Not all who lived in the 17th and 18th centuries died com­paratively early in life. Some lived to ripe old ages.

One of them, a Dutch merchant named Anton van Leeu­wenhoek, lived a full, productive 90 years—1632-1723.

He is important in the annals of medicine because he was one of the greatest of the early microscopists, and he was the first to see and describe bacteria and protozoa.

Leeuwenhoek probably would have denied that he was a scientist. In Amsterdam he worked for a linen draper for a time and he frequently had to examine cloth through magni­fying lenses. As a result of this, he became interested in grind­ing lenses as a hobby. He used his lenses to construct his own microscopes, building a total of 247 during his lifetime.

One day he decided to examine a drop of water under a microscope. On this day he became the first man to see mi­crobes. It opened a new and fascinating world to him. When he examined the white film collected on his teeth he said that he saw "little animals, more numerous than all the people in the Netherlands, and moving about in the most delightful manner."

The history of the microscope is a story in itself. When Leeuwenhoek made his exciting discoveries, his most power­ful microscopes obtained a magnification of only 160, at most.

Today, by using two systems of lenses, plus the many im­provements added to this type of microscope over the last 150 years or so, it is possible to see bacteria which are only 1/250,000th of an inch in diameter.

In the 1930s the electron microscope was developed. Whereas the most powerful compound microscopes using the familiar lenses may magnify some 2,500 times, the electron microscope magnifies about 25,000 times, and by photograph­ing the image, it is possible to attain a magnification of as much as 100,000 times.

When the Dutch merchant discovered bacteria, and when others began to employ the microscope, a new age of medi­cine was being born. The microscope also was to spell the beginning of the end for a great amount of folk medicine that had been accepted up to around 1850.

Previous to this period, people could recognize a large num­ber of illnesses. For some they had devised reliefs and reme­dies. But people actually did not know what caused illnesses.

For a very long time the general belief was that illness was caused by evil demons. The primitive medicine man or witch doctor devoted his skills to driving off the evil spirits that had attacked a sick person.

Usually he used one of three methods, or a combination of them.

One was religious or spiritual in concept. The doctor or medicine man used charms, talismans, magic words, chants, or spells to get rid of the evil spirits, or to ward them off.

A second method was to make things so unpleasant for the evil spirits that they would leave. Feeding the patient abomin­able, vile mixtures was a favorite method for this treatment.

A slightly more valuable method was the third. This in­volved use of plants and herbs resembling the various organs of the body that might be affected. Some of these remedies actually did cure some illnesses, or brought relief from pain, but not for the reasons believed at that time.

Whatever the "cures" might be, the causes of disease ac­tually remained a mystery until the microscope opened the doors and men became acquainted with the germ theory of disease, firmly established among scientists by the work of the famed Louis Pasteur, the Frenchman who lived from 1822 to 1895.

Pasteur's greatest ambition was to find an effective vaccine for each disease. His most sensational achievement—among many that made medical history—was his conquest of rabies by treating a victim bitten by a rabid animal. After an intense period of research, he first used his rabies vaccine out of pity, and before he felt ready to use it.

On July 6, 1885, a frantic mother brought her son, age 9, to Pasteur's laboratory.

Speaking with fright and anxiety she explained that her son, Joseph Meister, had been bitten a number of times by a rabid dog, two days before.

Carefully and with great kindness, Pasteur examined the boy. His eyes filled with pity and dismay when he saw the 14 wounds the boy had, and saw how weak he was.

Still hesitant, he consulted with two doctors who were fa­miliar with his work, Dr. Vulpian and Dr. Grancher.

"Use the vaccine," they urged. "Use it."

Pasteur began a series of vaccine injections. Anxiously the doctors and the boy's family watched and waited. Thirteen inoculations were given by Pasteur, each one stronger than the last. The child recovered and lived to die an old man in 1940.

Thus in similar situations, as with Jenner and smallpox in 1796, men learned to use vaccination, based upon the prin­ciple that if a person acquires the disease in a mild form, antibodies for the prevention of the ailment will be manu­factured in his own blood and render him immune to attack.

It was Pasteur, too, who discovered that wines were spoiled by parasitic growths which could be destroyed by heating the wine for a few moments. The process has since been extended to other fields and is familiarly known as "pasteurization."

Robert Koch, a Prussian born in 1843 and who died in 1910, discovered how to segregate different kinds of germs from one another. Following Pasteur, Koch set the pace for others and bacteriology came into its own.

The list of diseases that gave up their secrets to the bac­teriologists during these early years is impressive and im­portant.

In 1879 Neisser discovered the gonococcus that causes gonorrhea. The following year Eberth discovered the typhoid bacillus. In 1883 the diphtheria bacillus was discovered by Klebs, and the streptococcus of erysipelas by Fehleisen; the bacillus of tetanus by Nicholaier in 1884, meningococcus by Weichselbaum in 1887. Others followed.

When microbes finally were accepted and classified, they were identified as: bacteria, which are plantlike; protozoa, which have animal characteristics; and viruses, which are on the borderline.

Today the world has become quite familiar with bacteria. Protozoa is fairly well defined in some minds, and seldom mentioned in ordinary conversation. But the word "virus" has become probably one of the most used and least understood words in the layman's medical vocabulary.

A bus driver chats with a dispatcher. "The wife's down. Got a virus. Seems to be a lot of it around, but the doctors can't do much about it."

"Yeah, I know," says the dispatcher. "I had one of those viruses last year. And my kid had virus pneumonia."

Across town a middle-aged librarian disconsolately rubs the side of her neck and complains to an assistant, "I just can't understand where I picked up this pain in my neck. It's most annoying."

The assistant wrinkles her young forehead. "There's a virus going around that seems to act just like that. Maybe you'd better see your doctor."

Viruses, in comparison with other microbes, still are very much a mystery in many aspects.

Protozoa are classed as animals, are seen under a micro­scope to have a jellylike consistency, and they reproduce by splitting themselves into two units. Best known protozoa are the paramecium and the ameba.

We know that most forms of protozoa usually are harmless, although a few do cause devastating diseases. Among the harmful ones are those causing diseases such as malaria, African sleeping sickness, and amebic dysentery.

Bacteria rely upon outside sources for food. Usually a mag­nification of not less than lOOOx is needed to see most bacteria. They, too, reproduce by fission—splitting in two. Under exact conditions for ultimate reproduction, it is said that a single bacterium could produce some 17,000,000 bac­teria in 12 hours.

Of the some 1500 known kinds of bacteria, most are harm­less and some are quite useful. Soil enrichment is dependent upon bacteria in decomposition of dead leaves, twigs, and other materials. Processing of buttermilk, cheese, and butter depends upon bacteria.

But the viruses have kept their secrets well.

For one thing, they are so tiny that even the electron mic­roscope cannot reveal all of them. Most will pass through porcelain filters which will catch bacteria. It is believed that 25,000,000 polio viruses can fit on the head of a pin.

Unlike other members of the microbe family, the virus cannot produce its own. To reproduce it must find a "host" in a living cell.

The viruses have been much more difficult to track down in comparison with the ordinary germs which cause whoop­ing cough, scarlet fever, pneumonia, or typhoid fever. Also, they have caused some of our most stubborn illnesses, includ­ing poliomyelitis, rabies, smallpox, chicken pox, yellow fever, typhus, encephalitis, infectious hepatitis, influenza, and the common cold.

What is a virus if it isn't animal or plant?

The virus is a core of nucleic acid coated and protected by protein. It is believed that a virus penetrates a cell wall and forces the cell to use its "own machinery" to develop new viruses.

Outside a cell, a virus is virtually a piece of chemical sub­stance. It becomes active only when it injects itself into a cell. About this, Professor Ernest C. Pollard of Yale Univer­sity says: "Once there, it becomes intensely alive, so much so that a gram of virus turns over an amount of energy equiva­lent to that produced by five full grown men." The viruses force the cell to make an enzyme, virolysin, which attacks the substance holding the cell together. The cell explodes. Viruses escape into neighboring cells, the process is repeated.

The fight against the virus has been slow. As yet only a very few virus diseases can be prevented, and only a very few can be cured by drugs now available.

As has already been indicated, one of the great victories over a virus has been the conquest of polio. The story of the famous Salk vaccine is too familiar to be repeated here. Figures released in 1960 indicate that 40 million Americans had had at least one shot of the "dead" Salk vaccine. Twenty million had had two shots and 7 million had had all three shots.

Even while the drive has been on to have the population protect itself with the Salk vaccine inoculations, an equally intense drive has been going on among scientists, including Salk, to find a "live" vaccine that, preferably, could be taken orally. Three have been developed in this country by: Dr. Albert Sabin of the University of Cincinnati, Dr. Hilary Kop-rowski of the Wistar Institute, Philadelphia, and Dr. Herald Cox of the Lederle Laboratories, Pearl River, New York.

Recent licensing of the oral polio vaccines for commercial production will make it possible for children and adults to be immunized against polio orally instead of by injection.

Meanwhile, a new and highly purified Salk-type vaccine has been licensed and released for physician use. It is called Purivax and it is said that two spaced injections give polio immunity to 90 per cent of recipients within 60 days.

Within a comparatively few years the ravages of polio have been routed by a successful weapon in the use of a vaccine. What about other diseases?

Here is a rundown of vaccine progress at the beginning of 1961:

Influenza. Flu vaccines containing several strains of killed viruses appear to be effective, and may even protect to a de­gree during an epidemic resulting from a new strain not in­cluded in the vaccine.

Colds. As previously discussed, a good many viruses re­sponsible for specific kinds of colds have been tracked down and vaccines have been made from them. Much work is be­ing done in this area.

Croup. It is believed that certain viruses may cause more than half the attacks of acute infectious croup. Within a year or so a vaccine may be available for croup.

Rabies. A new rabies vaccine under study may give quicker and safer protection than the Pasteur treatment.

German Measles. Work is progressing toward an effective vaccine, and it is possible that a vaccine now being tested may be effective against rubeola, the more serious form of measles.

Mumps. An effective vaccine is now available. It is especi­ally valuable for young fathers who have not had the disease and who are exposed to the disease by their children.

Chicken Pox. Methods to cultivate a vaccine against this disease have not been wholly satisfactory. Better methods are being sought. If perfected, it is believed that the vaccine will also protect against shingles.

Infectious Hepatitis. This mysterious disease comes in six-year cycles. In 1960—a sixth year—estimates placed the num­ber of victims at about 50,000. About 65 per cent of cases in children hit between the ages of 5 and 14. Among adults the 25-40 group is most frequently affected. It is more common among children; more severe among adults. Its symptoms usually consist of nausea, weakness, vomiting, chills and fever. It frequently is fatal.

The disease is caused by a virus as yet uncaptured, so it has not been possible to make a vaccine. An injection of gamma globulin may give temporary protection.

Mononucleosis. This disease, also called glandular fever, is known to be caused by a virus, but—as with the virus that causes hepatitis—it has not been captured. No vaccine is available.

Smallpox. A new, improved smallpox vaccine, relatively free of foreign material, can be produced with better control of purity and potency.

Coxsackies. The many Coxsackies are said to be cousins of the polio virus, but they do not cause paralysis. Their symp­toms—sore throat, fever, vomiting, headache—are also early symptoms of polio and usually cause alarm. Test serums will quickly determine if the illness is polio or not. Vaccines against Coxsackies have been prepared on an experimental basis. If they are ever needed they will be available.

Cancer. This already has been discussed. Treatment of certain cancers with experimental vaccines has made some progress.

Certainly, few fields of endeavor in medicine hold greater challenge or importance than in virology.

Dr. Chauncey D. Leake of Ohio State University summed it up tersely by remarking that "Viruses are in the midst of many of our most pressing modern problems." He then enum­erated nuclear energy and radiation, genetic mutations, over­population, cancer, and even our philosophies.

Truly giant strides have been taken since the day that a Dutch merchant first viewed microbes and said that he saw: "Little animals, more numerous than all the people in the Netherlands, and moving about in the most delightful man­ner."

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