What reactivates to cause relapsing malaria?

• A. Hypnozoites
• B. Merozoites
• C. Sporozoites
• D. Gametocytes

Answer: (A)

Relapsing malaria is driven by dormant liver-stage parasites called hypnozoites. After the initial infection, these hypnozoites can remain hidden in liver cells and then reactivate weeks to months later, launching new rounds of blood-stage infection and causing a relapse. Merozoites are the actively invading blood forms released from liver schizonts that immediately infect red blood cells; they’re part of the ongoing infection, not a latent source. Sporozoites are the form transmitted by mosquitoes that initially infect the liver; they don’t cause relapse. Gametocytes are the sexual forms for transmission to mosquitoes and do not trigger relapse in the host.