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Tick Identification

Tick Identification



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While enjoying the outdoors in mid-Missouri and Northern Iowa, I came across this tick in my belongings. I can't distinguish whether it is a dog tick, a rocky mountain tick or some other species.


The tick you found is a female American dog tick (Dermacentor variabilis) and not a lone-star tick (Amblyomma americanum). Female lone-star ticks do not have white coloration towards the head and only a round dot in the middle of their body. The following PDF document offers a visual comparison of the two species:

https://store.extension.iastate.edu/Product/pm2036-pdf


Tick Identification - Biology

First published in 2003 by: A.R.Walker, A.Bouattour, J.-L.Camicas, A.Estrada-Peña, I.G.Horak, A.A.Latif, R.G.Pegram & P.M.Preston. Bioscience Reports, Edinburgh. Sponsored by the International Consortium on Ticks and Tick Borne Disease of the European Union. 221 pages, line drawings and photographs, illustrated glossary of all terms used for identification covers all of Africa, also Madagascar.

Summary of contents

Glossary of terms is illustrated as definitions of the characters and their states for identifying ticks.

Chapter 2 describes feeding, reproduction and life cycles of ticks. Instructions are provided for collecting and preservation of ticks.

Chapter 3 shows how to identify ticks to the correct genus. This is illustrated with 28 colour photographs and 8 sets of line drawings.

Chapter 4 consists of 176 pages showing how to identify the commonest 48 species of ticks that are important to health of domestic animals in Africa and Madagascar. Each species has descriptions of its general characters, hosts, life cycle, and disease relations, and its distribution is mapped. The adult female and male ticks are identified using a matrix of character and their states for each genus. Every relevant character state is illustrated by line drawings.

In association with publication of this identification guide the ICTTD distributed: "An introduction to the biology and control of ticks in Africa" by Abdallah A.Latif & Alan R.Walker.

For readers of the above article on ticks and their control, there is also a more detailed review paper, published in a research journal. "Eradication and control of livestock ticks: biological, economic and social perspectives". A.R.Walker, 2011.

More information and images of ticks can be found in Wikipedia and Wikimedia Commons, for example the article: Ticks of Domestic Animals.


First: Remove it promptly. Watch this video on how to properly remove a tick. You may want to save the tick for later ID (see Next). Perform a full tick check in case there are others. Remove clothing and tumble dry on high heat for 1 hour to kill additional ticks.

Next: Knowing the tick's species, life stage, and engorgement level can help you determine your risk of tick-borne disease. You may be able to bring it to your county's cooperative extension office or mosquito control agency for Tick ID, check with them for more information. You can also use this online tool from the University of Rhode Island to identify them yourself.
Be on the lookout for symptoms of a tick-borne disease, such as fever, headache, muscle ache, or rash. Should symptoms develop, see a physician immediately and tell them about the tick bite.

In the future: Prevent future tick bites by wearing repellents, avoiding tick-infested areas, and performing frequent tick checks. There are several key landscape modification techniques that can help reduce tick populations in your backyard.

Chemical control should always be a last resort as the pesticides sprayed for ticks will also kill beneficial insects, like butterflies and bees.


How Can I Recognize a Tick?

Ticks are wingless and possess a single, oval body region that is relatively flat (except when filled with blood). Adults and nymphs have eight legs larvae have only six legs. The so-called "head" of a tick includes structures involved in feeding, together known as the "capitulum." It consists of a pair of leg-like sensory structures known as "palps" that enable the tick to detect an approaching host, a pair of knife-like structures known as "chelicerae" that cut an opening in the host skin, and a single barbed structure known as a "hypostome" that enters this opening. The hypostome becomes anchored in the host flesh when the tick takes a blood meal.


Tick Identification - Biology

Dermacentor variabilis (Say), also known as the American dog tick or wood tick, is found predominantly in the United States, east of the Rocky Mountains, and as its name suggests, is most commonly found on dogs as an adult. The tick also occurs in certain areas of Canada, Mexico and the Pacific Northwest of the U.S. (Mcnemee et al. 2003). Dermacentor variabilis is a 3-host tick, targeting smaller mammals as a larva and nymph and larger mammals as an adult. Although it is normally found on dogs, this tick will readily attack larger animals, such as cattle, horses, and even humans. The 8-legged adult is a vector of the pathogens causing Rocky Mountain spotted fever (RMSF) and tularemia, and can cause canine tick paralysis. While the American dog tick can be managed without pesticides, when necessary a recommended acaricide is an effective way of eliminating an existing tick infestation near residences.

Figure 1. Adult female American dog tick, Dermacentor variabilis (Say). Photograph by Lyle J. Buss, University of Florida.

Distribution (Back to Top)

The American dog tick is widely distributed in the United States east of a line drawn from Montana to South Texas. It is also found in Canada, east of Saskatchewan, and in California, west of the Cascade and the Sierra Nevada Mountain ranges. This species is most abundant in the eastern United States from Massachusetts south to Florida but is also common in more central areas of the U.S., including Iowa and Minnesota (Matheson 1950).

It was been suggested that adult ticks move to the edge of the roads and trails in an attempt to find a host, or "quest." Some have hypothesized that because many animals typically follow trails, they leave an odor that attracts these ticks causing them to move toward and quest alongside trails in attempts to find a host (Mcnemee et al. 2003).

Description (Back to Top)

The 8-legged adult male and female D. variabilis ticks are typically brown to reddish-brown in color with gray/silver markings on their scutum (dorsal "shield"). The female will vary in size depending on whether or not it has blood fed. Unfed females are typically 5 mm long and are slightly larger than males, which are about 3.6 mm long. Females can be distinguished by a short or small dorsal scutum, right behind the mouthparts while the male scutum covers the majority of its dorsal surface. Blood-fed (engorged) females can enlarge up to 15 mm long and 10 mm wide.

Figure 2. Dorsal view of adult female American dog tick, Dermacentor variabilis (Say), with body parts marked. Photograph by J.F. Butler, University of Florida.

Figure 3. Dorsal view of American dog ticks, Dermacentor variabilis (Say), with male on left, and female on right. Photograph by J.F. Butler, University of Florida.

Figure 4. Ventral view of American dog ticks, Dermacentor variabilis (Say), with male on left, and female on right. Photograph by K. Wilson, University of Florida.

Figure 5. Engorged adult female American dog tick, Dermacentor variabilis (Say). Photograph by K. Wilson, University of Florida.

The mouthparts and their base, also known as the capitulum, are visible when viewing from above, with the second segment of the palps about as long as it is wide (Smith and Whitman 1992). The anal and genital openings occur on the underside of ticks. Only adults possess genital openings. Posterior to the anus, there is a groove and the spiracular plate is directly behind the fourth coxae (leg attachment segment).

Figure 6. Dorsal view of the head region from the American dog tick, Dermacentor variabilis (Say). For an even closer look at the mouthparts at the left of the image, seen slightly lower than a line drawn through the center of the image, click here. Photograph by Janice Carr, Center for Disease Control.

There are two stages of immature ticks: 6-legged larvae and 8-legged nymphs. Larvae are

0.62 mm long and are yellow before blood-feeding and gray to black when engorged. Nymphs are about 0.9 mm long, and a pale, yellow-like brown before blood-feeding and become slate gray when engorged (Smith and Whitman 1992). Both stages of immature tick will have red markings near their eyes and will lack white coloration on the scutum (shield). Nymphs can be distinguished from adults by the lack of a genital opening.

Figure 7. Relative sizes of American dog ticks, Dermacentor variabilis (Say), with male (left), female (center), nymph (right). Photograph by K. Wilson, University of Florida.

Life Cycle (Back to Top)

Dermacentor variabilis develops from the egg stage, to the 6-legged larva, to the 8-legged nymph, and finally to the adult. The cycle requires a blood meal before progression from larva to nymph, from nymph to adult and by the adult for egg production. This cycle also requires three different hosts and requires at least 54 days to complete, but can take up to two years depending on the host availability, host location and the temperature.

Figure 8. Life cycle of the American dog tick, Dermacentor variabilis (Say). Photograph by Center for Disease Control.

After five to 14 days of blood feeding, a fully engorged female D. variabilis drops from the host. She digests the blood meal and develops her egg clutch over the next four to 10 days. She then lays anywhere from 4,000 to 6,500 eggs on the ground (Matheson 1950). About 26 to 40 days later, depending on the temperature, the eggs hatch into larvae (James et al. 1969).

After hatching, larvae remain on the ground or climb growing vegetation where they wait for small mammals, such as mice, to serve as hosts for their first blood meal. This host location behavior is called questing. Under favorable conditions, larvae can survive up to 11 months without feeding. After contacting and attaching to a host, larvae require from two to 14 days to complete blood feeding. After feeding, larvae detach from their host and fall to the ground where they digest their blood meal and molt into the nymphal stage. This process can take as little as a week, although this period is often prolonged.

Nymphs can survive six months without a blood meal. After successfully questing for their second host, which is normally a slightly larger mammal (such as a raccoon or opossum), the nymphs will blood feed over a three to 10-day period. After engorging, they fall off the host, digest their blood meal and molt into an adult. This process can take anywhere from three weeks to several months.

Adults can survive two years without feeding, but readily feed on dogs or other larger animals when available. Questing adult ticks climb onto a grass blade or other low vegetation, cling to it with their third pair of legs, and wave its legs as a potential host approaches. As the hosts brush the vegetation, the ticks grab onto the passing animal. Mating occurs on the host and the female engorges within six to 13 days after which she drops from the host to lay her eggs and then she dies, thus completing the cycle (Matheson 1950).

Seasonality (Back to Top)

Adult American dog ticks overwinter in the soil and are most active from around mid-April to early September. Larvae are active from about March through July and nymphs are usually found from June to early September (Goddard 1996). In northern areas, such as Massachusetts and Nova Scotia, adults appear from April to August with a peak in May and June (Campbell 1979, McEnroe 1979a). In central latitudes of the U.S., such as Virginia, adults are found to be active from April to September/October with peaks in May and July (Sonenshine and Sout 1971, Carroll and Nichols 1986). In Ohio, adult activity occurred between April and September with a peak in May/June and a second smaller peak in August/September (Conlon and Rockett 1982).

A study done in Lexington, Kentucky, found the duration of D. variabilis' spring activity was related to its overwintering success. This study also concluded that overwintering adult D. variabilis ticks remained active throughout the entire season (Burg 2001). This same study reported that adult activity began a week or two earlier than in more northern states, such as Ohio, and a week or two later than in more southern states, such as Georgia. In Georgia, adult ticks are active from late March to August with peaks from early May to late June (Newhouse 1983). While in Florida, adult D. variabilis activity occurs from April to July (McEnroe 1979b).

Medical and Veterinary Importance (Back to Top)

The American dog tick is the primary vector for the pathogen causing Rocky Mountain spotted fever (RMSF), although it is also known to transmit the causative agent of tularemia and can cause canine tick paralysis. First discovered in the late 19th century in the Rocky Mountain region, RMSF is more commonly reported in eastern U.S. Rickettsia rickettsii, the causative agent of RMSF, is primarily vectored by D. variabilis to dogs and humans following its acquisition from rodents. Overwintering larvae can also acquire RMSF transovarially (mother to egg) yielding RMSF-infected larvae (Piesman and Gage 1996). Because larval and nymphal ticks rarely bite humans, the adult tick is the primary lifestage of concern for humans. In the southeast U.S., peak occurrence of the disease is in July, at or shortly after the peak activity of adult D. variabilis.

Rocky Mountain spotted fever is an infectious disease. The rickettsia affect small peripheral blood vessels causing rashes to develop within two to five days. These rashes are known to start in the wrists and ankles and move up to the rest of the body. Because of its direct association with adult D. variabilis, RMSF is a seasonal disease, and is more prevalent during the months between April and September. Symptoms usually appear within two to 14 days, with averages of around a week. Fever, nausea, vomiting, diarrhea, headaches, muscle pain and lack or appetite are all symptoms of this disease. Clinical symptoms include elevated liver enzymes, abnormal platelet count, and electrolyte abnormalities (ALDF 2006). Mortality from this disease in humans is 20 to 25% if untreated and 5% with appropriate clinical therapy. In order for transmission to occur, however, the tick must be attached for six to eight hours and in some cases transmission requires more than 24 hours (Thorner et al. 1998).

Dermacentor variabilis can also vector Francisella tularensis, the organism causing tularemia. This gram negative coccobacillus (bacteria) also can be transmitted by contact with arthropods including other ticks, deer flies, mosquitoes, fleas, as well as from infected animals (principally rabbits) to hunters and ranchers. However person-to-person contact is rare. Incubation for this disease is usually three to five days but can take up to 21 days for symptoms to appear (CCHDOE 2001). Symptoms of tularemia include chills, fever, prostration, ulceration at the site of the bite, and tender, swollen lymph nodes. If untreated, fatality rate may be as high as 5 to 7%. Tularemia occurs only in the northern hemisphere and most frequently in Scandinavia, North America, Japan, and Russia (Ellis et al. 2002).

Canine tick paralysis can occur due to the feeding of D. variabilis. In this case, the tick will attach to the back of the dog's neck, or at the base of the skull, and feed for at least five to six days. It is believed to release a salivary gland protein into the body. Paralytic symptoms then become visible through unsteadiness and loss of reflex actions. If the tick is not removed, respiratory failures can be fatal. Such paralysis is not limited to dogs, as it can happen to children as well. Once the tick is properly removed, recovery is usually within one to three days (Schmitt 1969). In the U.S., the fatality rate is about 10% in the Pacific Northwest, and most of those who die are children (Gregson 1973).

Removal (Back to Top)

Ticks should not be removed by handpicking because infected tick secretions can be transferred from a person's hands to his or her eyes, mucous membranes, mouth, etc. Therefore, forceps should be used when removing a tick (Smith and Whitman 1992). To properly remove a tick, grasp the mouthparts near the attachment site firmly with tweezers. Once the mouthparts are held, the tick should be pulled straight back slowly to ensure the entire mouthparts are removed from the body. It is important that the tick is removed slowly because the mouthparts are covered in sharp, backward directed barbs which assist the tick in holding onto its host (Parsons et al. 1989). Sometimes, by removing the tick, a piece of the hosts skin may break off, which should not be a great concern, but bears watching for infection or later reaction.

Figure 9. Enlarged view of the mouthparts of an American dog tick, Dermacentor variabilis (Say). Notice the hundreds of sharp, backward-directed barbs which assist the tick in holding onto its host. For an even closer look at these barbs, click here. Photograph by Janice Carr, Center for Disease Control.

Figure 10. Enlarged view of the hundreds of sharp, backward-directed barbs on the mouthparts of an American dog tick, Dermacentor variabilis (Say). Photograph by Janice Carr, Center for Disease Control.

To treat the wound, it is important to wash the area with soap and water followed by an antiseptic. Once the tick is removed, the recommendation is to save it in alcohol, with the date the tick was removed, in case it is needed for identification or pathogen testing, should disease symptoms occur. If no symptoms occur within a month of removal, the tick may be discarded (USACHPPM 2003).

Management (Back to Top)

The American dog tick occurs primarily in wooded, shrubby and long-grass areas. However, it is possible for residential areas to support populations of this tick. Shrubs, weeds, tall grass, clutter and debris on the property attracts the rodents that are hosts for immature ticks. By maintaining grass short, removing possible rodent harborages, and sealing cracks and crevices in and around the property one can directly reduce or prevent local tick populations. Keeping grass and weeds cut short decreases humidity, which helps kill ticks or makes an area undesirable for ticks and rodents. Additionally, it makes it difficult for ticks to climb on the vegetation and wait for its host. If pesticides are applied, cutting the vegetation short increases effectiveness and allows for better coverage. Removing rodent harborage areas may reduce an infestation.

Because dogs can easily pick up ticks while walking on infested grass or roaming through wooded areas, it is necessary to treat the pet properly. There are many products that can be applied to prevent or treat a tick infestation on an animal including topical treatments and sprays. Regularly grooming, washing bedding, and examining the dog are strongly recommended to prevent tick infestations.

Selected References (Back to Top)

  • Burg JG. 2001. Seasonal Activity and spatial distribution of host-seeking adults of the tick Dermacentor variabilis. Medical and Veterinary Entomology 15: 413-421.
  • Campbel A. 1979. Ecology of the American dog tick, Dermacentor variabilis in southwestern Nova Scotia. Recent Advances in Acarology. Rodriguez JG (editor). Volume 2: 135-143.
  • Carroll JF, Nichols JD. 1986. Parasitization of meadow voles, Microtus pennsylvanicus (Ord), by American dog ticks, Dermacentor variabilis (Say), and adult tick movement during high host density. Journal of Entomological Science 21: 102-113.
  • CDC 2019. Rocky Mountain Spotted Fever (RMSF). https://www.cdc.gov/rmsf/index.html. (30 March 2021)
  • Clark County Health District Office of Epidemiology (CCHDOE). (2001, May 11). Tularemia. http://www.southernnevadahealthdistrict.org/Health-Topics/tularemia/ (23 September 2008).
  • Conlon JM, Rockett CL. 1982. Ecological investigations of the American dog tick, Dermacentor variabilis (Say), in northwest Ohio (Acari: Ixodidae). International Journal of Acarology 8: 125-131.
  • Goddard J. 1996. Physician's Guide to Arthropods of Medical Importance. pp. 287-302. CRC Press. Jackson, Mississippi.
  • Gregson JD. 1973. Tick paralysis: an appraisal of natural and experimental data. Monograph No. 9. Canada Department of Agriculture, Ottawa.
  • Eddis J, Oyston CF, Green M, Titball RW. 2002. Tularemia. Clinical Microbiology Reviews: 15: 631-646.
  • James M, Robert FH. 1969. Herm's Medical Entomology. 6th Edition. pp. 326-329. The Macmillan Company. Toronto, Ontario.
  • Koehler PG, Oi F. (2003). Ticks. EDIS. http://edis.ifas.ufl.edu/IG088 (23 September 2008).
  • Matheson R. 1950. Medical Entomology, 2nd Edition. Comstock Publishing Company, Inc. Ithaca, NY.
  • McEnroe WD. 1979a. Dermacentor variabilis (Say) in eastern Massachusetts. Recent Advances in Acarology. Rodriguez JG (editor). Volume 2: 145-153.
  • McEnroe, W.D. 1979b. The effect of the temperature regime on Dermacentor variabilis (Say) populations in eastern North America. Acarologia 20: 58-67.
  • Mcnemee RB, Sames WJ, Maloney Jr FA. 2003. Occurrence of Dermacentor variabilis (Acari:Ixodidae) around a porcupine (Rodentia: Erthethizontidae) carcass at Camp Ripley, Minnesota. Journal of Medical Entomology 40: 108-111.
  • Newhouse VF. (1983) Variations in population density, movement, and rickettsial infection rates in a local population of Dermacentor variabilis (Acarina: Ixodidae) ticks in the piedmont of Georgia. Environmental Entomology 12: 1737-1746.
  • Parsons GL, Rossignol PA. 1989. Identifying adult hard ticks commonly found on humans in Oregon. EM8410. Oregon State University Extension Service.
  • Piesman J, Gage KL. 1996. Ticks and mites and the agents they transmit. The Biology of Disease Vectors. Beaty BJ, Marquardt WC (editors). pp. 160-174. University Press of Colorado. Newot, CO.
  • Schmitt N. Bowner EJ, Gregson JD. 1969. Tick paralysis in British Columbia. Canadian Medical Association 100: 417-21.
  • Smith EH, Whitman RC. 1992. Field Guide to Structural Pests. National Pest Management Association, Dunn Loring, VA.
  • Sonenshine DE, Stout IJ. 1971. Ticks infesting medium-sized wild mammals in two forest localities in Virginia. Journal of Medical Entomology 8: 217-227.
  • Thorner AR, Walker D, Petri WA. 1998. Rocky Mountain Spotted Fever. Clinical Infectious Diseases by the Infectious Diseases Society of America. 27: 1353-1360.
  • U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM). 2003. Entomological Sciences Program. Aberdeen Proving Ground, MD 21010-5403.

Authors: Wai-Han Chan and Phillip E. Kaufman, University of Florida
Photographs: K. Wilson, J.F. Butler, Lyle J. Buss, University of Florida Janice Carr, Center for Disease Control
Web Design: Don Wasik, Jane Medley
Publication Number: EENY-443
Publication Date: September 2008. Revised: January 2013. Last revised: April 2021.

An Equal Opportunity Institution
Featured Creatures Editor and Coordinator: Dr. Elena Rhodes, University of Florida


Tick Identification - Biology

Ticks represent a successful group of parasitic arthropods that are more closely related to mites, spiders, and scorpions than to insects. These destructive blood-feeding organisms are capable of persisting within a variety of environments worldwide, and when necessary, can survive for extended periods of time (2-3 yrs) without feeding. The life cycles of ticks consist of four distinct stages the egg, six-legged larva, eight-legged nymph, and adult.


Ticks utilize many different feeding strategies to complete their life cycles. The most common strategy requires three separate hosts (the so-called three-host ticks), one each for the larval, nymphal, and adult life stages. Host blood provides the nutrition needed for ticks to molt to the next stage, or to produce eggs for the next generation.

Three-host ticks are normally less host specific than one-host species. The immature larval and nymphal stages generally feed on a wide variety of animal classes (numerous bird or small mammal species), while adult ticks tend to utilize larger animals (deer, cattle, and horses). Three-host ticks generally complete a life cycle in one to two years depending on species. Adult ticks may survive several years without a blood meal.

One-host ticks attach to their host as unfed larvae where they proceed to feed and molt through larval, nymphal, and adult life stages, all on a single host. One-host ticks may produce 1-4 generations per year, depending on species.

As ticks feed, blood-meal nutrients are concentrated within their gut. To rid themselves of excess body water (a byproduct of the blood meal), they utilize their salivary glands to “pump” the waste water back into their host. It is through this process of gut-water expulsion that ticks have the potential to transmit a number of bacterial, rickettsial, protozoal, viral, and fungal pathogens to their animal and human hosts.

However, pathogen transmission via tick-bite is not an immediate nor automatic process, and in general, an infected tick must attach and feed for 1-2 days or longer for pathogen transmission to occur. Moreover, while not all ticks are infected, those that may be are not always successful in transmitting disease agents of sufficient volume to result in illness.

Soft vs. Hard Ticks

Ticks are separated into two main family groups: the less prevalent “soft ticks” or Argasids, and the more common “hard ticks” or Ixodids. Soft ticks are known to progress through several (2-7) instars in the nymphal stage prior to molting to the adult reproductive phase the number of nymphal stages is dependent on species, host availability, and climatic and/or environmental factors. There is little difference in appearance between male and female soft ticks.

Cuticle surfaces of soft tick species vary, but is frequently pebbled in texture with numerous grooves or undulations, appearing leathery-gray to tan in color, and without ornation. The head among soft tick species is ventrally located (not seen from the top/dorsal view), and the absence of a scutum is a key identifying characteristic common to all species. Soft tick females are capable of laying a few to several hundred eggs more than once during their lifetime. The Spinose ear tick, Otobius megnini, is one of the most numerous and wide-spread Argasid pests of cattle and horses in the Southern Region, and elsewhere throughout much of North America.

Hard ticks are more commonly encountered by animals and people than soft ticks. Male and female hard ticks appear visually distinguishable from each other (sexual dimorphism), and also present different physical characteristics between species than soft ticks.

Male Ixodid species have an inflexible scutum that spans the entire top side or dorsal surface among Ixodid females the scutum or dorsal shield is less than half the size of males, and limited to a small region directly behind the head (capitulum).

This smaller scutum size facilitates the expansion of the softer cuticle (alloscutum) among feeding females and immatures, allowing it to easily stretch and enlarge (e.g. up to 2-20X the unfed or “flat” size & up to a 250-fold weight gain) as blood-feeding progresses.

This ability is common to larval, nymphal, and adult life stages of Ixodid ticks, but is limited among the soft (Argasid) tick species.

Scutum color and ornation in adults of some Ixodid species (particularly several of the Amblyomma and some Dermcentor spp.) can be rather pronounced.

Male ticks are generally smaller than females and typically attach to hosts and feed prior to females. Fed male Ixodid ticks are not measurably larger than unfed males, as the primary purpose of feeding by male ticks is for attraction and reproduction of females. Attracted female ticks attach to hosts, mate on-host with nearby fed male ticks (except for some Ixodes spp.),

then blood-feed for 7-14 days before detaching and dropping from their host to find a suitable place on the ground to lay their fertilized eggs. Following this single oviposition event, all hard tick females expire as do their mated male consorts. Eggs laid (oviposited) by gravid females will typically incubate and hatch over several weeks to months (depending on temperature and concurrent weather conditions).

Depending on the influence of environmental cues and host availability, larvae will ascend surrounding vegetation to quest for a passing host and renew the cycle of parasitism.


Understanding Tick Biology and Its Implications in Anti-tick and Transmission Blocking Vaccines Against Tick-Borne Pathogens

Ticks are obligate blood-feeding ectoparasites that transmit a wide variety of pathogens to animals and humans in many parts of the world. Currently, tick control methods primarily rely on the application of chemical acaricides, which results in the development of resistance among tick populations and environmental contamination. Therefore, an alternative tick control method, such as vaccines have been shown to be a feasible strategy that offers a sustainable, safe, effective, and environment-friendly solution. Nevertheless, novel control methods are hindered by a lack of understanding of tick biology, tick-pathogen-host interface, and identification of effective antigens in the development of vaccines. This review highlights the current knowledge and data on some of the tick-protective antigens that have been identified for the formulation of anti-tick vaccines along with the effects of these vaccines on the control of tick-borne diseases.

Keywords: Borrelia Ixodes anti-tick vaccines blood saliva transmission-blocking.

Copyright © 2020 Bhowmick and Han.

Figures

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A schematic representation of tick physiological processes and involved molecules tested as vaccine…

A proposed model for the hemoglobinolytic pathway in I. ricinus [modified from (75)].…

A schematic representation of the…

A schematic representation of the integrative reverse vaccinology approach toward vaccine development.


Tick Identification - Biology

Perimeter Yard Sprays

In addition to permethrin-treated clothing/footwear a perimeter yard spray creates a good 1-2 punch program. Deer ticks are not found out in the open lawn…short grass, direct sunlight is a hostile environment for ticks. At the edge of the yard where the grass might be in partial shade and transitions to brush, trees, leaf litter this is perfect tick habitat and is the area you want to treat. This includes beneath woody ornamental plantings.

There are companies on the Cape that perform this as a service. The product that they should be using is Talstar (active ingredient bifenthrin). There are “all natural” products that are available but there are no research data to support that they are effective. Besides being highly active against ticks bifenthrin is immobilized when it contacts leaves or soil particles so it will not wash off site or leach through the soil. Product should not be applied around surface waters.

Applications are recommended for mid to late May and mid to late June when nymph stage ticks are active. A fall spray in mid-October can be considered as this is when adult stage ticks emerge.

Homeowners can also do this themselves. Garden centers carry a product under the Bonide brand. Eight is a hose-end sprayer that contains the active ingredient permethrin.

This product was designed to kill ticks on mice. It consists of a cardboard tube which contain cotton balls treated with permethrin. The product concept is that mice will remove the cotton balls and line their nest and self treat.

There were two studies done on this product. Both studies demonstrated that the product had NO material impact on tick populations. The papers can be found in the Research section of this website. It is a product that Larry Dapsis does not recommend.

Workshops

Lyme Disease is the most prevalent infectious disease in Massachusetts and is now considered to be a public health crisis. In addition to Lyme, deer ticks can carry the pathogens which cause Babesiosis, Anaplasmosis, Relapsing Fever and Powassan virus, all of which can be very serious and are on the increase.

This program will review the basic life cycle and ecology of deer ticks, incidence rates and distribution of tick-borne illnesses in addition to a database under development on infection rates of ticks. A three point protection plan will be presented: Protect Yourself, Protect Your Yard and Protect your Pet. Tick-Borne Diseases are preventable.


Ticks

Ticks drink the blood of humans and other mammals. The idea of blood-sucking parasites is hideous enough, but ticks can carry serious, sometimes deadly diseases. Keep up to date on tick-related health issues, and protect yourself from their bites.

Note: This field guide page is intended to supply basic introductory biology and natural history information about three Missouri species of ticks. It is not intended to diagnose tick-borne diseases or provide treatment information. If you are experiencing possible symptoms of tick-borne illness or have questions about medical issues, please consult your doctor or other health care provider. If you have a tick-borne illness, it is important to begin treatment as soon as possible. For up-to-date, detailed information about tick-borne diseases, consult the US Centers for Disease Control and Prevention (CDC) and the Missouri Department of Health and Senior Services (links at bottom of this page).

Our three species of hard ticks are mites with 8 legs, a small plate over their mouthparts, and tough "skin" (making it hard to crush a tick). Adults are 1/16 to 1/4 inch long (about the size of a sesame seed). When engorged with blood, ticks swell up to about 3/8 inch long and turn gray. During the larval, so-called seed tick stage, ticks have 6 legs and are about as large as a poppy seed.

Three species of hard ticks are commonly encountered in Missouri:

Lone star tick (Amblyomma americanum) — Females are easily identified by the white dot in the center of the back. Males often have dots or white streaks on the edge of their bodies. Very common in Missouri.

American dog tick (Dermacentor variabilis) — Newly hatched larvae are yellow. Adults are brown. Blood-engorged females are gray. Very common in Missouri.

Deer tick (blacklegged tick) (Ixodes scapularis) — Legs and upper body are black. Also common in Missouri.


Tick Identification - Biology

Scientific name: Ixodes scapularis
Common name:
Deer Tick

(Information in this Species Page was compiled by Brittany Wetzel in Biology 220W, Spring 2006, at Penn State New Kensington)

Deer ticks (Ixodes scapularis) are small, relatively hard-bodied, chelicerate arthropods that are found in some abundance in the northeast, midwest, and southeast sections of the United States. Adult deer ticks (seen at left next to the head of a pin) are approximately 3 mm in length and are dark brown to black in color (another common name for this species is the &ldquoblack legged tick&rdquo). Immature life stages (larvae and nymphs) are even smaller than the adults and were at one time thought to comprise a separate tick species (Ixodes dammini). These life stages now, however, have been clearly shown to be part of the developmental sequence of I. scapularis.

Life Cycle
The deer tick&rsquos life cycle represents a repeating pattern of blood feeding, growth and moulting, and the selection of ever larger vertebrate host species. Eggs laid in the leaf litter early in the spring hatch in mid to late July into 6-legged larvae. These larvae quickly attach themselves to small vertebrate host species (like white footed mice or chipmunks) and feed on these hosts for 3 to 5 days. Dropping off of these hosts and falling back into the forest leaf litter, the engorged, larval ticks either directly moult into the larger nymphal life stage or delay moulting and overwinter until the next May. The nymphs have the characteristic 8 legs of chelicerate arthropods. They seek out larger hosts (like squirrels or opossums) for their next blood meal. These nymphal life stages are very commonly the form of the deer tick that opportunistically attach to and feed on humans. After a 3 or 4 day feeding period, the nymphs drop back into the forest litter and moult into the adult life forms. These adult deer ticks become active starting in October and may remain active through the winter if non-freezing microhabitats are available (see discussion of the &ldquosubnivia&rdquo). The adult ticks attach to white tailed deer (hence the name &ldquodeer tick&rdquo) and females feed on the deer for 5 to 7 days becoming massively engorged. The males only feed slightly on the deer but may use their attachment time to seek out females. Mating may occur on the deer host or in the leaf litter immediately following release from the host. Females lay between 1000 and 3000 eggs in the leaf litter typically in May. Both males and females die soon after mating and egg laying.

Relationship to Deer
To successfully complete their life cycles, then, I. scapularis requires the presence of white tailed deer. It is not surprising, therefore, that any area with substantial populations of white tailed deer also frequently has high densities of I. scapularis. White tailed deer are also important dispersal agents in the spread of I. scapularis up and down the eastern seaboard, into the midwest, and across the southern sections of the United States. Within a forest ecosystem, I. scapularis is most abundantly found along deer trails and in feeding and bedding areas frequented by white tailed deer.

Habitat
Ixodes scapularis
is especially found in forested ecosystems but is also frequently abundant in shrub lands, leaf piles, and even in mowed fields and lawns. Ixodes scapularis is especially common in small forest plots (which by their geometry have a high percentage of edge ecotones which are typically rich in browse vegetation for white tailed deer). These ticks also seem to prefer mixed hardwood forests (especially mixes containing hickory, poplar, maple, and beech) and are also positively correlated with the presence of greenbrier, blueberries, pepperbush, snakeroot, and sassafras and with the abundance of the exotic, invasive plants like barberry and Japanese honeysuckle. The accumulation of leaf litter and brush is positively correlated with the presence and abundance of I. scapularis undoubtedly due to its contribution to the quality of the tick&rsquos &ldquooff-host&rdquo habitat. Moderate temperatures and high humidity also favor the survival and abundance of I. scapularis.

'Questing' Behavior
An interesting behavior called &ldquoquesting&rdquo has been observed in all three life stages of I. scapularis. When an individual is ready to find a host for a blood meal it climbs to the top of the surrounding vegetation (typically the herbaceous plants of the forest floor) and remains in place on the tips of these plants with its forelegs extended up from the plant&rsquos surface. When a potential host brushes past the plant, the tick clamps onto it with its front legs and then quickly moves up and over the host to find a suitable feeding spot.

Lyme Disease
One of the significant human related problems associated with I. scapularis concerns the tick&rsquos role in the transmission of the bacterium Borrelia burgdorferi. This bacterium is the pathogen that causes Lyme disease in humans. The bacterium is picked up by I. scapularis when it takes a blood meal from an infected host. Inside the tick the bacterium goes into an inactive state until the tick begins to feed on its next life-cycle host. It takes 12 to 48 hours for the bacterium to become active enough to be transmitted by a feeding tick. This information is extremely important to anyone who picks up an I. scapularis. Prompt removal of the tick (and this is best accomplished by using forceps to gently pull the entire feeding structure (&ldquohead&rdquo) of the tick out from the skin) greatly reduces the possibility that the Lyme disease pathogen, if present, will be transmitted. It is vital, then, to do a careful &ldquotick check&rdquo on anyone who has been out in the woods or in areas known to have I. scapularis populations. Of course, an even better way to prevent the possibility of getting Lyme disease is to prevent the tick attachment in the first place. Long sleeves and long pants, use of insect repellants with high concentrations of DEET, and avoidance of deer frequented areas are all excellent strategies by which one can deal with this species and still go out and enjoy hiking and exploring in our natural ecosystems.

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Watch the video: How to Identify Ticks - Tick Identification (August 2022).