Premunition, also known as infection-immunity, is a host response that protects against high numbers of parasite and illness without eliminating the infection. This type of immunity is relatively rapid, progressively acquired, short-lived, and partially effective. For malaria, premunition is maintained by repeated antigen exposure from infective bites. Thus, if an individual departs from an endemic area, he or she may lose premunition and become susceptible to malaria.
Antibody action contributes to premunition. However, premunition is probably much more complex than simple antibody and antigen interaction. In the case of malaria, the sporozoite and merozoite stages of Plasmodium elicit the antibody response which leads to premunition. Immunoglobulin E targets the parasites and leads to eosinophil degranulation which releases major basic protein that damages the parasites, and other factors elicit a local inflammatory response. However, Plasmodium can change its surface antigens, so the development of an antibody repertoire that can recognize multiple surface antigens is important for premunition to be achieved.
Premunition has not been well-studied, and although it likely occurs broadly, it is mainly emphasized for its role in malaria, tuberculosis, syphilis and relapsing fever.
Premunization is the artificial induction of premunition.