Diagnosis of rickettsial diseases using samples dried on blotting paper

The use of filter paper is an inexpensive and convenient method for collect ing, storing, and transporting blood samples for serological studies. In ad dition, samples occupy little space and can be readily transported without refrigeration. Rickettsial diseases often evolve according to an epidemic m ode and are now considered reemerging diseases, especially in developing co untries, under conditions where fieldwork could be difficult. The suitabili ty of collecting whole-blood specimens on filter paper discs for rickettsia l antibody assay was evaluated, Dried blood specimens from 64 individuals w ith antibodies to Coxiella burnetii, Bartonella quintana, or Rickettsia con orii were tested for rickettsial antibodies by microimmunofluorescence. Alt hough occasional titers were 1 or 2 dilutions lower than those of tested se rum samples, no statistically significant differences were observed. Among patients with negative serology, no False positives were found. This study demonstrated that the recovery of antibodies from finger-stick blood dried on filter paper after elution produces results comparable to those obtained by recovering antibodies from serum. Storing paper samples for 1 month at room temperature or at 4 degrees C did not significantly affect the level o f antibodies recovered. This report shows the utility of this sample collec tion method in developing countries where refrigeration is not possible and venipuncture is problematic.