Cross reacting antibodies against keyhole limpet haemocyanin may interfere with the diagnostics of acute schistosomiasis.

The number of individuals catching schistosomiasis has increased with the popularity of 'primitive tourism' in Africa. Highly immunogenic material originating from the intestine of intravascular adult schistosomes gives rise to an antibody response making possible early identification of infected individuals using serology. Antibodies against gut associated antigens (anti-GAA), detected by indirect immunofluorescence microscopy employing sections of adult worms as antigen may occur before the onset of egg production. In the present study we show that this well known schistosomiasis-specific anti-GAA staining reaction can be confused with a similar staining reaction with ducts of both male and female worms. Antibodies with duct reactivity were seen in sera both from schistosomiasis-patients and patients with some other invasive worm infections. Cross reactive anti-duct antibodies appear to have different specificity. One cross reactive antibody reacted with antigenic epitopes present in keyhole limpet haemocyanin (KLH). Anti-duct reactivity could be inhibited by absorption with KLH. This was most obvious in the trichinellosis patient sera.