Schistosomiasis is the second most common parasitic infection all over the world. It is responsible for thousands of deaths per year. Control of this infection depends mainly on praziquantel which unfortunately has many defects e.g. occurrence of reinfection and risk of resistance. So, a suitable vaccine is an urgent need. The vaccination that elicits a combined Th1 and Th2 is considered a proper vaccine candidate. Trehalose Dimycolate (TDM) is an immunogen that proved potent activation of Th1 lymphocytes. Effects of its combination with the Th2 stimulant, soluble egg antigen (SEA) in protection against Schistosoma mansoni infection in experimental animals were studied. Combined SAE+TDM achieved statistically significant protection against infection causing reduction of the worm load and ova count. A large percentage of the laid ova were even immature. Combined immunization was associated with reduced hepatic granuloma number, diameter and hepatic fibrosis percentage. Moreover, SEA+TDM increased stimulation of M2 type macrophages that limited the spread of hepatic fibrosis. It was concluded that SEA+TDM achieved the best protection from infection and the resulting pathology.
This can be regarded to increased activation of humoral and cellular wings of immunity and activations of both anti-S. mansoni and tissue protecting macrophages and cytokines.