What is zoon?

A zoon, also known as a merozoite, is a motile, feeding stage in the life cycle of some sporozoan protozoans, such as Plasmodium, the parasite responsible for malaria. It develops from a schizont, which is a cell that undergoes multiple fission to produce many merozoites. Zoon/Merozoites infect red blood cells or other host cells, and continue the parasitic life cycle. The name "merozoite" comes from the Greek words "meros" (part) and "zoon" (animal).

Key aspects of merozoites include:

• Infection: Merozoites are responsible for invading host cells and causing disease. In the case of malaria, merozoites released from the liver infect red blood cells, leading to the symptomatic phase of the disease.
• Morphology: Merozoites are typically small, elongated cells with a characteristic apical complex, which aids in cell invasion.
• Replication: Once inside the host cell, merozoites undergo asexual reproduction, producing more merozoites.
• Drug Targets: Merozoites are a key target for antimalarial drugs. Blocking the merozoite's ability to infect or replicate can prevent the progression of the disease. The apical complex is of particular interest for these drugs.
• Immune Response: The body's immune system attempts to target and eliminate merozoites, but the parasite has evolved mechanisms to evade immune detection. This can sometimes result in the immune response resulting in symptoms.
• Life Cycle: The merozoite stage is a crucial part of the parasite's complex life cycle, alternating between sexual and asexual reproduction in different hosts. Other than humans, they reproduce in mosquitoes.