
ye be a OO 

Relapsing fever is a tropical disease 
carried by ticks and caused by a blood 
parasite (Spzvocheta). 
Owing to social conditions in the 
tropics, control is difficult, and the method 
most often employed is the destruction of 
the infected dwellings. 
Elephantiasis: is another tropical dis- 
ease caused by a relatively large, worm- 
like parasite called /7/arza, This animal 
obstructs the blood vessels, causing an 
enlargement of some extremity. 
Mosquitoes of the genus Cz/ex carry 
the young parasites from diseased to 
healthy persons. 
Chagas fever is a disease of children 
in Brazil, which is carried by the bites of 
certain bugs. 
Diseases of Cattle: Cattle are fre- 
quently sufferers from the ravages of 
blood parasites of which little is known 
save that ticks are the sole carriers. 
‘The diseases are very serious in 
some parts of the United States and are 
responsible for great financial loss to the 
country. 
The most effective means of control 
is the frequent treatment of cattle with 
Arsenic solutions— 
the poison most used — may be applied 
poisonous washes. 
by immersion or by spraying. 
LAE ORLY 
A great many species of flies are found 
in houses, but the preponderant type is the 
well-known House Fly (JZusca domestica). 
‘This insect is our commonest and most 
dangerous household pest. 
|B 
A glass model of a Spirocheta will be 
found among the blood parasites in 
WALL CASE og. 
A mode! at the right of the bottom 
in WALL CASE to depicts such a 
scene. 
See model in WALL CASE go. 
In WALL CASE 10 isa picture of 
a person so afflicted. 
Specimens of these bugs are shown 
in WALL CASE to. 
In WALL CASE to are specimens of 
the principal offending ticks and a 
piece of cowhide which tells the story 
of the creature’s abundance. 
CHART 25 gives the distribution of 
the disease, and in CASE to is a 
picture of Bitter Root Valley, where 
a human tick-borne disease, Rocky 
Mountain Spotted Fever, has prevailed. 
The right of the middle shelf of 
WALL CASE io is devoted to the 
various devices used by cattle raisers 
for the protection of their stock. 
Just above CHART 33 will be found 
specimens of some of the commonest 
species of flies, and CHARTS 28 and 
33 include enlarged drawings of them. 
7 Pa 

