Studies on immunodiagnosis of dracunculiasis. II. Search for circulating antigens

Sera from individuals living in a dracunculiasis endemic area of northern Ghana were examined for circulating Dracunculus medinensis antigens by applying protocols previously developed for detection of circulating antigens in other helminth infections. Antisera from rabbits immunised with homogenized first stage D. medinensis larvae were used for antigen capture and detection in three different forms, namely non-treated, biotinylated and horseradish peroxidase (HRP)-labelled. Three different preparations of human sera were examined, namely non-treated, pre-treated with polyethylene glycol/ethylenediaminetetra-acetic acid (PEG/EDTA) for analysis of precipitated immune complexes, and pre-treated with trichloroacetic acid (TCA) for analysis of isolated glycoproteins. In both SDS-PAGE/Western blotting and ELISA, significant reactivity was observed between non-treated and treated rabbit-antisera on the one hand and non-treated and treated human sera on the other. However, no significant response differences were observed between sera obtained from individuals with dracunculiasis and non-endemic controls. The reasons are analysed and possible explanations presented. The study provided no evidence that D. medinensis-specific circulating antigens, detectable by relatively simple means, occur in infected individuals.