bovis - Articles
Tick-borne fever
Synonym(s): rickettsia, rickettsial, haematuria, hematuria
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.
Geographic incidence
- Worldwide.
Public health considerations
- Anaplasma phagocytophilum is responsible for human granulocytic anaplasmosis, a severe febrile illness increasing in incidence in the USA and Europe.
Cost considerations
- Significant economic impact is seen through reduced animal performance in terms of milk production and weight loss and through costs incurred through concurrent secondary infections.
Special risks
- Abortion storms when naïve animals are introduced to infected tick areas.
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.