Plasmodium Vivax Malaria Parasite PDF

Here is the text from the image converted into a structured markdown format. ### Plasmodium vivax: The Malaria Parasite **Systematic Position** | | | | :----- | :---------- | | Phylum | Protozoa | | Subphylum | Sporozoa | | Class | Telosporca | | Subclass | Coccidia |...

Here is the text from the image converted into a structured markdown format. ### Plasmodium vivax: The Malaria Parasite **Systematic Position** | | | | :----- | :---------- | | Phylum | Protozoa | | Subphylum | Sporozoa | | Class | Telosporca | | Subclass | Coccidia | | Order | Eucoccida | | Suborder | Haemosporina | | Genus | Plasmodium | | Species | vivax | **Distribution of Plasmodium** Geographical distribution of the species of *Plasmodium* is widespread in tropical and temperate countries. Where the migratory birds are hosts, the parasites are spread all over the world. Of the human infecting parasites, *P. vivax* is the most widely distributed. It prevails mainly in temperate regions of the world. *P. falciparum* is confined to the warmer parts only. *P. malariae* follows *P. vivax* in distribution. *P. ovale,* though widespread, is the rarest of the four. **Life Cycle of Plasmodium vivax** *P. vivax* is the most common of the human infecting malaria fever parasites. It is the causative organism of benign tertian or vivax malaria, which is characterized by a 48-hour cycle between the first malaria fever and subsequent recurrence of chills and fever. It is an intracellular parasite in man, living in the red blood corpuscles and liver cells, while extracellular in mosquito, living in its alimentary canal and salivary glands. Hosts. The life cycle, undergone by *P. vivax,* is very complicated. Being digenetic, it is completed in two hosts, man and mosquito. (a) Man. Asexual cycle is passed in man in two phases. First phase in liver cells is called liver schizogony. It involves multiple fission forming merozoites at the end. Second phase is completed in red blood corpuscles. It is known as erythrocytic schizogony which forms gametocytes at the end. (b) Mosquito. Sexual cycle is completed in female *Anopheles* mosquito. It also involves two phases, gametogony and sporogony. Gametogony is concerned with the production and fusion of gametes, whereas sporogony is postzygotic multiplication resulting the formation of infective individuals, the sporozoites. **[I] Asexual cycle of *P. vivax* in man** 1. **Infection.** A healthy person acquires infection when a female *Anopheles* mosquito, containing infective stages of parasite (sporozoites) in its salivary glands, bites him for sucking his blood. The mosquito punctures the host's skin by its proboscis and first introduces some saliva into blood stream. Along with saliva, thousands of sporozoites contained therein are also inoculated. Purpose of pouring saliva is to check clotting of blood, as it contains an anticoagulant. 2. **Sporozoites.** Sporozoites represent the infective forms of parasite. These are small spindle-shaped, slightly curved or sickle-shaped, and uninucleate organisms, measuring 11-12 µ in length and 0.5-1µ in width. Electron microscope reveals the complicated gross anatomy of sporozoite. External covering is the firm and elastic pellicle, which contains longitudinally arranged contractile microtubules for its wriggling movements. At the anterior end is the apical cap, made up of three or more concentric rings, into which open the secretory paired organelles. These are supposed to secrete tic juice to facilitate penetration into liver cells. A micropyle represents the cytostome of other protozoans. Many convoluted tubules of unknown function are found along the whole bo single vesicular nucleus with a centrally-located nucleolus and mitochondrion with tubular cristac. 3. **Liver schizogony.** Once within the human blood, the sporozoites circulate for about half an **Figure 1.** *Plasmodium*. Structure of a sporozoite as revealed by electron microscope. The structure includes: * mitochondrion * pellicle * nucleus * convoluted tubules * micropyle * microtubules of pellicle * paired organelles * apical cap hour and then get into liver to invade the hepatic cells. Here they multiply asexually by schizogony. Liver schizogony has two phases, pre-erythrocytic and exo-erythrocytic. (a) **Pre-erythrocytic phase.** After penetrating a hepatic cell each sporozoite becomes a cryptozoite. It grows for a number of days and becomes a spherical and non-pigmented schizont. It divides by schizogony (multiple fission) and forms a large number of uninucleate cells, the cryptomerozoites. Their reported number varies from one thousand to several thousands. They are liberated when the liver cell bursts. This is the end of pre-erythrocytic phase. During pre-erythrocytic schizogony, blood remains sterile and its inoculation does not produce infection. (b) **Exo-erythrocytic phase.** Cryptomerozoites enter fresh liver cells to become metacryptozoites. They undergo schizogony similar to the previous one producing enormous number of metacrypto-merozoites. This may be repeated several times and each time new liver cells are infected. All these succeeding schizogonic divisions are referred to as exoerythrocytic or phanerozoic schizogony. It has been reported that metacrypto merozoites produced are of two types. Smaller and more numerous are micro-metacrypto merozoites. They enter the red blood corpuscles to start the erythrocytic stage. Larger and less numerous are macro-metacrypto merozoites. They invade fresh liver cells to continue the exo-erythrocytic schizogony. Both types of schizogony continue side by side Pre- and exo-erythrocytic phases of parasite remain immune to the resistance of host and parasites are not susceptible to the action of any anti-malarial drug. Also little damage to the host is done during this stage. (c) **Pre-patent and incubation periods.** The duration between initial sporozoite infection and first appearance of parasites in blood is termed the pre-patent period. It varies from species to species, being of about 8 days in *P. vivax.* The period between infection and appearance of first malarial symptoms is the incubation period which is of about 10-17 days (average 14 days) in *P. vivax.* 4. **Erythrocytic schizogony.** Micro metacrypto-merozoites, after escaping into blood stream, invade the erythrocytes or red blood corpuscles. **Figure 3.** *Plasmodium*. Electron micrograph of a trophozoite. The structure includes: * Golgi complex * pinocytosis vesicles * vacuole * mitochondria * nucleus * nucleolus * endoplasmic vesicles * ribosomes * haemozoin granules * food vacuole * concentric body This starts the erythrocytic schizogony which includes the following stages. (a) **Trophozoite stage.** Inside R.B.C., the micro-metacryptomerozoite becomes rounded and modified into a young trophozoite. (b) **Signet ring stage.** As the trophozoite grows in size, a central vacuole is developed so that the nucleus is pushed to one side into peripheral cytoplasm. This stage is clinically referred to as signet ring stage as it resembles the signet ring with the peripherally located nucleus looking like the gem of the ring. Signet ring trophozoite ingest a large portion of cytoplasm of red blood corpuscle forming a food vacuole into which it secretes digestive enzymes. Besides, a number of pinocytotic vesicles are also formed around the periphery of parasite into which digestion takes place. The enzymes bring about proteolysis of blood haemoglobin, which breaks down into its protein component and hematin. Protein is used as food by the trophozoite, while the unused hematin forms the toxic malarial pigment, called haemozoin. (c) **Amoeboid stage.** Meanwhile, the signet ring trophozoite develops into an active amoeboid trophozoite. It sends pseudopodial processes into cytoplasm of the blood corpuscle. At this time, small red eosinophilic granules appear in the cytoplasm of the host corpuscle which are known as Schuffner's granules. (d) **Schizont.** The amoeboid trophozoite, after active feeding, becomes rounded, grows in size and becomes schizont. It now undergoes schizogony. Its nucleus divides to form 12-24 nuclei which get arranged at the periphery and cytoplasmic masses surrounding them. Each cytoplasmic mass with one nucleus becomes an oval-shaped merozoite. The haemozoin granules are gathered at the entre With the rupture of the red blood corpuscles, the merozoites are liberated into the blood plasma. These invade fresh erythrocytes to restart the erythrocytic cycle. Plasmodium, according to some workers (Bang, 1959), meiosis or reduction division takes places in the first divisions of zygote. Consequently, only zygote is diploid, while gametes and all ot stages of life cycle are haploid, as in higher plants. (a) Microgametes. The male or microgametocyte begins to undergo a process, called exflagellation, in the midgut of mosquito. The drop in temperature, due to transfer from warm-blooded human host to cold-blooded insect provides the stimulation for the process. In each microgametocyte, nucleus divides by mitosis to produce 6-8 haploid daughter nuclei, which assemble at the periphery. The cytoplasm outgrowths into long, thin and flagella-like and a daughter nucleus enters each one of them. These projections break away as mature male microgametes (spearas). Ea measures from 20-25y in length. (b) Megagametes. The female megagametocyte undergoes some reorganization and becomes a female that is, megagamete macro gamete which is ready fertilization. 3. Fertilization. The megagamete gives out small cytoplasmic projection, the cone reception or fertilization cone. Nucleus of megagamete comes to lie rear its receptive cone When a lashing microgamete comes in contact with a megagamete, the former penetrates latter through its receptive cone and fertilizatio of nuclei and cytoplasm of resulting in the formation of zygote with a diplaid nucleus or 4. Ookinete. The zygote remains rounded and motionless for some time, but soon becomes elongated, vermiform and motile. It perfonus 5. Encystement. Ookinete through the wall of midgut (stomada) to settle deon just under the thin membrane that separates midg from haemocoel. Here it becomes spherical and beigns to encyst. The cyst wall is then membranous and elastic, secreted partly Ookinete and partly deived finid gut tissues of mosquito. The encysted zygote is called cocvst or sparont Here is a comparative table of four species of human infecting *Plasmodium*: | Characters | *P. vivax* | *P. malariae* | *P. ovale* | *P. falciparum* | | :------------------------------------ | :-------------------------------------------------------------------------- | :-------------------------------------------------------------------------- | :------------------------------- | :----------------------------------------------------------------------------- | | 1. Geographical distribution | Worldwide, in tropical, sub-tropical and warmer temperate regions. | Worldwide, in tropical and sub-tropical regions. | Tropical Africa. | Worldwide, in tropical, subtropical and warmer temperate regions. | | 2. Duration of pre-erythrocytic cycle | 8 days | 7-12 days | 9 days | 5-6 days | | 3. No. of merozoites | 10,000 | 2,000 | 15,000 | 40,000 | | 4. Duration of cycle | 48 hours | 72 hours | 48 hours | 36-48 hours | | 5. of merozoites | 12-24 | 6-10 | 6-12 | 18-24 | | 6. Incubation period | 14 days | 28-34 days | 14 days | 12 days | | 7. Signet ring form | About 1/3 diameter of R. B. C. Large ring with vacuole. | About 1/3 diameter of R.B.C. Usually one ring. | About 1/3 diameter | Small ring situated edge of B. C. | | 8. Late trophozoite | Amoeboid and large. | Compact and often band-shaped, small. | slightly amoeboid | rarely seen blood. | | 9. Schizont | Large, 10u diameter. With 2-24 merozoites | Medium sized, µdiameter,diameter. 7With 6-12, With 6-12 merozoites | Medium sized, 7pRound, , or ovoid | Small,5µm&microSmall,diameter diameter. blood | | 10. Gametocytes | Round. Fil R.B.C Pigment granules evenly distributed. | Round, Pigment at center. | Round / Ovule | Centeric . Male 9-11 centeric. Female Centeric 12-14 | | 11. Host R.B.C. | Enlarged. -Schuffner's dots usually seen | Not Enlarged Ziemann's dots seen (23:6) | Slightly Enlarged | Not Elarged not Elarged green Maurers dots /left | | 12. Pigement (Hemozoin) | Yellowish Brown Fine gramules Rods | Dark Brown / Black Abundent Course gramnules | Dark Brown less Abundent | Dark Brown / Black Course | * A sporoblaast stage, as found in mocystitis it is absent in plasmocilium in with the sporocites are 4 *Sporoblast stage as found in monocystis. Is absent sparcity of forming oocysts. Figure 4. Stomach of midgunt. Described is the stomach of the mosquito includeing the following parts: - Hindgut - Esophagus - Stich - oocytes - Maphighlion Jubies Connited is popotiasie stand Daughter in uclei orange themself alory fingal, uke proses are given act foren me Daughter nuclear migtates into. Suck -like shapped Spares act tangled with oocytes. They salivary glands in mosquito