Malarial parasite – Part 3 – Plasmodium vivax, MP

Sample

1. Malarial parasite (MP) may be diagnosed from a blood smear of a patient with a fever.
   1. The best time to make a smear is during shivering.
   2. Make thick and thin blood smears.
2. Serum needed for a Serological method and for PCR.

P. Vivax

1. This is the most predominant parasite in most areas of the world.
2. 70-90% of cases in most of Asia and S. America.
   1. 50-60% of cases in SE Asia and the western Pacific.
   2. 1-10% in Africa.
3. P. vivax is the second most significant species and is prevalent in Southeast Asia and Latin America.
4. P. vivax have the complication of a dormant stage in the liver.
   1. The P. vivax while in the liver can become active without the mosquito bite and lead to clinical symptoms.

Erythrocytic cycle

1. P. vivax show ring form with chromatin dot and cytoplasm.
   1. It measures the 1/3 of the RBC.

2. Trophozoite may show remnants of the cytoplasm.
   1. It is an irregular and amoeboid appearance.
3. Schizonts are characterized by the presence of multiple chromatin dots.
   1. Cytoplasm often contains brown pigments.
   2. There are on average 12 to 24 merozoites with an average of 16.
   3. These merozoites occupy the majority of RBC.
   4. Brown pigments may be found.
4. Microgametocytes consists of large pink to purple chromatin mass.
   1. Brown pigments are usually seen.
5. Macrogametocytes is characterized by the round to oval homogenous cytoplasm and eccentric chromatin mass.
   1. There is the diffuse light brown pigment that may be visible throughout the parasite.
6. Schuffner dots are seen with Giemsa stain.
7. Infected RBCs are enlarged and distorted.

Clinical presentation

1. The patient develops signs and symptoms after the 10 to 17 days of incubation after following the infection (bite from the mosquito).
2. Early there are flu-like symptoms.
3. There may be nausea, vomiting, headache, muscle pain, and photophobia.
4. The toxins of the parasite give rise to paroxysm which occurs every 48 hours.
5. If the infection becomes chronic then it may cause damage to the kidney, brain, and liver.

Diagnosis

1. History of the patient in suspected areas.
2. Blood smear:
   1. Make a blood smear when the patient has a fever. Thin and Thick smears are made.
   2. The thick smear is more helpful to find M.Parasites.
      1. The thin smear is good to identify the type of malarial parasite.
   3. Collect blood 6 to 8 hourly till 48 hours to declare negative for malaria.
   4. Giemsa stain is the best choice.
3. Serologic methods are based on immunochromatic techniques. Tests most often use a dipstick or cassette format and provide results in 2-15 minutes.
4. Polymerase chain reaction (PCR): Parasite nucleic acids are detected using the PCR technique. This is more sensitive than smear microscopy. This is of limited value for the diagnosis of acutely ill patients because of the time needed for this procedure.

Mosquito control

1. Try to eliminate breeding places:
   1. Fill the vacant land and pump out the water.
   2. Remove the junk and water retaining debris.
2. Destroy the larvae:
   1. Clean the drains.
   2. Try to remove algae from the ponds.
   3. Add larva-eating fish to the ponds.
3. Use of the insecticide:
   1. The best example is DDT.
4. Use of mosquito repellent:
   1. Pyrethroid repellent.
   2. N, N- diethyl meta tolbutamide.
5. Use of mosquito nets.
6. Use of clothes to prevent mosquito bites.
7. Train people for malaria prevalence.
8. Train the people for the detection of malaria, treatment, and follow-up.
   

   Malaria Parasite Sexual and Asexual Cycle

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