Montana oil and mining journal., 1938-03-19
Scientists Issue Warning as
Wood Tick Season Nears

dangerous areas, the cost OF protection
for ranchers, fishermen, hunters, and
others who are often in tick-infested
areas, is very small. ANY physician IN
the western states, where tick fever Is
most prevalent, may obtain supply OF
the vaccine free of charge from the
laboratory at Hamilton. Persons de-
string to be vaccinated against Rocky
Mountain spotted fever may then do
charge for administering the vaccine
A supply Of the vaccine was received
in Billings last week.
Since the tick season usually starts
in March or in April, depending upon
climatic conditions, full protection for
the coming season may be obtained
through vaccinations at this time.
Vaccinations must be repeated each
year, however. Tests have revealed
that persons vaccinated in one year
may be susceptible to the disease in
a succeeding year unless they repeat
the treatment.
DR.. Parker has records Of IS cases
of infection which took place from one
to seven years after vaccination. There
were no fatalities among 20 Of these
cases that occurred from one to one
and one-third years after vaccination,
but three of the remaining is died.
Those who died had received vaccine
two, three and four years before in
lection. Two of these were infected in
western Montana.
Two Other Carriers
In addition to the Rocky mountain
wood tick, there are two other ticks
which commonly carry the virus Of
spotted fever, according to DR.. Parker.
These are the American dog tick, found
in central and eastern states, and the
rabbit tick, which is found throughout
the United States. The latter species,
however, rarely occurs on men, and Is
thus not an important source of the
disease in human beings.
While ticks In this region are eX-
tremely common during the spring,
and nearly every individual who re-
mains long in the fields or forests
finds ticks on his person or clothing,
the chances of becoming infected with
spotted fever are comparatively small.
According to DR.. Parker, the per-
centage of ticks that carry infectious
virus varies in different localities and
from year to year even in the same
locality ut Is frequently less than one
percent and rarely exceeds five percent,
although in small, localized areas as
high as IL percent has been demonr
have shown three percent to be infec-
tious one year have the next year
failed to show evidence Of single in
fected tick"
Even infected ticks, however, do not
always impart the disease to man. In
order for the virus to take effect, it
must be 'reactivated." This requires
about eight hours under ordinary. con-
ditiOnS and means that II the tick is
removed from the body in less than
eight hours 1t is not probable that the
disease will be transmitted
Adults More Susceptible
DR.. Parker also points out that the
virulence of the tick virus remains
fairly constant in each locality from
year to year, but may vary greatly
in different localities. Adults are ap-
parently more susceptible to the virus
than children, as shown in the Bitter
Root valley area of Montana.
In this area, noted for the high
percentage of deaths among victims of
tick fever, Al deaths resulted among
adults from total Of SIS cases over a
10-year period, for fatality rate Of
74.58 percent. Over the same period,
there were 16 cases among children
under 13 years of age, causing five
deaths, for fatality rate OF $3.50 per
cent. In most areas, however, the Ia
tality rate is far below that in the
Bitter Root valley, reaching minimum
of about 10 percent.
Except during the spring, the virus
is inactive and spotted
fever Is practically nonexistent DR..
Parker says: TN the west, most Of
the cases occur during the spring and
early summer, the greatest number
in April and May, this corresponding
to the season Of prevalence of the
Rocky mountain wood tick. In sections
of higher attitudes, wyoming, for ex-
ample however the danger season eX-
tends further into the summer. Oc-
casional cases have been reported
during the late summer, fall and
winter months. Fall and winter cases
become infected In mountain
Gus areas. In the east, most cases oc-
cur in the summer, the season Of
greatest activity of the American dog
In Eastern Montana
I'm those areas where agriculture
has become intensive, prevalence has