Good content in brief

1. PLASMODIUM
WWW.RCVETS.COM

2. Plasmodium
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> 100 species
Both animals and humans
1. P. vivax Benign Tertian Malaria (humans)
2. P. ovale Benign Tertian Malaria (humans)
3. P. malariae Benign Quartan Malaria (humans/chimpanzees)
4. P. falciparum Malignant Tertian Malaria (humans)

3. Plasmodia

4. Geographical Distribution
• P. vivax and P. falciparum more common
P. ovale rarest of the 4 species
• > 200 million people worldwide
> 1 million deaths per year
Most common lethal infectious disease

5. Geographical Distribution
• Tropical & subtropical areas
esp. Asia, Africa, Central and South America
Certain regions in SE Asia, S. America, E.
Africa Chloroquine Resistant strains of P.
falciparum

7. HABITAT
• Female Anopheles sexual cycle
• Liver & RBCs of man asexual cycle
RBC Age Variable:
➢ P. vivax youngest erythrocytes
➢ P. malariae oldest erythrocytes
➢ P. falciparum RBCs of every age

8. Anopheles, Culex and Aedes aegyptii

10. MORPHOLOGY
• Peripheral blood stained with Leishman’s stain
1. Small Trophozoites (Ring forms):
Infected RBC at first ring form
a) Dot/rod shaped nucleus (red)
b) Peripheral rim of cytoplasm (blue)
c) Central clear vacuole like area (not stained)
Different species have different rings

11. MORPHOLOGY
2. Large Trophozoite:
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Ring form Large trophozoite
Fine grains of pigment Hematin
3. Schizont:
Large trophozoite schizont N/C fragments merozoites
4. Gametocytes:
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Male and female distinguishable
Fully grown rounded occupies most of RBC
P. falciparum sausage shaped crescent in RBC

12. Plasmodia in RBCs

14. LIFE CYCLE
• HOST:
Definitive Host Female anopheles (sexual cycle)
Intermediate Host Man (asexual cycle)
• VECTOR:
Female Anopheles

15. LIFE CYCLE
• Sexual cycle initiated in Humans Gametocytes
oocyst
mosquitoes
many
(gametogony in RBCs)
fusion of M/F gametes
sporozoites (sporogony)
• Sexual cycle Sporogony (sporozoites)
• Asexual cycle Schizogony (schizonts)

16. Detailed Life Cycle

17. Oocysts in Mosquito

19. PATHOGENESIS
• Usual Incubation periods:
Vivax : 14 days
Malariae: 28 days
Falciparum: 11 days
• Transmission:
Mosquito bite
I/V drug abuse
Blood transfusion
Transplacental (congenital)
FEVER, ANEMIA, SPLENOMEGALY

20. PATHOGENESIS
• Malarial Relapses:
• P. vivax 2 years
• Para-erythrocytic stage liver parenchyma
dormant but viable
• Resistance lowered released and activated
complete erythrocytic cycle
• Not in P. falciparum as no para-erythrocytic stage
• Transmission other than mosquito bites no relapses

21. Natural Protection
• Sickle cell trait (heterozygous)
• Duffy blood group antigen –ve (homozygous
recessive) (P.vivax)
• G6PD deficiency
• Premunition:
• Partial immunity
• Humoral antibodies block merozoites from
invading RBCs
• Low level of parasitemia low grade symptoms

22. PATHOGENESIS
• Commonly Involved Organs:
1. Changes in Blood
2. Spleen
3. Liver
4. Bone Marrow

23. Signs and Symptoms
• Abrupt fever, chills and rigors
• Headache
• Initially may be continuous then periodic
• Upto 41ºC or 106 ºF
• Nausea, vomiting, abdominal pain, anorexia, distaste of mouth
• Drenching sweats afterwards
• Well between febrile episodes
• Splenomegaly
• 1/3 hepatomegaly
• Anemia
• Falciparum fatal bcz of brain and kidney damage

25. Laboratory Diagnosis
1. Blood Exam:
a. Microscopic Exam:
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Take blood during pyrexia
Not after even single dose of anti-malarials
Thick and thin smears made, dried and stained
Thick smear presence of organisms
Thin smear identification of species

26. Laboratory Diagnosis
• Thin Smear:
• Single drop of blood
• Spread to allow single cell layer
• Leishman’s stain
• Oil immersion lens
• Ring shaped trophozoites in RBCs
• P. falciparum gametocyte banana, sausage or crescent
shaped
• Other species gametocytes are spherical
• > 5 % RBCs infected Dx of P. falciparum

27. Laboratory Diagnosis
• Thick Smear:
• 3-5 drops on slide allowed to dry
• Several cell layers thick
• Field’s stain or Giemsa stain
• Oil immersion lens
• Stain removes Hb from RBCs

28. Thin and Thick Smear

29. Laboratory Diagnosis
1. Blood Exam:
b. TLC and DLC:
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TLC low leucopenia
In fever may be high
Monocytosis containing pigments

30. Laboratory Diagnosis
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2. Biopsy:
BM and liver biopsies in difficult cases
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3. Therapeutic Test:
Anti-malarials given if fever subsides Dx made
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4. Serological Tests:
Fluorescent antibody testing
Complement fixation test
Flocculation test
Hemagglutination test

31. Treatment
Falciparum easily treated before
complications as no relapses and no para-
erythrocytic stage
Chloroquine is treatment of choice for
sensitive strains of plasmodia (merozoites)
Primaquine (Hypnozoites)
Mefloquine or quinine and doxycycline
(chloroquine resistant strains of falciparum)
Atovaquone and proguanil (Malarone) (CR
falciparum)

32. Prevention
Chemoprophylaxis
Mosquito netting
Window screens
Mosquito repellants
Protective clothing
Special care during night time
DDT or kerosene oil spray over pools of
water
Drainage of stagnant water
No vaccine presently available

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