malaria lecture 1
TRANSCRIPT
Malaria
By : Najat Elhaj
Introduction:
a vector-borne disease caused by single celled parasites,
the Plasmodium protozoa, and transmitted by female
Anopheles mosquitoes.
Still an enormous pubic health problem and one of the
most common infectious diseases.
The word Malaria comes from 18th century Italian
mala meaning “bad” and aria meaning “air”.
Also known as jungle fever also marsh fever
Associated and cause of poverty and obstacle to
economic development.
History of the Disease:
Dr. Alphonse Laveran,
a military doctor in
France armed forces
health service
discovered malarial
parasite in 1880.
Cont
Later Sir Ronald Ross
,born in India, a British
doctor discovered
malarial parasite in GIT
of anopheles mosquito
that led to realization of
cause.
Malaria in Africa:
According to WHO, the
majority of death occur
among children in sub-
saharan Africa killing an
African child every 30
second.
Taxonomic Classification
Kingdom Animal
Subkingdom Protozoa
Phylum Apicomplexa
Class Sporozoasida
Order Eucoccidiorida
Family Plasmodiidae
Genus Plasmodium
Species falciparum, malariae,
ovale, vivax
Causal agent
The parasite which causes malaria (Plasmodium)
requires two different host:
a vertebrate intermediate host such as a human.
an insect definitive host, also known as the vector.
vertebrate host (Man) Invertebrate host
Female Anopheline mosquito
Transmission of Malaria
Mother to child
(rare)
Blood transfusion
(rare)
TRANSMISSION CYCLE
SPOROZOITES
LIVER
MEROZOITES
RBCs
SHIZONTS GAMETOCYTES
IN MOSQUITO GUT
GAMETE>
ZYGOTE>OOKINETE
Species and Morphology
Species Infecting Humans
Plasmodium falciparum
Malignant tertian malaria
Plasmodium vivax
Benign tertian malaria
Plasmodium ovale
Benign Tertian or ovale malaria
Plasmodium malariae
Quartan malaria
Plasmodium falciparum
(producing malignant tertian malaria)
The name was derived by Welch 1897 from “falx”
(sickle or crescent-like)
Distribution:
Tropics and sub-tropics Africa.
Subtropics Asia.
It is common in southern united states.
Life- cycle & Morphology
Gametes: produce eight microgamete (10 min).
Ookinetes: form in 12 to 18 hours after the insect
takes its blood meal (2.5 µm in breadth and 11 to
13 µm).
Oocysts: mature in 9 days at 30ºC and 23 at 20ºC.
Sporozoites: They are sickle-shaped 10.5-12 µm
They invade the salivary glands of the host
mosqiuto in 9 days after the insect’s blood meal.
Ex-oerythrocytic stages:
There is no secondary generation.
Fully mature EE schizont measure 60 µm and liberate
some 30,000 merzoites or more.
Erythrocytic stages:
Trophozoites are hair-like rings
Nuclei are prominent and may be in two parts that are
opposite to each other or side by side.
Some rings characteristically lie along the edges of red
cells “accolé” forms.
Red cell is invaded by several merzoites even eight.
When the ring become thicker, the host red cell shift from
the peripheral circulation to that of internal organs.
Cont
Schizont: Average of 16-8-32 merzoites.
Maurer’s dots appear as the parasite developed.
Gametocytes:
They are more Banana shape than crescentic shape.
Appear in peripheral blood after 8-11days of the
parasite patency.
Note:
Plasmodium falciparum invade old and young
RBCs.
Plasmodium faciparum invasion may reach 50%.
Schizogony of plasmodium faciparum completed
from 36-48 hours.
Usually only young trophozoites or :ring stage and
gametocytes are seen in peripheral blood smear.
Shizont my be seen in severe pernicious infection.
Thin blood film Giemsa's stain
Gametocyte of P.faciparum (Banana shape)
Plasmodium malariae
(producing malariae or quartan malariae)
Grassi & Feletti 1892
Distribution:
It is common in tropical africa, Burma, Sri lanka,Parts
of Inonesia
Life- cycle & Morphology
Gamete: Eight in number measure 16 µm
Ookinetes: little is Known about Plamodium
malariae ooknietes
Oocysts: mature oocyst rupture in 14 days at 30ºC.
Sporozoites:They are thicker and coarser.(13 to 14
µm).
Ex-oerythrocytic Stages:
EE schizogony is propably completed from 13 to
16 days.
Erythrocytic Stages:
Ring stage has thicker cytoplasm
stained deep blue colour.
Band form may seen.
Birds-eye also seen
Schizont:
Average 12 to 18 typically 16
Rosettes or rosette shape resemble P.vivax (infected
RBCs
aren’t enlarged in P.malariae infection.)
Gametocytes:
Resemble those of P.vivax but they are smaller in size
and less richly pigmented.
Note
Plasmodium malariae invade mature red blood
cell.
Trophozoites:
Ziemanns stippling are present in developed
stages.
Plasmodium malariae characterized by enrich
pigmentation.
Trophozoite of P.malariae (Band form)
Schizont of P.malariae
"Birds-eye" trophozoite of P. malariae in a thin blood smear.
Gametocyte of P.malariae
Plasmodium vivax
(producing vivax or tertian malaria)
Grassi and Feletti 1890.
Distribution:
It found in temperate than in tropical between 16º
to 20º north and 20º south
( Egnhland,Siberia,Argentina and south Africa.)
Life- cycle & Morphology
Gametes: Microgamete six in number
(20 to 25 µm).
Ookinetes: 15 to 22 in length and 3 µm in
width , mature in 24 to 48 hours after the
blood meal has been ingested.
Sporozoites :Narrow and slightly curved.
(14 µm in length).
Erythrocytic stages:
EE schizogony is probably completed from 7 to 8
days. It measure 40 µm I diameter, liberates 10,000
merzoites.
Secondary EE schizogony have been observed 14
days after infection and as late as 9 months after
infection.
Erythrocytic stages:
Delicate blue stained ring of cytoplasm with
red chromatin dot
Late trophozoite: markedly amoeboid,
abundant chromatin.
Schizont: schizont and merzoites large
12 to 24, usually 12 to 18.
Gametocytes: Spherical and compact.
Note
Plasmodium vivax invade young RBCs.
RBCs: Enlarged and decolourized; schüffners
dot usually seen
Ring-stage of P.vivax
Trophozoite of P.vivax
Schizont of P.vivax
Gametocyte of P.vivax
Plasmodium ovale
(producing ovale malaria)
Stephens 1922
Distribution:
Common in tropical Africa, principally on the West
Coast.
Cont
Gametes: Microgamete up to eight, smaller in size than those of Plasmodium vivax.
Ookinetes: smaller in size than those of Plasmodium vivax , appear some 18 to 24 hours after the blood meal has been ingested.
Oocysts: require two weeks to mature at 27ºC
Sporozoites: Elongate, pointed at one end
(11 to 12 µm in length).
Ex-oerythrocytic Stages:
EE schizogony is completed in 9 days. Secondary
EE schizogony occurs.
Erythrocytic stages:
Early trophozoites Compact with one chromatin dot
Two rings in one cell uncommon.
Late trophozoite: Small, compact , not
amoeboid, pigment coarse
Schizont: schizont small but merzoites large 6 to12, usually 8.
Note:
Gametocytes: Similar to P.vivax, but somewhat smaller
RBCs: Enlarged and decolourized; schüffners dot usually seen, infected cell may be oval-shape with fimbriation ends(20 % of the infected cells).
Ring-form trophozoites of P. ovale in thin blood smears.
Trophozoite of P. ovale in a thin blood smear. Note the
fimbriation and Schüffner's dots.
Trophozoites of P. ovale in a thin blood smear.
Schizont of P. ovale in a thin blood smear.
Macrogametocytes of P. ovale in thin blood smears.