Plasmodium cynomolgi

Plasmodium cynomolgi is a non-human primate parasite which usually been found in the Asian Old World monkeys. This species has been used as a model for human Plasmodium vivax because Plasmodium cynomolgi has shared the same life cycle and some important biological features with P. Vivax.^[1]

Life cycle

Since Plasmodium cynomolgi has shared the same life cycle with the P. Vivax. The sexual reproduction stage would be done in the mosquito (definitive host) and the asexual reproduction stage would be done in the monkey (intermediate host) in this case. The whole life cycle would contain 12 steps:^[2]

1. Sporozoites in mosquito’s salivary glands

2. The Sporozoites would infect into human’s blood during mosquito’s feeding.

3. The Sporozoites in the blood would invade the hepatocytes (an important liver cell) and turned into Trophozoites form.

4. The Trophozoites in the hepatocyte would then turned into Meront and undergoes merogony which would burst the hepatocyte cell in order to release the Merozoites into blood.

5. The Merozoites in blood would then invade the RBC (Red Blood Cell) and undergoes the merogony, which would burst the RBC in order to release the Merozoites into blood. This step would have several cycles before the Merozoites turned into Gametocytes.

6. After several cycles from step 5. The Merozoites would invade the RBC and turned into Macro & Micro- Gametocytes.

7. Those Gametocytes in the RBCs would be ingested into mosquitos mid-gut during feeding.

8. The Gametocytes in the mid-gut would either differentiate if it’s Macro (female) or divide and differentiate if it’s Micro (male).

9. The Macro & Micro- Gametes in the mid-gut would undergo fertilization and form into zygote.

10. The zygote in the mid-gut would elongate into Ookinete form.

11. The Ookinete would penetrated epithelium and undergoes meiotic & mitotic division.

12. The Sporozoites would be formed in the oocyst and migrated in hemolmph, which would end up in the salivary gland.

The asexual cycle is usually taken 48 hours to complete which is similar to P. Vivax.^[3]

Diagnosis

The host red blood would enlarge while the trophozoites grow would have prominence of schuffner’s stippling and pigmentation appeared in the mature trophozoites. The host’s cytoplasm would become amoeboid like and the yellowish brown small granules would appear and scattered throughout the cytoplasm. The effect of the parasite can cause anemia within the host.^[3]

Since Plasmodium cynomolgi is not a human infected parasite, however; one case has been recorded wherein a patient was misdiagnosis of been infected with P. vivax, wherein she was actually infected with P. cynomolgi. Due to the similarity of Plasmodium cynomolgi and Plasmodium vivax many doctors believe that have several undiagnosed or misdiagnosis. Symptoms associated with P. cynomolgi: 1. Continues fever (24 hours cycle) 2. Chills and rigor 3. Cough and cold The symptoms were very similar as a flu-like syndrome.^[3]

Human infected case

The first and the only human infected case were found a 39 years old patient who is a Malay woman from the east coast of peninsular Malaysia. The patient has no malaria infection history and also has no uneventful medical history before she gets infected. Also She lived and worked in the malaria free area.^[3]

The patient had experienced a 24-hour cycles of morning fever since 10 January 2011 with chills and rigor, cough and cold. She had visited her mother’s house at 6–9 January 2001, which is before the symptom appeared. Her mother’s house is in a non-endemic area and she had not travel to any malaria-endemic area before the symptom appeared. Because the symptom is pretty similar as flu, she took two days of patent medicine without any doctor’s treatment. The symptom had become worse after two weeks, she choice to attend the hospital on 20, January. After took a blood film test, the asexual stage plasmodium has been diagnosis, the patient had been given a three-day course of oral chloroquine. The patient had been completely discharged one week later. (26 January 2011)^[3]

References