V. Evaluation of Cross-Immunity against Type 1 Dengue Fever in Human Subjects Convalescent from Subclinical Natural Japanese Encephalitis Virus Infection and Vaccinated with 17D Strain Yellow Fever Vaccine
Department of Tropical Public Health, Harvard School of Public Health, Bureau of State Services, Center for Disease Control, U.S. Department of Health, Education, and Welfare, Boston, Massachusetts 02115
One hundred and eleven (111) blood specimens were collected from patients with known or suspected syphilis by venipuncture and on a small piece of No. 3 grade filter paper. Both specimens from each patient were tested by fluorescent treponemal antibody absorption (FTA-ABS) test. Of the 62 patients whose venipuncture sera were FTA-ABS positive, filter paper blood samples were also positive in 56 (90%) and negative in 6 (10%). Complete agreement was obtained on paired specimens from 49 patients who were FTA-ABS negative. These preliminary results suggest that finger stick blood samples, collected on filter paper, could be used for FTA-ABS testing of remote rural populations—such as in areas where yaws is endemic.