2. BY Dr. Hala Ahmed El Nahas Professor of Medical Parasitology,
Malaria BY
Dr. Hala Ahmed El Nahas
Professor of Medical Parasitology,

3. OUTCOMES:
1. Classification (Species) of Malaria Parasites. 2. Geographical Distribution of Malaria. 3. Biology and Life Cycle of Plasmodia parasites. 4. Differentiation Between Erythrocytic Forms of Plasmodia.

4. Phylum Apicomplexa Plasmodium species
Disease: Malaria, tropical fever .
Species: Human malaria is caused by 4 species of Plasmodia include:
Plasmodium vivax producing benign tertian malaria.
Plasmodium ovale producing ovale tertian malaria.
Plasmodium malariae producing benign quartan malaria.
Plasmodium falciparum producing tertian or subtertian malignant malaria.

5. Malaria Distribution

6. Geographical distribution:
P. vivax The most widely distributed species found in tropical, subtropical and temperate areas.
P. oval West Africa, India and Far East.
P. malariae tropical Africa, India and Far East.
P. falciparum tropics and Far East.
Hosts:
Definitive host: female Anopheles mosquito.
Intermediate host: man (schizogony cycle).
Reservoir host: No, except chimpanzee in P. malariae.

7. Habitat:
In mosquito: gut, salivary glands.
- In man: Intracellular location inside:
a- Parenchymal liver cells  Pre-erythrocytic cycle.
b- R.B.Cs Eryhrocytic cycle and gametocytes.
Life cycle:
Is heteroxenous where there is alternation of generation between man and female Anopheles.

8. I- In Man (I.H) asexual cycle:
a) Pre-erythrocytic cycle (exo-erythrocytic):
Sporozoites (infective stage) are inoculated during mosquito bites blood stream  1/2 hour invade the liver parenchyma cells i hypnozoites
ii trophozoites schizonts  thousands of merozoites.
b) Erythrocytic cycle (inside R.B.Cs):
Merozoites (from liver cells enter R.B.Cs ring forms  (48-72h) trophozoites schizonts  rupture merozoites  re-enter R.B.Cs
c) Gametocyte formation (inside R.B.Cs):
After some repeated cycles of asexual multiplication:
Merozoites i microgametocytes
ii macrogametocytes

9. Malaria.flv

10. II- In mosquito (gametogony, sporogony cycle or sexual multiplication):
Mosquito bite of infected person  ingestion of all blood forms  digestion of all except gametocytes.
- Macrogametocyte Macrogamete (♀)
- Microgametocyte exflagellation  6-8 Microgametes (♂)
 both ♂ & ♀ gamete fusion zygote.
Zygote ookinete  enter between epithelium and basement membrane of the stomach of mosquito  oocyst  sporocyst  rupture & release thousands of sporozoites (infective stages)  salivary gland of the mosquito  infect man during the bite act.
The cycle take days in mosquito.
Transmission of parasite by mosquito is cyclopropagative.

11. Malaria Life Cycle of Plasmodium.flv

13. Methods of infection:
1. Bite of infected female Anopheles. 2. Blood-borne transmission : a. Blood transfusion. b. Intravenous injections by needles contaminated with infected blood (drug addicts). c. Trans-placental or congenital transmission. d. Through organ transplantation.

14. Differentiation between human Plasmodia
a- Exo erythrocytic cycle
Difference
P. vivax
P. ovale
P. malariae
P. falciparum
Maturation
8 days
9 days
15 days
6 days
No. of merozoites
10.000
15.000
2000
30.000
Hypnozoites
Present
Absent

15. b- Erythrocytic cycle (infected R.B.Cs)
Difference
P. vivax
P. ovale
P. malariae
P. falciparum
Type of RBC affected
Reticulocytes
(young cells)
Young cells
Old & mature
All types
Size & shape
Enlarged, pale
Oval slightly enlarged, ragged ends
Normal or small
Normal size, knobbed RBCs
Pigments
(stippling)
Fine, Pink, rounded, (Schuffner's dots)
Numerous (Schuffner's dots)
Fine, pink (Ziemann's dots)
Irregular red clefts (Maurer's dots)
No. of affected cells
Moderate
Low
Very high
Rupture
48 hrs
72 hrs
Irregular

16. C- Erythrocytic cycle (parasite) 1- Ring stage:
Differences
P. vivax
P. ovale
P. malariae
P. falciparum
-No. inside RBCs
-Size of parasite
-Shape
-One
-1/3 RBC
-Thin cytoplasmic rim
-Fine chromatin dot
1/3 RBC
-Thin rim
-Large nucleus
-As P. vivax but more regular
-May be multiple
1/6 RBC
-May be double chromatin
-Accole form

17. 2- Trophozoite stage: Differences P. vivax P. ovale P. malariae
P. falciparum
-Movement
-Shape
-Pigment
-Presence in peripheral blood
-Very active
-Amoeboid
-Yellowish brown haemozoin granules
-Present
-Sluggish
Amoeboid
-The same but appear early
-Less active
May be Band shape
-Dark brown or black
-Less active than P. vivax
-Dark brown or black coarse pigments
-Absent

18. 3- Schizont stage: Differences P. vivax P. ovale P. malariae
P. falciparum
Maturation time
-No of merozoites
-Shape
-Pigment
-Presence in peripheral blood
48 hrs
12-24
average 16
-large fill cell
-rounded merozoites
-Yellowish brown
-Present
4-12
average 8
-1/2 cell size
-oval
-Dark brown
76 hrs
6-12
-Rosette around pigments
-Coarse Dark brown
36-48 hrs
8-36
-Compact, less symmetrical
-Dark pigments
-Absent

19. 4- Gametocytes stage: Diff. P. vivax P. ovale P. malariae
P. falciparum
Male
female
-To
mature
-Small, pale blue nucleus diffuse ½ size of parasite-Coarse pigment
Large, fill cell, bright blue- dark compact nucleus diffuse pigments
14 days
-Blue cytoplasm large nucleus pigments in rings
-Purplish cytoplasm small nucleus at one side
3 weeks
-Grayish cytoplasm large nucleus diffuse pigments
-Appear as uninucleate asexual stage
2 weeks
-Crescent, blunt ends, diffuse nucleus 1/2 size, pigments around nucleus
-Longer, slender, pointed ends, compact
darker nucleus
10 days

20. P. falciparum ring & gametocytes stages.

21. Notes: 1- Exflagellation:
Is a process in which the ingested male microgametocyte in mosquito stomach
 undergoes division of its chromatin dot into 6-8 nuclei that migrate to the periphery of the parasite
they form whip like actively motile filaments
they detach from parent cell forming individual microgamete (uninuclear microgamete)
that fuse later with female macrogamete forming the zygote.

22. 2- The entrance of merozoites into R.B.Cs:
It involves:
proper orientation of anterior end of merozoite & exposing special organelles to the red cell surface
recognition of a specific receptor site on the red cell which differ by the type of plasmodia
e.g. In P. vivax: Duffy blood group antigen,
When this antigen is lacking as in most African Negroes the parasite can’t enter the red blood cell resistance to P. vivax infection.

23. 3- Relapse:
In P. vivax and P. ovale, some of the exo-erythrocytic forms (called Hypnozoites) remain in dormant state  then resume their development later causing the relapse. Not present in P. malariae or P. falciparum.
So Relapse is : recurrence of the disease after complete initial clearance of erythrocytic forms due to reinvasion of blood by hypnozoites coming from exo-erythrocytic stages.
4- Recrudescence:
- It means recurrence of symptoms after apparent clinical cure, due to the persistence of low level of parasitaemia. It occur in all types of malaria especially P. malariae can live in blood up to 30 years.

24. 5- Absence of trophozoites & schizonts of P
5- Absence of trophozoites & schizonts of P. falciparum from peripheral blood:
Trophozoites produce specific protein inserted in plasma membrane of RBCs  leading to appearance of electron dense Knobs at the RBCs surface.
Focal junctions between these knobs and endothelial lining of capillaries sequestration of infected RBCs along the vascular endothelium of deep tissues (as brain, spleen).
Gametocytes does not form this protein No knobs RBCs with gametocytes not sequestered.
So in P. falciparum only RBCs containing ring stages & gametocytes are seen in peripheral circulation.

25. Pathogenesis of malaria:
The major clinical symptoms are attributed to:
I- Anaemia and tissue anoxia due to massive destruction of erythrocytes.
II- Host-inflammatory response as an immune response of the host to librated parasite metabolites and pigments.

26. III- Additional factors associated with P. falciparum:
- Sequestration of infected R.B.Cs in deep vessels &
ability of the parasite to infect all types of erythrocytes
 functional and actual tissue anoxia which result in:
1- Brain oedema and congestion (cerebral malaria).
2- Pulmonary oedema
3- Cardiac oedema
4- Acute renal failure & tubular necrosis
Massive intravascular haemolysis  dark black urine (Black Water Fever).
5- Adrenal & retinal haemorrhage.
6- Spontaneous abortion.
7- Dysenteric malaria.
8- Hyponatraemia, hypovolaemia, hypoglycemia & ↑ capillary permeability.

27. Clinical picture: 1- Incubation period:
- It is the time between sporozoite infection and appearance of symptoms (1st paroxysm).
- It represent the duration of exo-erythrocytic cycle.
- The patient may feel malaise, muscle pain, headache, loss of appetite and slight fever.
2- Malarial Paroxysm:
- It happens with maturation of schizont form & rupture of R.B.Cs releasing merozoites.
- It may be synchronous or not.
P. vivax
P. ovale
P. malariae
P. falciparum
8 days
9 days
15 days
6 days

28. The Paroxysm consist of:
a- Cold stage: due to activation of hypothalamus  shivering & cyanosis. It takes 1/2 -1 hour, followed by:
b- Hot stage: fever, flushing, intense nausea, vomiting and headache, it takes 4-6 hours.
c- Sweating stage: ↓ temperature, profuse sweating, relief of symptoms, it takes 2-3 hours.
- The paroxysms are repeated regularly according to the type of malaria.
Every 48 hours (third day) in P. vivax & P. ovale (tertian malaria).
Every 72 hours (fourth day) in P. malariae (quartan malaria).
Every hours or irregular in P. falciparum (sub-tertian)
- The patient feels exhausted (or quite well) in the period between paroxysms.

29. Diagnosis: I) Clinical diagnosis: II) Laboratory diagnosis:
Clinical picture represents typical malarial paroxysm or history of travel to or residence in a malarious area.
II) Laboratory diagnosis:
a- Direct:
1- Thin and thick Giemsa stained blood films reveal the presence of erythrocytic stages.
**in all types of malaria, all stages of the parasite could be detected in peripheral blood except in P. falciparum, only rings & gametocytes are seen.

30. 2- Provocative test
In chronic malaria, the parasite may not be seen in peripheral blood, so we use this test to stimulate deep organs to squeeze their blood contents to the peripheral circulation By: injection of TAB vaccine
- injection of milk cold showers
- injection of 0.5 ml of 1/1000 adrenaline subcutaneous (Ascole’s test) contraction of spleen blood contents pass to the peripheral circulation.
B- Indirect:
- Serological tests: as IHA, IEP and IFA.
- PCR.
- Therapeutic test: the non- subsidence of symptoms after administration of an antimalarial drug for 3 days means that the case is not malaria.

31. Control of malaria: 1- Mass treatment of cases. 2- Mosquito control.
3- Protection from mosquito bite.
4- Chemoprophylaxis.
5- Vaccination.

33. Thank You