MetaPathogen.com/Ixodes scapularis (deer tick)

 

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Ixodes scapularis, black-legged tick, deer tick

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Taxonomic lineage

cellular organisms - Eukaryota - Fungi/Metazoa group - Metazoa - Eumetazoa - Bilateria - Coelomata - Protostomia - Panarthropoda - Arthropoda - Chelicerata - Arachnida - Acari - Parasitiformes - Ixodida - Ixodoidea - Ixodidae - Ixodinae - Ixodes - Ixodes scapularis

Brief facts

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Importance of feeding habits of the vector

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Feeding stages

  1. Appetence (hunger) - waiting for or actively seeking a host. Ixodes scapularis congregate along animal trails, rest on vegetation and wait for appropriate hosts to brush past them.
  2. Engagement - adherence to the host's fur, feathers, or skin.
  3. Exploration - searching the host's external surface for a suitable attachment site.
  4. Penetration - insertion of the mouthparts into the host's skin, "tasting the host".
  5. Attachment - feeding site is established
  6. Ingestion - start of active feeding. There is little if any increase in the parasite's weight during first 24 hours of feeding.
  7. Engorgement (satiation) - partial or complete blood meals taken. Tick's weight increases gradually and slowly over several days, followed by a rapid increase on the last day. It is believed that high dosages of Borrelia burgdorferi (Lyme disease) are transferred during the later period of feeding.
  8. Detachment - withdrawal of mouthparts.
  9. Disengagement - tick drops off of the host to complete its current life stage using obtained nutrients.

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Life cycle

I. scapularis is a three-host tick; the larva, nymph and adult stages each feed on separate hosts. Although the life cycle of the tick species is relatively long in the wild (2 years), one generation can be produced in the lab within 9 to 12 months.

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Brief notes on reproduction in Ixodes ticks

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Tissue

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Major Ixodes-born diseases in United States

Disease Causative organism Organism description Disease description Region
Lyme disease Borrelia burgdorferi Bacteria (spirochete); invade blood and tissues; white-footed mouse is believed to be a natural reservoir Erythematous lesion at site of bite; fibromyalgia, malaise, fatigue, arthritis, neurologic manifestations (abnormalities in mood, memory, and sleep ) Connecticut, Midwest
Babesiosis Babesia microti Protozoa Malaria-like blood parasitic disease; can be asymptomatic (especially in people with healthy spleen); mild to severe fevers and anemia New York, Massachusetts, Minnesota
Anaplasmosis Anaplasma phagocytophilum (Ehrlichia phagocytophilum) Obligate intracellular gram-negative bacteria, rickettsia, infects neutrophils Fever, severe headache, muscle aches (myalgia), chills and shaking, similar to the symptoms of influenza, can be fatal California, Colorado, Connecticut, Florida, New Jersey, New York, Maryland, Minnesota, Wisconsin
Rickettsiosis (Rocky Mountain spotted fever (RMSF), also tick typhus) Rickettsia parkeri Obligate intracellular gram-negative bacteria, rickettsia, grow within damaged cells lining blood vessels The onset of symptoms is abrupt with headache, high fever, chills, muscle pain, and then a rash; blood vessel inflammation (vasculitis) is common Florida, Georgia, Kentucky, Mississippi, Oklahoma, and South Carolina

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Ixodes scapularis life cycle diagram

Shows the four life stages, egg, larva, nymph, adult, and the times during the life cycle that both abiotic (GDD -growing degree days, PPT - total precipitation), and biotic (acorns and various hosts) factors might exert influence. Year t is the year during which nymphal ticks seek hosts, including humans, and represents the focal year with respect to risk of exposure.
 

Ixodes scapularis, tick life cycle diagram
Ostfeld RS et al. Climate, deer, rodents, and acorns as determinants of variation in lyme-disease risk. (PLoS Biol. 2006 Jun;4(6):e145. )

 

White-footed mice
 
Photo credit: Dobson A et al. PLoS Med. 2006 Jun;3(6):e231.(PMID: 16729846)

Two Juvenile White-Footed Mice (Peromyscus leucopus) That Have Been Placed in a Plastic Pail before Being Marked with Ear Tags and Released.

Mice are important reservoirs for the pathogens that cause Lyme disease, human babesiosis, human granulocytic anaplasmosis, hantavirus pulmonary syndrome, and many other diseases. They thrive in low-diversity vertebrate communities that support few predators and competitors.

 

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Females Ixodes scapularis and Ornithodoros Ornithodoros hermsi ticks
 
Photo credit: Schwan TG and Piesman J Emerg Infect Dis. 2002 February; 8(2): 115121.

Dorsal view of a female Ixodes scapularis (family Ixodidae, hard ticks), a vector of Borrelia burgdorferi (left), and a female Ornithodoros hermsi (family Argasidae, soft ticks), the vector of B. hermsii (right).

 

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Amblyoma maculatum, Gulf Coast ticks
 
Article: Sumner JW et al. Emerg Infect Dis. 2007 May; 13(5): 751753.

Adult Amblyomma maculatum (the Gulf Coast tick), a vector of Rickettsia parkeri. A) Female; B) Male. Photographs courtesy of James Gathany, Centers for Disease Control and Prevention.

 

References

Websites

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