After a 36-year campaign, cattle fever ticks were finally declared eradicated
from the United States in 1943.
Smith found that the way to control tick fever of cattle was to control the
ticks, no one knew that his brilliant research would pave the way for control
of malaria, yellow fever, and many other scourges of the Tropics. These
developments came several years later and were the work of other men.
Around 1890 tick fever of cattle was causing
widespread losses, especially in the South. Southern cattle were often driven
to northern markets, and they usually left a trail of fever along the way.
Northern cattle, taken to the South for breeding, usually contracted the
disease and died.
Many southern cattlemen believed that ticks
were somehow responsible for the disease, because cattle that died from it
always had ticks on them. At first, there was no scientific evidence to support
the belief, but the scientists eventually proved that the cattlemen were right.
Theobald Smith began work on tick fever in
1888. Later he was jointed by Dr. F.L. Kilborne and Dr. Cooper Curtice. Smith
and Kilborne discovered the cause of the disease to be a protozoan parasite,
found in the blood of infected animals. In the summer of 1890, they definitely
established the fact that the disease was spread from animal to animal by the
That was the first demonstration that a
disease-producing micro-organism can be transmitted by an insect carrier from
one animal to another. (Working independently, as far as I can learn, Dr. M.B.
Waite made the same fundamental discovery in relation to insect transmission of
plant diseases.) The obvious cure for the disease was to get rid of cattle
ticks, and this was done through a long-time eradication program conducted
jointly by the Department and the states.
Getting rid of cattle ticks and tick fever
has meant untold millions of dollars to cattle growers of the South; this
research cost $65,999, for salaries and expenses, and the Department sets the
value of the discovery at about 40 million dollars a year (editors note:
these are in 1940 dollar values). But you cannot fully measure its value: The
implications of the research that paved the way for the discovery go far beyond
the borders of our country and the monetary value of livestock.
Other researchers were quick to see the
possibility for conquest of human diseases. In a few years the mosquito was
recognized as the carrier of yellow fever, and the work of another Department
scientist, Dr. L.O. Howard, furnished basic information for campaigns to
eradicate mosquitoes. With this malady under control, it was possible for the
United States to build the Panama Canal. French engineers had failed because
they were unable to control yellow fever.