Canis ISSN: 2398-2942

Thrombocytotropic anaplasmosis

Synonym(s): Infectious canine cyclic thrombocytopenia

Contributor(s): Leah Cohn, Severine Tasker

Introduction

  • Cause:Anaplasma platys (formerly Ehrlichia platys). It is a gram negative, obligate, intracellular bacteria from the family Anaplasmataceae that infects platelets. It is quite closely related to Anaplasma phagocytophilum.
  • Signs: often absent or mild; bleeding may be seen in more severe cases.
  • Diagnosis: cytology, serology, PCR.
  • Treatment: doxycycline.
  • Prognosis: usually mild disease.

Pathogenesis

Etiology

  • A. platys.

Specific

  • Infection with presumed tick vectors.

Pathophysiology

Timecourse

  • Incubation is around 8-15 days after experimental infection.
  • 1st parasitemic phase, with high numbers of platelets infected with morulae, occurs around 10 days after experimental infection; this is followed by rapid fall in platelet count (typically to <20 x 10*9/l) resulting in thrombocytopenia and an absence of microscopically detectable organisms.
  • Platelet counts increase again within 3-4 days of platelet nadir Hematology: platelet count.
  • Further peaks of parasitemia (although not as marked as first) and subsequent thrombocytopenias (these can be severe) occur as cycles, every 1-2 weeks.
  • Both severity of parasitemias and thrombocytopenias are reduced over time; chronic infection often accompained by thrombocytopenia without visible morulae.

Epidemiology

  • Believed to be transmitted primarily by tick bites; has been reported in the following species of ticks:
    • Rhipicephalus sanguineus Rhipicephalus sanguineus is most commonly implicated. Dual infections with E.canis Ehrlichia canis and A.platys are common, suggesting transmission by the same vector.
    • Dermacentor auratus.
    • Haemaphysalis longicornis.
    • Ixodes persulcatus.
  • Also in dog chewing louse in Australia.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Stillman B A et al (2012) Performance of the New in-clinic Snap (R) 4dx (R) Plus Test for the Detection of Ehrlichia Ewingii (Granulocytic Ehrlichiosis) and Anaplasma Platys (Thrombocytotropic Anasplasmosis) Antibodies in Dogs. JVIM 26, 795-796.
  • Gaunt S D et al (2010) Experimental infection and co-infection of dogs with Anaplasma platys and Ehrlichia canis: hematologic, serologic and molecular findings. Parasites & Vectors 3, 33-43 PubMed.
  • Beall M J et al (2008) Duration of infection and efficacy of doxycycline treatment in dogs experimentally co-infected with Anaplasma platys and Ehrlichia canis. JVIM 22, 703 VIN.
  • Eddlestone S M et al (2007) PCR detection of Anaplasma platys in blood and tissue of dogs during acute phase of experimental infection. Experimental Parasitology 115, 205-210 PubMed.
  • Gaunt S D et al (2007) Potentiation of thrombocytopenia and anemia in dogs experimentally coinfected with Anaplasma platys and Ehrlichia canis. JVIM 21 (3), 576 ResearchGate.


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