So much for the bubonic form of plague. The next is the pneumonia form, because it is apt to be mistaken for an ordinary lung disease — pneumonia. This form of plague is dangerous and deadly. It is dangerous because there are millions of little plague bacilli scattered about in the patient's expectoration, and whenever he coughs he sprays the disease to those near his bedside, unless they use extreme care. This plague pneumonia begins with a chill, vomiting, terrible headache, weakness, and high fever. The patient can scarcely get his breath and he coughs violently, bringing up a lot of watery, blood-tinged matter. All of this gets steadily worse and he "gets out of his head" and usually dies on the fourth or fifth day.
There is very little to say about the third variety of plague, the quick black death or the septicæmic plague, because when a person catches it he is soon overcome with weakness and lies down almost anywhere, and if there is no one to take him to a hospital he dies where he drops. For this reason one hears that in certain places where there is plague "people are dying all over the streets." As stated above, in this form of plague the patient usually dies before the swellings or buboes form; in fact, the patient is usually so collapsed from the first that he does not even have a fever.
Now enough has been said about plague as a disease. Most important is it to discuss the means of preventing it from infecting vessels.
In order to do this all rats on vessels must be destroyed and measures must be taken to prevent new rats from entering vessels.
Before describing the different ways of killing the rat let us consider what kind of animal the rat really is. In the first place, both Mr. and Mrs. Rat are good travelers. They can live on next to nothing and can go without water for a long time if they can get even a little food. For example, a rat can live a month on dry grain in a grain-carrying vessel.
The brown rat, the kind ordinarily found upon ships, breeds from three to five times a year, each time bringing forth from 6 to 19 young rats. The number of rats which Mr. and Mrs. Rat can produce in a year may be realized from a known case where 2 female rats, kept in a cage, within 13 months gave birth to 26 litters of young, numbering 180 in all. One of them produced young regularly every 25 days. It is plain from the above that once rats board a vessel they will increase rapidly through breeding and inbreeding alone, not to mention the number of stray rats from wharves which will enter the vessel either concealed in parcels of freight or else by walking up the ropes or gangplanks.
Rats besides carrying plague do other damage; they damage property and freight. One authority estimates that there are as many rats as there are people, and that each rat causes each day a loss by ruining freight and property of at least half a cent. It has been estimated that the rat costs Great Britain and Ireland $73,000,000 a year. An investigation made by Asst. Surg. Gen. Kerr as to losses by rats in the cities of Baltimore and Washington showed that the annual loss in the two cities was about $700,000 and $400,000, respectively.
The yearly loss from damage by rats to cargoes in the holds of vessels and in warehouses is always considerable where no rat-killing work is being carried out or else where nothing is done to keep rats from coming aboard. Rat killing in vessels should not be considered an easy task, in view of the many compartments and openings which are the natural result of the peculiar construction and arrangement of vessels. These compartments and openings afford comfortable places for rats to build their nests in. On the other hand, ship captains are familiar with the construction of their vessels and by going to a little trouble can "build out" against the rats and force them to live in places in which they can be killed either by fumigation or by poison.
Anti-rat measures to be observed by ship captains:
- Destruction of rats on vessels.
- Prevention of rats boarding a vessels.
To effect the destruction of rats on vessels the latter should be fumigated three or four times a year by sulphur burned in pots.
Almost any kind or size of iron pot will answer the purpose. The ordinary sugar pan 2½ feet in diameter is useful in disinfecting the hold of a vessel or a large compartment, the number of pans to be determined by the number of thousand cubic feet of area to be fumigated. Not more than 30 pounds of sulphur should be placed in each pot. For the fumigation of staterooms and the like the small iron cooking vessels are suitable. Each pot should always be placed in a tub of water, as shown in the illustration.
The tubs should be made of wood or compressed paper, as tubs made of galvanized iron or composition metal go to pieces rapidly through rust or breaks in the seams. The pots should never be placed on the floor of a compartment or bottom of the hold of a vessel. In compartments or storerooms they should be placed upon tables or chairs, and in the holds of vessels either on the "tween" decks, upon piles of ballast, or upon boxes. The sulphur should always be ground or mashed into a powder before being placed in the pots, and should be piled around the sides of the pot with a central depression or crater. Alcohol should always be used for lighting sulphur, although a hot coal will answer the purpose.
One pound of sulphur burned in a space containing 1,000 cubic feet will produce 1 per cent of the gas. Five pounds of sulphur burned in a space containing 1,000 cubic feet will produce 5 per cent of the gas.
On empty vessels burn 2 pounds of sulphur for every 1,000 cubic feet of space and let the gas stand for six hours.
In computing the capacity of the hold of a vessel for the purpose of determining the number of thousand cubic feet of space therein, and therefore the number of pounds of sulphur which will be required to produce a 2 per cent volume of the gas, the net tonnage of the vessel shows in a general way the cubic capacity of her cargo-carrying space. Ten net tons will represent 1,000 cubic feet of space; therefore, for every 10 net tons 2 pounds of sulphur must be used to get the average 2 per cent volume strength of sulphur gas. The capacity of the living apartments, storerooms, and the like had best be figured on separately.
In fumigating with sulphur gas all spaces must be made airtight. In fumigating the holds of vessels the hatches should be covered over with their regular waterproof tarpaulins and tightly battened down, leaving a small vent for the escape of the sulphur. All air slits, scuttles, and chain ports should be closed. The doors should be sealed by means of strips of paper pasted over the cracks left between the frame and the door.
If the vessel has cargo the killing of rats should be carried out under the direction of the nearest quarantine officer. After the fumigation is over the rats should be gathered (with the hands protected by heavy gloves) and burned in the ship's furnace or donkey boiler firebox, not in the galley.
Now, the important thing is to keep the vessel from becoming reinfested with rats. This is effected by (1) the use of rat funnels or guards on all lines while the vessel is in port, (2) by keeping a watch for rats attempting to walk up the gangplank, (3) by keeping a sharp lookout for rats being concealed in loosely crated freight, (4) by keeping the ship's food and stores carefully protected from rats, (5) by distributing rat poison (phosphorus or arsenic paste) in the vessel, (6) by keeping ship's cats (they should not be overfed, else they will not try to catch rats) , and, finally, by keeping rat traps constantly set. The following illustration shows what a rat-guard looks like:
The special points of this rat guard are these: A single shield in two parts with arms (funnels) from both sides. It is hinged by bolting at the outside of the shield. There is a guide permitting a perfect fit of the two parts of the disk when closed. It can be used on many different sizes of rope and when placed on the line fits closely by tying on both sides. Rivets are used throughout, thus increasing the strength. The outside half of the arms is cut lengthwise into three strips so that they may be bent to come into immediate contact with the rope when tied.
The details for making the rat guard are as follows: Flat sheet galvanized iron is used for all parts of the guard; 20 to 24 gauge answers best, for that weight of iron is strong enough and does not make the guard too heavy. The shield should not be less than 3 feet in diameter. The funnel tubes should be 18 inches long on each side of the shield. The central opening can be made to fit any size of rope. One made for a 3-inch diameter rope will serve for all smaller sizes. When made or used for encircling a number of lines at the same time the shield should be 4 feet in diameter and the funnel tube enlarged and supported by five flanges and five rivets instead of three. The guide piece, which is the one important feature of this rat guard, is riveted on one side only and then bent around the circumference. The rivets which fasten the funnel tubes go through the tube flanges on each side of the shield. One bolt, two washers, and five rivets are needed for each guard. When badly damaged by use or carelessness a block of wood and a hammer are all that is required to restore the guard to its former usefulness.
When a ship is in port, especially in a plague-infected port, all gangways should be hoisted at night. The captain of a vessel should insist upon the repeated distribution of rat poison in the warehouses from which his cargo is to be taken. He should in some manner be able to inspect the freight intended for his vessel to guard against rats being taken aboard with loosely crated freight. By loosely crated freight is meant such articles as crockery or china packed in straw or excelsior or furniture or matting wrapped in gunny and loosely crated, also peanuts, rice, sugar, wheat, corn, oats, etc., shipped in bags.
Wherever ships go—plague will go. No rats—no plague.
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