Low avidety IgG antibodies in diagnosis of recent human Schistosomasis

One hundred and thirty schoolchildren from a schistosomiasis endemic area in Sharqia Governorate were selected on parasitological findings. Seventy persons were negative on the first screen and turned positive after three months of the screening [recently infected]. Stool examination, ELISA [IgG and IgM], low avid IgG and circulating antigens were performed for all patients and controls. ELISA detected IgM in all cases. IgG and circulating antigens were in 90% of schistosomiasis patients. Low avidity IgG detected in 85.71% of recent cases. The specificity of ELISA appeared to be >99%. The IgM/IgG ratio was >1 in patients with recent infection. The percentage of fall of OD readings of IgG after addition of six molar urea was high among cases with recent infection. Low avid IgG appears to be good and valuable in diagnosis of recent schistosomiasis in man