Whenever you have a cold, keep away from everybody that you possibly can and stay at home from school or business for a day or two. You will do no good to yourself or others, working in that condition; and you may infect a dozen others. If you find anyone in your cla.s.s or room or shop, sneezing or coughing or running at the nose, report him to your teacher or foreman; and if he won't send him home, keep away from him as much as possible.

Diphtheria. Another common and serious disease, until quite recently very fatal, is diphtheria. This is caused by getting into your mouth or nose the germs from another case of the disease. This disease also is most likely to occur in childhood, though it may attack a person of any age, and is always serious. It may be prevented from spreading by keeping children who have it shut up in rooms, or wards, by themselves and keeping all other children away from them, or from their nurses or those who have anything to do with them. Up to about thirty years ago, it was one of the deadliest and most terrible diseases that we had anything to do with. We knew absolutely nothing that would cure it, or even check its course; and nearly half of the children attacked by it died.

About that time, however, two scientists, Klebs and Loeffler, discovered that, by taking some of the membrane, or tough growth that forms in the throat in this disease, and by rubbing it over a plate of gelatin jelly, they could grow on that gelatin a particular kind of germ. This germ, or bacillus, they then put into the throats of guinea pigs, and found that it would give them diphtheria.

This is the way disease germs are discovered, or, as we say, identified; but of course this did not give at once any remedy for the disease.

Scientists soon found, however, that, if a very small number of these bacilli were put into a guinea pig's throat, it would have diphtheria, but in a very mild form. If, when it had recovered, it was again infected, it would stand a much larger dose of the bacilli without harm.

This made them suspect that some substance had been formed in the guinea-pig's blood that killed the bacillus or worked against its toxin, or poison; and soon, to their delight, they succeeded in finding this substance, which they called _ant.i.toxin_ (meaning "against poison").

Then came the idea that if they could only get enough of this ant.i.toxin, and inject it into the blood of a child who had diphtheria, it might cure the disease. A guinea pig is such a tiny animal that the amount of ant.i.toxin which it could form would be far too small to cure a man, or even a child. So larger animals were taken; and it was finally found that the largest and strongest of our domestic animals, the horse, would, if the diphtheria germs were injected into its blood, make such large amounts of ant.i.toxin that merely by drawing a quart or two of the blood--and closing up the vein again--enough ant.i.toxin could be got to cure fifty or a hundred children of diphtheria. This treatment has not the slightest harmful effect upon the horse. The pain of injecting is only like sticking a pin through the skin, while the pain of bleeding is no greater than cutting your finger. There are now at our great manufacturing laboratories whole stables full of horses, for the production of this wonderful remedy.

[Ill.u.s.tration: DEATH-RATE FROM DIPHTHERIA AND CROUP

Statistics from the City of New York. Ant.i.toxin was used largely from 1893-95, during which time there was a steady decrease (from 60% to 30%) in the death-rate. After the Board of Health took up the matter, furnishing ant.i.toxin without cost, the death-rate continued to decrease to less than 10% of the total number of cases, in 1909.]

With this remedy, our entire feeling toward diphtheria is changed.

Instead of dreading it above all things, we know now, from hundreds of thousands of cures, that, if a case is seen on the first day of the disease, and this ant.i.toxin injected with a hypodermic needle, it is almost certain that the patient will recover; not more than two or three cases out of a hundred will fail. If the case is seen and treated on the second day, all but four or five out of a hundred will recover; and if on the third day, all but ten. In fact, the average death rate of diphtheria has been cut down now from forty-five per cent to about six per cent.

We now have ant.i.toxins, or _vaccines_, for blood-poisoning; for typhoid fever; for one of the forms of rheumatism; for boils; for the terrible _cerebro-spinal meningitis_, or "spotted fever"; and for teta.n.u.s, or lock-jaw. And every year there are one or two other diseases added to the list of those that have been conquered in this way.

None of these vaccines is so powerful, or so certain in its effects, as the diphtheria ant.i.toxin. But they are very helpful already; and some of them, particularly the typhoid vaccine, are of great value in preventing the attack of the disease, as small doses of it given to persons who have been exposed to the infection, or are obliged to drink infected water, as in traveling or in war, very greatly lessen their chances of catching the disease.

Vaccination, the Great Cure for Smallpox. Another valuable means of preventing disease by means of its germs is by putting very small doses of the germs into a patient's body, so that they will give him a very mild attack of the disease, and cause the production in his blood of such large amounts of ant.i.toxin that he will no longer be liable to an attack of the violent, or dangerous, form of the disease. Vaccines, for this purpose, usually consist either of a very small number of the disease germs, or of a group of them, which have been made to grow upon a very poor soil or have been chilled or heated so as to destroy their vitality or kill them outright. When these dead, or half-dead, bacilli are injected into the system, they stir up the body to produce promptly large amounts of its ant.i.toxin. In some cases the reaction is so prompt and so vigorous that the ant.i.toxin is produced almost without any discomfort, or disturbance, and the patient scarcely knows anything about it. In others there will be a slight degree of feverishness, with perhaps a little headache, and a few days, or hours, of discomfort. When this has pa.s.sed, then the individual is protected against that disease for a period varying from a few months to as long as seven or eight years, or even for life.

The best-known and oldest ill.u.s.tration of the use of these vaccines is that of _smallpox_. A little more than a hundred years ago, an English country doctor by the name of Jenner discovered that the cows in his district suffered from a disease accompanied by irritation upon their skins and udders, which was known as "cowpox." The dairymaids who milked these cows caught this disease, which was exceedingly mild and was all over within four or five days; but after that the maids would not take smallpox, or, as we say, were immune against it. Smallpox at that time was as common as measles is now. Nearly one-fourth of the whole population of Europe was pock-marked, and over half the inmates in the blind asylums had been made blind by smallpox. So common was it that it was quite customary to take the infectious matter from the pocks upon the skin of a mild case and inoculate children with it, so as to give them the disease in mild form and thus protect them against a severe, or fatal, attack; just as in country districts, a few years ago, some parents would expose their children to measles when it happened to be a mild form, so as to "have it over with."

It occurred to Dr. Jenner that if this inoculation with cowpox would protect these milkmaids, it would be an infinitely safer thing to use to protect children than even the mildest known form of inoculation. So he tried it upon two or three of his child patients, after explaining the situation to their parents, and was perfectly delighted when, a few months afterward, these children happened to be exposed to a severe case of smallpox and entirely escaped catching the disease. This was the beginning of what we now call _vaccination_.

The germ of cowpox, which is believed to be either the cow or horse variety of human smallpox, is cultivated upon healthy calves. The matter formed upon their skin is collected with the greatest care; and this is rubbed, or sc.r.a.ped, into the arm of the child. It is a perfectly safe and harmless cure; and although it has been done millions of times, never has there been more than one death from it in 10,000 cases. In a little over a hundred years it has reduced smallpox from the commonest and most fatal of all diseases to one of the rarest. But in every country in the world into which vaccination has not been introduced, smallpox rages as commonly and as fatally as ever. For instance, between 1893 and 1898 in Russia, where a large share of the people are unvaccinated, 275,000 deaths occurred from smallpox; in Spain, where the same condition exists, 24,000. In Germany, on the other hand, where vaccination is practically universal, there were in the same period only 287 deaths--1/1000 as many as in Russia; and in England, only a slightly greater number.

Another ill.u.s.tration, which comes closer home, is that of the Philippine Islands. Before they were annexed by the United States, vaccination was rare, and thousands of deaths from smallpox occurred every year. In 1897, after the people had been thoroughly vaccinated, there was not a single death from this cause in the whole of the Islands.

[Ill.u.s.tration: BILL OF HEALTH

No outgoing ship may "clear the port" without a Bill of Health, signed by the Collector of Customs and the naval officer of the Port.]

This discovery of Jenner's was most fortunate; for vaccination remains until this day absolutely the only remedy of any value whatever that we possess against smallpox.

Quarantine, inoculation, improvement of living and sanitary conditions, the use of drugs and medicines of all sorts other than vaccination, have no effect whatever upon either the spread or the fatality of the disease. The author, when State Health Officer of Oregon, saw the disease break out in a highly-civilized, well-fed, well-housed community, and kill eleven out of thirty-three people attacked, just as it would have done in the "Dark Ages." Not one of the cases that died had been vaccinated; and, with but one exception (and in this the proof of vaccination was imperfect), every vaccinated case recovered.

Vaccination will usually protect for from five to ten years; then it is advisable to be re-vaccinated, and in six to eight years more, another vaccination should be attempted. This third vaccination will usually not "take," for the reason that two successful vaccinations will usually protect for life.

Unexpected as it may seem, vaccination is not only a preventive of smallpox, but a cure for it. The reason being that _vaccinia_, the disease resulting from successful vaccination, being far milder than smallpox, runs its course more quickly,--taking only two days to develop,--while smallpox requires anywhere from seven to twenty days to develop after the patient has been infected, or exposed. So, if anyone who has been exposed to smallpox is vaccinated any time within a week after exposure, the vaccine will take hold first, and the patient will have either simple vaccinia, with its trifling headache and fever, or else a very mild form of smallpox.

Some persons object to having children deliberately infected with even the mildest sort of disease; but this is infinitely better than to allow, as was the case before vaccination, from one-fourth to one-fifth of them to be killed, twenty-five per cent of them to be pock-marked, and ten per cent of them to be blinded by this terrible disease. So far as any after-effects of vaccination are concerned, careful investigation of hundreds of thousands of cases has clearly shown that it is not so dangerous as a common cold in the head.

Infantile Paralysis. Another disease that has been unpleasantly famous of late is also caused and spread by a germ. This is a form of laming or crippling of certain muscles in childhood known as _infantile paralysis_. It is not a common disease, though during the last two years there has been an epidemic of it in the United States, especially in New York and Ma.s.sachusetts. The only things of importance for you to know about it are that it begins, like the other infections, with headache, fever, and usually with "snuffles" or slight sore throat, or an attack of indigestion; and that its germ is probably spread by being sneezed or coughed into the air from the noses and throats of the children who have it, and breathed in by well children. The best known preventive of serious results from this disease is the same as in the rest of infectious diseases, namely, rest in bed, away from all other children, which at the same time stops the spread of it. It furnishes one more reason why all children having the "snuffles" and sore throat with fever and headache should be kept away from school and promptly put to bed and kept there until they are better.

The reason why the disease produces paralysis is that its germs specially attack the spinal cord, so as to destroy the roots of the nerves going to the muscles. Unless the harm done to the spinal cord is very severe, other muscles of the arm or the leg can very often be trained to take the place and to do the work of the paralyzed muscles, so that while the limb will not be so strong as before, it will still be quite useful.

Malaria. Practically the only disease due to animal germs, which is sufficiently common in temperate or even subtropical regions to be of interest to us, is _malaria_, better known perhaps as _ague_, or "chills-and-fever." This disease has always been a.s.sociated with swamps and damp marshy places and the fogs and mists that rise from them; indeed its name, _mal-aria_, is simply the Italian words for "bad air."

It is commonest in country districts as compared with towns, in the South as compared with the North, and on the frontier, and usually almost disappears when all the ponds and swamps in a district are drained and turned into cultivated land or meadows.

About four hundred years ago, the Spanish conquerors of America were fortunate enough to discover that the natives of Peru had a bitter, reddish bark, which, when powdered or made into a strong tea, would cure ague. This, known first as "Peruvian bark," was introduced into Europe by the intelligent and far-sighted Spanish Countess of Chincon; and, as she richly deserved, her name became attached to it--first softened to "cinchona" and later hardened to the now famous "quinine." But for this drug, the settlement of much of America would have been impossible. The climate of the whole of the Mississippi Valley and of the South would have been fatal to white men without its aid.

[Ill.u.s.tration: GERMS OF MALARIA

(Greatly magnified)

These germs are animal germs and are in the red blood corpuscles, feeding on them.]

But although we knew that we could both break up and prevent malaria by doses of quinine large enough to make the head ring, we knew nothing about the cause--save that it was always a.s.sociated with swamps and marshy places--until about forty years ago a French army surgeon, Laveran, discovered in the red corpuscles of the blood of malaria patients, a little animal germ, which has since borne his name. This, being an animal germ, naturally would not grow or live like a plant-germ and must have been carried into the human body by the bite of some other animal. The only animals that bite us often enough to transmit such a disease are insects of different sorts; and, as biting insects are commonly found flying around swamps, suspicion very quickly settled upon the mosquito.

[Ill.u.s.tration: CULEX

Position on the wall.--After Berkeley.]

By a brilliant series of investigations by French, Italian, English, and American scientists, the malaria germ was discovered in the body of the mosquito, and was transmitted by its bite to birds and animals. Then a score or more of eager students and doctors in different parts of the world offered themselves for experiment--allowed themselves to be bitten by infected mosquitoes, and within ten days developed malaria. At first sight, this discovery was not very encouraging; for to exterminate mosquitoes appeared to be as hopeful a task as to sweep back the Atlantic tides with a broom. But luckily it was soon found that the common piping, or singing, mosquito (called from his voice _Culex pipiens_) could not carry the disease, but only one rather rare kind of mosquito (the _Anopheles_), which is found only one-fiftieth as commonly as the ordinary mosquito. It was further found that these malaria-bearing mosquitoes could breed only in small puddles, or pools, that were either permanent or present six months out of the year, and that did not communicate with, or drain into, any stream through which fish could enter them. Fish are a deadly enemy of the mosquito and devour him in the stage between the egg and the growth of his wings, when he lives in water as a little whitish worm, such as you may have seen wriggling in a rain-barrel.

[Ill.u.s.tration: ANOPHELES

Position on the wall.--After Berkeley.]

It was found that by hunting out a dozen or twenty little pools of this sort in the neighborhood of a town full of malaria, and filling them up, or draining them, or pouring kerosene over the surface of the water, the spread of the malaria in the town could be stopped and wiped out absolutely. This has been accomplished even in such frightfully malarial districts as the Panama Ca.n.a.l Zone, and the west coast of Africa, whose famous "jungle fever" has prevented white men from getting a foothold upon it for fifteen hundred years. Since the young mosquitoes, in the form of wrigglers, or _larvae_, cannot grow except in still water, draining the pools kills them; and, as they must come to the surface of the water to breathe, pouring crude petroleum over the water--the oil floating on the surface and making a film--chokes them.

The common garden mosquito, while not dangerous, is decidedly a nuisance and can be exterminated in the same way--by draining the swamps and pools, or by flooding them with crude petroleum,--or by draining swamps or pools into fresh-water ponds and then putting minnows or other fish into these ponds. There is no reason why any community calling itself civilized should submit to be tormented by mosquitoes if it will spend the few hundred, or the thousand, dollars necessary to wipe them out. It is prophesied that the use of quinine will soon become as rare as it is now common, because malaria will be wiped out by the prevention of the mosquito.

Disinfectants. So far we have been considering how to attack the germs after they have got into our bodies, or to prevent them from spreading from one patient to another; but there is still another way in which they may be attacked, and that is by killing, or poisoning them, outside the body. This process is generally known as _disinfection_, and is carried out either by baking, boiling, or steaming, or by the use of strongly poisonous fluids or gases, known as _disinfectants_.

While fortunately none of these disease germs can breed, or reproduce their kind, outside the human body, and while comparatively few of them live very long outside the human body, they may, if mixed with food or caught upon clothing, hangings, walls, or floors, remain in a sort of torpid, but still infectious, condition for weeks or even months.

Consequently, it has become the custom to take all the bedding, clothing, carpets, curtains, etc., that have touched a patient suffering from a contagious disease, or have been in the room with him, and also any books that he may have handled, any pens or pencils that he may have used, and either destroy them, or bake, boil, or fumigate them with some strong germicidal, or disinfectant, vapor.

[Ill.u.s.tration: OILING A BREEDING GROUND OF MOSQUITOES

The photograph shows work done in the Panama Ca.n.a.l Zone. The swamp has already been drained by ditches, and the work of destroying the larvae is being completed by the use of oil.]

This is usually done by closing up tightly the sick-room, putting into it all clothing, bedding, pictures, books, hangings, and other articles used during the illness (except wash-goods, which, of course, can be sterilized by thorough boiling; and dishes and table utensils, which also can be scalded and boiled); draping the carpet over chairs so as to expose it on all sides, opening closets and drawers, and then filling the room full of some strong germ-destroying fumes.

One of the best disinfectants, and the one now most commonly used by boards of health for this purpose, is _formaldehyde_--a pungent, irritating gas, which is an exceedingly powerful germ-destroyer. This, for convenience in handling is usually dissolved, or forced into water, which takes up about half its bulk; and the solution is then known as _formalin_.

When formalin is poured into an open dish, it rapidly evaporates, or gives up its gas; and, if it be gently heated, this will be thrown off in such quant.i.ties as to completely fill the room and penetrate every crevice of it, and every fold of the clothing or hangings. One pound, or pint, of formalin will furnish vapor enough to disinfect a room eight feet square and eight feet high, so the amount for a given room can thus be calculated. The formalin vapor will attack germs much more vigorously and certainly if it be mixed with water vapor, or steam; so it is usually best either to boil a large kettle of water in the room for half an hour or more, so as to fill the air with steam, before putting in the formalin, or to use a combination evaporator with a lamp underneath it, which will give off both formalin and steam. This, if lighted and placed on a dish in the centre of a wash-tub or a large dishpan, with two or three inches of water in the bottom of it, can be put into the room and left burning until it goes out of its own accord.

Another very good method is to take a pan, or basin, with the required amount of formalin (not more than an inch or two inches deep) in the bottom of it, get everything ready with doors and windows fastened tight and strips of paper pasted across the cracks, pour quickly over the formalin some permanganate of potash (about a quarter of a pound to each pound of formalin), and then bolt for the door as quickly as possible to avoid suffocation. The resulting boiling up, or effervescence, will throw off quant.i.ties of formaldehyde gas so quickly as to drive it into every cranny and completely through clothing, bedding, etc. The room should be left closed up tightly for from twelve to thirty-six hours, when it can be opened--only be careful how you go into it, first sniffing two or three times to be sure that all the gas has leaked out, or holding your breath till you can get the windows open; and in a few hours the room will be ready for use again.

Another older and much less expensive disinfectant for this purpose is common _sulphur_. From one to three pounds of this, according to the size of the room, is burned by a specially prepared lamp in a pan placed in the centre of a dishpan of water, and the vapor thus made is a very powerful disinfectant. This, however, is a very poisonous and suffocating gas (as you will remember if you have ever strangled on the fumes of an old-fashioned sulphur match) and, compared with formalin, is nearly five times as poisonous to human beings, or animals, and not half so much so to the germs. Where formalin cannot be secured, sulphur is very effective; but its only merit compared with formalin is that it is cheaper, and more destructive to animal parasites and vermin such as bugs, c.o.c.kroaches, mice, rats, etc., when these happen to be present.

Formalin has the additional advantage of not tarnishing metal surfaces, as sulphur does.

It is a good thing for every household and every schoolroom to have a bottle of formalin on hand, so that you may sniff the vapor of it into your nostrils and throat if you think you have been exposed to a cold, or other infectious disease, or make a solution with which to wash your hands, handkerchiefs, pencils, etc., after touching any dirt likely to contain infection. Half a teaspoonful in a bowl of water is enough for this. A saucerful of it placed in an air-tight box, or cabinet, will make a disinfecting chamber in which pencils, books, etc., can be placed over night; and a teaspoonful of it in a quart of water will make an actively germ-destroying solution, which can be used to soak clothing, clean out bedroom utensils, or pour down sinks, toilets, or drains. It is a good thing also to pour a few teaspoonfuls occasionally on the floor of the closets in which your shoes, trousers, dresses, and other outdoor clothing are kept, as these are quite likely to be contaminated by germs from the dust and dirt of the streets.

Formalin is one of the best and safest general disinfectants to use. Its advantages are, that it is nearly ten times as powerful a germicide as carbolic acid, or even corrosive sublimate, so that it may be used in a solution so weak as to be practically non-poisonous to human beings. It is so violently irritating to lips, tongue, and nostrils as to make it almost impossible for even a child to swallow it, while the amount that would be absorbed if taken into the mouth and spit out again would be practically harmless, so far as danger to life is concerned, though it would blister the lips and tongue.