Phylum Apicomplexa
Characteristics of Apicomplexa
• Shape of cell maintained by pellicle.
Characteristics of Apicomplexa
• Shape of cell maintained by pellicle.
• Locomotion characterized as gliding. Cilia
absent, but some species produce flagellated or
ameboid gamest.
Characteristics of Apicomplexa
• Shape of cell maintained by pellicle.
• Locomotion characterized as gliding. Cilia absent, but
some species produce flagellated or ameboid gamest.
• Asexual and sexual reproduction.
Characteristics of Apicomplexa
• Shape of cell maintained by pellicle.
• Locomotion characterized as gliding. Cilia absent, but
some species produce flagellated or ameboid gamest.
• Asexual and sexual reproduction.
• Unique system of organelles, the apical complex
in anterior region of cell.
Characteristics of Apicomplexa
• Shape of cell maintained by pellicle.
• Locomotion characterized as gliding. Cilia absent, but
some species produce flagellated or ameboid gamest.
• Asexual and sexual reproduction.
• Unique system of organelles, the apical complex in
anterior region of cell.
• All intracellular parasites at some stage in the
life cycle.
Classification
• Perkinsasidea- parasites of oysters.
• Conoidasida- gregarines and coccidians.
• Aconoidasida- malaria parasites and
piroplasms, usually blood parasites of
vertebrates, with an arthropod host.
Protozoan Reproduction
• Amoeba reproduce by binary fission
essentially mitosis.
• Other types of fission:
Protozoan Reproduction
• Repeated fission: Process by which
colonies are made; like binary fission
except daughter cells don’t separate!
Volvox
Protozoan Reproduction
• Multiple fission: nucleus divides
(multinucleated) before cytoplasm; the
cytoplasm divides secondly.
– Schizogony: asexual process done by an
organism that is itself asexual.
– Sporogony: formed by a sexual process.
Generalized Life Cycle of an Apicomplexan
1. Schizogony (Merogony)
Schizont
or meront
Sexual Reproduction
• Gamete: formed by sexual process
(meiosis); sperm and egg.
• Microgamete (sperm) and macrogamete
(egg).
• Gametes are made by a process called
gametogenesis.
Sexual Reproduction
Gametocyte gametogenesis gametes
Generalized Life Cycle of an Apicomplexan
2. Gamogony: sexual reproduction.
Generalized Life Cycle of an Apicomplexan
3. Sporogony: multiple fission of a zygote.
Malaria
Disease has been known since antiquity - one of first
reports described fevers in 1550 BC.
Malaria
Disease has been known since antiquity - one of first reports
described fevers in 1550 BC.
Malaria was commonly found in swampy areas and
was thought to be contracted by breathing in "bad
air" (= mal aria) in the swamps.
Malaria
Disease has been known since antiquity - one of first reports
described fevers in 1550 BC.
Malaria was commonly found in swampy areas and was
thought to be contracted by breathing in "bad air" (= mal
aria) in the swamps.
• Much effort was directed towards finding a
causative agent in the water or air of these
swamps.
• We now know that the mosquitoes that vectors
the disease lived in these swamps.
Malaria (Plasmodium) Life Cycle
• Has a two host life cycle.
• Mosquitoes in the genus Anopheles are
the vector hosts.
Anopheles quadrimaculatus
200 mm
Mosquito Life Cycle
Life Cycle of Plasmodium –Human Cycle
Life Cycle of Plasmodium –Mosquito Cycle
Some Stages of Malaria in Anopheles
Feeding female Anopheles
Sporozoites from salivary gland
Exflagellation showing microgametes
Oocysts on outside of mosquito stomach
Some Stages of Malaria in the human
Cryptozoite in liver cell – it will
burst releasing merozoites
Schizont – multinucleate form in rbc
Trophozoite – uninucleate form in rbc
Gametocyte – uninucleate form in rbc
Ring Stage
Ring Stage
Schizonts
Gametocytes
Blood Apicomplexans
• Plasmodium-cause malaria in people;
occur in birds, lizards, mammals.
• Have exoerythrocytic and erythrocytic
schizogony.
Blood Apicomplexans
• Leucocytozoon: only
have exoerythrocytic
schizogony.
• Occur in birds can
cause severe
economic loss in
poultry (ducklings,
turkeys).
Black Flies: Simuliidae
Blood Apicomplexans
• Haemoproteus: only
have exoerythrocytic
schizogony.
• Occur in birds and
reptiles common in
the Midwest.
Culicoides spp. are vectors
Malaria
•
•
•
•
•
•
Plasmodium
Tropical and sub-tropical regions
40% of the world’s population are at risk
300 million illnesses per year
1.2 million deaths per year
90% deaths in sub-Saharan Africa
Life Cycle of Plasmodium –Human Cycle
Life Cycle of Plasmodium –Mosquito Cycle
Period of Schizogony
• Breaking of erythrocytes Paroxysm.
Period of Schizogony
• Breaking of erythrocytes Paroxysm.
• Tertian – 48 hr erythrocytes break;
attacks every other day, P. vivax and P.
ovale.
Period of Schizogony
• Breaking of erythrocytes Paroxysm.
• Tertian – 48 hr erythrocytes break; attacks every other
day, P. vivax and P. ovale.
• Quartan – 72 hr erythrocytes break;
attacks three days, P. malariae.
Period of Schizogony
• Breaking of erythrocytes Paroxysm.
• Tertian – 48 hr erythrocytes break; attacks every other
day, P. vivax and P. ovale.
• Quartan – 72 hr erythrocytes break; attacks three days,
P. malariae.
• P. falciparum- attacks not as predictable
36-48 hr.
Malaria
• We usually think of malaria as a tropical
disease, but it can occur in temperate
zones.
• There have been cases of malaria above
the arctic circle.
Species of Plasmodium
• Four species that infect humans
Species of Plasmodium
• Four species that infect humans
– Plasmodium vivax
• Widespread, temperate areas, Asia, North
Africa
• 43%
• Tertian malaria
Species of Plasmodium
• Four species that infect humans
– Plasmodium vivax
• Widespread, temperate areas, Asia, North Africa
• 43%
• Tertian malaria
– Plasmodium falciparum
• Tropics, 50% of malaria in the world
• Falciparum malaria, malignant tertian
malaria
Species of Plasmodium
• Four species that infect humans
– Plasmodium vivax
• Widespread, temperate areas, Asia, North Africa
• 43%
• Tertian malaria
– Plasmodium falciparum
• Tropics, 50% of malaria in the world
• Falciparum malaria, malignant tertian malaria
– Plasmodium malariae
• Rare, localized, but widespread
• Quartan Malaria
Species of Plasmodium
• Four species that infect humans
– Plasmodium vivax
• Widespread, temperate areas, Asia, North Africa
• 43%
• Tertian malaria
– Plasmodium falciparum
• Tropics, 50% of malaria in the world
• Falciparum malaria, malignant tertian malaria
– Plasmodium malariae
• Rare, localized, but widespread
• Quartan Malaria
– Plasmodium ovale
• Very rare, Africa, Philippines, India, S.
America, Vietnam
• Mild tertian malaria
What is Happening in The Human?
• Parasite in RBC.
• When RBC erupts
–
–
–
–
Parasite in blood stream
Pigment from parasite
Hemoglobin from RBC
Metabolic byproducts of parasite
What is Happening in The Human?
• 200 parasites per cc of blood.
• So how many parasites in a person?
• Cardinal symptom of malaria
Paroxysm!
Paraxysm
• 1st Chill (violent) even when surrounding
temperature is stable.
– Chill lasts about 1 hr
Paraxysm
• 1st Chill (violent) even when surrounding temperature
is stable.
– Chill lasts about 1 hr
• Then comes the fever.
– Fever (as high as 106°F) headaches,
nausea, vomiting, rapid pulse
– Lasts several to 10 hr and then breaks.
Paraxysm
• 1st Chill (violent) even when surrounding temperature
is stable.
– Chill lasts about 1 hr
• Then comes the fever.
– Fever (as high as 106°F) headaches, nausea,
vomiting, rapid pulse
– Lasts several to 10 hr and then breaks.
• Profuse sweating 2-4 hr.
Paraxysm
• 1st Chill (violent) even when surrounding temperature
is stable.
– Chill lasts about 1 hr
• Then comes the fever.
– Fever (as high as 106°F) headaches, nausea,
vomiting, rapid pulse
– Lasts several to 10 hr and then breaks.
• Profuse sweating 2-4 hr.
• Person is spent but symptoms subside
until next cycle.
Periodicity
• Synchrony of the
Erythrocytic Cycle
Day
Temperature
1
2
3
4
5
6
7
8
Symptoms
• After three weeks primary attacks stop!
• Why?
Life Cycle of Plasmodium –Human Cycle
Malaria Relapse
• Relapse occurs after primary attack.
Malaria Relapse
• Relapse occurs after primary attack.
• True relapse persistent exoerythrocytic
schizogony produces merozoites that
infect RBC’s that then produce more
merozoites.
Malaria Relapse
• Relapse occurs after primary attack.
• True relapse persistent exoerythrocytic schizogony
produces merozoites that infect RBC’s that then
produce more merozoites.
• Only occurs in P. vivax and P. ovale. Why
is this important?
Mechanisms for Malaria Relapse
• When sporozoites are inoculated, not all
genetically identical.
Mechanisms for Malaria Relapse
• When sporozoites are inoculated, not all genetically
identical.
• When they infect liver cells some turn
into schizonts but others turn into
dormant stages known as hypnozoites.
Mechanisms for Malaria Relapse
• When sporozoites are inoculated, not all genetically
identical.
• When they infect liver cells some turn into schizonts
but others turn into dormant stages known as
hypnozoites.
• Can be dormant for up to 3 years!
Reoccurrence of P. malariae
• After primary attack there are a small
number of organisms that remain in the
blood stream but don’t turn into
gametocytes!
• Reoccurrence (Recrudescence) has been
known to happen 50 yrs after the
primary attack!
P. falciparum
• No relapse!
• Survival of primary attack reconstitutes
a cure!
• There have been a few cases of
reoccurrences; same mechanism as P.
malariae but will not last for 50 yrs.
Pathology
Pathology
• Destruction of RBC’s.
Pathology
• Destruction of RBC’s.
– Loss of Oxygen to tissues and cells
Pathology
• Destruction of RBC’s.
– Loss of Oxygen to tissues and cells
• Accumulation of iron pigment in liver,
spleen, or brain.
Pathology
• Destruction of RBC’s.
– Loss of Oxygen to tissues and cells
• Accumulation of iron pigment in liver, spleen, or brain.
– When RBC’s burst they release cell debris,
hemoglobin and metabolites of parasite
Pathology
• Destruction of RBC’s.
– Loss of Oxygen to tissues and cells
• Accumulation of iron pigment in liver, spleen, or brain.
– When RBC’s burst they release cell debris,
hemoglobin and metabolites of parasite
– Iron pigment can disrupt functions of cells
and tissues
Pathology
• Destruction of RBC’s.
– Loss of Oxygen to tissues and cells
• Accumulation of iron pigment in liver, spleen, or brain.
– When RBC’s burst they release cell debris,
hemoglobin and metabolites of parasite
– Iron pigment can disrupt functions of cells and
tissues
– Sometimes iron pigment will collect under
skin cause jaundice
Pathology
• Destruction of RBC’s.
– Loss of Oxygen to tissues and cells
• Accumulation of iron pigment in liver, spleen, or brain.
– When RBC’s burst they release cell debris,
hemoglobin and metabolites of parasite
– Iron pigment can disrupt functions of cells and
tissues
– Sometimes iron pigment will collect under skin
cause jaundice
– Pigment can collect in kidneys, causing them
to shut down
Pathogenesis
• 2 Major aspects during the erythrocytic
cycle.
– Host Inflammatory response
– Anemia
Most Severe P. falciparum
• More cells infected (about 60%).
• Infected cells clump more.
• Cause clogging of capillaries and
hemorrhaging.
Clinical Conditions associated with
Plasmodium falciparum
• Complications
– Cerebral Malaria
• Headache, Coma
• High temp (>108 F)
• Psychotic symptoms
• Hypoxia
Clinical Conditions associated with
Plasmodium falciparum
• Complications
– Pulmonary edema
– Algid Malaria
– Shock
– Circulatory collapse, low blood pressure
– Blackwater fever
– Associated with massive RBC lysis
– Hemozoin in urine
– Usually occurs in patients that previously had the
disease and received inadequate drug treatment
Drugs
• Quinine found in a specific tree disrupts erythrocytic
schizogony; no effect on sporozoites or exoerythrocytic
schizogony.
• Chloroquine drug of choice against non resistant
malaria; no adverse side-effects. Acts on sporozoites
and erythrocytic schizogony. Often give with
Primaguine.
• Primaquine acts on exoerythrocytic schizogony, not
used to replace others because it is toxic.
Drugs
• Mefloquine (Larium) widely used; used for
chloroquine resistant strains of P. falciparum; acts on
sporozoites; schizonts; exo-erythrocytic schizonts and
gametocytes, but people don’t react to it very well lots
of side effects!
Immunity to Plasmodium
• If you recover, somewhat protected
against reinfections.
• Subsequent infections won’t produce as
many symptoms.
• Antibodies and their response (acquired
immunity).
Side Effects of Malaria
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•
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Malnutrition
Shutting down of organs
Stunts growth of children
Affects growth of children
Ancient disease
Endemic that can turn to epidemics