malaria notes

1. MALARIA
MC 3 LESSON 12

2. Laveran

5. 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. In the
Philippines there were 3,157 cases in
2022.

7. The malaria life cycle is a complex system with both sexual and asexual aspects.
There is an exogenous sexual phase in the mosquito called sporogony during
which the parasite multiplies. There is also an endogenous asexual phase that
takes place in the vertebrate or human host that is called schizogeny.

8. A complex Life
cycle

9. Human Cycle
1 Pre erythrocytic
schizogony
2 Erythrocytic
Schizogony
3 Gametogony
4 Exoerythrocytic
schizogony

10. Events in Humans start
with Bite of Mosquito
 Man – Intermediate
host.
 Mosquito – Definitive
host
– Sporozoites are
infective forms
 Present in the salivary
gland of female
anopheles mosquito
 After bite of infected
mosquito sporozoites are
introduced into blood
circulation.

11. Pre erythrocytic
cycle
 Sprozoites undergo
developmental phase in
the liver cell
 Multiple nuclear divisions
develop to Schizonts
 A Schizont contains
20,000 – 50,000
merozoites.

12. Period of Pre erythrocytic
cycle
 1 P. vivax 8 days
 2 P. falciparum – 6 days
 3 P. malariae - 13 – 16 days,
 4 P. ovale 9 days
On maturation, liver cells rupture to liberate
Merozoites into the blood stream

13. Erythrocyte
cycle
 Merozoites released invade red cells
 P. vivax infects young erythrocytes
 P. malariae Infects old erythrocytes
 P. falciparum infects RBC of all ages
 The Merozoites are pear shaped and has 1-5
microns in length
 The receptors for Merozoites are on the red
cells glycoprotein

14. Erythrocytic Schizogony
 Liberated Merozoites
penetrate RBC
 Three stages occur
1. Trophozoites
2. Schizont
3. Merozoite

15. Exo-erythrocytic (tissue) phase
 P. malariae or P. falciparum sporozoites
do not form hypnozoites, develop
directly into pre-erythrocytic schizonts in
the liver
 Schizonts rupture, releasing merozoites
which invade red blood cells (RBC) in liver

16. Gametogony
 Merozoites differentiate into Male and female
gametocytes
 They develop in the red cells
 Found in the peripheral blood smears
 Microgametocyte of all species are similar in
size
 Macro gametocytes are larger in size.

17. Mosquito cycle
Sexual cycle
 Sexual cycle will be initiated in the Humans by
the formation of Gametocytes
 Develop further in the femaleAnopheles
Mosquito
 Fertilization occurs when a Microgametocyte
penetrate into Macrogametocyte
 ZYGOTE is formed matures into OOKINETE
 OOKINETE to OOCYST
 OOCYST matures with large number of
Sporozoites ( A few hundred to thousands)

18. Mosquito cycle
A definitive Host – Mosquito

20. Malaria the disease
 9-14 day
incubation period

21. Early symptoms
 The common first symptoms –
fever, headache, chills and
vomiting – usually appear 10 to 15
days after a person is infected. If
not treated promptly with effective
medicines, malaria can cause
severe illness and is often fatal.

22. Clinical Presentation
 Stage 1(cold stage)
 Chills for 15 mins to 1 hour
 Cause is due to rupture from the host red
cells escaping into Blood
 Preset with nausea, vomiting, headache
 Stage 2 (hot stage)
 Fever may reach up to 400c may last for
several hours.

23. Clinical
Malaria
 Stage 3(sweating stage)
Patient starts sweating, concludes the
episode
Cycles are frequentlyAsynchronous
Paroxysms occur every 48 – 72 hours
In P. malariae pyrexia may last for 8 hours
or more and temperature my exceed 410c

24. Malaria stages of the disease

25. More commonly, the patient presents with a
combination of the following symptoms
 Fever
 Chills
 Sweats
 Headaches
 Nausea and vomiting
 Body aches
 General malaise.

26. Periodicity can be clue in Diagnosis
and species relation
 Malaria tertiana:
48h between fevers
(P. vivax and P.
ovale)
 Malaria quartana:
72h between fevers
(P. malariae)
 Malaria tropica:
irregular high fever
(P. falciparum)

27. SEVERE COMPLICATED MALARIA
Confusion, or drowsiness with extreme weakness
(prostration).
In addition, the following may develop:
 Alteration in the level of consciousness (ranging from drowsiness to deep coma)
 Cerebral malaria (unrousable coma not attributable to any other cause in a
patient with falciparum malaria)
 Respiratory distress
 Multiple generalized convulsions (2 or more episodes within a 24 hour period)
 Shock (circulatory collapse, septicemia)
 Pulmonary edema
 Abnormal bleeding (Disseminated Intravascular coagulopathy)
 Jaundice
 Hemoglobinuria (black water fever)
 Acute renal failure - presenting as oliguria or anuria
 Severe anaemia (Hemoglobin < 5g/dl or Hematocrit < 15%)
 High fever
 Hypoglycemia (blood glucose level < 2.2.mmol/l)
defined as the detection of P. falciparum in the peripheral blood

28. Malaria the disease

29. Why Falciparum Infections
are Dangerous
 Can produce fatal complications,
1.Cerebral malaria
2.Malarial hyperpyrexia
3. Gastrointestinal disorders.
4. Algid malaria (SHOCK)
5. Black water fever can lead to death

30. Pernicious Malaria
 Is a life threatening complication in acute
falciparum malaria
 It is due to heavy parasitization
 Manifested with
1. Cerebral malaria – it presents with
hyperpyrexia, coma and paralysis. Brain is
congested
2. Algid malaria – presents with clammy
skin leading to peripheral circulatory failure.

31. Cerebral Malaria
Malignant malaria can
affect the brain and
the rest of the central
nervous system. It is
characterized by
changes in the level
of consciousness,
convulsions and
paralysis.

32. Cerebral Malaria
 Present with
Hyperpyrexia
 Can lead to Coma
 Paralysis and other
complications.
 Brain appears
congested

33. Black Water Fever
 In malignant malaria a large
number of the red blood
cells are destroyed.
Hemoglobin from the blood
cells are excreted in the
urine, which therefore is dark
and almost the color of cola

34. How long Malaria infection
can lost in Man
 Without treatment P. falciparum will terminate
in less than 1 year.
 But in P. vivax and P. ovale persist as
hypnozoites after the parasites have disppeared
from blood.
 Can produce periodic relapses upto 5 years
 In P. malariae may last for 40 years
( Called as recrudescence X relapse )

35. LABORATORY
DIAGNOSIS OF MALARIA

36. Diagnostic Tools
for Human Infections with Malaria
 Blood film examination(Microscopy)
 QBC system
 Rapid Diagnostic Tests (RDTs)
 PCR

37. Thin and Thick smear

38. 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.

40. 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)

41. Appearance of Malarial
parasite in QBC system

42. Antigen Detection Methods
are Rapid and Precise
Antigen Detection
 Various test kits are available to detect antigens
derived from malaria parasites and provide results in
2-15 minutes. These "Rapid Diagnostic Tests"
(RDTs). Rapid diagnostic tests (RDTs) are
immunochromatographic tests based on detection of
specific parasite antigens. Tests which detect
histidine-rich protein 2 (HRP2) are specific for P.
falciparum while those that detect parasite
lactate dehydrogenase (pLDH)-OptiMAL
 or aldolase have the ability to differentiate between
P.falciparum and non-P.falciparum malaria

43. 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
(even though technical advances will likely result in
field-operated PCR machines).

44. Malaria Relapses
 In P.vivax and P.ovale infections, patients
having recovered from the first episode of illness
may suffer several additional attacks
("relapses") after months or even years without
symptoms. Relapses occur because P. vivax
and P.ovale have dormant liver stage parasites
("hypnozoites") that may reactivate.

50. Prevention
Avoid mosquito bites:
Wearing long sleeves,
trousers.
Insecticide Treated Bednets
Repellent creams or sprays.