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 Exflagellation showing microgametes Sporozoites from salivary gland Oocysts on outside of mosquito stomach

Some Stages of Malaria in the human Cryptozoite in liver cell – it will burst releasing merozoites Trophozoite – uninucleate form in rbc Schizont – multinucleate 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 Plasmodium vivax Four species that infect humans Plasmodium vivax Widespread, temperate areas, Asia, North Africa 43% Tertian malaria

Species of Plasmodium Plasmodium falciparum 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 Plasmodium malariae 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 Plasmodium ovale 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 Then comes the fever. 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 Profuse sweating 2-4 hr. 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 Person is spent but symptoms subside until next cycle. 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 3 1 4 5 6 7 8 2 Day Temperature

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 Accumulation of iron pigment in liver, spleen, or brain. 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 Iron pigment can disrupt functions of cells and tissues 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 Pigment can collect in kidneys, causing them to shut down 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 Malnutrition Shutting down of organs Stunts growth of children Affects growth of children Ancient disease Endemic that can turn to epidemics