DISEASES FROM MICRO-ORGANISMS. 131 
years 50,000 people have been immunized in this way, 
with failure in only 1 per cent. In cases of dogbites 
where there is a suspicion that the animal is rabid the 
wound should be cauterized with pure nitric acid. The 
animal should not be killed but kept in confinement. 
If it is rabid it will develop unmistakable symptoms 
and die in five or six days. The whole head of the dog 
should be sent at once to the nearest laboratory where 
the diagnosis can be made. 
Yellow Fever. 
This is an acute infectious disease the cause of 
which is unknown, but it has been proved that the in¬ 
fection may be transmitted by a certain kind of mos¬ 
quito called the Stegomyia fasciata. The blood of 
yellow fever patients contains the virus for a period of 
three days during the sickness, and as the stegomyia 
feeds on the blood of the patient during this time, it 
becomes infected. The mosquito cannot transmit the 
infection at once; not until twelve days have elapsed. 
Yellow fever is primarily a disease of the tropical 
climate, particularly of the Spanish-American coun¬ 
tries. It is occasionally imported to the temperate 
climate, as numerous epidemics in the seaport cities of 
the United States testify. To prevent the spread of 
the disease efforts must be directed to the destruction 
of the breeding places of the mosquitoes, and to prevent 
them from biting yellow fever patients. The former 
means the complete cleaning up and draining of the 
swamps and marshes. All yellow fever patients must 
Distri¬ 
bution 
Preven¬ 
tion 
