Rickettsia rickettsii
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Rocky Mountain spotted fever
- Caused by Rickettsia rickettsii
- Affects humans and dogs
- Various tick vectors, which acquire the organism from small mammals
- Transovarial and trans-stadial transmission within the tick population
- Organisms replicate in endothelial cells of infected dogs, cause vasculitis, increased vascular permeability and haemorrhage
- Clinical signs
- Incubation period 2-10 days; course less than 2 weeks
- Fever, depression, conjunctivitis, retinal haemorrhage, muscle and joint pain, coughing, dyspnoea, oedema of extremities
- Neurological signs in dogs include stupor, ataxia, neck rigidity, seizures and coma
- Death from cardiovascular, neurological or renal damage in severely-affected animals
- Gross pathology includes haemorrhage, splenomegaly and lymphadenopathy
- Diagnosis
- Rising antibody titre during an indirect fluorescent antibody test or ELISA
- Thrombocytopenia and leukopenia during early phase
- Treatment and control
- Tetracycline therapy for two weeks
- Tick removal from dogs