Deer Tick in SD
Deer Tick in SD
Mike Catangui, Ph.D. Associate Professor, South Dakota State University
Posted on April 19, 2000. Last updated on April 3, 2003.
(Click on thumbnails for bigger images)
The first record of deer tick or blacklegged tick (Ixodes scapularis) in South
Dakota
was made 31 years ago. Former SDSU Professor of Entomology, Dr. Burruss
McDaniel, collected a deer tick from a road-killed doe in Brookings County in 1969.
For over 20 years since, deer ticks were not observed
in the state. Then on October
14, 1991, a second specimen was found in Watertown (Codington County). This
time the deer tick was found in a home on a bed sheet after being dislodged from
a pet dog.
The third specimen was collected crawling on an adult
near Lake City (Marshall County)
on August 5, 1998. A retired Extension personnel brought the specimen in.
On August 9, 1999, a girl from Watertown who took a
vacation in Wisconsin was
determined to be infested by a single deer tick.
On September 17, 1999, a deer tick was found attached
to a child who visited a park
in Sioux Falls (Minnehaha County). And the last deer tick collected was from a dog
that had roamed around Deuel and Codington Counties.
Deer ticks are capable of transmitting the
microorganism that causes
Lyme disease
in humans.
Life Cycle of Deer Ticks
Adult deer ticks usually spend the winter on
white-tailed deer. Hunters may therefore
encounter adult deer ticks starting in the fall. Engorged adult female deer ticks
drop
from the host then lay eggs on the ground in the spring. These eggs will hatch into
tiny larvae (almost microscopic) in the summer then will attach to small animals like
mice, voles, and chipmunks. The white-footed mouse is the preferred host of the
larvae and is a reservoir host of the spirochete that may cause Lyme disease.
The deer tick larvae, after engorging on the blood of
the small animal host will detach
and drop to the ground, then overwinter in sheltered areas close to the host's habitat.
The overwintered larvae will molt into nymphs in the spring, then attach again to an
animal host.
Nymphs may infest a variety of hosts including dogs,
cattle, rodents, birds,
squirrels, and humans. Nymphs are believed to be the most capable vector of
the
Lyme disease spirochete. Nymphs may be encountered from late spring through
summer.
Engorged nymphs will detach from the host then molt
into adult deer ticks in late
summer. These adult ticks will then attach to a white-tailed deer (usually) to
overwinter.
Any stage of the deer tick is capable of transmitting
the Lyme disease spirochete.
Once infected, a deer tick will be infected through its life span. Thus, a larval
deer tick
may ingest the spirochete from a white-footed mouse early in its life and potentially
transmit the spirochete to any host later after it molted into a nymph or adult deer tick.
In humans, an infected deer tick will have to be
attached to the skin for at least 6 hours
for it to successfuly transmit the Lyme disease-causing spirochete. Timely detection
and removal of potentially infected deer ticks after an outdoor excursion may enable
humans to avoid contracting Lyme disease.
