Malaria

1. MALARIA
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2. Introduction:
• Linked with poisonous vapors of swamps or stagnant water.
• Italian: Mala = Bad ; aria = Air
• Term used by Italians to describe cause of intermittent fevers
associated with exposure to marsh air.
• Other names: Jungle fever, Marsh fever, Swamp fever.
• Malaria continues to be most important cause of fever and
morbidity in the Tropical world.
• “HIV, Malaria and TB are among the most important
infectious agents in the world.
• Malaria has been eradicated from Europe, Most of North
America, USA, Korea and Japan. 2

3. Introduction
• Malaria is probably one of the oldest diseases known to mankind that has had
profound impact on our history.
• Malaria is a vector-borne infectious disease caused by single-celled protozoan
parasites of the genus Plasmodium.
• Malaria is transmitted from person to person by the bite of female mosquitoes.
• Malaria remains the world's most devastating human parasitic infection.
• Malaria affects over 40% of the world's population.
• WHO, estimates that there are 350 - 500 million cases of malaria worldwide, of
which 270 - 400 million are Falciparum malaria, the most severe form of the
disease.
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4. Global problem
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5. Malaria Kills more people than AIDS
• Malaria kills in one year what AIDS kills in 15 years.
• For every death due to HIV/AIDS there are about 50 deaths
due to malaria.
• To add to the problem is the increasing drug resistance to the
established drug.
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6. Ancient History of Malaria
• Malaria parasites have been with us since the
dawn of time. They probably originated in Africa
(along with mankind), and fossils of mosquitoes
up to 30 million years old, show that the malaria
vector, the malaria mosquito, was present well
before the earliest history.
• Hippocrates, a physician born in ancient Greece,
today regarded as the "Father of Medicine", was
the first to describe the manifestations of the
disease. 6

7. History
• 1880 - Charles Louis Alphose Lavern discovered malarial
parasite.
• 1891 - Polychrome stain- Romanowsky.
• 1898 - Italian scientists Amico Bignami, Battista Grassi
and Giovanni Bastianelli - Life cycle of parasite.
• 1902 – Ronald Ross was awarded Nobel Prize for
demonstration of vector Anopheles mosquito while serving
in India.
• 1976 – Trager and Jensen in vitro cultivation of parasite.
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8. Nature of parasite as Drawn by Lavern
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9. What causes Malaria?
• Malaria is caused by a parasite called
Plasmodium, which is transmitted via the
bites of infected mosquitoes. In the human
body, the parasites multiply in the liver, and
then infect red blood cells.
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•Malaria is caused by an infection by one of four
single celled Plasmodia species, they are:
falciparum, vivax, malariae, and ovale.
•The most dangerous of the four is P. falciparum.

10. • Phylum: Apicomplexa
• Class: Haematozoea
• Order: Haemosporida
• Genus: Plasmodium
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11. Etiology of Malaria
Four Species known to infect Human
• Plasmodium vivax – Benign Tertian Malaria
• P. ovale - Ovale tertian Malaria
• P. malariae – Quartan malaria
• P. falciparum – Falciparum malaria or Malignant Tertian malaria.
• Falciparum accounts for 90% of deaths due to malaria and vivax is the most
widely spread species because it exists in both temperate and tropical climates.
• The malaria life cycle is a complex cycle with both sexual and asexual aspects.
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12. Life Cycle:
• Intermediate host : Human
• Definitive host : Mosquito
• Infective stage : Sporozoite
• Infective way : mosquito bite skin of
human
• Parasitic position : liver and red
blood cells
• Transmitted stage : gametocytes
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13. • Human Cycle: (Intermediate
host)
– Primary exoerythrocytic / pre-
erythrocytic schizogony
– Erythrocytic schizogony
– Gametogony
– Secondary exoerythrocytic or
dormant schizogony
• Mosquito cycle (Definitive
host)
– Sporogony
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14. 14

15. Primary exoerythrocytic or pre-erythrocytic schizogony:
• Sporozoites leave the blood stream within one hour
and enter liver parenchyma cells.
• Becomes rounded and multiple nuclear division,
followed by cytoplasmic division and develop into
primary exoerythrocytic schizont.
• Size varies according to species, from 24-60 um in
diameter.
• Contains 2000 – 50,000 merozoites.
• Duration:
– P. falciparum: 6 days
– P. vivax: 8 days
– P. ovale: 9 days
– P. malariae: 13-16 days
• Liver cell ruptures and merozoites released to blood
stream.
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16. Erythrocytic schizogony:
• Merozoites enter blood stream and invade RBCs.
• Trophozoites, Schizonts and Merozoites stages are
passed on here.
• 6-32 nuclei are produced followed by cytoplasmic
division.
• RBC ruptures to release merozoites.
• Metabolism dependent on digestion of Haemoglobin
which transformed to malaria pigment.
• Clinical attack of malaria is due to this stage;
parasitic multiplication.
• Only young ring forms are found in peripheral blood in
case of P. falciparum due to the tendency of its
developing erythrocytic schizonts to aggregate in
capillaries of brain and other internal organs. 16

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21. Gametogony:
• Some merozoites develop into male and female
gametocytes in RBC after erythrocytic schizogony.
– Microgametocytes (male)
– Macrogametocytes (female)
• Only mature gametocytes are found in peripheral
blood.
• Do not cause any febrile condition.
• Hyperparasitaemia, anaemia and antimalarial drugs
stimulates Gametogony.
• CARRIER - Host carrying gametocytes.
• Half life of mature gametocytes in blood stream
may be up to 2- 3 days only.
• Taken up by mosquito.
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22. Secondary exoerythrocytic or dormant schizogony:
• Sporozoites of P. vivax and P. ovale enter into
resting (dormant) stage before undergoing asexual
multiplication in hepatocytes.
• Sporozoites attain rounded shape of 4-6 um in
diameter, uninucleate known as Hypnozoite.
• These reactivates after weeks or months or years to
become secondary exoerythrocytic schizonts and
release merozoites.
• Infects RBC causing RELAPSE.
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• This does not occur in P. falciparum & P. malariae.
• But RECRUDESCENCE may occur, which is caused may be due to drug resistance
and waning of host immunity.
• This may occur in all species of Plasmodium.

23. Mosquito Cycle:
• Sexual cycle starts in human.
• Only mature sexual forms are capable of further development in mosquito.
• Human blood must contain at least 12 gametocytes/ul to infect mosquito.
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24. CULTURE
• Trager and Jensen (1976), successfully cultivated and
maintained P. falciparum in vitro in human RBC.
• Medium RPMI (Roswell Park Memorial Institute) 1640 was
used in a continuous flow system in which human erythrocytes
were in a shallow stationary layer covered by a shallow layer of
medium.
• The medium was made to flow slowly and continuously over the
layer of settled red cells, under an atmosphere with 7% carbon
dioxide and 1-5% oxygen.
• Culture is used for the production of antigen. 24

25. Mode of transmission:
• Through infected Mosquito.
• Trophozoite induced malaria:
– Transfusion associated malaria
– Congenital malaria
– By the use of contaminated syringe particularly in drug addicts.
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26. PATHOGENICITY
INCUBATION PERIOD:
• Following the infective bite by the Anopheles mosquito a period of time
(the "incubation period") goes by before the first symptoms appear.
• The incubation period in most cases varies from 7 to 30 days.
• The shorter periods are observed most frequently with P. falciparum and
the longer ones with P. malariae.
– P. falciparum: 12 days
– P. vivax & P. ovale: 13-17 days
– P. malariae: 28-30 days
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27. 27

28. Clinical Features:
1. Periodic bout of fever with chills and rigor (Febrile paroxysm)
2. Anaemia
3. Splenomegaly
4. Pernicious malaria
– Cerebral malaria
– Algid malaria
– Septicaemic malaria
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29. Febrile Paroxysm:
• Clinical manifestation is because of
Erythrocytic schizogony.
• Begins early afternoon.
• Cold stage: last for 15 to 60 minutes; intense
cold feeling.
• Hot stage: Last for 2 to 6 hrs; intense hot
feel; fever (40-40.6 C); severe headache,
nausea and vomiting.
• Profuse Sweating
• Periodicity varies according to species:
– P. vivax & P. ovale – 48 hrs
– P. malariae- 72 hrs
– P. falciparum- typical tertian fever is not usual
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30. Anaemia
• Occurs after few paroxysms.
• Microcytic or normocytic hypochromic anaemia develops.
• Causes:
– RBC lysis
– Splenic removal of both infected and uninfected RBCs
– Autoimmune lysis of coated infected and uninfected RBCs.
– Decreased incorporation of iron into heme.
– RBC fragility.
– Decreased RBC production from bone marrow suppression.
• P. vivax and P. ovale- infects young RBC
• P. malariae- old RBC
• P. falciparum- all age type RBC ( may infect upto 50% of RBCs)
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31. Splenomegaly:
• Followed after few paroxysms.
• Becomes palpable.
• Caused due to massive proliferation of macrophages which
phagocytose parasitised and non-parasitized RBC.
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32. Pernicious Malaria:
• It is a complex of complications of falciparum malaria:
• Cerebral malaria:
– Severe complication frequently leads to death.
– Hyperpyrexia, coma and paralysis.
– Capillaries of brain plugged by parasitized RBCs which
contains malaria pigment.
– Commonly occurs in children of age 3 – 4 yrs.
• Algid Malaria:
– Resembles surgical shock with cold clammy skin.
– Peripheral circulatory failure and profound shock.
• Septicemic malaria:
– High degree of prostration, continuous fever and involves
various organs.
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33. Blackwater fever:
• Manifestation of repeated falciparum infection.
• Due to inadequate treatment with quinine.
• Mechanism yet unknown but Autoimmune mechanism
has been suggested.
• Parasitized and quininized RBCs during previous
infection act as antigen.
• Blackwater fever has now become rare due to
replacement of quinine with other antimalarial drugs.
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34. Host Immunity:
Innate immunity:
• Age of RBC
• Nature of haemoglobin:
– Resistance to all Plasmodium spp.- Thalassemia haemoglobin, & Hb-F
– P. falciparum - Hb-S
– P. vivax - Hb-E
• Enzyme content of RBC:
– G6PD deficiency
• Presence or absence of certain factor:
– Duffy antigen
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35. Acquired immunity:
• Antibodies against sporozoites and asexual and sexual blood
stages develops which protects by inhibiting invasion to
RBCs.
• Activation of T- cells, Macrophages & Killer cells.
• P. falciparum in other hand, avoid frequent passage through
spleen and thus exposure to immune effector mechanisms by
cytoadherence to capillary lining.
• This does not occur in other species so the difference in
disease severity.
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36. Laboratory Diagnosis
• Laboratory diagnosis of malaria can be made through microscopic
examination of thick and thin blood smears.
• Thick blood smears are more sensitive in detecting malaria parasites
because the blood is more concentrated allowing for a greater volume
of blood to be examined; however, thick smears are more difficult to
read.
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37. Blood collected with sterile technique
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38. Making of Thick smear
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39. Microscopy
• Malaria parasites can be identified by
examining under the microscope a
drop of the patient's blood, spread out
as a "blood smear" on a microscope
slide.
• Prior to examination, the specimen is
stained (most often with the Giemsa
stain) to give to the parasites a
distinctive appearance.
• This technique remains the gold
standard for laboratory confirmation
of malaria
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41. QBC system has evolved as rapid and precise method
in Diagnosis
• The QBC Malaria method is the simplest and most sensitive method
for diagnosing the following diseases.
– Malaria
– Babesiosis
– Trypanosomiasis (Chagas disease, Sleeping Sickness)
– Filariasis (Elephantiasis, Loa-Loa)
– Relapsing Fever (Borreliosis)
• It involves staining of centrifuged and compressed red cell layer with
acridine orange and its examination under UV light source.
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42. Principle of QBC System
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43. Rapid Diagnostic Test (RDTs) :Antigen Detection Methods
• Various test kits are available to detect antigens
derived from malaria parasites.
• Such immunologic ("immunochromatographic")
tests most often use a dipstick or cassette format, and
provide results in 2-15 minutes.
• Antigens targeted are:
– Histidine-rich protein II (HRP II)- Produced by
trophozoites and young gametocytes of P. falciparum.
– Parasite lactate dehydrogenase (pLDH): produced by
asexual and sexual stages (gametocytes) of all 4
species.
– Aldolase (pan-specific)malarial antigen of all species.
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44. 44

45. Serology
• Serology detects antibodies against
malaria parasites, using either
indirect immunofluorescence (IFA)
or enzyme-linked immunosorbent
assay (ELISA).
• Serology does not detect current
infection but rather measures past
experience.
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46. Newer Diagnostic methods
Molecular Diagnosis
• Parasite nucleic acids are detected using
polymerase chain reaction (PCR). This
technique is more accurate than microscopy.
• However, it is expensive, and requires a
specialized laboratory and technician.
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47. Other Laboratory Findings
• Normocytic anemia of variable severity.
• CBC: Leukopenia, Thrombocytopenia, Eosinophilia
– Increased ESR
• Liver function tests may be abnormal.
• Presence of protein in the Urine of children with P. malariae is
suggestive of Quartan nephrosis.
• In severe Falciparum malaria with renal damage may cause oliguria
and appearance of protein, and red cells in the Urine.
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48. Treatment:
• Chloroquine was the drug of choice.
• Quinine being the most reliable
alternative.
• Tetracycline and clindamycin used as
an adjunct to quinine therapy.
• Mefloquine and halofantrine active
against chloroquine resistant strains.
• Primaquine used for eliminating
exoerythrocytic parasites in liver.
• In patient with G6PD deficiency,
Primaquine may precipitate
haemolysis.
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49. Prophylaxis
• Elimination of mosquito breeding sites.
– Spraying insecticides, petroleum oils in the breeding
sites.
– Using larvivorous fish and bacterium, Bacillus
thuringiensis var. israelensis, in breeding places.
• Protection of individuals.
– Wearing long sleeved clothing and trousers after
sunset.
– Using bed nets impregnated with pyrethroids.
– Application of mosquito repellents containing
diethyltoluamide to skin.
– Early diagnosis and prompt treatment.
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50. Vaccine:
• No effective malarial vaccine is yet available.
• Vaccines under research:
– Anti-sporozoite vaccines: aimed to prevent entry of sporozoites in
liver cell by blocking the invasion.
– Vaccines against asexual forms of parasite in blood- surface
antigen of trophozoites and schizonts have been characterised and
cloned.
– Antigametocyte vaccine: Antigametocyte antibody might control
transmission and fertilization of parasite in vector.
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