A Comparative Study of ELISA versus Conventional Methods in Diagnosis of Microfilariae

Introduction: Filariasis has been known from antiquity. Elephantiasis-painful, disfiguring swelling of the legs and genital organs-is a classic sign of late-stage disease. The genus is named after Wucherer, a Brazilian physician who reported microfilariae in chylous urine in 1868. Lymphatic filariasis is a devastating disease and it is found in more than 80 countries across the world [1,2]. Approximately 1 billion people across the world are at risk. It affects countries like south and Central America, West and East Africa, East Mediterranean, Southeast Asia, and Western Pacific. W bancrofti accounts for 90% of all filariasis cases in the world [3].

National Filaria Control Programme launched in 1955 has operational, training and research components [4]. The main strategies of which were the vector control, detection and treatment of filarial cases and delimitation of endemic areas. This program continues to be in place, in addition to the program to eliminate LF in India. Measurement of microfilaremia is a well-recognized gold standard for demonstrating the impact of interventions but is not an optimal method of monitoring or surveillance because of requirement of nocturnal blood collection and relatively less insensitive test for infection [5].

Materials and Methods: This study was carried out in Govt General Hospital & Filaria Clinic, Guntur District of Andhra Pradesh, and Ethical Permission for the study was obtained

90 samples were collected from those attending the Government General Hospital with signs and symptoms of filariae they were designated as Group I [Test]. 10 normal serum samples Group II [Normal Controls] and 10 serum samples Group III [Endemic Normal] from normal individuals in the endemic pockets identified by filarial control program officers which were detected smear negative were collected as controls

Results: The results of ELISA were compared with the microfilariae detection by slide method, it was found that the only 2 cases each in the male and female, a total of 4 cases were detected by the slide methods rest all the cases were detected as negative. With ELISA method it was found that the total numbers of positive cases were 53 and total numbers of negative cases were 37 in the test group I. The comparison of the same results with the normal control samples revealed that all the cases were reported as negative by slide method however by ELISA 7 out of total 10 cases were detected with the antigens and antibodies to microfilariae.

Discussion: We in the present study tried to compare the results obtained by conventional slide method of detection of filarial versus the ELISA method; we found that ELISA was far superior in detecting the filariae antigen, antibodies where the conventional slide methods failed to identify the microfilariae

Conclusion: ELISA is superior & cost effective in detection of all cases of microfilariae. Since conventional methods may not able to reliably identify microfilariae in all samples, it is recommended that ELISA be used to detect the presence of microfilariae, particularly in Endemic areas.