Laveron discovered that 'Plasmodium is the causative agent of Malaria'.
The term 'Plasmodium' was coined by Laveron.
❖ Ross:
Ross discovered 'Oocyst stage of Plasmodium on the gut wall of Female Anopheles Mosquito (FAM)'.
Ross won the 1st Nobel Prize for his work on Malaria.
❖ Grassi: Grassi discovered the life history of Plasmodium in FAM.
▢ SPECIES OF PLASMODIUM:
S.N.
Parasite name
Disease (Types of Malaria)
Dots/ Granules
Pre-patent period
Incubation period
a.
Plasmodium vivax
Benign Tertian Malaria
Tertian Ague
Schuffner's dots/ Schuffner's granules
8-10 days
14 days
b.
Plasmodium falciparum
Sub-tertian Malaria
Malignant tertian Malaria
Cerebral Malaria
Black water 💦 Fever
Estivoautumnal Malaria
Maurer's dots
5-10 days
12 days
c.
Plasmodium ovale
Benign Tertian Malaria
Mild Tertian Malaria
Jame's dots/ Schuffner's dots
9 days
14 days
d.
Plasmodium malariae
Benign Quartan Malaria
Longest incubation period
Ziemann's dots
14-15 days
28 days
Note
All Plasmodium species cause Benign Malaria except P. falciparum.
Cerebral Malaria is drug-resistant and fatal.
All Plasmodium species cause Tertian Malaria except P. malariae.
Quotodian malaria results from mixed infection
Plasmodium falciparum is the most fatal species.
Exo-Erythrocytic cycle is absent in Plasmodium falciparum
Pre-patent period is the duration between the initial sporozoite infection and the first appearance of the parasites in blood.
Incubation period is the duration between the initial sporozoite infection and the first appearance of malarial symptoms.
▢ GRANULES:
❖ Schuffner's granules: Numerous yellowish eosinophilic granules appear in the cytoplasm of Host corpuscle, known as Schuffner's granules. These dots are believed to be antigens produced by Parasites.
▢ LIFE CYCLE:
❖ Asexual Cycle / Schizogony - Human (Secondary host):
■ Sporozoites feed upon the glycogen of liver cells, and this feeding stage is called Cryptozoite.
Fig. Sporozoite of Plasmodium vivax
■ Infection: When an infected Female Anopheles Mosquito bites a person, thousands of Sporozoites are inoculated into the bloodstream of the person along with saliva.
■ Infective stage: The Infective stage of Plasmodium is Sporozoite.
■ Structure of Sporozoite:
Sporozoite is Sickle-shaped.
Pellicle acts as an outer boundary to Sporozoite.
Proteolytic enzyme is produced by Paired Organelles and secreted by the Apical cap 🧢 to break down the cell membrane of liver cells.
■ Cycle start: Sporozoites directly go to Parenchyma cells of the liver within half an hour for multiplication. They start their life-cycle from liver cells to get protection against WBCs and utilize the liver's rich source of Glycogen.
◈ Cryptozoite(n): Cryptozoite increases in size and becomes Schizont.
◈ Schizont(n): The nucleus of Schizont divides and forms numerous nuclei, each surrounded by little cytoplasm, forming Cryptomerozoites.
◈ Cryptomerozoites(n): Cryptomerozoites are liberated into Liver Sinusoids.
◈ Cryptomerozoite (n): Each Cryptomerozoite again enters liver cells, and Second liver schizogony occurs.
◈ Metacryptozoite (n):
◈ Schizont (n):
◈ Metacryptomerozoite (n):
■ Types:
● Micrometacryptomerozoites:
Small
Attack RBCs to start the Erythrocytic cycle.
● Macrometacryptomerozoites:
Larger
Attack Liver cells.
◉ Erythrocytic Cycle 🚴 (Golgi Cycle):
◈ Micrometacryptomerozoite (n): Micrometacryptomerozoite starts feeding and changes into Trophozoite.
◈ Trophozoite (n): Trophozoite form is called the feeding stage.
Fig. Trophozoite of Plasmodium vivax
◈ Signet Ring Stage 💍 (n):
During feeding, trophozoite creates a vacuole in the middle of the cytoplasm of RBC, pushing the nucleus towards the periphery. This gives the appearance of a ring with a signet, called the Signet ring stage.
The Signet ring trophozoite throws out pseudopodial processes and assumes an Amoeba-like shape, known as Amoeboid trophozoite.
◈ Amoeboid/ Amoeboid Trophozoite.(n): Amoeboid trophozoite becomes large and spherical and is now called Schizont.
◈ Schizont(n):
Schizont contains Haemozoin and Schuffner's dots (in P. vivax).
Haemozoin causes chills and fever.
◈ Rosette/ Rosette stage 🏵 (n): The Schizont stage gives rise to the Rosette stage, which gives a petal-like appearance.
◈ Merozoites/ RBC merozoite(n):
Schizonts give RBC merozoites, which are released along with haemozoin with the bursting of RBCs.
This causes high fever, chills, and shivering.
Ruptured RBCs and schizonts are called Ghost cells, which are destroyed by the spleen.
◈ Gametocyte(n):
After repeated schizogony, numerous RBC merozoites are formed, losing their power of asexual multiplication, so they undergo a sexual cycle. RBC merozoites become rounded and are known as Gametocytes.
■ Types:
Microgamonts (Micro-gametocytes, male)
Macrogamonts (Macro-gametocytes, female)
◉ Post-Erythrocytic Cycle 🚴 /Post-Erythrocytic Schizogony (Ross Cycle): Some of the RBC merozoites invade liver cells and continue a cycle called Post-Erythrocytic schizogony.
❖ Sexual Cycle/ Gamogony and Sporogony - Mosquito (Primary host):
◉ Gametocytes(n): When an Anopheles mosquito bites an infected person, along with all stages, gametocytes are ingested into the mosquito's gut. All stages except Gametocytes are digested in the mosquito's gut.
◉ Gametes(n):
Gametocytes develop into Gametes. There are two types of gametes:
◈ Types:
Microgametes (Male 👨 gametes): Micro-gametocyte gives rise to 6-8 haploid microgametes after meiotic division. The formation of whip-like micro-gametes or sperms is known as Ex-flagellation.
Macrogametes (Female 🚺 gametes): Macro-gametocytes give rise to one haploid macrogamete after meiotic division. It has a cone receptor.
◉ Zygote (Synkaryon)(2n): Micro and Macrogametes fuse to form Zygote (Synkaryon).
◉ Ookinete(2n):
Zygote transforms into Ookinete, which is motile 🚶.
Ookinete penetrates the Peritrophic membrane of the gut wall and forms an encysted zygote called Oocyst.
◉ Oocyst(2n):
Oocyst undergoes Sporogony, which is meiosis followed by mitosis. Sporogony occurs in the Stomach wall of the mosquito, producing about 10,000 sporozoites from each oocyst.
◉ Sporoblast (n):
◉ Sporozoite(n): Sporozoites migrate to the salivary gland.
▢ TREATMENT OF MALARIA:
❖ Drugs:
◉ Quinine:
Quinine is an important alkaloid in the treatment of malaria.
◈ Source: Quinine is extracted from the bark of the Cinchona tree.
◉ brin:
Atebrin
Melubrin
◉ quin:
Basoquin
Camoquin
Chloroquin
Emquin
◉ quine:
Plasmoquine
Primaquine
Nivaquine
◉ Others:
Daraprim
Paludrine
Mepacrine
Resochin
◉ Mefloquine: Mefloquine is used to treat multidrug-resistant Plasmodium falciparum.
❖ Biological treatment:
◉ Gambusia affinis (mosquito fish): Gambusia affinis feeds on larvae and pupae of mosquitoes.
