1 4 
PROPHYLAXIS OF MALARIA. 
for some of the discrepancies between the results of different in¬ 
vestigators as to the efficiency of various sized wire screens. 
In 1908 Col. J. It. Kean, Medical Corps, United States Army, sent 
Dr. Guiteras, in Habana, some 16-mesh wire screening and requested 
that experiments be made regarding its efficiency in excluding ste¬ 
gomyia mosquitoes. After many very careful experiments Dr. Gui¬ 
teras reported to Col. Kean that the netting sent kept out Stegomyia 
fasciata , using the following words: 
It is my opinion that we may conclude from these experiments that the Ste- 
iiomyia calopus ( fasciata ) can not pass through the wire gauze sent for trial. 
The gauze is 16-wire mesh—that is, it presents 16 wires or threads to the linear 
inch. 
In 1910 Darling, as the result of his experiments in the Canal Zone, 
states: 
In regions where it is only necessary or desirable to protect against anophe- 
lines a No. 16 mesh screening (16 holes to the inch) would answer the purpose, 
and where, as in this region, it is necessary to protect against some of the 
smaller varieties, such as Stegomyia calopus , a No. 16 mesh would be practically 
safe, but not absolutely so. 
He found that none of the anophelines in the Canal Zone could 
pass the 16-mesh screening, but that some specimens of Stegomyia 
fasciata (calopus ) could, as well as several species of Culex. 
Owing to the uncertainty caused by the divergent reports of 
Guiteras and Darling, the Surgeon General of the Army, in 1912, 
requested the Army Board for the Study of Tropical Diseases in the 
Philippine Islands to determine what sized copper-wire gauze would 
prevent the passage of anophelines and other mosquitoes. The 
board, as the result of very careful experiments, found that 16-mesh 
wire gauze was impervious to the following mosquitoes: Myzomyia 
rossii , Mizorhynchus barbirostris , Pyretophorus freerae , Mansonia 
annulifera, Mansonia uniformis , Culex fatigans , and Culex microan- 
nulatus. As Myzomyia rossii is as small as any of the anophelines 
connected with malaria, their observations confirm mine, made in 
1905 at Camp Stotsenburg, but they also determined that this same 
species could be excluded by either No. 12, 14, or 16 mesh screening. 
In addition they found that Stegomyia fasciata (calopus) could pass 
No. 16 mesh netting with considerable ease, and concluded that while 
the No. 16 mesh will keep out all malaria mosquitoes found in the 
Philippines its use is inadvisable because it does not keep out the 
yellow-fever mosquito. 
From these various observations it appears to me that in the mili¬ 
tary service all screening should contain at least 18 meshes to the 
linear inch, and I believe that it is a mistake to use wire gauze con¬ 
taining more than this number, both because it is unnecessary so far 
as practical protection goes and because it reduces by just so much 
the amount of air admitted to a room or building. 
