Hydrocele fluid: can it be used for immunodiagnosis of lymphatic filariasis?

BACKGROUND & OBJECTIVES Diagnosis of lymphatic filariasis using serum has been established but the utility of hydrocele fluid for the purpose is not exactly known. Since, hydrocele is a chronic form of the disease manifestation in a variety of situations and often poses difficulty in diagnosing its origin, we have evaluated the usefulness usage of hydrocele fluid for diagnosis of filarial origin of hydrocele in this study. METHODS Paired samples of serum and hydrocele fluid from 51 individuals with hydrocele, living in an endemic area of Wuchereria bancrofti were assessed. Circulating filarial antigen, filarial specific antibody and cytokine assay were performed in both serum and hydrocele fluid of patients. RESULTS Og4C3 assay detected circulating filarial antigen (CFA) in serum and corresponding hydrocele fluids. The level of IgG, IFN-γ and IL-10 were found to be high in CFA-negative, while IgM and IgE were high in CFApositive hydrocele fluid and serum samples associated with hydrocele. On the other hand neither CFA-positive nor CFA-negative hydrocele fluid and serum samples associated with hydrocele showed any difference in IgG4 level. INTERPRETATION & CONCLUSION This study showed that the filaria related antigens and antibodies found in serum can be detected with equal sensitivity in hydrocele fluid. Therefore, it can be used as an alternative to serum for immunodiagnosis of filariasis, and help monitoring the filarisis elimination programme.