Sporozoa - PLASMODIUM SPECIES LIFE CYCLE PDF

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PARASITOLOGY LECTURE NOTES SPOROZOA A. Genus Plasmodium (Include species causing malaria); these are the malarial parasites I. Important species: Plasmodium falciparum Plasmodium vivax Plasmodium malariae Plasmodium ovale  Plasmodium knowlesi – emerging Plasmodium species that can infect old world monkeys/macaques in SEA countries including the Philippines II. General characteristics (these characteristics are common to ALL Plasmodium) 1. No definite organ for locomotion 2. Arthropod –transmitted ( needs vector for transmission) VECTOR: Female Anopheles Mosquitoes  Male Anopheles is NOT capable of transmitting malaria since it is NOT blood feeder (does not take blood meals) 3. Mode of Transmission: Malarial Parasites, species under genus Plasmodium may be acquired thru SKIN INOCULATION/BITES ( this is the primary mode of transmission) OTHER MODES of TRANSMISSION: a) Blood transfusion – malaria maybe acquired thru transfusion of infected blood b) Transplacental – vertical transmission from mother to fetus 4. Requires 2 host to complete the cycle DEFINITIVE HOST: Female Anopheles INTERMEDIATE HOST: Man 5. Life cycle is consist of 2 phases/parts:  Sexual cycle also known as SPOROGONY cycle – happens in the VECTOR  Asexual cycle also known as SCHIZOGONY cycle – happens in Man  Asexual cycle in Man has 2 parts: a) Exo-erythrocytic cycle – part of the cycle that happens within LIVER/HEPATIC CELL b) Erythrocytic cycle – part of the cycle that happens within RBCs  How long is the cycle in man (asexual cycle)? the length of the cycle varies according to species Prepared by: Ma. Cristina Liwanag

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PARASITOLOGY LECTURE NOTES a) b) c) d)

Plasmodium falciparum - 36 hours Plasmodium vivax and Plasmodium ovale – 48 hours Plasmodium malariae – 72 hours Plasmodium knowlesi – 24 hours

Note: part of the asexual cycle in man is the RUPTURING of INFECTED RBC, and in the case of P. falciparum as example, rupturing of RBC happens every 36 hrs. In P. vivax rupturing happens every 48 hrs.etc)  The primary mode of transmission is thru BITES/skin inoculation, and if Malaria is acquired thru bites BOTH exo-erythrocytic and erythrocytic cycle happens in man. But if the mode of transmission is thru Blood transfusion or transplacental, there is NO exoerythrocytic cycle, in man it is only erythrocytic cycle Padaliin natin… pag kinagat ka ng infected Female anopheles, una syang pupunta sa liver/hepatic cell, part ng life cycle ang pag rupture din ng infected liver cell, matapos mag rupture ang infected liver cell, ang next naman na einfect ay RBC.

Asexual/Schizogony cycle happens in Man ( initially within liver cell, then within RBCs)  Sexual/Sporogony cycle happens in the vector 

6. Infective stage of Plasmodium spp to Man : SPOROZOITES (given by vector to man) Infective stage of Plasmodium to Vector: Gametocyte (acquired by vector from an infected host) 7. Plasmodium species are INTRAERYTHROCYTIC parasites (they infect RBCs) Plasmodium falciparum – infects RBCs of all ages (young & mature RBCs) Plasmdoium vivax and Plasmodium ovale – infect Young/Immature/juvenile RBCs example of which are the Reticulocytes Plasmodium malariae – infects Mature/older RBCs 8. When Plasmodium parasites infect RBCs they alter/change RBC size. In addition, once they are within RBCs, they consume hemoglobin so RBC stipplings may be found within infected RBCs. Effect to RBC size Prepared by: Ma. Cristina Liwanag

P. falciparum No change in rbc size

P. vivax Enlarged RBC

P. ovale Enlarged RBC

P. malariae RBC reduced in size Page 2

PARASITOLOGY LECTURE NOTES Stipplings are called

Maurer’s dots

Schuffer’s granules

James dots

Ziemann’s dots

9. All species can cause MALARIA  Paroxysm is the characteristic /unique symptom of malaria characterized by chills fever and sweating. This is the symptom regardless of malaria type.  Paroxysm happen upon rupture of every RBCs  In the case of P. falciparum, rupturing of INFECTED RBCs happens every 36 hours, so paraoxysm happen at intervals, that is every 36 hrs.. In P. vivax and P. ovale it happens every 48 hrs and in P. malariae it happens every 72 hrs Type of Malaria P. falciparum -

Causes the most SERIOUS form of malaria because this species can infect almost half of the total RBCs in the blood 90% of malaria cases is due to this species

Malignant tertian malaria / Estivo autumnal malaria

P. vivax

Benign tertian malaria

P. ovale P. malariae

Ovale malaria Quartan malaria

Rupturing of infected RBC happens Every 36 hrs

Every 48 hrs



Every 72 hrs

Black water fever – complication which may develop following P. falciparum infection. This is characterized by massive loss of hemoglobin thru the urine. ( in short, if Malignant tertian malaria is left untreated it can lead to this)

10. to detect malaria we examine the blood. We examine THICK and THIN Blood Smear With the emergence of molecular techniques like PCR, in Malaria detection Thick and Thin Blood Smear is still regarded as the GOLD STANDARD.

Thick smear = Prepared by: Ma. Cristina Liwanag

for RAPID diagnosis. To establish presence of Malaria Page 3

PARASITOLOGY LECTURE NOTES To check if blood is (+) or not to malaria Part of the smear that needs to be dehemoglobinize Thin smear = for species identification (para malaman anong species) Part of the smear that needs to be fixed.  To dehemoglobinize we use distilled water and to fix, we use alcohol  To stain the smear we use Giemsa or Wright’s  Smear must be Examined under OIO (lumalabas sa board exam ito) Diagnostic stages (these are the stages that can be noted in smears)  Gametocytes  Ring form trophozoite  Schizont  Merozoites

P. falciparum

P. vivax P. ovale

Stages seen in the gametocyte Ring form Blood trophozoite Crescent/sausage Aplique/accole Only Ring and forms Gametocytes may or banana shaped be found in the blood Amoeboid All diagnostic Round to oval stages shaped

P. malariae

Band form

# of merozoites per infected RBC 8 - 36

12-24 8, and arranged around a central block of pigment 6-12 average of 8-10. Arranged in “rosette” or “daisy” formation

Note: all in BOLD LETTERS are important.

Life Cycle of Malarial Parasites: A) ASEXUAL CYCLE – in Man Introduction of infectious sporozoite to man. Sporozoite enters hepatic cells initiating the so-called “ exo-erythrocytic cycle “. Extensive multiplication within hepatic cells follows producing Cryptozoic Schizonts- Merozoites. Hepatic cell ruptures liberating merozoites. Liberated merozoites then invades RBC’s starting the so-called “ erythrocytic cycle “. Within RBC, merozoite develops into ring form trophozoite, schizont then divides into several merozoites. RBC ruptures, liberating merozoites which then invades other RBC’s. Some that invades the RBC do not undergo division as schizont but instead transforms into male and female gametocyte ( Macrogametocyte- female gametocyte and Microgametocyte-male gametocyte ) B) SEXUAL CYCLE – in Female Anopheles Prepared by: Ma. Cristina Liwanag

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PARASITOLOGY LECTURE NOTES Gametocyte ingested by female anopheles during blood meals. Male gametocyte undergo exflagellation while female gametocyte undergo maturation process. Male and Female gametes are the products of maturation process. Female gamete fertilized by male gamete. Union of male and female gamete produces a Zygote which in turn develops into a worm like form, the ookinete. Ookinete penetrates wall of mosquito gut and develops into an oocyst. Sporozoites develops within sporocyst. Sporocyst ruptures liberating sporozoites. Sporozoites migrate to salivary glands, when female anopheles feeds on human, sporozoites are introduced. Developmental stages of Malarial Parasites; 1. Cryptozoite - stage that initially develops in hepatic cells 2. Trophozoite( ring stage ) - vegetative stage containing one nucleus and develops within RBC 3. Schizont - a trophozoite in which the nucleus has divided 4. Merozoite - cell resulting from the final division of schizont or cryptozoite 5. Hypnozoite - dormant stage that persist in the liver cells, but only in the case of P. vivax and P. ovale 6. Gametocyte - sexually differentiated but immature cells 7. Gamete - mature sex cells 8. Zygote - cell resulting from the union of male and female gamete 9. Ookinete - a motile zygote 10. Oocyst - an encysted form of ookinete 11. Sporocyst - an oocyst in which sporozoites have developed 12. Sporozoites - form which develops within sporocyst and infects the salivary glands of mosquito

Additional information:  Duffy negative individuals may show resistance to P. vivax infection  Those with sickle cell anemia trait may show resistance to P. falciparum infection  P. falciparum is associated with G6PD deficiency  Multiple infection is due to P. falciparum  Cases of relapse may be due to P. vivax and P. ovale due to development of HYPNOZOITES

Prepared by: Ma. Cristina Liwanag

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