What does a Dermacentor tick transmit? - briefly
Dermacentor ticks are vectors for several pathogens, including the bacteria that cause Rocky Mountain spotted fever, tularemia, and ehrlichiosis, as well as the Colorado tick‑fever virus and the agent of bovine anaplasmosis. Additional, less common agents such as Heartland virus may also be transmitted.
What does a Dermacentor tick transmit? - in detail
Dermacentor ticks act as vectors for a limited but clinically significant group of microorganisms. The most widely recognized agents include:
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Rickettsia rickettsii – causative organism of Rocky Mountain spotted fever. Transmission occurs through the bite of Dermacentor variabilis (eastern United States) or Dermacentor andersoni (western United States). Early symptoms comprise fever, headache, myalgia, and a characteristic maculopapular rash that may become petechial. Prompt doxycycline therapy reduces mortality.
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Francisella tularensis – agent of tularemia. Both D. variabilis and D. andersoni acquire the bacterium from infected rodents or lagomorphs and pass it to humans during feeding. Clinical forms range from ulceroglandular (skin ulcer with regional lymphadenopathy) to pneumonic disease, each responding to streptomycin or gentamicin.
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Ehrlichia chaffeensis and Ehrlichia ewingii – cause human ehrlichiosis. D. variabilis can harbor these intracellular bacteria, leading to fever, leukopenia, thrombocytopenia, and elevated liver enzymes. Tetracycline-class antibiotics are the treatment of choice.
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Rickettsia parkeri – responsible for spotted fever rickettsiosis. Transmitted primarily by D. variabilis in southeastern United States, infection presents with fever, headache, and an eschar at the bite site, often milder than Rocky Mountain spotted fever.
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Colorado tick fever virus – a coltivirus spread by D. andersoni in the Rocky Mountain region. It produces a biphasic febrile illness with headache, myalgia, and occasional neurologic symptoms. No specific antiviral therapy exists; supportive care is indicated.
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Babesia species (e.g., Babesia microti) – occasional reports document Dermacentor ticks as secondary vectors for babesiosis, a hemolytic disease characterized by fever, anemia, and jaundice. Treatment combines atovaquone with azithromycin or clindamycin with quinine.
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Cytauxzoon felis – a protozoan parasite of felids transmitted by D. variabilis. In domestic cats, infection is often fatal, presenting with high fever, lethargy, and icterus. Imidocarb and supportive measures provide limited success.
In veterinary contexts, Dermacentor species also convey Anaplasma marginale (bovine anaplasmosis) and Ehrlichia ruminantium (heartwater) in regions where these ticks are endemic. Recognition of the tick‑borne pathogen profile guides both diagnostic testing and empiric antimicrobial selection, emphasizing the necessity of early tick removal and prophylactic measures in endemic areas.