Bovis ISSN 2398-2993

Tick-borne fever

Synonym(s): Anaplasmosis, Anaplasma phagocytophilium, pasture fever

Contributor(s): Mike Reynolds , Andrew Forbes

Introduction

  • Anaplasma phagocytophilium is the causal agent of bovine anaplasmosis or tick borne fever.
  • It is a Gram-negative obligatory intracellular bacterium, which is transmitted by hard ticks belonging to the Ixodes persulcatus complex.
  • It is the cause of significant financial cost to the cattle industry.

Pathogenesis

Etiology

  • Disease outbreaks normally occur in endemic areas in the spring and summer when cattle enter infected pastures.

Predisposing factors

General

  • The presence of appropriate tick habitat.
  • The movement of naïve animals into tick infected areas.
  • The presence of other carrier species such as feral goats, deer and rodents.

Specific

  • The movement of naïve animals into tick infected areas.

Pathophysiology

  • Affected cattle develop a severe febrile reaction, bacteremia and leukopenia due to neutropenia, lymphocytopenia and thrombocytopenia within a week of exposure to a tick bite.
  • Such immune compromise makes affected individuals susceptible to other pathogenic agents.

Timecourse

  • The incubation period is 5-14 days after the tick bite.

Epidemiology

  • Young animals are most susceptible as maternally derived antibody is not protective and immunity increases with age.

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.
  • Harrison A, Brown K J, Montgomery W I (2012) Anaplasma phagocytophilum in feral goats in Northern Ireland. Vet Rec 170, 602-603 PubMed.
  • Woldehiwet Z (2010) The natural history of Anaplasma phagocytophilum. Vet Parasitol 167, 108-122 PubMed.
  • Guglielmone A A (1995) Epidemiology of babesiosis and anaplasmosis in South and Central America. Vet Parasitol 57,1 09-119 PubMed.
  • Cranwell M P (1990) Efficacy of long-acting oxytetracycline for the prevention of tick-borne fever in calves. Vet Rec 126, 334-336 PubMed.

 


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