This document discusses malaria, caused by Plasmodium parasites including P. vivax, P. falciparum, P. ovale, and P. malariae. It covers the life cycle of the parasites between human and mosquito hosts, morphological forms, pathogenicity, clinical manifestations, laboratory diagnosis, treatment, epidemiology, prevention and control of malaria. Key points include: 1) Malaria affects hundreds of millions annually and kills over a million people mostly children in endemic areas. 2) The parasite life cycle involves sexual reproduction in the mosquito and asexual reproduction in humans, allowing transmission between hosts. 3) P. falciparum infection can cause severe complications like cerebral malaria and

1. Aetiology
Management and Science University
International Medical School • Mosquito transmitted Disease
Female Anopheles mosquito
MBBS YEAR II
H & L System Module • Caused by –
Lecture 16 : MALARIA - Plasmodium vivax – beningn tertian malaria
- Plasmodium falciparum – malignant tertian malaria
- Plasmodium ovale – ovale tertian malaria
DR.DURGADAS Date : 19/12/2012 - Plasmodium malariae – quartan malaria
Plasmodium knowlesi
Malaria
• World wide 300-500 million cases/year
- Autochthonous (native) cases have been • And 1-3 million deaths (most 6 months – 3 years)
documented in Malaysia, Thailand, Myanmar, • Pl.falciparum accounts for 95 % of deaths
Singapore, the Philippines, • HIV and Malaria co infection is common in some area
and other neighboring countries. and takes severe form
• P.vivax and P.ovale cause latent infection because of
- Present in Monkey and can cause malaria in humans hypnozoite (slow growing parasite) in liver cells
• Malaria in first trimester of pregancy (P.falciparum)
- Morphology similar to P.malariae results in severe anaemia, complications include
miscarriage
• Fetal complications include low birth weight,
premature birth, death)
• Mixed infection P.v/P.f/P.o (~2-5%)
Life cycle involves two hosts –
Life cycle
1. Humans – Intermediate host
2. Female Anopheles Mosquito – Definitive host
Schizogony
1. Schizogony – asexual reproduction of parasite
(In Humans –Schizogony occurs in
Liver cells –Exoerythrocytic schizogony and
RBCS – Erythrocytic schizogony)
Gametogony
2. Gametogony – Production of Male and Female
gametocytes (Mosquito)
3. Sporogony – Production of sporozoites(Mosquito)
Sporogony
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2. Morphological forms
1. Schizogony (in Humans)
a. Trophozoite – Early (ring form), Late (amoeboid form)
b. Schizont – Early (Only nuclei), Late (with merozoites)
c. Merozoites
2. Gametogony (In mosquito)
a. Gametocytes forming cells
b. Gametocytes – Male, Female
3. Sporogony (In Mosquito)
a. Zygote
b. Ookinete
c. Oocyst
d. Sporozoites
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3. P.vivax, P.ovale – Hypnozoites
Slow growing parasites-
Responsible for relapse
Complications in P.falciparum malaria –
Pathogenicity/Clinical manifestations
Heavy parasitized RBCs (>5%)become deformed, sticky, and
P.vivax, P.falciparum, P.ovale, P.malariae, P.knowlesi adhere to endothelium of capillaries in internal organs.-
Results in vascular damage and vascular obstruction.
• Malaria – Febrile paroxysm (8-12 hours)
consists of cold stage, hot stage and profuse sweating. 1. Cerebral malaria - Haemorrhage & Necrosis.
Typical picture is typical bouts of fever with rigors
followed by Anaemia and Spleenomegaly. 2. Black water fever –extensive haemolysis, Kidney damage
• Anaemia – destruction of RBCs by parasite and haemoglobinuria, with Hb pigments
black colour urine –renal failure
autoantibodies
• Associated symptoms – Severe headache, nausea, 3. Pernicious anaemia – haemolytic
vomiting, Fever – 41 degree Centigrade
4. Septicemic malaria – involving many organs
Pulmonary edema – Lungs
5. Hypoglycemia
Incubation Period –
Merozoite induced Malaria
P.vivax & P.ovale : 10-14 days
P. falciparum : 8-12 days • Blood transfusion
P.malariae : 18-40 days
• Congenital malaria
Malaria pigments – Residues of Haemoglobin
• Shared syringes
(Haemozoin – toxic product)
Disease is self limited as no exoerythrocytic schizogony
P. vivax – Numerous Golden brown pigments
P. falciparum – few black pigments
P.malariae – Numerous dark brown pigments
P.ovale – Numerous blackish brown pigments
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4. Immunity :
Laboratory Diagnosis
Partial immunity. Antibodies block merozoites
resulting in low level of Parasitemia and 1. Microscopy :
low grade symptoms – premunition.
• Duffy blood group antigen is receptor for parasite. Thick smear – detects genus
Thin smear – detects species
• Sickle red cells (abnormal Hb) donot
support parasite growth
Smear is stained by Leishman or Giemsa
• Individuals deficient in G6PDH also resistant to malaria
& examined for any of the morphological
• Severe Malnutrition and iron deficiency gives protection forms of Plasmodium
against malaria
Plasmodium falciparum
with two chromatin dots
Growing stages of P.f.
P.falciparum gametocytes 27, 28 = Male and 29, 30 = Female
Trophozoite P.f. Schizont
P.falciparum gametocytes
In stained blood smear
P.vivax – Trophozoite -amoeboid
P.vivax – Ring stage
P.v. Gametocyte , 28,29 = Female
P.v. Schizont 30 = male
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5. 2. Detection of Antibodies 4. Species-specific PCR diagnosis of malaria
• Used in screening blood donors
• Suspected malaria with blood smear negative for parasite
Lane S: Molecular base pair standard
(50-bp ladder). Black arrows show the
size of standard bands.
Lane 1: band for P. vivax (size: 120 bp)
Lane 2: band for P. malariae (size:144 bp)
Lane 3: band for P. falciparum (size:205bp)
Lane 4: band for P. ovale (size: 800 bp)
Indirect immunoflourescence Test – Schizont
3. Detection of Protein antigen of P.falciparum by ELISA
Malaria – Epidemiology
Prevention and Control
• Personal prophylaxis – avoid mosquito bite,
use bed nets, insect repellent applications on
exposed skin.
• Chemoprophylaxis to travellers visiting
endemic countries
• Control by – Mosquito breeding sites, use of
• ~200 million cases of malaria worldwide insecticides.
• ~1 million die of malaria every year
• Increased cases of Choroquine resistant
P.falciparum strains
• Disease is endemic in many countries
Q. 1. Write causative agents of Malaria
Treatment – drugs in use
Q.2. Define Schizogony, gametogony and sporogony
• Chloroquine Q.3. In Plasmodium parasite which one is intermediate host
and Definitive host.
• Primaquine
• Combination of sulphadoxine & Q.4. Write life cycle of Plasmodim.
pyrimethamine or mefloquine
Q.5. Write morphological forms of parasite found in humans
• Chinese Herbal drug – Artesunate
that are diagnostic importance
• In severe p.f. infection quinine
Q.6. Name infective morphological form of Plasmodium
Q.7. Write Pathogenicity of P.vivax
Q.8. Write pathogenicity of P.falciparum & complications
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6. Q.9. State the reason for severity of P.falciparum infection
Q.10. Write laboratory diagnosis of malaria
Q.11. How do you differentiate trophozoite and
gametocytes of P.vivax and P.falciparum.
Q.12. Write transmission mode – name Vector involved
Q.13. What is merozoite induced malaria,
Give two examples.
Q.14. Why individuals who lack in duffy blood group
antigen on RBCs are resistant to Malaria
Q.15. Why malaria eradication is difficult.
Give two reasons
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