Nature of Diphtheria.—Diphtheria is one of the most common diseases with which a health officer has to deal. Its nature and the manner in which it spreads have been ascertained with a considerable degree of exactness. The methods of its prevention and control have been standardized and can readily be applied by every health officer and physician.
Diphtheria is a disease of the throat, nose, or trachea, caused by a germ called the Klebs-Löffler bacillus. The bacilli produce a white or yellow membrane which is usually plainly visible when it is on the tonsils and surrounding parts, but it may be so thin that it can scarcely be noticeable. If it is in the nose or trachea, its location prevents it from being seen. Other bacteria often grow with the diphtheria bacilli and produce swellings and abscesses. The disease will usually develop within a few hours or days after infection with the germs.
The danger in diphtheria is from two causes: 1, a poisoning by the toxins of the bacilli; and 2, an obstruction of the trachea interfering with breathing. The toxin of diphtheria produces a rapid and general poisoning of the cells of the body, and especially those of the heart. A poisoning of the nerves is also likely to occur, leading to paralysis, especially of the motor nerves of the throat.
Recognition of Diphtheria.—Diphtheria may be suspected if any throat trouble is present; or if the breathing is obstructed; or if there are signs of a paralysis of the throat, such as difficulty in swallowing. There is usually a fever and a great weakness of the body. There may be a sore throat, although the worst cases are often painless, owing to the paralysis of the nerves. If there is no soreness, there may be no special signs to call attention to the throat, and the disease may reach a dangerous stage before its existence is suspected.
There are two methods of recognizing diphtheria: 1, by looking into the throat for a membrane; and 2, by taking a culture from the throat or nose.
When a doctor is called to see a sick child, the invariable rule ought to be that he look into the child’s throat. Doctors sometimes yield to the desires of the child or of its parents and do not examine the throat, and thus they often fail to recognize diphtheria in its early stages while it may readily be cured. The presence of spots or a membrane on the tonsils or other situation in the back part of the throat is strongly suggestive of diphtheria, but it is not always a proof of the disease, for they may be due to other causes, such as simple tonsillitis, or septic sore throat, or Vincent’s angina.
Cultures.—The only sure indication of diphtheria is to find diphtheria bacilli in a culture from the throat or nose. The New York State Department of Health requires a culture to be taken of every case having a membrane in the throat, whether the membrane is characteristic or is only suspicious. The department furnishes every health officer with outfits for taking the cultures, and examines the cultures without charge. The examination of cultures sometimes shows the absence of diphtheria from throats in which a membrane is present, and often reveals the germs when no membrane can be seen.
How to Take a Culture.—The outfit for taking a diphtheria culture consists of (1) a sterile cotton swab, and (2) a culture-tube containing a culture-medium of coagulated blood-serum.
When the throat is to be examined, or a culture is to be taken, arrange a light to shine into the throat. Have the child open its mouth wide. Depress its tongue with the handle of a spoon or with a tongue-depressor, in order to get a good view of the tonsils and back part of the throat.
If a child refuses to remain still or to open his mouth, have a strong person hold him in the following manner: Seat the child on the left knee of the person holding him, and throw the right leg over the child’s legs. Clasp the left hand around the child’s forehead and hold its head firmly against the shoulder. Hold the child’s hands firmly with the right hand. The child can now be held firmly in position. If the child will not open its mouth, press a spoon handle between the teeth and into the back of the throat. This will cause a retching or gagging. During the act the chlid will hold its mouth open. The procedure causes no pain or discomfort, and is a far more kind procedure than prolonging the child’s baseless fears of an examination.
The method of making a culture from the throat is as follows:
1. Depress the tongue with the left hand.
2. Hold the swab in the right hand and rub it over the membrane, or tonsils, or back of the throat.
3. Hold the culture-tube in the left hand, and remove the plug from its mouth by grasping it with the little finger of the right hand.
4. Rub the swab lightly over the surface of the culture-medium and replace the plug.
5. Throw the swab into a fire, or replace it in its container, if one is provided.
6. Place the tube in the container which is provided with the outfit and mail it to the laboratory.
In order to take a culture from the nose, pass the swab into a nostril horizontally backward along the nasal floor until it touches the posterior wall of the pharynx, and at once withdraw it. Rotating the handle of the swab between the thumb and finger will aid in its passage.
Do not use a culture-tube that is dry or moldy. Be sure that the swab is rubbed over the membrane. Do not allow the swab to touch anything except the throat and the culture-tube. The danger is (1) that it may pick up the ordinary bacteria of the mouth, and (2) it may contaminate other objects with diphtheria germs.
Do not mail the culture-tube in any other container than the one provided by the laboratory, for the postal laws forbid the use of any other container.
Make out a report of the case on a blank that accompanies each outfit, and send it to the laboratory with the specimen.
If the case appears to be diphtheria, do not wait for a report, but begin treatment at once.
When the culture reaches the laboratory, it will be placed in an incubator. The germs grow more rapidly than most other kinds of bacteria, and in from twelve to twenty-four hours the growth will be sufficient for an examination and report. This rapidity of growth causes diphtheria germs to outgrow other bacteria, and the growth that is obtained in positive cases is usually a pure culture of diphtheria germs.
The diseases for which diphtheria is often mistaken are tonsillitis, septic sore throat, and Vincent’s angina. No one can always tell these three diseases from diphtheria without a culture.
Manner of Spread.—Almost the only source of diphtheria germs is the human throat. Very rarely diphtheria germs may be found growing in sores on the skin or in the eye. It is barely possible that a cat or other domestic animal may have the disease.
Most cases of diphtheria are acquired by contact with a person who has diphtheria germs in his throat, or with something which has recently touched his mouth or nose, such as a drinking-cup or a towel. Some cases are acquired from milk which contains diphtheria germs, but the germs themselves come from an infected person who handles the milk. If milk is the cause of diphtheria, there is likely to be a number of cases distributed along a milk route. A few diphtheria germs, introduced into milk by a carrier, may multiply to a sufficient number to infect susceptible persons all along a delivery route.
The germs of diphtheria are not long lived, but soon die when they are exposed to the light or to drying, or to the action of bacteria of fermentation and putrefaction, as they are in ordinary cesspools. Diphtheria is not spread by sewer-gas, as was formerly taught.
Isolation.—When a case of diphtheria is reported, the first duty of a health officer is to prevent the disease from spreading to other persons. He will therefore, 1, isolate the case; 2, place a placard on the house stating that there is a contagious disease in the house; and 3, give the people in the house definite instructions regarding (a) the method of maintaining the isolation, (b) the care of clothing, dishes, and other things in the sick room, and (c) the disposal of all excretions from the sick persons. He will also give the parent or nurse a copy of a pamphlet on diphtheria such as that supplied by the New York State Department of Health.
Measures of isolation and quarantine are not strictly legal until the existence of diphtheria has been proved beyond dispute. Yet it would be wrong to delay isolation or quarantine until a report of a culture can be received. A health officer will be upheld by the courts if he begins the isolation or quarantine as soon as he has a strong suspicion that the case is one of diphtheria. Even if the case turns out to be tonsillitis or septic sore throat, the measures for its isolation are justifiable, for both of these diseases are contagious, and are often dangerous to life.
People in a community will sometimes disregard a quarantine from ignorance, or prejudice, or crowded conditions. If a health officer cannot enforce a strict quarantine during an epidemic, the best thing for him to do is to get his board of health to establish an isolation hospital. If the board does this, it must also authorize the health officer to remove to the hospital every case that cannot be properly isolated or treated at home. If this authority is not given, the health officer cannot legally compel a person to go to the hospital.
The end of a period of isolation in diphtheria is determined by the absence of germs from the throat. A throat may appear to be well, and yet it may continue to harbor virulent germs for days and weeks. The rule is not to release a person from isolation until at least two negative cultures have been obtained on successive days. If the germs persist after four weeks, it will be proper for a health officer to ask that a virulence test be made, and if the germs are proved to be non-virulent, he may dismiss the case.
The health officer must give instructions for the disposal of excretions, the cleanliness of the persons in attendance, and of the utensils in use in the rooms.
It is the duty of a health officer to assist in treating cases of diphtheria, even though the burden and responsibility of the treatment is on the family physicians. Every health officer ought to prepare himself to be a specialist in diphtheria, and to place his services freely at the disposal of the physicians.
It is essential that every person who has diphtheria should go to bed and stay there as long as a membrane can be seen in the throat. The toxin of diphtheria is a poison to the heart, and sudden death may occur after an exertion which would ordinarily be harmless.
Difficult breathing in diphtheria usually signifies that the membrane is obstructing the trachea. This condition is now rarely seen, owing to the general use of antitoxin. But a health officer may encounter it at any time in neglected cases. The saving of life may then depend on relieving the obstruction promptly. A former remedy for this condition was to perform the operation of tracheotomy, or opening the trachea. This is a simple operation, and requires no special skill, but the opening allows dust to enter the lungs, and thus it often produces pneumonia. It is now performed only in emergency cases when nothing else can be done.
The modern remedy for difficult breathing in diphtheria is intubation, or the introduction of a tube into the windpipe. Difficult breathing is slow in its development and there is usually abundant warning of impending danger. A set of intubating instruments costs about $20, and their use requires considerable skill, but no more than a health officer can readily acquire. While intubation may seldom be needed, yet, when obstruction does occur, the operation is life-saving. No other result in the whole range of medicine is so striking and satisfactory as the quiet breathing and calm sleep which follow the intubation of a suffocating child. One health officer in every rural section should be prepared to do intubations for the other health officers and for physicians.
Nature of Immunity.—Immunity to diphtheria is due principally to the presence of antitoxin in the blood. About half of the persons who recover from diphtheria have no antitoxin in their blood. Their immunity is bacteriolytic. Inducing an antitoxin immunity is the only practical means either of curing or of preventing diphtheria in an artificial manner.
Giving Antitoxin.—The principal treatment of diphtheria consists in giving antitoxin. The secret of success consists in giving the antitoxin (1) early in the disease, and (2) in a sufficient amount to overcome the toxins that are present in the blood. The smallest quantity that is usually required is 3000 units, and the largest about 20,000 units.
Antitoxin is given with a hypodermic syringe, and by one of three methods: 1, subcutaneously; 2, intramuscularly; and 3, intravenously.
In the subcutaneous method a fold of skin is pinched up between the thumb and finger. The needle is thrust through the skin and the injection is made wider the skin. When the antitoxin is given in this way, it is slowly absorbed into the blood, and from twelve to twenty-four hours are required for it to enter the blood in sufficient quantity to produce its effects.
In the intramuscular method the needle is thrust at right angles to the skin into a muscular part of the body. Antitoxin given in this way reaches the blood in large amounts within three or four hours.
In the intravenous method the needle is thrust into a vein by the following method:
Tie a bandage around the upper arm in order to obstruct the flow of blood and distend a vein at the bend of the elbow. Paint the skin with tincture of iodin in order to sterilize it. Hold the needle parallel with the skin with the slanting side of its tip upward. Thrust it into the vein, remove the bandage, and inject the antitoxin slowly. When the antitoxin is given in this way, it begins to produce its effects within an hour or two.
Timid physicians often give 3000 units subcutaneously and wait twenty-four hours, and if there is no improvement, they repeat the close. Giving antitoxin in this way is like pouring a little water on a big fire. The proper plan is to give a sufficient quantity in one dose and then stop giving it. When the blood has sufficient antitoxin to neutralize the toxin there is no advantage in giving more.
The persons to whom antitoxin is dangerous are those who suffer from asthma, and the only form of asthma in which there is danger is that which is produced when a person goes near a horse. This is a rare form, but yet a health officer ought to ask if a person has asthma before he gives antitoxin to him. The bad effects come on suddenly within a few seconds after the injection and may produce death almost instantly. If it is necessary to give antitoxin to a person who has attacks of asthma, give only ½ c.c. of antitoxin and wait an hour. If no bad effects are seen, give the remainder of the dose. The bad effects are not due to the antitoxin, but they are due to the fact that the antitoxin is contained in horse-serum which is a foreign protein. The sickness is a manifestation of anaphylaxis, and comes on in a minute or two after the injection.
Antitoxin sometimes produces an eruption on the skin consisting of red, raised, itching blotches. These effects come on about a week after the antitoxin is given, and are caused by the horse-serum and not by the antitoxin itself. They are harmless and disappear in a few hours or days.
Antitoxin for the Prevention of Diphtheria.—Antitoxin is also given in order to produce a passive immunity to diphtheria in those who are well. The dose for this purpose is 1000 or 1500 units given subcutaneously. When a case of diphtheria occurs in a family, the rule is to immunize the other members of the family. The immunization lasts about a month and then ceases, for the antitoxin that is injected is a foreign protein which is soon thrown off from the body and is not reproduced.
The Schick Test.—The existence of antitoxin in the blood may be determined by the Schick test. This consists of injecting a quantity of diphtheria toxin amounting to one-fiftieth of a fatal dose for a guinea-pig. This quantity of toxin is diluted so that it is contained in a single drop of the injected liquid. The injection is not made under the skin, but into it as near the surface as possible. A successful injection produces a raised white spot which has about the size and appearance of a swollen spot produced by a mosquito bite.
If antitoxin is present in the blood, it will neutralize the injected toxin, and no effects will be visible. But if there is no antitoxin in the blood, the toxin will poison the cells which it touches, and will produce a red spot about the size of a one cent coin which appears on the third or fourth day after the injection. The spot will not be sore, but it will persist for a few days and will then disappear, leaving a transient pigmentation. A positive Schick test, therefore, indicates an absence of anti-toxin and a susceptibility to diphtheria. A negative Schick test indicates the presence of antitoxin and an immunity to diphtheria.
About two-thirds of all persons will give a negative Schick reaction, indicating that they naturally have antitoxin in their blood, and are immune to diphtheria. One-twentieth of a unit of antitoxin in each cubic centimeter of blood is sufficient for protection against ordinary infection with diphtheria. Some persons have one or two units of antitoxin in their blood.
The Schick test is of great value in at least three ways:
1. To detect those who are immune and those who are susceptible during an epidemic, especially in an institution. There is no advantage in giving antitoxin to a person who is naturally immune; but a non-immune needs it after exposure to diphtheria.
2. To determine whether or not a nurse or attendant is immune to diphtheria. A non-immune person ought not to be allowed to care for a diphtheria case.
3. To determine immunity in experimental work.
The Schick test shows that 1000 units of antitoxin produce a passive immunity that lasts about thirty days. If another 1000 units are given, the immunity lasts for from seven to ten days only, for the dose partly sensitizes the body to horse-serum, and causes it to throw off the second dose more quickly than it did the first one.
Toxin-antitoxin Immunity.—An active immunity to diphtheria may be induced by the subcutaneous injection of a mixture of toxin and antitoxin. The standard mixture consists of toxin amounting to 200 fatal doses for a guinea-pig, and of antitoxin in sufficient amount to overneutralize the toxin. Three injections are given a week apart. A protective amount of anti-toxin appears in the blood in about a month, and persists for years. Over 90 per cent. of persons who have no antitoxin in their blood will produce antitoxin under the stimulus of the toxin-antitoxin mixture.
The toxin-antitoxin method of inducing an immunity to diphtheria is as valuable and practical as the injection of vaccine in the prevention of typhoid fever. A health officer will use it in producing permanent immunity in persons who show a positive reaction to the Schick test.
Carriers.—Diphtheria germs may grow in the throat without producing sickness. They usually disappear from the throat in about two weeks after a person recovers from diphtheria. If they persist for three weeks or more, the person is classed as a carrier.
Carriers harbor the bacilli in situations to which the blood-serum is unable to penetrate. The bacilli have been found among the epithelial cells of the tonsils. They may also grow in the crypts of the tonsils and in folds of the mucous membrane of the nose. An abnormal condition of the nose or throat can be seen in nearly every diphtheria carrier, and the germs persist because of the abnormality.
A diphtheria carrier can give the disease to another person. Most cases of diphtheria are caught from unrecognized and unsuspected carriers.
Virulence Test.—Diphtheria bacilli vary in their virulence and in their ability to produce toxin. If a variety has only a slight virulence, it cannot produce the disease in another person, and the carrier is harmless.
A virulence test is performed in the following manner: A culture is taken from a carrier, and the diphtheria germs are isolated from it in a pure culture. A small quantity of the germs are taken and killed and are then injected into the skin of a normal guinea-pig. If the bacilli are virulent, they will produce a red, sore spot in three or four days. The test is like the Schick test on human beings. Laboratories of departments of health are now prepared to make virulence tests on cultures from carriers.
The control of diphtheria carriers is one of the most perplexing and aggravating problems with which a health officer has to deal, for healthy carriers do not always understand how they endanger the health of others. A carrier who takes reasonable precautions against transferring excretions of the nose and throat to others may safely go about his work. Child carriers must stay at home and away from other children. If a carrier is reliable, he need not be quarantined, but if he is unreliable and defiant, a health officer’s duty is to restrain and quarantine him. If a virulence test shows the bacilli to be non-virulent, a carrier may be discharged from observation.
Treatment of Carriers.—A healthy nose or throat will seldom harbor diphtheria bacilli. The procedures which are of value in ridding a carrier of the bacilli are those which would tend to restore the throat to a normal state if no diphtheria germs were present. Most carriers have enlarged tonsils. The removal of the tonsils and adenoids from the throats of those who have them is almost certain to rid a carrier of the germs. Nearly every diphtheria carrier is immune. If he were not immune he would have the disease in an active form. The administration of antitoxin, therefore, has no effect on the bacilli in their throats.
Epidemiology.—When an epidemic of diphtheria occurs, the duty of the health officer is to make an investigation. The disease is spread by contact of one individual with another in most cases, but an epidemic may be due to milk. A health officer can soon determine whether or not the epidemic is milk-borne, and if it is, he will close the infected dairy. The principal duty of a health officer is to find the positive cases and also the carriers of diphtheria germs. From 5 to 20 per cent. of all children may be found to be carriers of diphtheria germs while an epidemic is going on. The health officer will find the carriers by means of cultures. If the epidemic is prevalent in a restricted district, he may have to examine each person in the district, but it has usually been found sufficient if he will take cultures only from those who show a redness of the throat. He will also take cultures from school children whose throats are red, but he need exclude only those who have the germs present.
A health officer must be thorough in discovering diphtheria cases and carriers. If he misses a few, the epidemic is likely to continue. If an epidemic of a dozen cases breaks out in a village of 5000 inhabitants, one man might not be able to take all the cultures which are necessary in order to suppress the epidemic quickly. It is the duty of the health officer in such an emergency to ask for help from the state department of health.
Diphtheria in Schools.—When diphtheria occurs among school children, a health officer will be expected to protect the rest of the children. The principal danger will be from carriers. His duty is to take cultures from all children whose throats are red or sore, and to exclude all the carriers that are found. It is also his duty to investigate all cases of sickness among children who are absent from school. If a health officer or medical inspector will examine the school children daily and take cultures from all suspects during an epidemic, there will be no need to close the school.
Diphtheria in Institutions.—When diphtheria occurs in an institution, the precedure for a health officer to follow is:
1. Take cultures from all children who have been associated with the sick.
2. Isolate the sick and the carriers.
3. Do the Schick test on each inmate in order to determine who are immune and who are not.
4. Give all those having a positive Schick reaction an immunizing dose of antitoxin.
5. Secure the removal of tonsils and adenoids from the carriers.
Vincent’s angina is a form of sore throat in which there is usually a membrane resembling that of diphtheria. It usually begins as a small, whitish ulcer upon the tonsils or other part of the throat. The ulcer often extends through the crypts of the tonsils and produces an extensive loss of tissue. The disease is to be suspected when a deep ulcer can be seen in the throat or when the throat remains sore and raw after what was called diphtheria. It is caused by a spirochete which occurs in two forms: (1) a large crescent-shaped organism which stains heavily and unevenly; (2) a long, slender spirillum which stains faintly. A diagnosis may be made by taking a specimen of membrane with a swab, making a smear upon a cover-glass, and examining it at once. Large numbers of both organisms will usually be present in a smear from a positive case. A health officer can make a smear from a suspected case and send it to a laboratory for examination.
Vincent’s angina is not common, but it sometimes occurs in epidemics, and a health officer must keep the disease in mind. A case must be controlled in the same manner as one of diphtheria. Its treatment consists of swabbing the ulcer daily with a 20 to 50 per cent. solution of silver nitrate, and of painting the throat frequently with weaker solutions. A cure is indicated by a healing of the ulcer and by the absence of the organisms from smears.