Plasmodium: Clinical Features (Malaria)

Most forms of malaria cause chronic disease with significant morbidity but very little mortality.

The exception is malaria caused by Plasmodium falciparum sometimes still called malignant tertian malaria), which has a propensity for being severe and having life-threatening complications.

Falciparum malaria may have very severe anemia with hemoglobin less than 5 g/dL and more than half of the erythrocytes bearing parasites.

Complications of this form of malaria include pulmonary edema, renal failure with or without hemoglobinuria, shock, hypoglycemia, and cerebral malaria. Episodes occur with an irregular periodicity with fever spikes at 48-hour intervals during symptomatic periods.

Ans. is ‘c’ i.e., Multiple infection of erythrocytes are seen

.   Multiple infection of the red blood cel i.e., more than one parasite (from 2 to 6) invading a single red blood cell is very common with P flakiparum.

.   Infected erythrocytes are normal in size.

.   Erythrocytic Schizogony occurs inside the capillaries of the internal organs (spleen, liver and bone marrow), hence
only the ring forms (not the growing trophozoites and schizonts) and gametocytes are seen in peripheral blood.

.   Each erythrocytic cycle (schizogony) lasts 48 hrs (not 72 hrs.)

Ans. is ‘a’ i.e., Falciparum

Ans. is ‘b’ i.e., Plasmodium falciparum

.  Pernicious malaria is synonym of falciparum malaria.

Ans. is ‘a’ i.e., Lung; ‘d’ i.e., Heart

Ans. is ‘a’ i.e., Plasmodium vivax

Ans. B i.e. Plasmodium vivax

Duffy antigen/Chemokine receptor (DARC)/ Fy glycoprotein (FY) or CD234 (Cluster of Differentiation 234)

• It is a protein that in humans is encoded by the DARC gene.
• The Duffy antigen is located on the surface of red blood cells, and is named after the patient in which it was discovered.
• The protein encoded by this gene is a glycosylated membrane protein and a non-specific receptor for several chemokines.
• The protein is also the receptor for the human malarial parasites Plasmodium vivax and Plasmodium knowlesi.
• Duffy negative individuals whose erythrocytes do not express the receptor are believed to be resistant to merozoite invasion

Ans. C i.e. Falciparum malaria

Plasmodium falciparum

• It is a protozoan parasite, one of the species of Plasmodium that cause malaria in humans.
• It is transmitted by the female Anopheles mosquito.
• Malaria caused by this species (also called malignant or falciparum malaria) is the most dangerous form of malaria, with the highest rates of complications and mortality.
• Almost every malarial death is caused by P. falciparum

Ans. B: P.falciparum

P. falciparum often contains a single black dot. P. vivax often contains countless fine golden yellow/brown specks of malaria pigment. In P. ovale and P. malariae the pigment inclusions are many and brownish black.

Countless fine red spots in the red blood cell (Schiiffner’s dots) can be seen in P. vivax and P. ovale (the more mature the parasite, the more dots).

In P. ovale the dots are sometimes called James’s dots.

Sometimes a few flecks can be observed in P. falciparum (Maurer’s dots or clefts).

P. malariae almost never exhibits dots (Ziemann’s dots).

The visibility of these dots depends to a great extent on the acidity (pH) with which the thin slide preparation is stained (slightly alkaline: pH = 8 is best). The acidity is important because blood smears are usually stained for haematological tests with a slightly acid pH.

Ans: C i.e. Hypnozite

• In malaria, size of RBC is increased in: Vivax
• Infective agent of malaria is: Sporozoite

Falciparum malaria

• Gametocytes are seen in peripheral blood smear
• Parasitemia is highest
• Most virulent plasmodium species
• Exo-erythrocytic stage is absent
• Multiple infections of RBC’s
• Splenic rupture is common

Ans. c. Recurrence of sexual parasitemia after completion of treatment

Recrudescence-
Seen in P. falciparum & P. malariae
Due to persistence of the asexual parasiteo (crypticerythrocytic rather than exoerythrocytic stage) at subclinicallevel in circulation even after completion of treatment. lt can be due to waning immunity or antigenic variation.
Occurs within a few weeks or months of a previous attack (period of latency usually 8 weeks after primary attack)
Can be prevented by adequate drug therapy or use of newer antimalarial drugs in case of drug resistance.

Ans. is ‘a’ i.e., Plasmodium falciparum 

• The possession of the sickle cell allele protects these individuals against malaria because the parasite dies when potassium leaks out of RBCs as they become sickle shaped.
• Types of anemia that have protective effect against P. falciparum malaria : – G6PD deficiency, Sickle cell anemia, Thalassemia, HbC, Pyruvate kinase deficiency
• Persons having heterozygous sickle cell trait are protected from plasmodium falciparum
• People who are heterozygous for the sickle cell trait (Hbs) become infected with plasmodium falciparum but they are less likely to die from infection. The Hbs trait causes the parasite to grow poorly or die because of the low oxygen concentration.