The malarial patient feels chill and fever when:

Explanation

During the erythrocytic stage of the plasmodium life cycle, merozoites invade red blood cells and reproduce inside them. As the number of merozoites increases within the RBCs, the RBCs eventually burst open (lysis), releasing more merozoites into the bloodstream. This bursting of infected RBCs leads to the release of toxic substances and triggers an immune response, resulting in symptoms such as chills and fever.