Clinical presentation, convalescence, and relapse of rocky mountain spotted fever in dogs experimentally infected via tick bite

PLoS One. 2014 Dec 26;9(12):e115105. doi: 10.1371/journal.pone.0115105. eCollection 2014.

Abstract

Rocky Mountain spotted fever (RMSF) is a tick-borne disease caused by R. rickettsii in North and South America. Domestic dogs are susceptible to infection and canine RMSF can be fatal without appropriate treatment. Although clinical signs of R. rickettsii infection in dogs have been described, published reports usually include descriptions of either advanced clinical cases or experimental infections caused by needle-inoculation of cultured pathogen rather than by tick bite. The natural progression of a tick-borne R. rickettsii infection has not been studied in sufficient detail. Here, we provide a detailed description of clinical, hematological, molecular, and serological dynamics of RMSF in domestic dogs from the day of experimental exposure to infected ticks through recovery. Presented data indicate that neither the height/duration of fever nor detection of rickettsial DNA in dogs' blood by PCR are good indicators for clinical prognosis. Only the apex and subsequent subsidence of neutrophilia seem to mark the beginning of recovery and allow predicting a favorable outcome in Rickettsia-infected dogs, even despite the continuing persistence of mucosal petechiae and skin rash. On the other hand the appropriate (doxycycline) antibiotic therapy of sufficient duration is crucial in prevention of RMSF relapses in dogs.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / therapeutic use*
  • Disease Models, Animal
  • Dog Diseases / blood*
  • Dog Diseases / drug therapy*
  • Dog Diseases / microbiology
  • Dogs
  • Doxycycline / therapeutic use*
  • Male
  • Prognosis
  • Recurrence
  • Rickettsia rickettsii / genetics*
  • Rocky Mountain Spotted Fever / blood
  • Rocky Mountain Spotted Fever / drug therapy
  • Rocky Mountain Spotted Fever / microbiology
  • Rocky Mountain Spotted Fever / veterinary*
  • Tick Bites / blood
  • Tick Bites / drug therapy
  • Tick Bites / microbiology
  • Tick Bites / veterinary

Substances

  • Anti-Bacterial Agents
  • Doxycycline

Grants and funding

Funding for work was provided by the US Government within the CDC budget. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.