Transcript Lab3_Apicomplexa_pre lab_presentation

Biological Sciences 318 - Parasitology Lab
Apicomplexa
Apicomplexa
Kingdom II Euprotista
Phylum Apicomplexa
Protozoa
Apicomplexa
Gregarina
Sarcomastigophora Ciliophora
Coccidia
Haemosporidia
Classes (& Genus):
Gregarina (Monocystis), Coccidia (Eimeria, Sarcocystis, Toxoplasma,
Haemogregarina), Haemosporidia (Plasmodium, Haemoproteus), Piroplasmea,
Perkinsea
Apicomplexa
Apical complex:
Polar rings (one or more)
Conoid
Rhoptries (cell penetration and nutrient transport)
Micronemes (attachment of parasite to host cell)
Subpellicular microtubules
Dense granules
(containing proteins; released after invasion to
function in calcium binding and formation of cysts)
• Diverse group
• All are Parasitic - endoparasitic
• Most have complex life cycles
• Many have a spore stage
• Exquisitely evolved interaction with their host
• Associations range from avirulent to virulent pathogens
• No obvious external organelles involved in locomotion
• No cilia or flagella, except for gametes
• Feeding: Osmotrophy, Phagotrophy (Micropore/Cytostome)
• Asexual (Schizogony or Endopolyogeny) and sexual reproduction (Syngamy, Conjugation).
• Include parasites with huge impact on human and animal health.
Apicomplexa
Life cycles: Asexual (Schizogony or Endopolyogeny) and sexual (Syngamy) development
4 general components
Sporogony: the product of a large number of sporozoites
Merogony: production of merozoites
Gamogony: formation of gametes
Syngamy: fertilization of gametes to produce a zygote
The sporont, meront, and gamont multiply asexually by schizogony
[Schizogony: multiple nuclear divisions and then plasmotomy]
Class Gregarina: Genus Monocystis
• some elements of AC converted into holdfast organelles (attachment to host cell)
• Hosts: invertebrates primarily annelids (earthworm) and arthropods
• no schizogonic phase (trophozoite instead merogony)
• sporozoites form trophozoites in sperm mother cell of earthworm
Life cycle: direct
Slide
1.Troph attached to cell
2.Syzygy (2 Trophs associate in cyst)
3.Gamogony
4.Syngamy
5.Sporogony
6.Gametocyst with Oocysts each with 8
Sporozoites
Class Coccidia
Intestinal Coccidia
Eimeria, Isospora, Cyclospora, Cryptosporidium
•
•
•
•
Eimeria spp.
Intestinal coccidiosis
great economic importance in domestic animals
Every species of mammal has 2 to a dozen species
Coccidia!
•
Host: intracellular parasites (principally vertebrates)
•
Life cycle: complex; include 3 sequential stages
endogenous merogony, gamogony
followed by sporogony (exogenous)
•
Transmission: Ingestion of resistant Oocyst
•
Pathology: Diarrhea (watery, bloody), sloughing
of epithelium, cell death
of
Class Coccidia
Intestinal Coccidia
Eimeria, Isospora, Cyclospora, Cryptosporidium
Order Eimeriidae
• Homoxenous (direct life cycle)
• Merogony, gamogony and the formation of oocysts occurs within the same host.
• Oocysts leave the host via the feces, and are unsporulated (undeveloped, non-infective).
 Exogenous Sporogony
 Sporulated oocysts of Eimeria contain 4 sporocysts, each with 2 sporozoites.
Eimeria stiedae is a parasite of rabbits
development in the bile ducts of liver
Transmission: ingestion of oocysts.
Sporozoites break out, travel to bile duct
Penetrate epithelial cells.
Undergo schizogony forming a schizont
Schizont produces merozoites
Some merozoites undergo gamogony
Syngamy
Oocyst
Class Coccidia
Intestinal Coccidia
Eimeria, Isospora, Cyclospora, Cryptosporidium
Order Eimeriidae
Slide: Liver tissue section infected with Eimeria stiedae.
Trophozoites are round inclusions in the biliary epithelium.
Macrogametocytes are large oval bodies with peripheral red-staining granules.
Microgametocytes are few in number and more diffusely stained than macrogametocytes.
Schizonts (contain 6-20 banana-shaped merozoites).
Class Coccidia
Extraintestinal Coccidia (tissue Coccidia)
Toxoplasma, Sarcocystis, Neospora
• Large group of organisms important to humans and animals
• Isosporoid oocyst: 2 Sporocyst with each 4 Sporozoites
Two host life cycles
 obligate for Sarcocystis
 facultative for Toxoplasma
Definitive Host (carnivore or omnivore)
• adult forms
• sexual reproduction
• usually in intestinal tract
Intermediate Host (herbivore)
• immature forms
• asexual reproduction
• usually extra intestinal (blood vessels, liver, muscle, brain)
Class Coccidia
Extraintestinal Coccidia (tissue Coccidia)
Toxoplasma, Sarcocystis, Neospora
•
•
Sarcocystis spp.
Sarcocystosis
•
Hosts
Definitive: canids (intestinal tissue)
Intermediate: domestic ox, sheep, ducks (somatic muscle)
•
Transmission
Definitive: prey-predator (ingestion of flesh)
Intermediate: Ingestion of Oocyst (intermediate host)
•
Two host indirect life cycle
•
Pathology
Definitive: not very pathogenic
Intermediate: brain, muscle, and kidney tissues
may be damaged by infection.
Clinical signs: loss of appetite, fever, weight loss, anemia,
and death in severe in infections.
Slide
Class Coccidia
Extraintestinal Coccidia (tissue Coccidia)
Toxoplasma, Sarcocystis, Neospora
•
•
Toxoplasma gondii
Toxoplasmosis
•
Hosts (low host specificity)
Definitive: Felines (intestinal tissue)
Intermediate: almost any mammal, bird (most nucleated cell types)
•
Transmission
Definitive: prey-predator (ingestion of flesh)
Intermediate: Ingestion of oocyst (cat feces)
Ingestion of bradyzoites (raw meat)
Congenital
•
Two host indirect life cycle; intermediate host not mandatory!
•
Pathology
In most humans infected with Toxoplasma, the disease is asymptomatic.
However, under some conditions, toxoplasmosis can cause serious pathology, including
hepatitis, pneumonia, blindness, and severe neurological disorders.
 immuno-compromised individuals (AIDS)
Class Coccidia
Extraintestinal Coccidia (tissue Coccidia)
Toxoplasma, Sarcocystis, Neospora
•
Two host indirect life cycle;
intermediate host not mandatory!
 Extraintestinal phase (intermediate host)
 Intestinal phase (definitive host)
Intestinal coccidia:
Eimeria, Isospora, Cryptosporidium
Genetically programmed number of asexual cyclessexual reproduction-oocysts- exit with feces
Extra Intestinal coccidia:
Toxoplasma, Sarcocystis
Genetically programmed number of asexual cyclessexual reproduction-oocysts- exit with feces some
stages enter muscle or other tissues- transmitted
via predation
Class Heamosporidia
Genus Plasmodium
• This group includes the most pathogenic parasites of man.
• Cosmopolitan disease in tropical and sub tropical regions of the world
• Most important vector-borne disease
• Romans called it “mala aria”- disease emanating from the swamps
• The causal agent only identified in 1897
•40% of the world population is at risk for contracting malaria.
•It occurs in over 90 countries.
•500 million new cases and 2-3 million deaths annually.
•Problems with vector resistance to insecticides, Plasmodium
resistance to drugs, no vaccine have made malaria an excellent
example of a re-emerging infectious disease.
Class Heamosporidia
Genus Plasmodium
Human malaria parasites belong to one of four species
Plasmodium vivax
benign tertian malaria, vivax malaria
Plasmodium falciparum
malignant tertian malaria, falciparum malaria
Plasmodium ovale
tertian malaria, ovale malaria
Plasmodium malariae
quartan malaria, malariae malaria
• Cosmopolitan disease in tropical and sub tropical regions of the world
• It occurs in over 90 countries.
• 500 million new cases and 2-3 million deaths annually.
• Most deaths occur among young children in tropical Africa who are infected with P. falciparum.
Class Heamosporidia
Genus Plasmodium
Life cycle
Two host indirect life cycle (Vector required for completion)
Definitive Host: Mosquito; sexual cycle; Maturation of gametes, fertilization, Sporogony
Intermediate Host: Human; asexual cycle; Merogony, Gamogony
3 Cycles: Sporogonic cycle, Exo-erythrocytic cycle (liver cells), Erythrocytic cycle (RBC)
Class Heamosporidia
Genus Plasmodium
Malaria
• Symptoms of malaria include fever and flu-like illness, including shaking chills, headache,
muscle aches, and tiredness. Nausea, vomiting, and diarrhea may also occur.
• Malaria may cause anemia and jaundice (yellow coloring of the skin and eyes) because of the
loss of red blood cells. Infection with one type of malaria, P. falciparum, if not promptly treated,
may cause kidney failure, seizures, mental confusion, coma, and death.
• For most people, symptoms begin 10 days to 4 weeks after infection, although a person may feel
ill as early as 8 days or up to 1 year later.
• Two kinds of malaria, P. vivax and P. ovale, can create problems later: some parasites can rest
in the liver for several months to 40 years after a person is bitten by an infected mosquito, and
can cause disease.
Class Heamosporidia
Genus Plasmodium
Slide: Blood smear of Plasmodium vivax: Plasmodium vivax can be recognized by its variable ring stage.
Schizonts contain about 16 merozoites and the infected cell is enlarged and contains Schuffner’s dots. The
disease caused by this Plasmodium is mild and known as benign tertian malaria (fever paroxysms typically every
48 hours)
Schizont
Ring stage
Schizont with Schuffer’s
dots
Class Heamosporidia
Genus Plasmodium
Slide: Blood smear of Plasmodium falciparum: has a very neat ring stage trophozoite. Multiply infected cells are
common. Schizonts are rare in the peripheral blood. Gametocytes are crescent shaped. The disease caused by
this organism is severe and known as malignant tertian malaria (fever paroxysms every 48 hours). It is this
species that kills the vast majority of humans that die of malaria.
Ring stage
Schizont
Macrogametocyte
Class Heamosporidia
Genus Plasmodium
Slide: Human malaria in liver tissue:
Hemozoin (digested hemoglobin) deposited in
the cells of the spleen in a human infected with
malaria.
Slide: Sporozoite human malaria
Genus Haemoproteus & Haemogregarina
Genus: Haemoproteus
Parasites of birds
Similar life cycles to Plasmodium (but: no asexual stages in circulating blood cells; they remain in the tissues).
The gamonts remain in the erythrocytes.
.
Slide: Haemoproteus columbiae gametocytes. This preparation is a blood smear collected from birds. Note that
bird erythrocytes are nucleated. You will find Haemoproteus gametocytes in the cytoplasm of the red blood cells.
Genus: Haemogregarina
are parasites of the blood of frogs, lizards and turtles, and are transmitted by leeches or mites. Related species
occur in fish.
Slide: Haemogregarines gametocytes in frog blood.
Monocystis sp.
Eimeria sp.
Haemogregarina sp.
Plasmodium sp.
Learning Objectives
1. Phylum Apicomplexa
- General characteristics
- Apical complex!!
- 4 general components of Apicomplexan development
2. Class Gregarina – Monocystis spp.
- Visual Id – common cysts, oocysts, sporozoite
- Trophozoite stages feeding on sperm
- There is no schizogonic phase
- Host + tissue infected
3. Class Coccidia – Eimeria stiedae
- Host, tissues infected, transmission
- Life cycle
- Visual id trophozoite, macrogametocyte, microgametocyte, liver/bile ducts
4. Class Coccidia – Genus Sarcocystis
- Host, tissues, life cycle, transmission
- Visual id
5. Class Coccidia – Genus Toxoplasma
- Life cycle, transmission, hosts, tissues infected
- Intestinal vs. extraintestinal phase (where they occur, in what species…)
- Pathogenecity
- Visual id - tachyzoites
6. Class Haemosporidia – Genus Plasmodium
- Life cycle – what is definitive host
- Transmission,
- Visual id different stages and how they fit in life cycle
- Pathology vivax and falciparum
- Hemozoin in liver tissue
7. Genus Haemoproteus
- Visual id gametocytes
- Life cycle, host , transmission, etc.
8. Genus Haemogregarina
- Visual id, host, transmission
Vocabulary
Apical complex
Schizogony
Syngamy
Sporogony
Merogony
Gamogony
Oocyst
Sporozoite
Meront/Trophozoite
Merozoite
Microgametocyte
Macrogametocyte
Zygote
Bradyzoite
Sarcocyst
Tachyzoite
Exoerythrocytic cycle
Erythrocytic cycle
Sporogonic cycle
Ring-form trophozoite
Ookinete
Schuffner’s dots
Hemozoin