Diagnosis of malaria by the peripheral blood smear

Diagnosis of malaria by the peripheral blood smear
For Medical Lab.students

1. 1 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare
Diagnosis of Malaria in the Peripheral Blood Smear
 4 species of Plasmodium
 300-500 million cases/year
 1-2 million deaths/year
 Spread via female anopheles mosquitoes, blood transfusion, IVDA
 Cyclic fevers, headache & malaise
 Thick & thin blood smears prepared
 Collection – midway between fever cycles

female anopheles mosquitoes

2. 2 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare

Cycle life

3. 3 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare
Plasmodium falciparum
1. Malignant tertian malaria
2. Asia & Africa
3. Most deadly and severe infections
4. Shortest incubation period = 7-10 days
5. Infects all ages of RBCs higher parasitemia
6. Mature trophozoites and schizonts sequestered in microvascular system tissue ischemia
7. Rarely seen in peripheral smear
8. GI symptoms
9. Black water fever
 Intravascular hemolysis kidney damage
 Capillary plugging due to RBC debris
 Can involve CNS
 Widespread drug resistance

4. 4 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare
Plasmodium vivax
1. Benign tertian malaria
2. Latin America, India, Pakistan
3. Only infects reticulocytes
4. Produces HYPNOZOITES
5. Relapses up to 5 years after infection
6. Uses Duffy (Fy) antigen as receptor
7. Treatment = Primaquine (for hypnozoite)

5. 5 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare
Plasmodium ovale
1. Ovale/benign tertian malaria
2. Africa, Asia, South America
3. Only infects reticulocytes
4. Produces HYPNOZOITES
5. Relapses up to 5 years after infection
6. Treatment = Primaquine (for hypnozoite)


Early trophozoite (ring)


Mature trophozoite


Schizont


Gametocytes

6. 6 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare


Plasmodium malariae
1. Quartan malaria
2. Asia & Africa
3. Only infects mature RBCs
4. Low-grade parasitemia that can persist >40 years
5. Longest incubation period = 18-40 days, even years



Early trophozoites (rings)


Schizont

Mature trophozoite (band
form)


Gametocyte

7. 7 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare
MALARIA - Laboratory diagnosis
Laboratory diagnosis of malaria requires the identification of the parasite
Microscopy
Thick and thin blood smear study
thick smears are mainly used to detect infection and to estimate parasitemia.
Thin film identify malaria species,, quantify parasitemia, and recognize parasite forms like schizonts and gametocytes.

8. 8 Diagnosis of malaria

Prepared by Dr.Abddulrazzaq Alagbare
Advantages:
 It is an inexpensive method
 It gives the examiner the opportunity to quantify parasites and differentiate malaria species
Disadvantages:
 The diagnostic accuracy depends on quality of blood smear and equipment, abilities of the microscopist, parasite density and
the time spent on reading the smear. All these may result in therapeutic delays.
 Not suitable for large- scale epidemiological studies .
 False positive. Defective blood film preparation may lead to artifacts that can be incorrectly regarded as malaria parasites.
Sometimes, platelets also confound diagnosis.
 False negative. It is associated with low parasite density or low number of fields examined by the microscopist.