The problem was at last solved by the great English physician, Edward Jenner, in 1798.
He found that a form of small-pox was prevalent among cows, and that by taking the germs of this disease, which was called cow-pox, and putting them into the blood of human beings, he could produce a mild form of small-pox, which never assumed a dangerous character, and yet prevented the person treated from taking the real deadly small-pox.
From this experiment vaccination, as we know it to-day, resulted. The practice was given this name in France; the word is derived from vacca, the Latin for cow.
Since vaccination became general, the decrease in the rate of deaths from small-pox has been wonderful, and there has not been one serious epidemic where the practice has been followed.
Yellow fever is a much worse enemy to all people who live in warm climates than small-pox. It is a terrible disease, and often kills its victims in a few hours. All sailors and travellers in southern countries have to meet with the scourge, the sailors calling it familiarly "Yellow Jack."
If it is indeed true that by inoculation people can be made proof against this awful disease, it will be one of the greatest blessings this wonderful century has given to man.
As we have said, yellow fever visits our southern shores every year, though happily not often in an epidemic form. The Government has therefore sent an expert down to the affected districts to discover, if possible, where this disease comes from, and ascertain the best means of preventing it.
Dr. John Guiteras was chosen as the best man to send, and he reports that it is from Cuba that this unwelcome visitor makes its yearly call on us.
The doctor declares that the sanitary conditions in Cuba are dreadful. He says that nothing is done to keep the cities clean or healthy. The drainage in Havana is of the worst possible description, and in times of epidemic no attempt is made to prevent the spread of disease.
There is such constant communication between Cuba and the United States that our Government has been obliged to keep three health officers in the island to report on the state of things and enforce quarantine regulations when necessary.