1. History

2. Life Cycle

3. Vectors

4. Clinical Features

5. Use as a Model Organism

6. References

While P. coatneyi cannot be transmitted to humans, it is similar enough to Plasmodium falciparum to warrant laboratory study as a model species.^[4]

History

Plasmodium coatneyi was first discovered in 1961 by Dr. Don Eyles in the Malaysian state of Selangor.^[2] Plasmodium coatneyi was isolated from an Anopheles hackeri before being found in its primate host species. This was the first occurrence of acquiring a new form of malaria through its vector instead of an infected host specimen.^[4] The sample was first thought to be Plasmodium knowlesi due to the morphological similarities of the two species, but was later identified as separate due to having a tertiary periodicity compared to P. knowlesi’s quartan periodicity. The presence of P. coatneyi in a host was confirmed in 1963 by Dr. Eyles and his team when the protozoan was discovered in a crab-eating monkey found in the same area Selangor and again in a separate crab-eating monkey in the Philippines.^[2] The newly discovered species was then named in honor of Dr. G. Robert Coatney, an American malariologist.

Life Cycle

The life cycle of P. coatneyi takes the complex form representative of the genus Plasmodium. When a female Anopheles mosquito bites a human, a haploid form of the protozoan called a sporozoite is transferred from the salivary glands into the circulatory system of the human. These motile sporozoites are then taken by the circulatory system to the liver, where they invade the liver cells (hepatocytes).^[5]

During the next 5–16 days,^[6] these sporozoites mature and divide by asexual reproduction into schizonts. Schizonts are structures that contain thousands of haploid merozoites, and rupture to release merozoites into the circulatory system.^[7]

These merozoites then infect the red blood cells (erythrocytes) where they consume the hemoglobin of the red blood cells for energy and become immature, ring stage trophozoites.^[6] The trophozoites act as an intermediate stage, from which two forms can be formed. The trophozoites can mature into schizonts and release more merozoites into the circulatory system, or they can differentiate into still haploid gametocytes. The gametocyte is the sexual stage of the life cycle, with female macrogametocytes and male microgametocytes.^[2][7]

Vectors

• Anopheles balabacensis
• Anopheles freeborni^[1][2]
• Anopheles hackeri
• Anopheles maculatus

Clinical Features

When infected with P. coatneyi, the host shows the general symptoms of malaria are fever, headache, chills, vomiting, diarrhea, jaundice, joint pain and anemia.^[9] These symptoms occur in the form of paroxysmal attacks, which is a sudden increase of these symptoms after a period of remission. This is due to the release of merozoites from schizonts inside the red blood cells.^[7] This cyclic cycle occurs every other day when infected with P. coatneyi, a tertiary periodicity. This is compared to the quartan periodicity shown in some other Plasmodium species, such as P. knowlesi which occurs every three days.^[10]

Due to the fact that it is species of Plasmodium which only causes malaria in nonhuman primates,^[2] no treatment for this form of malaria has been specifically adapted. However, treatment with subcurative levels of artemether has been shown to reduce symptoms. This used to treat P. falciparum, and is grouped into artemisinin-based combination therapies used most for P. falciparum treatment.^[12]

Use as a Model Organism

While more closely related to Plasmodium vivax than to P. falciparum,^[13] P. coatneyi has been used as a model organism for P. falciparum in a model organism for humans, rhesus macaques.^[4] This is due to the several similarities that P. coatneyi and P. falciparum have in common. These similarities includes having a tertiary periodicity, causing cerebral malaria, causing knob protrusion on the surface of infected red blood cells, and adhering the red blood cells to the same sites of the endothelium. Because of these similarities, experiments have been run to further research the mechanism(s) for cerebral malaria.^[11][14]

On a broader scale, P. coatneyi can cause metabolic dysfunction, coagulopathy, and anemia very close to that found in humans. Therefore, P.coatneyi was predicted to be able to test pathophysiological interactions between the parasite and its host. This can be used to mimic the conditions of a human with malaria, allowing for testing without any sort of human exposure taking place.^[14]

References

• Campeonato da Liga
• Campeonato de Apertura (Chile)
• Campeonato de liga
• Campeonato de Portugal
• Campeonato Gaúcho de Futebol Segunda Divisão
• Campeonato Gaúcho Second Division
• Campeonato Gaúcho Second Level
• Campeonato Gaúcho Série A2
• Campeonato Gaúcho Third Division
• Campeonato Gaúcho Third Level
• Campeonato Mineiro da Segunda Divisão
• Campeonato Mineiro da Terceira Divisão
• Campeonato Mineiro de Futebol
• Campeonato Mineiro (lower levels)
• Campeonato Mineiro Second Level
• Campeonato Mineiro Segunda Divisão
• Campeonato Mineiro Terceira Divisão
• Campeonato Mineiro Third Level
• Campeonato Nacional da Guiné-Bissau
• Campeonato Nacional de Fútbol de Cuba
• Campeonato Nacional de Fútbol de Puerto Rico
• Campeonato Nacional de Rodeo
• Campeonato Paulista de Futebol
• Campeonato Paulista de Futebol Feminino
• Campeonato Paulista Série A2