Malaria

 An ancient disease : substantial toll of human life and
sufferings
 Originated from Italian word Mala (bad) and ayia(air)
 Latin word : Marshy
 So
 , malaria : disease caused by heat humidity and marshy areas
 1st discovered : Alphonse Laveran : 1880 in RBC of patient
(Algeria)

 Transmitted by female Anopheles mosquito
 Common insect borne infection
 Most deadly vector borne disease in the world
 Life threatening parasitic problem : global problem worldwide
 40% of world’s population : (2.4) billion risk
 400-900 million people are affected

 Kingdom: Animalia
 Phylum: Apicomplexa
 Class: Coccidia
 Order: Haemosporidia
 Genus: Plasmodium
 Species: vivax, falciparum, ovale , malariae

 P.vivax and P.falciparum : account 95% of infection
 Some estimate : P.vivax : accounts 80% of infections : widely
distributed in tropics, subtropics and temperate zones

Different stages:
1.Pre-Erythryocytic Schizogony
2. Erythrocytic Schizogony
3. Gametogony
4. Exo-Erythryocytic Schizogony (P.vivax, P.ovale)

1.Pre-erythrocytic Schizogony
 1st stage of human cycle
 Sporozoites : doesn’t directly enter into RBC : so k/as PES
occurs : inside parenchyma of cells
 Fully developed schizont measures 42µm : contains large no of
merozoites
 Smaller micromerozoites : enter into circulation : to start ES
 Larger macromerozoites : Re-enter liver cells : to start Exo ES
 Some sporozoites : remain dormant in liver : Hypnozoites : cause relapse

Duration of this phase :
 P.falciparum : 6 days
 P.vivax : 8 days
 P.ovale : 9days
 P. malariae :13-16days

2. Erythrocytic schizogony
 Infected liver ruptures : merozoites release : invade RBC’s
 Parasite reside the RBC and passes through :
RBC Trophozoite Schizont Merozoite
 P.vivax : greater tendency for younger erythrocytes and
reticulocytes
 P.falciparum : any age
 P.malariae : old
 P.ovale : Young

 Parasitised red cells : enlarged : cells mature with parasites :
show stippling(formation of small dot)
 P.vivax : Schuffner’s dot
 P.falciparum : Maurer’s dot (large red spots)
 P.malariae : Ziemann’s dot (few tiny dots)
 P.ovale : Schuffner’s dot

 Trophozoite : Have active amoeboid
 2 forms :
1. Ring form (early trophozoite)
 Nucleus : thinner side of ring
2. Amoeboid form (late trophozoite)
 Presence of pseudopodia
 Contains malarial pigment

Schizont
 Appears after a period of 36-40 hours
 Full grown trophozoite : ready to divide
 Round in shape
 Lost all amoeboid activities
 Nucleus is large and lie at periphery
 2 form :
Immature schizont (Nucleus not divided)
Mature schizont : Nucleus divided

3.Gametogony
 After ES : some merozoites : give rise to gametocytes : sexual function
after leaving man host
 Occurs inside capillaries of bone marrow and spleen
 Mature gametocytes : appears in peripheral blood
 Microgametocyte (male) : boarder, shorter with blunt ends
 Macrogametocyte (female): longer, narrower, pointed ends
 Changes in infected RBC’s (increase in size, pallor and different dots )

4.Exo-erythrocytic Schizogony
 Resembles PE form in morphology
 Maintained upto 3 yrs and independent of ES
 Short term and long term relapses (deteriorate after a period of
improvement)
Sporozoite PES Development of hypnozoites
ES EES
primary malaria Relapses

Relapse :
 in case of P.vivax and P.ovale
due to the presence of hypnozoites
Recrudescence :
 situation : RBC infection is not eliminated by the immune
system or by therapy
 No of RBCs begin to increase again with subsequent clinical
symptoms
 All species may cause

 Sexual cycle of malarial parasite
 Starts in human body : formation of gametocytes
 Mosquito : blood meal : ingests both sexual and asexual forms
 Asexual forms : digested
 Sexual forms (gametocyte) : undergo further development
 Blood of human carrier : must contain 12 gametocytes/mm3

 No of female gametocytes more than male gametocytes
 1st phase : mid-gut of stomach
 Nucleus of each male gametocyte : 8 long flagellates(microgamete)
: highly motile
 Process : observed : outside mosquito : thick film: exflagellation
 Female gametocyte : don't divide : Macrogamete
 Fertilizes : Zygote : motion less: later becomes motile : Ookinite

 Ookinite : migrates to stomach wall : oocyst
 Large no of sporozoites inside oocyst
 When fully mature : oocyst ruptures : liberates sporozoites :
spread all parts : salivary gland
 Ready to be transmitted : when it takes blood meal

MOT : bite of Anopheles mosquito
Extrinsic Incubation period :
 different periods for the development of sexual cycle at given
temp
 Varies : 8 to 21 days
Incubation period
 P. falciparum : 12 days(9-14 days)
 P. vivax : 14 days (8-17 days)
 P. malariae : 28 days (18-40 days)
 P. ovale :17 days (16-18days)

Main features : fever peaks followed by anemia and splenomegaly
Mild to severe and complicated :
 According to species of parasite present
 Patient’s state of immunity
 Certain disease like : malnutrition and other disease
 Severe in children and pregnancy

Main clinical features
1.Prodromal period
 Malarial paroxysm :preceed by prodromal period
 Non-specific symptoms : malaise, myalgia, headache and
fatigue
 Some localized symptoms :chest pain, abdominal pain and
arthalgia
2. Malarial paroxysm
 Classical manifestation of acute malaria
 Characterised by fever chills and rigors

Primary fever
 Typical attack 3 distinct stages: cold stage, hot stage and
sweating stage
a. Cold stage :
 Onset with lassitude (lethargy), headache, nausea and chilly
sensations followed in an hour or so by rigors
b. Hot stage :
 Patient feels hot and the skin is hot and dry to touch
 Headache intense
 Lasts for 30 min to 6 hrs

c. Sweating stage
 Profuse sweating follows the hot stage
 Continues for hour or so
 Temp drops rapidly to normal
 Skin is cool and moist
So, primary attack follows a febrile interval of 48-72hrs

3.Anemia
 Normocytic normochromic anemia
 Severe in falciparum malaria
4. Hepatospleenomegaly
 Spleen : palpable after 2nd weeks of fever
 Severe in P.falciparum : so K/as malignat malaria
5. Malaria in pregnancy
 Miscarriage or abortion
6.Malaria in children
 More severe than as in adults
 May develop convulsion (muscular contarction) during malarial
attack
 Dehydration: as a result of vomiting and sweating.

 P.vivax : Benign tertiary malaria : 48hrs
 P.falciparum : Malignant tertiary malaria:36-48hrs
 P.malariae : Benign Quartan Malaria : 72 hours
 P.ovale : Benign Tertian Malaria : 48 hrs

1.Black water fever
 Repeated infection of P.falciparum: inadequately treated
with quinine
 Massive hemolysis followed by fever and
haemoglobinuria(black coloured urine),hyperbilirubenemia
 Complication : uraemia (blood poisoning), renal failure
,anemia, pigment calculi

2.Pernicious anemia (Cerebral malaria or algid malaria)
May be different forms :
a. Pernicious malaria affecting nervous system : cerebral malaria
b. Pernicious malaria affecting GIT system (algid malaria)
c. Pernicious types affecting cardiovascular, respiratory and
genitourinary tract

Specimen :
 Blood (before antimalarial drug)
 Earlobe or finger in adults
 Toe in infants
 Collected : peak fever
 More imp : frequently examination of blood smear

1.Light microscopy
2. Fluorescence microscopy
3. Quantitative buffy coat
1.Light microscope
 Blood smear
 Gold standard method
 Most commonly used
 Depends upon : demonstration of parasite in stained PBS
 Ring forms and gametocyte : commonly seen in PBS

1.Thick smear
 Smear preparation
 Dehaemoglobinisation with d/w
 Dried and stained with Romanowsky’s stain : Leishman stain.
Geimsa stain
Uses
 To detect parasite
 Demonstrating malarial pigment

P. falciparum : (only ring and crescent form)
 Many ring forms
 Crescent forms gametocyte
 Malarial pigments : inside the blood
P. vivax
 Trophozoites, Schizont and Gametocytes can be seen in PBS
 Ring form : nucleus more thicker
 Gametocyte : spherical or globular
 Schufnner’s dot

Thin smear
 Rapidly dried
 Fixed in alcohol and stained
Uses
 Detecting parasites
 Identify species
P. falciparum
 Ring form alone or along with gametocytes
 Multiple rings in individual RBC’s
 Presence of Maurer’s dot
 Banana shaped gametocytes

The rings are small:
1/3 or less of the rbc

Ameboid trophozoite, enlarged RBC
, Schüffner’s dots
Gametocyte

2. Fluorescence microscope
 Kawamoto technique : fluorescent staining methods : malarial
parasite
 Blood smear : slide : stain with Acridine orange
 Nuclear DNA : green
 Cytoplasmic RNA : Red
 Examined under fluorescence microscope

3. Quantitative buffy coat (QBC)method
 Sensitive method
 Based on : ability of acridine orange to stain
nucleic acid containing parasites
 Blood : capillary tube : coated with fluorescent
dye : microhaematocrit centrifugation
 Buffy coat : observed under fluorescent
microscope
 Acridine orange stained malarial parasite :
brilliant green

4.Serodiagnosis
 IHA
 ELISA
 IFA
5. Rapid diagnostic kit
6. Dipstick method
 An enzyme immunoassay : which detects histidine rich protein 2
Pf(HRP-2) : metabolic product produced by P.falciparum
7. Molecular diagnosis
 DNA and RNA : PCR

 Chloroquine
 Amodiquine
 Proguanil
 Quinine

Malaria

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