Plasmodium circumflexum

Plasmodium circumflexum is a species of protozoan parasite that belongs to the genus Plasmodium. It is primarily known for causing avian malaria in birds. This article will provide an overview of Plasmodium circumflexum, its life cycle, transmission, and the impact it has on avian populations.

Taxonomy and Classification

Plasmodium circumflexum was first identified and described by Marchoux and Simond in 1902. It is classified under the phylum Apicomplexa, which includes other parasitic organisms such as Plasmodium falciparum, the causative agent of human malaria. Within the genus Plasmodium, P. circumflexum is classified under the subgenus Haemamoeba.

Life Cycle

The life cycle of Plasmodium circumflexum involves both a vertebrate host, which is usually a bird, and an invertebrate host, which is a mosquito. The parasite undergoes several stages of development within these hosts.

Invertebrate Host

The life cycle begins when an infected mosquito, belonging to the genus Culex or Aedes, takes a blood meal from an infected bird. The mosquito ingests the gametocytes, which are the sexual stage of the parasite. Within the mosquito's midgut, the gametocytes mature and undergo sexual reproduction, resulting in the formation of zygotes. These zygotes develop into motile ookinetes, which penetrate the midgut wall and form oocysts.

Inside the oocysts, multiple rounds of asexual reproduction occur, resulting in the production of thousands of sporozoites. These sporozoites are released into the mosquito's body cavity and migrate to the salivary glands, where they can be transmitted to a new host during a subsequent blood meal.

Vertebrate Host

When an infected mosquito takes a blood meal from a susceptible bird, the sporozoites are injected into the bird's bloodstream. The sporozoites invade hepatocytes, where they undergo asexual reproduction, resulting in the formation of merozoites. These merozoites are released into the bloodstream, where they invade red blood cells.

Within the red blood cells, the merozoites undergo further replication, leading to the destruction of the host cell. This cycle of invasion, replication, and destruction of red blood cells continues, causing the characteristic symptoms of avian malaria, such as anemia, lethargy, and organ damage.

Transmission

Plasmodium circumflexum is primarily transmitted through the bite of infected mosquitoes. Mosquitoes become infected when they feed on birds that harbor the parasite. The parasite completes its life cycle within the mosquito, and when the infected mosquito subsequently feeds on a susceptible bird, the parasite is transmitted.

The transmission of Plasmodium circumflexum can also occur through blood transfusions or the sharing of contaminated needles, although these modes of transmission are relatively rare.

Impact on Avian Populations

Avian malaria caused by Plasmodium circumflexum can have significant impacts on bird populations. Infected birds may experience reduced fitness, including decreased reproductive success and increased mortality. The severity of the disease varies among bird species, with some species being more resistant or tolerant to the infection than others.

Avian malaria can also have ecological implications, as it may affect bird migration patterns and alter the dynamics of bird communities. In areas where the parasite is endemic, avian malaria can be a significant factor influencing the distribution and abundance of bird species.

References

1. Marchoux, E., & Simond, P. L. (1902). Sur un hématozoaire des oiseaux, le Plasmodium circumflexum. Comptes rendus hebdomadaires des séances de l'Académie des sciences, 135(2), 100-102.

See Also

• Plasmodium falciparum
• Avian malaria
• Mosquito-borne diseases