''Dermacentor andersoni'', commonly known as the Rocky Mountain wood tick, is a hard tick, or member of the

Ixodidae The Ixodidae are the family of hard ticks or scale ticks, one of the three families of ticks, consisting of over 700 species. They are known as 'hard ticks' because they have a scutum or hard shield, which the other major family of ticks, the 'sof ...

family, with three life stages including larvae,

nymph A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label= Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ...

, and finally adult, or, more entomologically,

imago In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...

. This tick is generally located in the northwest

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

and southwest

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

along the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...

. This tick is generally a

vector Vector most often refers to: *Euclidean vector, a quantity with a magnitude and a direction *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...

for

Colorado tick fever Colorado tick fever (CTF) is a viral infection (Coltivirus) transmitted from the bite of an infected Rocky Mountain wood tick ('' Dermacentor andersoni''). It should not be confused with the bacterial tick-borne infection, Rocky Mountain spotted f ...

, but can also be a vector for

Rocky Mountain spotted fever Rocky Mountain spotted fever (RMSF) is a bacterial disease spread by ticks. It typically begins with a fever and headache, which is followed a few days later with the development of a rash. The rash is generally made up of small spots of bleedin ...

and

tularemia Tularemia, also known as rabbit fever, is an infectious disease caused by the bacterium ''Francisella tularensis''. Symptoms may include fever, skin ulcers, and enlarged lymph nodes. Occasionally, a form that results in pneumonia or a throat infe ...

. During the larval and nymphal stages, the tick does not feed on humans, but during the adult stage, it will. Prevention of infections associated with these ticks is based on control of exposure to the vector, including wearing proper clothing when in woods/wet areas, and checking oneself thoroughly after returning home. Adult female ticks can feed for 5 to 15 days, thus removing a tick if present is very important. Follow general tick removal tips.

Life cycle

''Dermacentor andersoni'' is a three-host tick with larval, nymphal, and adult life stages. During each life stage, the tick takes a single blood meal from a mammalian host. The duration of the lifecycle varies between 1 and 3 years and is influenced by factors such as temperature, humidity, and host availability. From the beginning of May through June, ticks' eggs are deposited on moist vegetation after the engorged female ticks drop off their hosts. The female lays about 2500–4000 eggs over 10–33 days. Larval ticks hatch in early summer and begin questing for small mammalian hosts, seeking the stimuli of carbon dioxide, light, temperature, and humidity. A larva may cling to a passing host with the first pair of legs, climb upwards, and then attach with its

gnathostome Gnathostomata (; from Greek: (') "jaw" + (') "mouth") are the jawed vertebrates. Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. In addition to opposing jaws, living ...

to the neck or shoulder region. They feed about 2–6 days. After becoming engorged, larvae drop off the host, and

molt In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

into

s. Nymphs remain dormant for extended periods of time unless stimulated by presence of a host. Nymph feeding behavior is like that of larvae. Nymphs and larvae do not feed on humans, but adults do. If they find a host and attach, the adult females feed continuously throughout that time, around 5–15 days. Males, though, feed for a shorter period and copulate with several, partially fed females that are still on the host. Females drop off the host when fully engorged and seek an area to oviposit. Both sexes die shortly after reproducing.

Morphology

''Dermacentor andersoni'' hard ticks are generally brown or reddish brown in color. Females have a distinct dorsal silver-gray ornamentation that turns more gray when the tick feeds, while males are spotted gray and white with no distinctive shield marking. Their bodies are flat and pear-shaped, ranging from 2.0 to 5.3 mm in length, and have 11 festoons on their lower dorsal portion. This species is sexually dimorphic; females are generally larger and can increase their size by nearly three times when fully engorged. This species is also polymorphic, with much physical variation between individuals. Features that distinguish this species from other ticks include the number and size of goblets, which are used for respiration on its spiracular plates; ''D. andersoni'' typically has 100-200 goblets on average. This is only observable with a light microscope.

Disease transmission

These ticks are generally a vector for

and can possibly be a vector for

and

. However, the related species, ''D. varabilis'' is more likely to be a vector for Rocky Mountain spotted fever than ''D. andersoni.'' As stated above, ''D. andersoni'' is generally located in the NW USA/ SW Canada whereas ''D. varabilis'' is generally located in the eastern USA. The border separating these two species could be considered to be the Missouri River. Thus, if one were to find a ''Dermacentor'' tick on oneself when west of the Missouri River, the risk for Colorado tick fever would be higher than for Rocky Mountain spotted fever. The tick can become infected with a disease by feeding on a small mammal during its larval or nymphal stage and can generally be a vector in its nymphal or adult stage.

References

{{Taxonbar, from=Q4298306 Ticks Endemic fauna of North America Animals described in 1908 Ixodidae

Life cycle

Morphology

Disease transmission

See also

References