IMMUNOMONITORING OF FILARIAL PATIENTS DURING DEC THERAPY IN AN ENDEMIC AREA - A 7-YEAR FOLLOW-UP

A group of 27 Wuchereria bancrofti infected persons from an endemic ar ea, who had undergone treatment with diethyicarbamazine (DEC), were fo llowed for 7 years to understand its effect on microfilaraemia, immune status and on the recurrence of infection. Treatment with DEC was for 14 days (day 1, 1 mg kg(-1) body weight, day 2, 2 mg kg(-1) body weig ht and from day 3 onwards 6 mg kg(-1) body weight) followed by one dos e (6 mg kg(-1) body weight) on days 360, 540 and at the end of years 2 , 3, 4, 6 and 7. After a 2-year follow-up the patients were divided in to two groups. Group A consisted of cases that showed no reappearance of microfilariae (mf) and Group B of those cases that showed reappeara nce of mf. Further follow-up in the next 5 years showed that none of t he cases in Group A were positive for mf at any time. In contrast, mf were detected in Group B in 14, 15, 27 and 33% of the cases followed a t the end of years 3, 4, 6 and 7 respectively. Both groups showed a de crease in filarial IgG antibody and mf excretory-secretory antigen lev els in the initial 4 years followed by increased levels at the end of years 6 and 7. The reappearance of filarial antibody and antigen in 50 -70% of Group A and 68-100% of Group B at the end of year 7 suggests t he existence of active infection in these cases. No cases followed in this study developed clinical symptoms. This study shows that long-ter m DEC therapy and immunomonitoring of mf patients is essential in an e ndemic area for arresting transmission and prevention of pathology ass ociated with clinical manifestations.