[Music]
[Narrator:] This is a rat, a common domestic rat.
Probably you have never had more than a fleeting glimpse of one, for the rat is a very stealthy
and suspicious animal, and rarely leaves its nest except under cover of darkness.
But whether you have ever seen one or not, there's a great deal you should know about rats,
for they play an important part in your life.
This is a Norway rat, called rattus norvegicus, one of the two common domestic species
in the United States.
And these are roof rats, known technically as rattus rattus, members of the other species common to the United States
These two species, the roof rat and the Norway rat, have attached themselves to man,
eating his food, and when they leave in search of food, fighting over it too.
Rats like man's dwelling places as well as his food.
Often to suit themselves they make minor alterations in our homes.
All too often, they are as familiar with our kitchens as we are.
For as far back as recorded history, rats have made free with man's property and invaded his homes,
coming and going about their stealthy business throughout the night hours.
The rat doesn't have a narrow range of taste in food.
It takes its food where it finds it.
And what better place to look for food then in the cold storage room of a butcher shop?
Rats have successfully adapted themselves to man's living places, his places of work, and to his food,
thus they have become man's unwanted companion and unwelcome guest.
Unwelcome indeed, for the rat is the most wasteful and destructive animal known to man.
He not only eats man's food, but contaminates many times more than he can devour,
rendering the remaining food unfit for human consumption.
In such places as butcher shops and groceries, the rat plies his destructive trade.
The continuous drain of nightly losses is an economic factor, which in a small business,
may make the difference between success and bankruptcy.
In a typical case, a small warehouse recorded a merchandise lost by rat damage
of $300 in one month.
An extra fulltime employee was hired for the sole purpose of sewing up holes cut nightly in feedbags by rats.
In addition to consuming and contaminating foodstuffs, rats damage property.
Sometimes the destruction occurs purely through the accident of random activity.
More often their destructiveness is purposeful, supplying them with nesting material for their harborage use.
There is little doubt that rat spoilage runs into hundreds of millions of dollars annually
in the United States alone.
Yet this economic destruction is overshadowed by the threat to man's health and welfare.
In many diseases the rat is the source of man's illness.
For example, take Harold Simpson, 55, a mechanic.
Harold had such a violent attack of abdominal cramps, diarrhea, and nausea
that he had to stay home from work.
Food poisoning, the doctor called it.
This was the sixth case in two weeks.
And of all those afflicted were employees at the Walters plant.
Could it be that the source of trouble was the hash house around the corner from the plant?
Maybe the answer could be found there.
Yes, quite likely.
During the night rats had used the shelves and dishes as a runway.
There was hardly a piece of chinaware that they left untouched.
They had scampered across the chopping block, contaminating the work surface
on their way to feed at the uncovered garbage pail.
In the morning, through ignorance or negligence, the block was not properly cleaned,
although it was contaminated with rat feces and urine, teeming with bacteria.
Bacteria, salmonella bacteria, were mixed with the salads.
Those unlucky enough to eat the salads for supper were infected with a painful disease,
salmonellosis.
But rats are also the carrier of other diseases.
Henry Travis, 35, with a good health record, came down a week ago with fever, vomiting, jaundice.
A medical examination showed enlargement and tenderness of the liver.
Hemolytic jaundice, or Weil's disease, was the diagnosis.
Henry Travis will have to stay in the hospital four to six weeks, and it may be three months
before he'll be strong enough to return to work at his fish market.
How did Henry contract Weil's disease,
and is Frank, Henry's fellow fish-handler, in danger of getting the same disease?
Let's see how the fish market is run.
It often happens that Frank receives a late shipment of fish shortly before closing,
pretty good fish, usually freshly caught.
No time to dress them though, so why worry about that?
Ice and salt will keep them fresh until morning.
Meanwhile, there are more interesting things to do, like a game of bridge, a trip to a bowling alley,
or the movies.
Now, a closed door won't keep rats out of a building they've already infested, nor will boards nailed over a rat hole
deter them long, especially with excellent food such as fresh fish lying around,
ready for the taking.
Rats gnaw vigorously, stopping from time to time to test the hole for size.
Sometimes one rat spells another at the job.
So much for that, now for the fish.
Keeping food on ice may prevent spoilage but it will not protect it from hungry rats.
Of course, during this night-long feast the rats urinated and defecated at their own convenience.
Their feces and urine containing the organisms that cause Weil's disease were deposited
on wet surfaces, ideal for the survival of the disease organisms.
Hmmm, rats again, got to get rid of those critters.
I believe the rat-contaminated fish and waste was probably what put Henry in the hospital,
and Frank's prospects for health don't look too good either.
Weil's disease is an occupational hazard among fish workers and others who, like troops in combat,
are exposed to wet conditions where rats are prevalent.
Although Weil's disease is most unpleasant to humans, the rats don't mind it at all.
The organism of Weil's disease can enter the body not only through abraded skin,
but also through unbroken skin.
Although rats will rarely attack an adult, they are attracted by the helplessness of children
and by the food left around the child's mouth after feeding.
[Baby crying]
Frequently, very young children are bitten by rats.
In large cities hundreds of children are bitten by rats each year.
In any case of rat bite, more important than disfigurement or minor infection is the danger of rat-bite fever.
This may develop in five to ten percent of the cases.
Another case, Jim Bates, 45...came down with a high fever, general weakness, and muscular pain.
He had violent headaches.
A few days after hospitalization a rash appeared on Jim's body.
Laboratory tests showed the presence of rickettsia organism.
The diagnosis was murine typhus fever.
Jim will have to spend about a week in the hospital, plus a convalescence that may last several months.
His recovery will cost plenty too, in drugs, hospital care, and loss of wages.
Now, just how did Jim contract murine typhus?
Jim was sweeping up in the cellar of the grocery store where he works.
That trap did the trick.
Better get rid of the dead rat.
Now to set the trap again.
While he was sweeping, something must have irritated the back of Jim's hand.
Two weeks later he was in the hospital.
Here is the probable chain of transmission of the disease.
Rats are the reservoir of murine typhus fever.
The disease is transmitted from rat to rat by a flea known as the oriental rat flea.
The flea engorges itself with the rat's blood,
and deposits its feces containing the diseased organisms on the rat's skin.
After the flea has had its blood meal, it drops off.
In the meantime the rat scratches itself, forcing the organisms into the abraded skin.
It is the flea feces, not the flea bite, that carries the murine typhus organism.
Typhus organisms from the feces can enter the bloodstream through abrasions or other openings
in the skin.
When the flea is hungry again it bites another rat and leaves its infected feces on the rat's skin.
Thus the disease is spread by rat fleas from rat to rat and to man.
Jim Bates probably scratched some of the infected flea feces into his skin.
Murine typhus is prevalent in all the southern states and in certain other areas.
But of all the diseases the rat carries, the most dreaded is plague.
Historically plague, called the Black Death, has been the worst scourge of mankind.
In past centuries plague has taken the lives of more than 25 million people.
Through plague alone the rat has carried death to more people than all the battles of history combined.
But new drugs and insecticides will undoubtedly prevent any large outbreaks in the future.
Nevertheless, plague still exists in many parts of the world.
It is endemic in the Middle East, Africa, India.
China,
the East Indies,
South America
and the United States.
Within recent times plague has broken out in seaport cities of the United States.
In these outbreaks, infected ship rats coming from foreign ports infected the local rats.
But since 1924 the constant vigilance of our modern quarantine service has protected
the United States from repetitions of such outbreaks through rigorous ship and aircraft inspection.
However, a plague reservoir exists among wild field rodents in the western half of the United States.
Plague exists among a number of wild rodents.
This reservoir of plague and wild rodents, called sylvatic plague, constitutes an ever-present danger.
Domestic rats take over burrows of wild rodents,
in which infected fleas transmit the disease to the domestic rats.
The finding of many dead rats indicates active transmission of plague and is a sign of danger to humans.
For the rat fleas will leave the dead animal and carry the infection to live rats or humans.
The infected flea attempts to feed on the blood of his new host.
The plague organism, Pasteurella pestis, clogs up the flea's alimentary canal,
resulting in regurgitation of the infectious material into the bitten skin.
Again, infected fleas seek another host.
Plague kills the rat and the fleas within a few days.
When man comes along the flea adopts him as host, bites and infects him.
Plague kills the rat, the flea and the man.
The rat is a spoiler and a killer which has flourished by adjusting himself to man's ways.
The rat's problem is man's problem, a problem which will be solved only when man,
knowing the ways of rats, adapts the methods of science to rat control and eradication.
[Music]