Sanitation in Panama

by William Crawford Gorgas

Another very great advantage of this style of building was that the galleries could be used as living- and sleeping-rooms, and this at Panama was very generally the case. It was found that the cost of screening the gallery was very little more than that of screening the doors and windows. While screening the whole gallery required much more wire netting, the work itself was very simple. Making the window and door frames brought up the cost of screening them to about the cost of screening the galleries.

Care must be taken as to the quality of the wire netting. We were put to a great deal of expense at Panama by sometimes getting wire netting that would last only two or three months. We finally adopted a specification requiring that our netting should be at least ninety per cent copper, allowing not more than ten per cent of non-corrosive metals. All netting was carefully tested to see that it came within these specifications. It was the very general opinion on the Isthmus that houses thus screened protected us much more thoroughly from insect life than is the case in most parts of the United States during the summer months. The dwellers in these houses habitually sat on the galleries, with electric lights burning, and would read for a whole evening without being disturbed by any kind of insect.

The inspector had a man constantly employed patching holes and looking after the condition of this wire screening. In our barracks, in which forty or fifty Jamaican negroes lived, it was much more difficult to keep the wire netting in repair, and to keep the screened door of entrance closed, and some mosquitoes would always get in, if there were any mosquitoes around. In many of our stations we succeeded in entirely eliminating the mosquito, as in the district of Ancon. In such districts it made little difference as to the condition of the wire netting; in other districts where the anti-malarial work had been curtailed, mosquitoes were troublesome, and every day some would get into such barracks as I have described.

For these cases Mr. Le Prince and his assistants developed a very effective method. They took an ordinary test tube, put at the bottom of it a few pieces of ordinary rubber, dropped on this rubber a few drops of chloroform and placed a small layer of absorbent cotton over it to keep it in place. When the mouth of this test tube is placed over the mosquito, she in a few seconds becomes narcotized by the chloroform and dies.

This method of killing infected mosquitoes was developed by Mr. Le Prince and his sanitary inspectors into one of our most effective anti-malarial measures. It can be used where none of the other anti-malarial measures is possible.

For instance, at one time we had railroad construction going on near Diablo Hill. This hill is surrounded by fresh-water swamps on three sides. We put a force of several hundred men to work on this. They were fairly comfortably housed in ordinary box cars, the doors and windows of which had been carefully screened with wire netting. These cars were located at the foot of Diablo Hill, on the edge of the swamp. No anti-malarial work having been done here up to this time, anopheles were very numerous. The swamp was so extensive that efficient anti-malarial work was not considered then practicable. Prophylactic quinin in five-grain doses was being taken by these men, but we knew from a recent experience in this same locality that infection was so severe that prophylactic quinin alone would not protect our men. We knew, also, that a certain number of mosquitoes would get by the screens every night. With a number of men living in a car and using one door, we knew that on the average that door would be open a large portion of the time. From inspections, we had found that there were always a considerable number of mosquitoes in the cars. Mr. Le Prince reasoned that while the mosquito-catcher could not by any possibility catch all the mosquitoes in every car every day, he would catch most of them. It was therefore extremely improbable that any individual mosquito would escape the mosquito-catcher for ten successive days. As it takes ten days from the time at which the female anopheles mosquito bites the man sick with malaria until she herself becomes able to transmit the disease, no mosquito would live long enough under these conditions to become disease-bearing. And in practice this proved to be the case. The mosquito-catcher went through the cars every day and caught all the mosquitoes he could find, and continued this day after day as long as the cars remained in this swamp. The force was kept here for several months without suffering appreciably from malaria.

This was the more impressive from the fact that just before we had our negro employees in cars on the edge of the swamp, we had kept a considerable force of marines for several weeks camped in tents on top of Diablo Hill. These marines suffered very severely from malarial fever, very few of them escaping. The tents not being screened, we could not carry out the same method of catching infected mosquitoes which was so successful in the case of our negro laborers, a couple of hundred yards distant from this same camp. One of the medical officers reported to me one day that, under a mosquito-bar which he had kept over a sick man during the preceding night, he caught in the morning quite a large number of anopheles—about fifty, as I recall it. We used this method more and more during the later years of our work on the Isthmus.

It is quite feasible everywhere, by proper drainage, to eliminate entirely the anopheles mosquito, and in several of our towns and villages we succeeded in doing this, and could have done it everywhere if it had been thought desirable by the authorities to apply the same methods, which had been successful at these places, and previously at Havana.

At stations where mosquitoes were more or less troublesome, the mosquito-catching method above described was very useful in the barracks of the laborers. In a barrack building which quarters forty or fifty men the best screening will not altogether keep out mosquitoes, if there are many mosquitoes around. Holes will continually be punched in the wire netting, but mosquitoes enter principally through the constant opening of the door, and through the door being carelessly left open. We found that at such stations we could keep malaria down by catching malarial mosquitoes.

Occasionally, at a station where we had controlled mosquitoes for several years, a great swarm would appear for reasons which we could not explain. These swarms would not remain for a long time, and usually they were not made up of anopheles. While they lasted, we used the method of catching infected mosquitoes for the protection of our force. On one occasion, however, we had a large flight of anopheles. They swarmed everywhere about the station, and we could not account for them, or discover where they came from. The sanitary inspectors’ department devoted all its spare force to investigating this point, and for a considerable period Mr. Le Prince devoted all his time to the subject. He finally located the breeding area in a small swamp about a mile from the town. This swamp had existed there during the preceding years when Gatun had been comparatively free from mosquitoes. At this particular time when the anopheles were so troublesome, the engineers had begun to pump silt from the channel of the Canal into this swamp. This silt was carried by salt water, which made the water of the swamp brackish. This brackish water apparently favored the development of the anopheles, and they were produced in enormous numbers. The engineers were requested to pump sea water into the swamp area for a few days. This soon made the water of the swamp too salty for the breeding of the anopheles, and in a few days the mosquitoes disappeared from the town.