1. If this is malaria, what are the probable reasons for this patient to have another episode of malaria?

2. Host Response Initially, the host responds to plasmodial infection by activating nonspecific defense mechanisms – Stop the infection’s expansion Subsequent specific immune response controls the infection Harrison’s Principle of Internal Medicine, 17 th ed.

3. Host Response Exposure to sufficient strains confers protection from high-level parasitemia and disease, but not from infection Immunity is mainly specific for both the species and the strain of infecting malarial parasite Both humoral and cellular immunity are necessary for protection Harrison’s Principle of Internal Medicine, 17 th ed.

4. Host Response Immune individuals have a polyclonal increase in serum levels of IgM, IgG, and IgA Antibodies to a variety of parasitic antigens act in concert to limit in vivo replication of the parasite This complex immunity to disease declines when a person lives outside an endemic area for several months or longer Harrison’s Principle of Internal Medicine, 17 th ed.

5. Factors that retard development of cellular immunity to malaria Absence of major histocompatibility antigens on the surface of infected RBCs, which precludes direct T cell recognition Malaria antigen-specific immune unresponsiveness Enormous strain diversity of malarial parasite – Ability of the parasites to express variant immunodominant antigens on the erythrocyte surface Harrison’s Principle of Internal Medicine, 17 th ed.

6. Relapsing Malaria Parasites can remain dormant (inactive or hibernating) in the liver cells Some of these dormant parasites can remain even after a patient recovers from malaria Patient can get sick again http://www.medicinenet.com/malaria/page2.htm#5whatis