2. Malaria is a major public health
problem in warm climates especially
in developing countries.
It is a leading cause of disease and
death among children under five
years, pregnant women and non-
immune travellers/immigrants.
Malaria
3. Name means “bad air”-
A life-threatening parasitic disease
40% of the world’s population is at risk
90% of the deaths due to Malaria occur in Sub-
Sahara Africa, mostly among young children.
Around 400-900 million people are affected
At least 2.7 million deaths annually.
4. What is malaria ?
Malaria is a disease caused by the protozoan parasites of the genus Plasmodium.
The 4 species that commonly infect man are:
Consists of 4 species:
P. vivax
P. falciparum
P. malariae
P. ovale
• Plasmodium parasites are highly specific with female Anopheles
mosquitoes
6. Landmarks in the evolution of Malaria
• 1880 – Laveran identified the malarial parasite in
an unstained smear
• 1885 – Golgi described the blood stage
(erythrocytic schizogony) of malarial parasite –
Golgi cycle
• 1898 – Amigo & Grassi described the life cycle
• 1891 – Romanowsky introduced the staining
method
• 1897 – Ronald Ross while in Calcutta, India,
demonstrated Anopheles sp. of mosquitoes as
vectors of malaria.
Got Nobel prize for his work in 1902
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Transmission & Life Cycle
Definitive host Female Anopheles mosquito
Intermediate host Man
Infective form Sporozoites
Portal of entry Skin
Mode of transmission Bite of an infected mosquito
Site of localization First in liver cells & then in
RBCs
8. Malaria parasites are transmitted from one
person to another by the bite of a female
anopheles mosquito.
The female mosquito bites during dusk and dawn
and needs a blood meal to feed her eggs.
Male mosquitoes do not transmit malaria as they
feed on plant juices and not blood.
There are about 60 species of anopheles are able
to transmit malaria.
Like all mosquitoes, anopheles breed in water -
hence accumulation of water favours the spread
of the disease.
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Clinical Features
• Series of febrile paroxysms – fever is caused
by the release of merozoites & toxins from
ruptured erythrocytic schizont which in turn
causes the release of cytokines.
Quartan malaria – every 72 hrs
Tertian malaria - every 48 hrs
* each paroxysm has 3 stages - cold stage
(rigors), hot stage (high temp., body & joint
pains, vomiting & diarrhoea) and
perspiration stage (fall in temp.)
13. Erythrocytic schizogony is the
time taken for trophozoites to
mature into merozoites before
release when the cell ruptures.
It is shortest in P. falciparum (36
hours), intermediate in P. vivax
and P. ovale (48 hours) and
longest in P. malariae (76
hours).
Note how the frequency of spikes of fever differ according
to the Plasmodium species. In practice, spikes of fever in
P. falciparum, occur irregularly - probably because of the
presence of parasites at various stages of development.
14. o Vomiting
o Diarrhoea – more commonly seen in young children and, when vomiting also occurs, may be misdiagnosed as
viral gastroenteritis
o Convulsions – commonly seen in young children. Malaria is the leading cause of convulsions with fever in African
children.
o Pallor – resulting mainly from the lysis of red blood cells. Malaria also reduces the synthesis of red blood cells in
the bone marrow.
o Jaundice – mainly due to haemolysis.
Malaria is a multisystem disease. Other common clinical features are:
o Anorexia
o Cough
o Headache
o Malaise
o Muscle aches
o Splenomegaly
o Tender hepatomegaly
These clinical features occur in “mild” malaria. However, the infection requires urgent diagnosis and
management to prevent progression to severe disease.
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Falciparum Malaria
• Most widespread
• Accounts for 80% of malaria cases worldwide
• Most pathogenic of human malaria species
• Untreated infections - severe disease & even
death, particularly in young children, pregnant
woman & non immune adults.
16. 1. Cerebral malaria
2. Severe malaria anaemia
3. Hypoglycaemia
4. Metabolic acidosis
5. Acute renal failure
6. Pulmonary oedema
7. Circulatory collapse, shock or
“algid malaria”
8. Blackwater fever
Nearly all severe disease and the estimated >1 million deaths from malaria
are due to P. falciparum. Although severe malaria is both preventable and
treatable, it is frequently a fatal disease.
The following are 8 important severe manifestations of malaria:
Click on each severe manifestation for details
Note: It is common for an individual patient to have more than
one severe manifestation of malaria!
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Pernicious Malaria
• Def: refers to a series of phenomenon occurring
during infection with P. falciparum which, if not
effectively treated, threatens the life of the patient
with in 1 to 3 days
• In children & non immune adults, can cause coma &
death – Cerebral malaria.
• Occurs as a result of capillary blockage.
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Anaemia
• Can be severe & occur rapidly, particularly in
young children
• Occurs due to destruction of parasitised RBCs
– phagocytosis & destruction in the spleen
• Decreased production of RBCs in the bone
marrow.
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Black Water Fever
• Occurs in previously infected subjects
• Can also occur in non immune adults with severe
falciparum malaria, and also as a complication of
quinine therapy.
• A rare but acute condition characterised by sudden
& massive hemolysis of parasitised & non
parasitised RBCs followed by fever and
haemoglobinuria.
• Often fatal due to renal failure
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Black Water Fever
• Difficult to find the parasites
in the blood following a
hemolytic attack.
• Urine appears dark red to
brown black due to the
presence of free Hb.
• Clinical features – fever, rigor, aching pains in the loin,
icterus, bilious vomiting, circulatory collapse,
haemoglobinuria & acute renal failure.
• Treatment – Chloroquine, blood transfusion, peritoneal
dialysis in ARF.
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Recurrence of Malaria
• Two types of recurrences known in malaria:
1. Recrudescence –
– seen in P. falciparum & P. malariae
– due to persistence of blood infection (some erythrocytic
forms evade host immunity) even after clinical illness has
subsided.
– The numbers may increase later, leading to reappearance
of clinical symptoms
– Occur mostly up to one year or so but in P. malariae, it
can occur even after decades
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Recurrence of Malaria
2. Relapse
– Occurs due to a special form of parasites –
hypnozoites.
– Hypnozoites are the sporozoites that remain
dormant after infecting liver
– Activated from time to time to initiate pre
erythrocytic schizogony - Exoerythrocytic
schizogony
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Laboratory Diagnosis
• Microscopy – detecting & identifying malarial
parasites in peripheral blood films.
• Concentrating parasites in venous blood by
centrifugation when they can not be found in blood
films
• Using a rapid malaria Ag or enzyme detection test
• Other tests – Hb, PCV, Blood glucose, total WBC &
platelet count.
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Examination of Blood film
• Collection of blood
- best prepared directly from capillary
blood in EDTA bulb (used within 30
mins)
• Time of collection
- as soon as possible if malaria is
suspected before administering
antimalarials during pyrexial phase
25. Investigations
Blood Film Examination
Thick and thin blood films (or “smears”) have remained
the gold standard for the diagnosis of malaria. The
films are stained and examined by microscopy.
Thick blood film - Used for detecting malaria: a larger
volume of blood is examined allowing detection of
even low levels of parasitaemia. Also used for
determining parasite density and monitoring the
response to treatment.
Thin blood film – Gives more information about the
parasite morphology and, therefore, is used to
identify the particular infecting species of
Plasmodium.
Show Me
Show Me
26. Ring forms or trophozoites; many
red cells infected – some with more
than one parasite
Gametocytes (sexual stages); After a blood
meal, these forms will develop in the
mosquito gut
http://phil.cdc.gov/phil/quicksearch.asp
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Buffy Coat preparation
• To concentrate malarial parasite
• Centrifuge EDTA anticoagulated venous blood
in a thin bore capillary tube
• Buffy coat layer is formed between the RBCs &
the plasma.
• Break the tube & transfer buffy coat & RBCs to
a slide - make a thin smear – air dry – fix with
ethanol – stain with Giemsa.
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Quantitative Buffy Coat
• Capillary tube is coated with an anticoagulant
& Acridine orange fluorescent dye
• After centrifugation, the tube can be used for
two purpose:
1. Complete blood count
2. Identification of malarial parasite using a
fluorescence microscope.
29. Other methods of diagnosis of malaria
These are not routinely used in clinical practice. They include :
a) Antigen capture kits. Uses a dipstick and a finger prick blood
sample. Rapid test - results are available in 10-15 minutes.
Expensive and sensitivity drops with decreasing parasitaemia.
b) PCR based techniques. Detects DNA or mRNA sequences
specific to Plasmodium. Sensitivity and specificity high but test is
expensive, takes several hours and requires technical expertise.
c) Fluorescent techniques. Relatively low specificity and
sensitivity. Cannot identify the parasite species. Expensive and
requires skilled personnel.
d) Serologic tests. Based on immunofluorescence detection of
antibodies against Plasmodium species. Useful for epidemiologic
and not diagnostic purposes.
30. Parasitized RBC
• All: Plasmodium falciparum.
• Young (reticulocytes, larger rbc):
Plasmodium ovale and Plasmodium vivax.
• Old (smaller rbc): Plasmodium malariae.
31. Malaria in pregnancy
More than 45 million women (30 million in
Africa) become pregnant in malaria endemic areas each year.
Common adverse effects of malaria in pregnancy include:
• Maternal anaemia
• Stillbirths
• Premature delivery and intrauterine growth retardation result in the delivery of low
birth weight infants
The WHO now recommends intermittent preventive treatment (IPT): the administration
of anti-malarial drugs (e.g. sulphadoxine-pyrimethamine) during antenatal care
whether or not women show symptoms. IPT has been shown to substantially
reduce the risk of maternal anaemia in the mother and low birth weight in the
newborn.
Previously, chemoprophylaxis (e.g. with chloroquine) was recommended for all women
living in malaria endemic areas.
33. Treatment of Chloroquine resistant malaria
Quinine + tetracycline
or clindamycin
or Fansidar (sulfadoxine and pyrimethamine)
Malarone (paludrine/atovaquone)
Mefloquine (a quinoline methanol)
Qinghaosu (artemesinin)
34. Malaria Prevention
Mosquito avoidance - evening and night
behavior
- mosquito nets
- air conditioning
- screens
- mosquito repellants
- pyrethrin coils
Mosquito killing - destroying breeding sites
- fog spraying
- residual spraying
Plasmodium killing - chemoprophylaxis
35. Despite all these advances, malaria will likely be with
us as long as there are humans on this earth.
