselves both on clinical (see Nephritis) and some experimental data (Zillessen, Afanasiev). However, the results of experiments in this area are extremely inconsistent: many authors who applied severe cooling of the skin in animals found no changes in the kidneys, others noted only functional disorders in the form of albuminuria and cylindruria. In humans, so-called physiological albuminuria (see) is directly associated with cooling, which occurs especially after cold baths. On this basis, some put forward cooling as an important factor also in the etiology of nephrosis and nephritis, mainly based on very convincing clinical facts, however, there are no direct experimental proofs in favor of this view. Some authors (Stemler) believe that under the action of cold various physicochemical changes in the blood also occur, which can lead, for example, to phenomena of thrombosis even in remotely located organs (Aufrecht's experiments).

Finally, there exists a series of data that allows one to consider the effect of cooling on the organism from the point of view of allergic reactions, and to interpret some cold diseases as manifestations of these latter. For example, attention is drawn to the connection between the effect of cold and hemoclastic crises (Vidal, Stéghelin). Finally, the application of a skin test with Pondorf's mixture B gives a more or less clearly expressed reaction in a large number of patients with 'rheumatic', nervous, joint and muscle diseases (Straus). Observations of this kind are directly connected with modern concepts of the allergic nature of such a typical 'cold' disease as joint rheumatism. From the point of view of allergic reactions, the long-noted fact of the sharp individual sensitivity of some persons to the effect of cold, expressed in them by a special ease of occurrence and recurrence of many cold diseases, apparently finds its explanation in part. All of the above shows that theories about C. [Common Cold] as a decisive external pathogenic factor do not yet have universally recognized successes. As a rule, C. [Common Cold] is only some condition or occasion for diseases, and moreover, one that is rather diverse in its essence. In other words, one should consider not only and not even so much C. [Common Cold] as such, but rather, on the one hand, susceptibility to cold, or predisposition to cold diseases, the special sensitivity of the organism to them, and, on the other hand, those concrete conditions (presence of infectious foci, etc.) in which C. [Common Cold] occurred.