COLD. The common cold (known technically as Acute Co ryza) is an acute catarrhal inflammation of the upper respiratory tract, caused by infection with bacteria. The most careful bacter iological studies have failed to demonstrate a single specific germ as the cause of this disease ; but the contagious character of many of these infections makes it almost certain that we are dealing with an infectious process. It is more likely that the common cold is not a specific infection like typhoid fever, which is always caused by the same micro-organism, but that it results from infec tion by any one of a number of different bacteria. The organisms most commonly found in the nasal secretions are the streptococ cus, staphylococcus, pneumococcus and influenza bacillus. In addition to these well-known species, certain ultra-microscopic organisms have been isolated from the nasal secretions during colds.
Foster in 1916, and Olitsky and McCartney in 1923, described a filterable virus, which they claimed was capable of transmitting the common cold from infected individuals to healthy individuals. The fact that many species of bacteria are constant inhabitants of the healthy throat and nasopharynx has made bacteriological studies of the common cold extremely difficult, and it has been rather disturbing to find that this bacterial flora undergoes very little change in character during the acute stage of a cold. (Bloomfield, Dochez and others.) The common cold bears con siderable resemblance to hay fever, and for this reason a prevalent theory as to its etiology is that acute coryza is an expression of a hypersensitive condition of the nasal mucous membrane to some protein, probably bacterial in nature.
The environmental factors causing the common cold are well known. Unequal chilling of the body, sudden cooling after exer cise, wearing of wet shoes and wet clothing, fatigue and irritants in the air, all predispose to the onset of a cold. The exact effect of chilling of the body is not understood, but Mudd, Grant and Goldman have found that in experiments on human subjects, chilling of the skin invariably causes a lowering of the tempera ture of the skin, with a reflex lowering in temperature of the mu cous membrane of the nose and nasopharynx. They believe that this drop in temperature depresses the resistance in the throat and thereby allows infection to take place.
Colds occasionally become epidemic. Epidemic colds are usually more severe than ordinary colds, and have been spoken of as grip, or influenza. It is probable that these epidemics are caused by some micro-organism, other than that producing the common cold.
The common cold usually starts in the posterior pares, or in the nasopharynx, but it may originate in any portion of the upper respiratory tract. The first symptom is a sensation of burning and discomfort in the part affected. As the infection spreads, the mucous membrane becomes red and swollen, the nostrils are oc cluded, and there is a profuse watery discharge from the nose. The patient complains of a dull headache, and a sense of conges tion in the eyes, nose and throat. The voice is husky and the senses of taste, smell and hearing are impaired. The skin about the nostrils becomes red and excoriated. If the infection extends down into the bronchial tree, hoarseness develops and then a cough, which at first is dry and hacking, but later is accompanied by an expectoration of mucopurulent sputum. Involvement of the bronchial tree causes a sense of tightness and soreness in the chest, which may be increased with breathing.
The constitutional symptoms of acute coryza vary considerably with the patient, and with different infections in the same patient. In mild cases, there may be nothing more than slight languor and disinclination for exertion. In more severe cases there is some fever (IOO° to F), rapid pulse, chilly sensations and aching in the back and extremities. Some patients develop gastrointest inal symptoms, such as abdominal cramps, nausea, vomiting and diarrhoea. As a rule the common cold presents no diagnostic difficulty. Some of the infectious diseases, such as measles and scarlet fever, may begin with symptoms which are suggestive of coryza, but by the second or third day characteristic symptoms develop which make the differentiation easy. Grip and influenza are infections which are closely allied to the common cold. The differential diagnosis depends largely upon the severity of the symptoms. Grip is a term which is used rather loosely to desig nate an acute respiratory infection accompanied by some consti tutional symptoms. It is really nothing more than a severe cold. Whether the causative agent is the same as that of the common cold is not known. Influenza is a highly contagious infection of the upper respiratory tract which occurs in large or small epi demics during which it spreads with remarkable rapidity. Many bacteriologists believe that it is caused by the influenza bacillus, but Olitsky and Gates have isolated a filterable virus, known as the bacterium pneumocintes, which they believe is the causative agent. The local symptoms of influenza are similar to those of coryza and grip, but the constitutional symptoms are much more marked. The fever is higher, and there is considerable prostration, associated with aching pains in the back and limbs. Influenza nearly always affects the bronchial tree, and a considerable num ber of patients develop influenzal pneumonia.
The complications of the common cold give the disease its med ical significance. As a simple infection it runs a mild, short course, in many cases interfering but little with one's usual routine of life. The complications, however, are numerous and important. Bronchitis occurs so frequently that it can hardly be called a complication. Infection of the accessory sinuses is also extremely common, and sometimes brings on acute constitutional symp toms. More often a sinus infection simply means a prolongation of the nasal symptoms. Not infrequently the condition becomes chronic, and necessitates treatment by a nose and throat special ist. Involvement of the middle ear (otitis media) is a frequent complication, particularly in children, and may lead to a mastoid itis. Occasionally, the infection is not limited to the mastoid, but extends through the bone and invades the meninges. When this happens, meningitis or brain abscess results. When the infec tion. extends downward, bronchitis may be followed by broncho pneumonia or lobar pneumonia, and these in turn by pleurisy or empyema. In addition to these direct complications, the common cold may be the means of lighting up an old tuberculous process in the lungs, or, by lowering the resistance of the patient, it may lead to an exacerbation of some systemic condition, such as rheumatism, nephritis or heart disease.
The common cold usually runs a definite course of three to ten days. If the nasal discharge persists longer than this, one should suspect a complicating infection of one of the sinuses. As recovery from the cold progresses, the congestion decreases, and the secretions become scanty and more purulent. The treat ment consists largely in the relief of symptoms. Occasionally, a cold may be aborted in the early stage, but once the infection gets a start, efforts to check it are usually futile. Colds have been successfully aborted only when the infection has been checked at the very outset by the local application of some germicide, such as argyrol or silver nitrate. These applications should, of course, be made by a specialist, as it is almost impossible for the patient to reach the infected area with a gargle or spray. It has been claimed by some that measures which promote sweating some times check a coryza. The treatment usually advocated is a hot foot bath, some kind of hot drink, and a Dover's powder or a drink of whisky. Even if these measures fail, they tend to make the patient much more comfortable, and are certainly worth a trial. The best treatment for the common cold is rest in bed. Rest should be insisted upon if the temperature rises above Ioo° F, or if the patient is the victim of some chronic constitutional disease, such as diabetes or heart disease. The patient should be isolated as much as possible, not only to protect others, but to minimize the chances of acquiring a secondary infection at a time when the patient's resistance is at a low ebb. The diet should be simple and nutritious, and fluids should be taken in liberal amounts. Tobacco smoke, cold damp air and other irritants must not be allowed to enter the respiratory tract, as these tend to carry the infection down into the finer divisions of the bronchial tree. A saline cathartic is indicated, even when the bowels are active. Various drugs are used to counteract the unpleasant symptoms. Perhaps the most popular of these is aspirin, but phenacetin and codein are also popular. Locally, various sprays are used to lessen the irritation in the nose and throat. Most of the sprays have an albolene base to which has been added thymol, menthol or euca lyptol. If the infection invades the larynx or trachea, the voice should be rested as much as possible. If the cough becomes violent, some sedative, such as codein, is usually sufficient to control it. A favourite remedy is the old-fashioned croup kettle, containing a pint of hot water and a teaspoonful of compound tincture of benzoin. The patient is placed under a sheet and allowed to inhale the fumes from the steaming croup kettle. If there is much pain and tightness in the chest, counter-irritation with some stimulating liniment, ur with a mustard plaster, often gives relief.
One of the most difficult problems which the modern health officer has to face is the prevention of the acute respiratory in fections, particularly as the population tends more and more to concentrate in cities. Probably the most effective method of pre venting colds is to reduce to a minimum contact with crowds. Yet such a measure is almost impossible to enforce in modern urban life. Antiseptic sprays and gargles have been advocated and are widely advertised, but their value is questionable. Most anti septics strong enough to kill bacteria will cause irritation to the mucous membrane. Hardening the body by exposure to cold air or to cold water has been recommended to increase one's resistance to respiratory infections, but the value of this procedure has been very much questioned of late.
Vaccines are a very popular prophylactic and appear to have some value, particularly when prepared from the patient's own bacteria. Statistics by Park and Von Sholly among employees of the Metropolitan Life Insurance Company show that subjects inoculated with "stock" vaccines contract colds about as readily as the uninoculated. For those, however, who suffer from repeated infections because of some chronic focus, an autogenous vaccine is well worth trying and often gives much relief.
(R. L. C.)