ABSTRACT
BACKGROUND &
OBJECTIVE:
Bancroftian filariasis caused by
Wuchereria bancrofti is endemic in many parts of
India. In recent years
diagnosis of W. bancrofti
infection has been revolutionized with the availability of filarial
antigen tests, which is important in
monitoring success of
chemotherapy. We carried out this study to
measure microfilariaemia and antigenemia levels in bancroftian
microfilariae (mf) carriers at 1 yr follow up after
chemotherapy, in lymphoedema
patients and in endemic controls from a
filariasis endemic area in Tamil Nadu
State using Og(4)C(3)
ELISA to identify the best marker to assess success of
chemotherapy.
METHODS:
Serum samples were collected from 30 bancroftian microfilaremic (Mf) carriers pre-
treatment and at sequential intervals (7,30,60,90,180 and 365 days) following
treatment with
diethylcarbamazine (DEC6mg/kg
body weight,
single dose), 30 lymphoedema
patients (without
treatment) at periodic intervals, and 68 control subjects (24 endemic normal subjects in
filariasis endemic area in Tamil Nadu
State, 24 non-endemic normal subjects residing in Chandigarh,
India; 5
brugian filariasis, 5 endemic control subject in
brugian filariasis endemic area and 10 other
disease controls). The circulating
antigen of W. bancrofti was measured quantitatively using Og(4)C(3)
ELISA kit.
RESULTS:
In Mf carriers, there was no significant difference in
microfilariae count in pre- and post-
treatment (PT) samples till day 30 while significant differences were observed in pre- and sequentially collected post-
treatment (PT) samples day 60 to 180 (P<0.001), day 365 (P<0.005). However, there was no significant difference in antigenaemia levels between pre-
treatment (day 0) and PT samples collected on day 7 onwards till day 365. Though of the 19
patients who could be followed up till 365 days PT, 4 (21%) were amicrofilaraemic, none became
antigen negative. No significant difference was found in antigenaemia levels in sequentially collected samples from lymphoedema
patients. Significant differences were observed in antigenaemia levels in samples collected at the start of study in mf carriers as compared to lymphoedema
patients and endemic normal subjects (P<0.001). Subjects (non-endemic control) residing in
filariasis free area (24), brugian endemic area (5), B.malayi infected
patients (5) and
patients with other
parasitic diseases (10) were found
antigen negative. INTERPRETATION &
CONCLUSION:
Annual
single dose of DEC
therapy alone may not result in complete clearance of
infection and
detection of antigenaemia rather than microfilaraemia may be taken into consideration as an
indicator of successful
chemotherapy. The study supports the earlier view that filarial antigenaemia is relatively common in amicrofilaraemic and asymptomatic subjects in endemic areas and further studies are needed to determine the
clinical significance,
prognosis and effective management of such
infections in endemic areas.