Progress in the development of vaccines against parasitic diseases.

Vaccines for parasitic diseases have lagged behind the development of vaccines for important viral and bacterial diseases. Among the reasons for this is the extreme antigenic complexity of parasites and also the adaptive ability of parasites to co-exist with their host, often through modulation of the host's immune response. Advances in technology including in vitro cultivation, hybridoma and recombinant DNA methods have provided valuable tools for the study of parasite immunology and have resulted in major strides toward vaccines for several protozoan and helminth parasites.