CLASSIFICATION &

LIFE CYCLE OF

PLASMODIUM

• Plasmodium is a parasitic protozoa

• Causes malaria.

• Plasmodium, which infects red blood

cells in mammals (including humans),

birds, and reptiles, occurs worldwide,

especially in tropical and temperate

zones.

Plasmodium

Taxonomic classification

• Kingdom: Protista

• Subkingdom: Protozoa

• Phylum: Apicomplexa

• Class: Sporozoa.

• Order: Eucoccidiida.

• Family: Plasmodiidae

• Genus: Plasmodium

Species infecting human :

• P. vivax

• P. falciparum

• P. malariae

• P. ovale

Malaria

Plasmodium

speciesHuman infection

Plasmodium vivax Benign tertian malaria

Plasmodium falciparum Malignant

tertian/pernicious

malaria (most common

and fatal)

Plasmodium malariae Quartan malaria

Plasmodium ovale Ovale tertian malaria

Causative agents

Vector:

• The female Anopheles sp. Mosquito.

Plasmodium have two hosts:

1- A vertebrate host in which reproduction is

asexual (intermediate host):Human

2- A blood-sucking insect, in which sexual

reproduction takes place (definitive host)-

mosquito .

-The infective stage(For Human) :

sporozoites.

- The infective stage for the mosquito is

the gametocytes.

In the intermediate host:

-Liver stage: 6 - 14 days.

- Blood stage: 48 - 72 hrs.

- Incubation period: 21 days.

Life cycle of Plasmodium

• Divided into 3 stages-

1. Exoerythrocytic stage – in liver of man.

2. Erythrocytic stage- in RBCs of man.

3. Sporogonic stage- in mosquito (female

Anopheles)

Exo-erythrocytic (hepatic) cycle

Hypnozoites

Sporozoites

Salivary Gland

LIFE CYCLE OF MALARIA

Gametocytes

Erythrocytic Cycle

Zygote

Oocyst

Stomach Wall

Pre-erythrocytic (hepatic) cycle

sporozoites

Anopheles

Transmission• sporozoites injected

with saliva

• enter circulation

• trapped by liver

(receptor-ligand)

Exoerythrocytic Schizogony

• hepatocyte invasion

• asexual replication

• 6-15 days

• 1000-10,000 merozoites

Hyponozoite Forms• some EE forms exhibit delayed

replication (ie, dormant)

• merozoites produced months after

initial infection

• only P. vivax and P. ovale

relapse = hypnozoite

recrudescence = subpatentt

Erythrocytic

Stage• intracellular parasite

undergoes trophic phase

•young trophozoite called

‘ring form’

• ingests host hemoglobin

•cytostome

• food vacuole

•hemozoin (malarial

pigment)

Erythrocytic Schizogony• Nuclear division-begin

schizont stage

• 6-40 nuclei

• budding merozoites

• erythrocyte rupture

releases merozoites

• characterized by acute

febrile attacks (malaria

paroxysms)

• Causes periodic episodes of

fever alternating with

symptom-free periods

• paroxysms associated with

synchrony of merozoite

release

• between paroxysms temper-

ature is normal and patient

feels well

• falciparum may not exhibit

classic paroxysms

(continuous fever)

Malaria

Paroxysm

tertian malaria

quartan malaria

gametocytes

erythrocytic schizogony

• 48 hr in Pf, Pv, Po

• 72 hr in Pm

Gametogenesis

• occurs in mosquito gut

• ‘exflagellation’ most

obvious

•8 microgametes

formed

Sporogony

•occurs in mosquito (9-21 days)

•fusion of micro and

macrogametes

•zygote ookinete (~24 hr)

•ookinete transverses gut

epithelium ('trans-invasion').

•ookinete oocyst

• between epithelium and

basal lamina

•asexual replication

sporozoites

•sporozoites released.

•sporozoites migrate through

hemocoel

•sporozoites 'invade' salivary glands.

•Stored in salivary glands of

mosquito.

•Released into human body when

mosquito bites another person.

THANK U