Malaria .docx

Human Malaria

malaria parasite belongs to
- phylum: apicomplexa
- class: sporozoa
- order: hemosporida
- genus: plasmodium
the genus plasmodium is classified into two subgenera
- Plasmodium
  - plasmodium vivax
  - plasmodium malariae
  - plasmodium ovale
- Laverania
  - plasmodium falciparum
plasmodium knowlesi, a parasite of long-tailed Macaque monkeys may also affect man
- Plasmodium vivax: Benign tertian malaria
  - Commonest in Sri Lanka
- Plasmodium falciparum: Malignant tertian malaria
- Plasmodium malariae: Benign quartan malaria
- Plasmodium ovale: Benign tertian malaria
Tertian malaria - get fever every other day
Quartan malaria - get fever every third day

distribution of the malaria

incidence of malaria is more in
- poor population in rural areas
- bad sanitary condition in urban area
an epidemic can develop when there are changes in environmental, economic and social conditions such as migrations and heavy rains following draughts
relative prevalence of the four species of malaria parasites varies in different geographical regions
- Plasmodium vivax
  - most widely distributed
  - being most common in Asia, North Africa, and Central and South America
- Plasmodium falciparum
  - predominant species in Africa, Papua New Guinea and Haiti
  - rapidly spreading in Southeast Asia and India
  - results in most severe disease
  - responsible for almost all malaria related deaths
- Plasmodium malariae
  - is present in most places but is rare, except in Africa
  - least severe but most persistent
- Plasmodium ovale
  - is virtually confined to West Africa
  - less prevalent ovale on
In Sri Lanka only Plasmodium vivax and Plasmodium falciparum

vectors

human malaria is transmitted by over 60 species of female anopheles mosquito
the male mosquito feeds exclusively on fruits and juices
the female needs at least two blood meals, before the first batch of eggs can be laid

life cycle of Plasmodium (plasmodium vivax)

malaria parasite passes its life cycle in two hosts
- definitive host
  - female anopheles mosquito
- intermediate host
  - man
the life cycle of malarial parasite comprises of two stages
- an asexual phase occurring in humans - intermediate host
- a sexual phase occurring in mosquito - definitive host for the parasite

asexual phase

the malaria parasite multiplies by division or splitting a process - schizogony
asexual phase occurs in man, it is also called the vertebrate, intrinsic, or endogenous phase
in humans, schizogony occurs in two locations
- in the red blood cell (erythrocytic schizogony)
- in the liver cells (exoerythrocytic schizogony or the tissue phase)
because schizogony in the liver is an essential step before the parasites can invade erythrocytes, it is called pre-erythrocytic schizogony
the products of schizogony, whether erythrocytic or exoerythrocytic, are called merozoites

human transmission

human infection comes through the bite of the infective female anopheles mosquito
the sporozoites, which are infective forms of the parasite are present in the salivary gland of the mosquito
they are injected into blood capillaries when the mosquito feeds on blood after piercing the skin
usually, 10- 15 sporozoites are injected at a time, but occasionally, many hundreds may be introduced
the sporozoites pass into the bloodstream
many are destroyed by the phagocytes, but some reach the liver and enter the parenchymal cells (hepatocytes)

pre-erythrocytic (tissue) stage or exoerythrocytic stage

within an hour of being injected into the body by the mosquito, the sporozoites reach the liver and enter the hepatocytes to initiate the stage of pre-erythrocytic schizogony or merogony
the sporozoites, which are elongated spindle-shaped bodies 🡪 rounded inside the liver cells
- they enlarge in size and undergo repeated nuclear division to form several daughter nuclei
- each of which is surrounded by cytoplasm
the hepatocyte is distended by the enlarging schizont and the liver cell nucleus is pushed to the periphery - pre-erythrocytic or exoerythrocylic schizont or meront
mature liver stage schizonts are spherical (45-60 µm), multinucleate and contain 2,000-50,000 uninucleate merozoites
unlike erythrocytic schizogony, there is no pigment in liver schizonts
these normally rupture in 6-15 days and release thousands of merozoites into the bloodstream
the merozoites infect the erythrocytes by a process of invagination

prepatent period

the interval between the entry of the sporozoites into the body and the first appearance of the parasites in blood

latent stage

in plasmodium vivax and plasmodium ovale, two kinds of sporozoites are seen, some of which multiply inside hepatic cells to form schizonts and others persist and remain dormant (resting phase)

relapse

the resting forms are called hypnozoites
from time to time, some are activated to become schizonts and release merozoites, which go on infecting RBCs producing clinical relapse

recrudescence

in plasmodium falciparum and plasmodium malariae, initial tissue phase disappears completely, and no hypnozoites are found
however, small numbers of erythrocytic parasites persist in the bloodstream
in due course of time, they multiply to reach significant numbers resulting in clinical disease (short-term relapse or recrudescence)

erythrocytic stage

the merozoites released by pre-erythrocytic schizonts invade the RBCs
- usually one merozoite invades a red cell
- plasmodium vivax prefers young RBCs
- need 48 hours to complete the cycle
the receptor for merozoites is glycophorin, which is a major glycoprotein on the red cells
the differences in the glycophorins of red cells of different species may account for the species specificity of malaria parasites
merozoites are pear-shaped bodies, about 1.5 µmin length, possessing an apical complex (rhoptery)
they attach to the erythrocytes by their apex
the merozoites lie within an intraerythrocytic parasitophorous vacuole formed by red cell membrane by a process of invagination
in the erythrocyte, the merozoite loses its internal organelles and appears as a rounded body having a vacuole in the centre with the cytoplasm pushed to the periphery and the nucleus at one pole
these young parasites are, therefore called the ringforms or young trophozoites
the parasite feeds on the haemoglobin of the erythrocyte
- it does not metabolize haemoglobin completely and therefore, leaves behind a hematin-globin pigment called the malaria pigment or hemozoin pigment, as residue
- the malaria pigment released when the parasitized cells rupture is taken up by reticuloendothelial cells
- such pigment-laden cells in the internal organs provide histological evidence of previous malaria infection
as the ring form develops, it enlarges in size becoming irregular in shape and shows ameboid motility – ameboid form or late trophozoite form

when the ameboid form reaches a certain stage of development
- its nucleus starts dividing by mitosis followed by a division of cytoplasm to become mature schizonts or meronts
a mature schizont contains 8-32 merozoites and hemozoin
the mature schizont bursts releasing the merozoites into the circulation
the merozoites invade fresh erythrocytes within which they go through the same process of development
this cycle of erythrocytic schizogony or merogony is repeated sequentially, leading to progressive increase in the parasitemia, till it is arrested by the development of host immune response
the rupture of the mature schizont releases large quantities of pyrogens
- this is responsible for the febrile paroxysms characterizing malaria

gametogony

after a few erythrocytic cycles, some of the merozoites that infect RBCs do not proceed to become trophozoites or schizonts but instead, develop into sexually differentiated forms – gametocytes
they grow in size till they almost fill the RBC, but the nucleus remains undivided
development of gametocytes generally takes place within the internal organs
- only the mature forms appear in circulation
gametocyte appears in circulation after the first appearance of asexual form
- 4-5 days in plasmodium vivax
- 10-12 days in plasmodium falciparum
a person with gametocytes in blood is a carrier or reservoir
the gametocytes do not cause any clinical illness in the host, but are essential for transmission of the infection
a gametocyte concentration of 12 or more per mm³ of blood in the human host is necessary for mosquitoes to become infected

sexual phase

female anopheles mosquito represents definitive host, in which sexual forms takes place
- sexual forms of the parasite (gametocytes) originate in human RBCs
maturation and fertilization take place in the mosquito, giving rise to a large number of sporozoites
- phase of sexual multiplication is called sporogony
- called the invertebrate, extrinsic, or exogenous phase
extrinsic incubation period
- the time taken for completion of sporogony in the mosquito is about 1-4 weeks (extrinsic incubation period), depending on the environmental temperature and the species.

mosquito cycle (sporogony)

when a female anopheles mosquito ingests parasitized erythrocytes along with its blood meal, the asexual forms of malaria parasite are digested
the gametocytes are set free in the midgut (stomach) of mosquito and undergo further development
the nuclear material and cytoplasm of the male gametocytes divides to produce eight microgametes
- long, actively motile, whip-like filaments (flagellating male gametocytes)
- the female gametocyte does not divide but undergoes a process of maturation to become the female gamete or macrogamete
- it is fertilized by one of the microgametes to produce the zygote
fertilization occurs in 0.5-2 hours after the blood meal
the zygote
- initially a motionless round body
- gradually elongates and within 18-24 hours
- becomes a vermicular motile form with an apical complex anteriorly - ookinete (travelling vermicule).
it penetrates the epithelial lining of the mosquito stomach wall and comes to lie just beneath the basement membrane
it becomes rounded into a sphere with an elastic membrane – oocyst
- multiplicatory phase, within which numerous sporozoites are formed
the mature oocyst, which may be about 500 µm in size, bulges into body cavity of mosquito and when it ruptures
the sporozoites enter into the hemocele or body cavity, from where some sporozoites move to the salivary glands
the mosquito is now infective and when it feeds on humans, the sporozoites are injected into skin capillaries to initiate human infection

sporogonic cyle

only female anopheline mosquitoes transmit human malaria
male and female gametocytes enter the mid gut with the blood meal
male gametocyte 'exflagellation' → male gametes
female gamete gets fertilized by male gamete in the mid gut of the mosquito
maturation of the oocysts depend on
- longevity of the mosquito species
- temperature and humidity of the environment

lifecycle of Plasmodium (plasmodium falciparum)

asexual phase

exo-erythrocytic stages

erythrocytic cycle

in plasmodium falciparum, erythrocytic schizogony always takes place inside the capillaries and vascular beds of internal organs
therefore, in plasmodium falciparum infections, schizonts and merozoites are usually not seen in the peripheral blood
usually one or more merozoites invades a red cell
plasmodium falciparum prefers RBCs of all ages
need 48 hours to complete the cycle

cytoplasm condenses round each of 8 to 24 nuclei
late or mature schizont erythrocytic merozoite they are sequestrated in the capillaries and venules of deep organs
the schizont ruptures at 48 hours
erythrocytic merozoites enter new RBCs in capillaries of deep organs.
the schizont ruptures at 48 hours
erythrocytic merozoites enter new RBC

gametogony

lifecycle of Plasmodium (plasmodium malariae)

asexual phase

exo-erythrocytic
- development takes a longer time

erythrocytic cycle

infected RBCs do not enlarge
Zeiman's stippling appears only with special staining
ring stage having thicker cytoplasm than in other species
trophozoite takes a characteristic 'band' form
prolonged erythrocytic cycle - 72 hours
schizonts have characteristic 'daisy head' pattern
pattern of life cycle is similar to that of plasmodium vivax with some exceptions

lifecycle of Plasmodium (plasmodium ovale)

relapse could occur following formation of hypnozoites

asexual phase

erythrocytic cycle

is similar to that of plasmodium vivax
the infected RBCs are enlarged
stippling is more intense than schuffner's dots
infected RBCs wall become weakened and may have irregular shapes

transmission of malaria

subcutaneous inoculations of sporozoites by anopheline mosquitoes
blood transfusion
through the contaminated syringes of drug addicts
congenital or trans-placental

pathophysiology and pathology of malaria

almost all severe forms of malaria are caused by infection of plasmodium falciparum
the following serious complications are rarely seen plasmodium vivax and plasmodium knowlesi
- severe anaemia
- respiratory distress
- splenic complications
- shock
- multiple organ dysfunction

activation of cytokine storm

clinical features of malaria are developed in the erythrocytic stage
both parasite and host related factors contribute to the pathogenicity of the severe forms of malaria
rupture of the parasitized RBCs (pRBCs) in each erythrocytic cycle and destruction of pRBC at high levels in the spleen
lead to
- activation of innate immunity
- release of inflammatory mediators (TNF-α, IFN-γ, IL-1, IL-6)
  - activation of cytokine storm
- symptoms associated with the malaria
clinical features of malaria are initiated mainly due to the excessive release of various cytokines
- classical malaria fever
- headache
- nausea and vomiting
- diarrhea
- anorexia
- tiredness
- aching joints and muscles
- thrombocytopenia
- immunosuppression
- changes of central nervous system

erythrocytic stage of malaria

erythrocytic stage of malaria induces changes in the
- surface of the parasitized RBCs (pRBCs) and high levels of inflammatory cytokines induces
  - endothelial activation
    - mainly on the surface of the microvasculature of vital organs
  - expression of the endothelial receptors (act as adhesion molecules)

surface of the pRBCs

as plasmodium falciparum matures it release parasite proteins to the surface of pRBC that forms “knobs”
parasite proteins of the PfEMP-1 (Plasmodium falciparum Erythrocyte Membrane Protein-1) family mainly found on the surface of these knobs

surface of the endothelium microvasculature

due to the effects of inflammatory cytokines and other cellular mediators 🡪 increased expression of some of the endothelial cell receptors
- Intra Cellular Adhesion Molecule-1 (ICAM 1)
- Endothelial Protein C Receptor (EPCR)
- CD-36
- E-selectin
- Neural Cell Adhesion Molecule (NCAM)
- CD 56 Chondroitin Sulphate (CSA) – mainly in the placenta

cytoadherence

severe malaria is mainly caused by plasmodium falciparum because of its ability to induce pRBCs cytoadherence to the vascular endothelium
pRBCs binds to the endothelial receptors of the microvasculature of the deeper organs
cytoadherence leads to sequestration of the pRBCs in the microvasculature of vital organs
- allows the maturing pRBCs to get away from the splenic clearance

sequestration

increased rigidity of both iRBCs and uninfected RBCs (increased deformability of RBCs)

rosettes

binding of pRBCs with the uninfected RBCs

agglutination

binding of pRBCs with other pRBCs

clumps

binding of pRBCs with platelets

microvasculature manifestation consequences

pathological changes occur due to above processes in the microvasculature leading to
- reduce or obstruction of blood flow
  - limits the oxygen supply 🡪 tissue anoxia
- concentration of toxins within the tissue 🡪 release of inflammatory mediators
- endothelial apoptosis
sequestration and other pathological changes occur in many internal organs including
- brain, lungs, eyes ,kidneys, heart ,GIT (liver), bone marrow , adipose tissue, skin / placenta

pathology cerebral malaria

is a complex neurological syndrome of severe falciparum malaria
- is often fatal
- presence of plasmodium falciparum in the blood slide examination
is characterized by
- altered consciousness
- seizures
- neurological defects

brain endothelium changes

obstruction of blood flow caused by
- cytoadherence
- resetting
- agglutination
- clumping
- decreased RBCs and pRBCs deformability
breakdown of the blood-brain barrier due to
- reduction of the nutritional supply and hypoxia 🡪 cell death and tissue damage
- excess activation of endothelial cells and excess releases of pro-inflammatory cytokines
blood-brain barrier breakdown followed by other secondary neuropathologic events in the brain parenchyma
damage to the blood vessels causes intracranial haemorrhage can lead to cerebral malaria

macroscopic and microscopic changes

macroscopic changes in central nervous system

brain swelling with flattened gyri and narrowed sulci
brain shows gross congestion
petechial haemorrhages found in white matter of cerebrum, brain stem and cerebellum

microscopic changes in central nervous system

capillaries are packed with parasitized RBC
ring haemorrhages – classical characteristic feature in cerebral malaria

pathology associated with blood

anaemia

problem in pregnancy & children
plasmodium vivax predominantly invades young RBC
- parasitaemia rarely exceeds 2%
plasmodium falciparum affects red cells of all ages
- parasitaemia can be high as 5-10% or more

mechanism of anaemia

multifactorial
haemolysis of pRBCs
immune and non-immune haemolysis of non-infected RBCs
increased splenic clearance of pRBC and normal RBCs
- in plasmodium falciparum – per 1 iRBC – 8 non infected RBC
- in plasmodium vivax – per 1 iRBCs - 32 non infected RBCs
decrease of RBC production in the bone marrow (dyserythropoiesis and bone marrow suppression)
reduction of red cell survival even after disappearance of parasitaemia
the red cell becomes more spherical and difficult to circulate

microscopic changes of RBCs

invasion of the malaria parasites causes extensive changes of the RBCs
- specially in plasmodium falciparum infections
these includes
- loss of the normal discoid shape
- increased rigidity of the membrane
- increased permeability to a variety of substances
- increased adhesiveness
  - most notably to endothelial surfaces

malaria thrombocytopenia

reduction of platelet count is common in both plasmodium falciparum & plasmodium vivax
- mainly in the early stage of the infection
due to
- sequestration of platelets in the spleen
- platelet destruction by macrophages
- bone marrow alterations
- antibody-mediated platelet destruction
- oxidative stress
- platelet aggregation

pathology bone marrow

bone marrow undergoes several changes including
- dyserythropoiesis – production of immature or dysfunctional RBCs
- thrombocytopenia – impaired production of platelets
- leucocytosis (acute condition)
  - high white blood cell count
- leukopenia (late stage)
  - diminished white blood cell count
- hemophagocytosis
  - histiocytes engulf red blood cells, white blood cells, platelets

macroscopic changes in bone marrow

expansion of the marrow space and reddish appearance in bone marrow
- due to an increase in RBC production / hyperplasia
in severe cases bone marrow becomes pale in appearance
- due to hypoplasia or aplasia
fatty infiltration
- in chronic, repeated severe malaria adipose tissue replaces hematopoietic cells within the marrow

microscopic changes in bone marrow

sequestration of the iRBCs within erythroid precursors and other blood cell lineages

pathology in spleen

spleen mainly involved in
- selective clearance of iRBCs and deformed RBCs
- immune activation
  - serving as a site for the proliferation and activation of immune cells (T cells, B cells, and antigen-presenting cells) in response to malaria Ags
- extramedullary haematopoiesis
  - production of RBCs outside of the bone marrow

macroscopic changes

splenomegaly
- increased immune activity
- sequestration of iRBCs and congestion of spleen blood vessels
- enlarged spleen detected during physical examinations
dark red or pale appearance of the spleen
- due to the accumulation of iRBCs and other blood cells
focal necrosis areas
- may develop and appear as pale or discoloured patches on the surface of the spleen
infarction
- tissue death due to lack of blood supply in certain parts of the spleen
- results in areas with pale of haemorrhagic discolouration

microscopic changes

sequestration of iRBCs within sinusoides with red pulp
Hemozoin deposition
- haemozoin accumulates in the macrophages mainly in red pulp
- microscopically visualized as dark brown granules at the cytoplasm of the macrophages
hyperplasia of red pulp
accumulation of the inflammatory cells - mainly in the red pulp
histopathological changes of the splenic architecture
microscopic examination may reveal the
- loss of lymphoid follicles
- fibrosis of red pulp
- changes of the marginal zone of the spleen

splenic complications

splenic complications of malaria includes
- hypersplenism (overreactive spleen)
- hyperreactive malarial syndrome
- splenic infarction
- splenic rupture

splenic rupture

rapid and significant enlargement of spleen
can rarely result in splenic rupture
is more common in primary attack and due to fibrosis, less likely happen in case of chronic malaria infections
is common in infections with plasmodium vivax but can happen in plasmodium falciparum infections

hyperreactive malarial splenomegaly / tropical splenomegaly syndrome

condition is characterized by abnormal enlargement of the spleen
- response to repeated or persistent malaria infections
- mainly found in malaria endemic countries in Africa, Asia and South America
- due to chronic / repeated stimulation by the anti-malarial immunoglobulins (IgM and other immunoglobulins) for long period

pathology in kidney

three main clinical forms are associated with malaria
- acute kidney injury
- quartan malaria nephropathy
- black water fever acute

kidney injury / renal failure

microcirculation disorders due to the
- microvasculature block
- anoxia
  - absence of oxygen
- necrosis of the glomeruli and renal tubules
mainly associated with plasmodium falciparum

quartan malaria nephropathy

found in plasmodium malariae infection
deposition of the malaria antigens and immune complex (IgM + compliment + antigens) causes
- inflammation and tissue damage
- haematuria, proteinuria, impaired renal function

black water fever/ malarial hemoglobinuria

occurs only with infection from plasmodium falciparum
dark red/black urine
- due to the presence of large amounts of haemoglobin
- rapid severe haemolysis, jaundice, haemoglobinuria and anuria (absence of urine)🡪 lead to death

pathology of the lungs / pulmonary

found in plasmodium falciparum infection mainly
lung involvement in malaria is less common compared to other complications
dysfunction of the endothelial blood vessels (due to obstruction and inflammation) leads to
- vascular permeability 🡪 leakage of fluid and proteins into lung tissue and alveolar space
severe malaria
- pulmonary oedema
- acute respiratory distress syndrome
  - diffuse alveolar damage
  - impaired gas exchange
  - respiratory failure 🡪 hypoxemia and respiratory compromise

placental complications in malaria

malaria during pregnancy is associated to high morbidity and mortality both in mother and the child
- pregnant women more susceptible to malaria
- more frequent in first pregnancy
iRBCs mainly bind with the chondroitin sulphate A (CSA) and also with hyaluronic acid (HA)
- expressed in the placenta
iRBcs are found in large numbers in the intervillous space
- parasite can avoid maternal immune response when iRBCs located in the placenta
monocyte and macrophages infiltrates to intervillous space and induces releasing of inflammatory cytokines
increased inflammatory responses result into oxidative stress induced placental cell death
severe malaria in pregnant women especially in first pregnancy
- IUGR (Intrauterine growth restriction), LBW (low birth weight) in infants
- miscarriage and still birth
primigravidae are more susceptible to malaria than multigravidae
- resistance to the malarial infection in multigravidae is due to the development of placental parasite-specific immunity in second and third pregnancies

clinical features of malaria

malaria has a variety of clinical presentations
- acute
  - uncomplicated malaria
  - malaria in children
  - malaria in pregnancy
  - complicated severe malaria
  - mixed infection
  - relapses
- chronic
clinical presentation depends on
- species of the parasite
- immunity of the host
time period from sporozoites inoculation to appearance of the first symptom

falciparum malaria

Plasmodium falciparum: Malignant tertian malaria
Tertian malaria - get fever every other day
tertian fever pattern is hardly seen
leads to severe complications
- cerebral malaria
- severe anaemia
- renal failure
- acute respiratory distress syndrome (ARDS)
- acidosis
- hypoglycaemia

vivax malaria

Plasmodium vivax: Benign tertian malaria
Tertian malaria - get fever every other day
is absent in Duffy blood group negative people
- Duffy antigens act as receptors for chemokines and attract immune system cells
- Duffy antigens also act as receptors for the Plasmodium species
- Duffy negative individuals whose erythrocytes do not express the receptor are believed to be resistant to merozoite invasion
incubation period longer
relapses present
tertian fever pattern is frequent
severe disease is uncommon

ovale malaria

Plasmodium ovale: Benign tertian malaria
Quartan malaria - get fever every third day
infection occurs in Africa
overlying plasmodium vivax areas
is absent in duffy blood group negatives
clinically similar to plasmodium vivax
incubation period is relatively long
early phase is absent or unrecognized
relapses are present
low parasitaemia - difficult diagnosis

malariae malaria

Plasmodium malariae: Benign quartan malaria
Quartan malaria - get fever every third day
least aggressive of all forms of malaria
early phase very mild renal involvement—mostly in children

uncomplicated malaria

malaria fever presentation

comes on with the rupture of erythrocytic schizonts
malaria fever stages
- cold stage
- hot stage
- sweating stage

cold stage

febrile episode
- starts with shaking chills (chills & rigor)
usually at mid-day (between 11 a.m. to 12 noon)
lasts for 15 minutes - 1 hour

hot stage

cold stage symptoms followed by high grade fever and rigors
- temperature exceeds 39 degrees
lasts 2 - 6 hours

sweating stage

hot stage symptoms followed by profuse sweating fever gradually subsides over 2-6 hours

atypical malaria fever presentation

atypical presentation is common among
- people of endemic zone
- immuno-compromised people
- extremes of age
- pregnancy
- early infection
- plasmodium falciparum infection

malaria in children

infant

severe falciparum malaria is rare
- if it occurs with infancy the mortality is very high

1-3 years

severe malaria is common among this group

older children

severe disease is rarely seen

malaria in pregnancy

primigravidae (a woman who conceives for the first time)
- develops severe falciparum malaria
multigravidae (woman that is or has been pregnant for at least a second time)
- develops severe vivax malaria
in a low endemic area
- malaria affects birth weight of first three pregnancies
- can develop symptoms in 2nd and 3rd trimesters
in a high endemic area
- usually asymptomatic

complicated severe malaria

always caused by plasmodium falciparum
- usually due to delayed and ineffective treatment
commoner among the non-immune 1-3 year old children
plasmodium vivax can cause splenic rupture rarely
plasmodium malariae can cause fatal nephrotic syndrome

features of complicated severe malaria

cerebral malaria (coma for > 30 minutes)
severe anaemia (Hb< 40mg / 2.2mmol /dl)
circulatory collapse (SBP < 50 - 1 to 5 yrs & SBP < 70 - >5 yrs)
spontaneous bleeding – disseminated intravascular coagulation
acidosis (rapid breathing with clear lungs)
macroscopic haemoglobinuria – blackwater fever

complicated severe malaria clinical symptoms

cerebral malaria clinical symptoms

is the most prominent feature of falciparum malaria

clinical symptoms

coma
altered consciousness or no loss of consciousness (sometimes)
symmetrical encephalopathy
five distinct fundoscopic abnormalities
- retinal whitening
- retinal haemorrhages
- focal whitening of vessels
- papilledema
- cotton wool spots

poor prognostic signs of cerebral malaria

deep coma convulsions
opisthotonus position

respiratory distress
hyper-parasitaemia
hypoglycaemia
severe anaemia

anaemia clinical features

pallor

acute respiratory distress clinical features

metabolic acidosis clinical features

hypotension
hyperventilation

blackwater fever clinical features

severe anaemia
slate – grey appearance
dark – brown – red urine

acute pulmonary oedema clinical features

tachypnoea
high fever
reduced air
crepitations and ronchi lung sounds
interstitial shadowing - X ray

algid malaria clinical features

algid maria
- prostration, cold and clammy skin, and low blood pressure

hypoglycaemia clinical features

deterioration of coma
sweating

chronic malaria

hepatosplenomegaly (tropical splenomegaly syndrome (TSS))
nephrotic syndrome – plasmodium malariae

severe malaria in children and adults

management of malaria

ministry of health 2008 circular

ministry of health 2014 circular

ministry of health 2023 circular

management of malaria

history taking & clinical examination (signs & symptoms)
- travel history with duration
- past history of malaria
- taken antimalaria before
- any recent blood transfusions
- any close contact members with malaria
laboratory diagnosis
- parasitological
- immunological
  - rapid diagnostic tests
  - ELISA based tests
empirical chemotherapy
- indications
  - severe morbidity with high suspicion
  - absence of laboratory facilities with high suspicion
- procedure
  - collect a blood smear
  - full course of treatment for vivax infection
after confirmation of malaria
- - plasmodium vivax infection
    - clinical cure – getting rid of symptoms (fever)
    - radical cure ((due to hypnocytes) clinical relapse)
  - plasmodium falciparum infection
    - clinical cure
    - transmission blocking - getting rid of gametocytes

anti-malarial drugs

clinical cure in patients
prevention of relapses in plasmodium vivax & plasmodium ovale
prevent transmission
prophylaxis (prevention)

anti-malarial drugs history

assess previous treatment with anti-malarial
previous history of adverse reactions to anti-malarial
identify early and late treatment failures

CURRENT REGULATIONS / REMOVED REGULATIONS

ACT (Coartem®) tropic

indications

plasmodium falciparum infection

contradictions

pregnant mothers - first trimester
children weight <5kg (2014 circular)
lactating mothers (2014 circular)

plasmodium vivax infection

uncomplicated children weight <5kg

chemotherapy starts after 1 year of age

clinical cure

oral 25 mg/kg chloroquine base over three days

radical cure

oral 0.75 mg/kg primaquine base daily over a period of 7 days (2023 circular)
oral 0.25 mg/kg primaquine base daily over a period of 14 days (2014 circular)

uncomplicated pregnant mother (T1/T2/T3)

chemotherapy starts 6 weeks after delivery

clinical cure

oral 25 mg/kg chloroquine base over three days

radical cure

oral 0.75 mg/kg primaquine base daily over a period of 7 days (2023 circular)
oral 0.25 mg/kg primaquine base daily over a period of 14 days (2014 circular)

uncomplicated lactating mother

chemotherapy starts after exclusive breast feeding (4-6 months)

clinical cure

oral 25 mg/kg chloroquine base over three days

radical cure

oral 0.75 mg/kg primaquine base daily over a period of 7 days (2023 circular)
oral 0.25 mg/kg primaquine base daily over a period of 14 days (2014 circular)

uncomplicated others

chemotherapy starts after completion of chloroquine therapy

clinical cure

oral 25 mg/kg chloroquine base over three days

radical cure

oral 0.75 mg/kg primaquine base daily over a period of 7 days (2023 circular)
oral 0.25 mg/kg primaquine base daily over a period of 14 days (2014 circular)

uncomplicated G6PD deficiency

chemotherapy starts after completion of chloroquine therapy
administration is done under special supervision

clinical cure

oral 25 mg/kg chloroquine base over three days

radical cure

oral 0.75 mg/kg primaquine base weekly over a period of 8 weeks

plasmodium falciparum infection

uncomplicated pregnant mother (T1)

clinical cure

oral 10 mg/kg quinine dihydrochloride 8 hourly for 7 days + clindamycin for 7 days (2014 circular)

transmission blocking

no primaquine therapy
achieved via obstructing patient-vector contact

uncomplicated pregnant mother (T2/T3)

clinical cure

oral weight adjusted dose of artemisinin-based combination therapy (ACT) over 3 days

transmission blocking

no primaquine therapy
achieved via obstructing patient-vector contact

uncomplicated lactating mother – exclusive breast feeding

clinical cure

artemisinin-based combination therapy (ACT)

transmission blocking

no primaquine therapy
achieved via obstructing patient-vector contact

uncomplicated others

clinical cure

oral weight adjusted dose of artemisinin-based combination therapy (ACT) over 3 days

transmission blocking

0.75 mg/kg primaquine single dose after ACT
achieved via obstruct patient-vector contact

severe infection

clinical cure

intravenous artesunate 2.4mg/kg at 12 and 24 hours
- if not available parenteral quinine
parenteral treatment for a minimum of 24 hours, then a full course of ACT

transmission blocking

0.75 mg/kg primaquine single dose after ACT
achieved via obstruct patient-vector contact

severe infection in pregnancy

clinical cure

1st trimester - parenteral quinine and then oral quinine for a total of 7 days
2nd and 3rd trimester – parenteral artesunate/quinine and later ACT

transmission blocking

no primaquine therapy
achieved via obstruct patient-vector contact

plasmodium vivax infection & plasmodium falciparum infection

uncomplicated mixed infection

clinical cure

oral weight adjusted dose of artemisinin-based combination therapy (ACT) over 3 days

transmission blocking

oral 0.75 mg/kg primaquine base daily over a period of 7 days (2023 circular)
oral 0.25 mg/kg primaquine base daily over a period of 14 days (2014 circular)

follow-up - warded patients

daily blood smears for 3 days
if parasitaemia persists more daily films
Anti-Malarial Campaign and their field staff will follow up for one year period

chemoprophylaxis for malaria

chemoprophylaxis is not needed for
- visitors to Sri Lanka
- anyone living within the country including pregnant women
chemoprophylaxis is recommended for
- travellers to malaria endemic countries
- contact Anti-Malarial Campaign if travelling to such countries
Chloroquine
- recommended for Plasmodium vivax risk countries only
Hydroxychloroquine
- recommended for Plasmodium vivax risk countries only
Mefloquine
- recommended for Plasmodium falciparum risk and Chloroquine resistant Plasmodium vivax risk countries
Atovaquone– Proguanil combination tablet
- recommended for Plasmodium falciparum risk and Chloroquine resistant Plasmodium vivax risk countries
Doxycycline
- recommended for Plasmodium falciparum risk and Chloroquine resistant Plasmodium vivax risk countries

Laboratory Diagnosis of Malaria

clinic-epidemiological diagnosis

element in the clinical diagnosis of malaria, in both endemic and non-endemic areas
- have a high index of suspicion
- visit to a malaria endemic area?
- history of malaria
- blood transfusions

malaria differential diagnosis

malaria suspicion

laboratory investigation – parasitological

the two most widely used methods in diagnosis of malaria are
- demonstration of malaria parasite in suspected patients’ peripheral blood
  - Thin or Thick blood film screening
- demonstration of malaria antigens in patients’ blood
  - Rapid Diagnostic Test (RDT)
- if there is a strong clinical suspicion of malaria, and the blood smears / RDT are negative at the time of initial testing, a minimum of three consecutive blood smears / RDTs should be done before concluding that the patient is negative for malaria
- if there is a strong clinical suspicion of malaria, and the blood smears / RDT are positive at the time of initial testing the patient is positive for malaria
mandatory prior to start anti-malarial treatment

DO NOT TREAT MALARIA BASED ON CLINICAL SUSPICION. LABORATORY CONFIRMATION IS A MUST

demonstration of malaria parasite in blood films

blood obtained by pricking a finger or earlobe is the ideal sample
density of developed trophozoite or schizonts are greater in blood from these capillary-rich area
microscopy remains the gold standard method for
- diagnosis
- identification of parasite species
- estimation of parasite density
ideal time to collect blood sample
- venous blood
- cord blood
- blood from donor pack
- after peak of fever

thick blood film

mainly use to find the parasite present or not
provides enhanced sensitivity of the blood film
used in detection of low levels of parasitaemia
high RBC , high sensitivity
RBC destroyed in thick blood

thin blood smear

RBC not destroyed in thin blood
mainly use to confirm the different plasmodium species present
used for morphological / stage identification of the parasite species
- provides higher specificity than thick film
low RBC, low sensitivity
can use to monitor the treatment response and detect drug resistance
estimation of parasitaemia is possible

blood film examination advantages and disadvantages

false negatives due to low parasitemia
false negatives due to low skill in lab researcher (not identifying the parasite)

plasmodium parasite under microscope

rapid diagnostics tests

RDTs detect the parasite specific antigens circulating in blood stream
RDTs are based on the immunochromatographic lateral flow-strip technology
several commercial test kits are currently available developed in different test formats
- dipstick, card, cassette
RDTs
- highly specific
- no false positives - minimal cross reaction

parasite antigens mainly used in commercial RDTs

Histidine-rich protein 2 (HRP-2)
Parasite lactase dehydrogenase (pLDH)
- found in all 4 human malaria parasites (PAN malaria antigen)
Aldolase
- all 4 human malaria parasites (PAN malaria antigen)

Histidine-rich protein 2 (HRP-2)

unique to plasmodium falciparum
produce by trophozoites and young gametocytes of plasmodium falciparum
- is a water-soluble Ag and found in circulating peripheral blood
results will be given even the iRBCs are sequestrated
may remain in the blood at least 28 days after the initiation of antimalarial therapy
- can give false positive even after parasite cleared from the blood
certain plasmodium falciparum strains may not have the HRP2 antigens

Parasite lactase dehydrogenase (pLDH)

produced by asexual and sexual stages of all 4 human malaria parasites
different isomers of pLDH for each of the 4 species exist
pLDH is produced only by live plasmodium parasites
- test can differentiate untreated from treated malaria
commercial RDTs use
pLDH specific for plasmodium falciparum
pLDH specific for plasmodium vivax
pLDH common for all human malaria parasites - pan LDH

plasmodium aldolase

aldolase is an enzyme of the parasite glycolytic pathway
it is expressed by the blood stages of all four human malaria parasites (PAN malaria antigen)
commercial RDTs use Plasmodium aldolase (PAN malaria antigen) with PfHRP2

Three band RDTs

interpretation of care stat malaria RDT results

mode of action of common RDTs

card & cassette / dipstick

molecular diagnostic methods

use of molecular test for malaria is use primarily for research purposes of epidemiological studies
it is limited for certain reference laboratories
based on the detection of the parasite nucleic acid - PCR
- highly sensitive
- very effective in diagnosis of mix infections at low parasite densities that are not detectable by conventional microscopy or even RDT

Malaria Epidemiology

plasmodium species

plasmodium falciparum
- responsible for almost all severe and complicated malaria cases
- > 98% mortality due to malaria
- most prevalent in Africa
plasmodium vivax
- most widespread human malaria parasite outside Africa
plasmodium ovale
- morphologically much similar to plasmodium vivax
- mainly confined to Africa
- causes a relatively mild, low-grade, infection
- it is commonly present in mixed species infections
plasmodium malariae
- least severe infection with longer asymptomatic period
plasmodium knowiesi
- infections should be treated aggressively as those infected with falciparum malaria
- plasmodium knowlesi may cause fatal disease

transmission of malaria

primarily transmitted by the bite of an infected female anopheles mosquito
- by subcutaneous inoculation of sporozoites
congenital
blood transfusion
through contaminated syringes of drug addicts

populations at risk

infants,childrenunder5years of age
pregnant women - specially primigravids
patients with HIV/AIDS
non-immune migrants to malaria endemic areas
travellers to malaria endemic areas

when to suspect malaria

malaria in Sri Lanka

malaria was moderately endemic in dry and intermediate zones (2/3 land areas) of the country
plasmodium vivax and plasmodium falciparum was the most predominant species recorded in Sri Lanka
vectors in Sri Lanka
- anopheles culicifacies - principal vector
- anopheles subpictus
- anopheles annularis
- anopheles varuna
anti malari campaign was established in 1911
malaria was declared as a notifiable disease in 1961
Dichlorodiphenyltrichloroethane (DDT) insecticide was introduced in Sri Lanka in 1945 as an indoor residual insecticidal spray
Sri Lanka started malaria eradication program in 1958
Since October 2012 no indigenous / Iocally transmitted malaria cases were reported from Sri Lanka
Sri Lanaka eliminated malaria in 2016