Evidence of acute rickettsioses among patients presumed to have chikungunya fever during the chikungunya outbreak in Sri Lanka

SummaryBackgroundChikungunya fever (CGF) and rickettsioses are known to cause acute onset febrile illnesses associated with severe arthritis. Rickettsial arthritis is curable with the use of appropriate anti-rickettsial antibiotics, however the arthritis of CGF tends to have a prolonged course leading to protracted disability. The aim of this study was to investigate the contribution of CGF and rickettsioses to cases of fever and arthritis during a presumed CGF outbreak in Sri Lanka.MethodsFifty-eight consecutive patients with presumed CGF were further investigated to determine the occurrence of rickettsioses among them, and to identify differences in clinical, hematological, and biochemical parameters between the two diseases.ResultsNearly a third of the patients had serological evidence of rickettsioses accounting for their illness. The presence of a late onset major joint arthropathy sparing the small joints of the hands and feet, and the occurrence of a late onset discrete maculopapular rash over the trunk and extremities, suggested rickettsioses over CGF. White blood cell count, erythrocyte sedimentation rate, C-reactive protein, and liver function tests were not helpful in differentiating rickettsioses from CGF. Patients with rickettsioses and arthritis who received an empirical course of doxycycline recovered faster than those who did not receive specific treatment.ConclusionsThe establishment of rapid diagnostic methods able to differentiate the etiological agents of fever and arthritis, such as CGF and rickettsioses, would be beneficial in endemic settings