Malaria Parasite Evades Immunity by Hiding Intracellularly

Steps:

• Identify the Plasmodium life cycle: sporozoites invade liver cells, multiply, then infect red blood cells (RBCs).
• Recognize immune challenge: antibodies target extracellular parasites, but most stages hide inside host cells.
• Evaluate vaccine targets: effective vaccines need to hit pre-erythrocytic (liver) or erythrocytic (RBC) stages, but intracellular hiding limits access.
• Conclude difficulty: parasites are shielded from immune attack during key replication phases.

Why C is correct:

• Plasmodium spends critical stages inside liver cells and RBCs, evading humoral immunity per immunological principles of cellular invasion and antigen sequestration.

Why the others are wrong:

• A: Mosquito life cycle affects transmission, not human vaccine efficacy.
• B: The immune system recognizes parasite antigens, but evasion occurs via antigenic variation and hiding.
• D: Malaria vaccines are injected, bypassing stomach proteases.

Final answer: C