Malaria parasite – Part 5 – Plasmodium ovale, 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.

Indication

• For the diagnosis of the malarial parasite.

P. Ovale

1. 8% of cases in parts of Africa.
   1. Few cases in Asia.
2. P. ovale represents only a small percentage of infections.
3. P. ovale has the dormant stage in the liver which can become active without the mosquito bite.

Erythrocytic cycle

1. Ring form is like P. vivax.
   1. The difference is that there is a ring larger than the P. vivax.
   2. The ring is also thicker.
2. Trophozoites maintain its ring form.
   1. The amoeboid tendency is common.
      

      Malarial Trophozoites

3. Schizonts consist of dividing chromatin surrounded by the cytoplasm.
   1. There are Rossetts of merozoites, 8 on average.
   2. 3/4 of the cell is occupied by the parasite.

Clinical presentation

1. Initial symptoms are flu-like.
2. The typical paroxysm is every 48 hours.
3. Relapse may take place and there is spontaneous recovery.
4. The above feature is not seen in the P. vivax.

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. A thick smear is more helpful to find M.Parasites.
      1. A 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.
   1.  This is more sensitive than smear microscopy.
   2. 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.
   

   MP Sexual Asexual Cycle

Treatment

1.  Antimalarial drugs used are quinidine, chloroquine, primaquine, pyrimethamine, sulfadoxine, mefloquine, tetracyclines, and proguanil.
2. Chloroquine is the drug of choice and best for P. falciparum.
   1. This is effective for the erythrocytic stage and not for the liver stage.
   2. Must use primaquine to eradicate P. ovale and P. vivax.
   3. there are chloroquine resistant cases of P. falciparum.
3. Amodiaquin, piperaquin and pyronaridine are close to chloroquin.
   1. Amodiaquine is less toxic, cheap, and in some areas effective against chloroquine-resistant P. falciparum.
4. Mefloquine is effective against choloquin resistant P. falciparum.
5. Quinine and quinidine are still the first line of therapy against P.falciparum.
6. Primaquine is a synthetic drug and is the drug of choice for the eradication of the liver stage from P. vivax and P. ovale.
7. Antibiotics and Inhibitors of folate synthesis are slow-acting antimalarial drugs.
8. Halofantrine and Lumefantrine are related to quinine and effective against the erythrocytic stage.
9. Malaria drug-resistant strains are emerging. 

---