Apicomplexan life cycle

Apicomplexan Life Cycle

Apicomplexa structure

The apicomplexan life cycle is a complex series of developmental stages that occur in the life of organisms belonging to the phylum Apicomplexa. These protozoan parasites are known for their intricate life cycles, which often involve multiple hosts and both sexual and asexual reproduction phases.

Babesia life cycle human en

General Overview

Apicomplexans are obligate intracellular parasites, meaning they must live and reproduce within the cells of a host organism. The life cycle of apicomplexans typically includes the following stages:

• Sporozoite: The infective stage that is transmitted to a new host.
• Merozoite: The stage that invades host cells and undergoes asexual reproduction.
• Gametocyte: The sexual stage that differentiates into male and female gametes.
• Zygote: The fertilized cell that undergoes meiosis to produce new sporozoites.

Key Stages

Eimeria life cycle usda

Sporozoite

The sporozoite is the stage that initiates infection in a new host. It is typically introduced into the host through a vector, such as a mosquito in the case of Plasmodium species, which cause malaria. Once inside the host, sporozoites travel to specific tissues, such as the liver in Plasmodium infections, where they invade host cells and begin the next stage of their life cycle.

Ookinete, sporozoite, merozoite

Merozoite

After invading host cells, sporozoites transform into merozoites. This stage is characterized by rapid asexual reproduction, known as schizogony, resulting in the production of numerous merozoites. These merozoites are then released from the host cell to infect new cells, perpetuating the cycle of infection and increasing the parasite load within the host.

Gametocyte

Some merozoites differentiate into gametocytes, the sexual stage of the apicomplexan life cycle. Gametocytes are taken up by a vector during a blood meal, where they mature into male and female gametes. This stage is crucial for the transmission of the parasite to new hosts.

Parasite140105-fig3 Toxoplasmosis in a bar-shouldered dove - TEM of 2 tachyzoites

Zygote

Fertilization occurs within the vector, resulting in the formation of a zygote. The zygote undergoes meiosis to produce new sporozoites, which migrate to the salivary glands of the vector, ready to be transmitted to a new host, thus completing the life cycle.

Host Interaction

Apicomplexans have evolved various mechanisms to evade the host's immune system and ensure their survival and replication. These include antigenic variation, intracellular hiding, and manipulation of host cell functions.

Examples of Apicomplexan Parasites

• Plasmodium species (causative agents of malaria)
• Toxoplasma gondii (causative agent of toxoplasmosis)
• Cryptosporidium species (causative agents of cryptosporidiosis)

Related Pages

• Apicomplexa
• Plasmodium
• Malaria
• Toxoplasmosis
• Cryptosporidiosis