GENERAL PROPERTIES OF PROTOZOA

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GENERAL PROPERTIES OF PROTOZOA HELMINTS

• Doç.Dr.Hrisi BAHAR

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GENERAL PROPERTIES OF PROTOZOONS
Doç.Dr.Hrisi Bahar
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General Characteristics

• ? Unicellular animal with full functions
• ? Distribute widely water,soil, etc.
• ? Total species 65,000
• Free-living majority
• Parasitic about 10,000

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General Characteristics

• ? Size 2 - 100 micrometers
• ? Parasitic protozoa are most facultative
  anaerobes
• ? Mostly heterotrophic,chemoorganotrophs
• ? Nutrients assimilated via phagocytosis,
  pinocytosis, diffusion
• ? Digestion may be both extracellular and
  intracellular.

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Medical Protozoa

• ? Pathogenic protozoa
• ? Opportunistic parasite
• Not normally pathogens
• Become pathogenic due to impairment of host
  resistance
• Clinical importance of the AIDS epidemic

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Basic Structures

• ? Plasma membrane
• ? Cytoplasm
• Ectoplasm locomotion , ingestion, etc
• Endoplasm metabolism
• ? Nuclear
• Vesicular form or compact form
• ? Locomotive organelle
• Pseudopodium, flagellum, cilia

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Protozoon
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Mode of Reproduction

• ?Asexual reproduction
• Binary fission results in 2 daughter cells
• Schizogony multiple fission, results in
  multiple cells
• ?Sexual reproduction
• Conjugation exchange of nuclear materials of 2
  cells
• Gametogony sexually differentiated cells unit ?
  zygote

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Life Cycle Patterns

• ? One stage form
• Trophozoite ( vegetatif form.Take food, be
  mobile, multiply)
• ? Two-stage form
• Trophozoite cyst (not mobile, with cyst wall.
  cystprotective form)
• ? Two-host form
• Mammals mammals
• Mammals - insect vectors

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Site of infections

• ? Gastrointestinal system
• (E.histolytica,B.coli,G.intestinalis,D.fragilis,
• Cryptosporidium,Isospora,Blastocystis,Sarcocystis,
  
• Microsporidia)
• ? Urogenital system (T.vaginalis)
• ? Blood (Plasmodium,babesia)
• ? Tissue (T.gondii,Leishmania sp,E.histolytica,
• Naegleria sp,Acanthamoeba sp)

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A-The Sarcomastigophora (Amoeboflagellates)

• 1-Sub phylum Sarcodina
• (The amoebas)
• Motility via Pseudopoda
• Extensions of the cell membrane
• into which the cytoplasm flows
• Cyclosis
• No cell wall thus, no uniform shape
• Shape changes with movement
• Reproduce asexually by mitosis
• Sexually by meiosis
• Trophozoite
• Motile vegetative stage
• Cyst
• Latent survival stage

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Medically important species of this philum

• 1-Entamoeba histolytica which causes amoebic
  dysentery .
• The organism produces
• protective cysts which pass
• out of the intestines of the
• infected host and are
• ingested by the next host
• (fecal-oral route).

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Medically important species of this philum

• 2-Acanthamoeba .
• Can infect the eye, blood, spinal cord, and
  brain and is transmitted by waterborne cysts
  picked up while swimming in contaminated water,
  crossing the mucous membranes.

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• 2-Subphylum Mastigophora
• (Protozoa-flagellates)
• Motility via flagella
• One or more whip-like filaments move in
  counter-clockwise fashion creating rapid movement
• A flagellum is a complex organelle composed of
  many smaller tubules
• Flagella attach to the cell membrane and derive
  energy from movement from this membrane
• Most numerous of the protozoan types
• Several are pathogens of humans
• All reproduce asexually some reproduce sexually

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Medically important species

• a. Giardia lamblia Can cause a gastrointestinal
  infection called giardiasis. Cysts pass out of
  the intestines of the infected host and are
  ingested by the next host (fecal-oral route).

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Medically important species

• b-Trichomonas vaginalis infects the vagina and
  the male urinary tract.
• It does not produce a cysts stage and is
  usually transmitted by sexual contact.

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Medically important species

• c. Trypanosoma brucei gambiens causes African
  sleeping sickness and is transmitted by the bite
  of an infected Tsetse fly.

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B-The Ciliophora

• Protozoa-ciliates
• Motility via cilia
• Cilia surround the cell their coordinated
  movement
• Uses energy from the cell membran
• Two nuclei per cell
• Small micronucleus governs sexually reproduction
• Large macronucleus governs metabolism and growth
• Both nuclei divide during asexual mitosis
• Intracellular organelles
• Function in digestion and excretion
• Only one ciliate pathogen affects humans

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Pathogenic ciliate

• The only pathogenic ciliate is Balantidium coli
  which causes a diarrhea-type infection. Cysts
  pass out of the intestines of the infected host
  and are ingested by the next host (fecal-oral
  route).

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C. The Apicomplexans

• No established means of movement
• Thus, not motile
• All are intracellular parasites in a variety of
  hosts
• Several parasitic species affect humans
• They possess a complex of organelles called
  apical complexes
• All lack intracellular organelles
• All have three things in common
• No motility
• Sexual and Asexual mode of Reproduction
• Intracellular parasites

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Medically important species

• Species of Plasmodium .cause malaria and are
  transmitted by the bite of an infected female
  Anopheles mosquito. They reproduces asexually by
  schizogony in human liver cells and red blood
  cells but also reproduce sexually by gametes
• in the mosquito.

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Medically important species

• Toxoplasma gondii causes toxoplasmosis
• It can infect most mammals and is contracted by
  inhaling or ingesting cysts from the feces of
  infected domestic cats, where the protozoa
  reproduce both asexually and sexually, or by
  ingesting raw meat of an infected animal.

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Medically important species

• Cryptosporidium is an intracellular parasite
  that causes diarrhea, although in people who are
  immunosuppressed it can also cause respiratory
  and gallbladder infections. It is transmitted by
  the fecal-oral route

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Protozoan Diseases

• Intestinal
• Amebiasis.....................Entamoeba
  histolytica
• Giardiasis.....................Giardia
  lamblia
• Balantidiasis...Balantidium coli
• Crytosporidosis. .Cryptosporidium
• 
  parvum
• Urogenital
• Trichomoniasis.Trichomonas vaginalis

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Protozoan Diseases

• Blood and Tissue
• Malaria ......Plasmodium spp
• Meningoencephalitis..Naegleria fowleri
• Toxoplasmosis....Toxoplasma gondii
• Trypanosomiasis
• African Sleeping Sickness...Trypanosoma brucei
• Chagas Disease......................Trypanosoma
  cruzi

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Protozoan Diseases

• Leishmaniasis
• ?Visceral leishmaniasis( Kala-azar) Leishmania
  donovanii
• ? Cutaneous leishmaniasis Leishmania
  topica/braziliensis

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Virulence Factors that Promote Colonization of
Protozoans

• The ability to
• 1. Contact host cells2. Adhere to host
  cells and resist physical
• removal3. Invade host cells4. Compete
  for nutrients5. Resist innate immune defenses
  such as
• phagocytosis and complement and6. Evade
  adaptive immune defenses.

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GENERAL PROPERTIES OF HELMINTES
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HELMINTHS

• ?The helminths are worm-like parasites.
• ? Helminths are separated according to their
  general external shape and the host organ they
  inhabit.
• ? The definitive classification is based
• on the external and internal morphology of
  
• egg, larval, and adult stages
• ?Helminths are multicellular eukaryotes.

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There are three classes of helminths

• Nematodes "roundworms"
• ? Adult and larval roundworms are bisexual,
  cylindrical worms.
• ? They inhabit intestinal and extraintestinal
  sites.
• ? The nematodes include Trichinella, Ascaris, and
  Enterobius.

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There are three classes of helminths

• ? Trematodes "flukes"
• ? Adult flukes are leaf-shaped flatworms.
  Prominent oral and ventral suckers help maintain
  position.
• ? The life cycle includes an intermediate host.
• ? An example is the organism that causes
  schistosomiasis.

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There are three classes of helminths

• Cestodes pig and cattle "tapeworms"
• ? Adult tapeworms are elongated, segmented,
  hermaphroditic flatworms that inhabit the
  intestinal lumen.
• ? Larval forms, which are cystic or solid,
  inhabit extraintestinal tissues

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NEMATODES

• ? Some species require an intermediate host to
  complete development.
• ? Intestinal nematodes all mature into adults
  within the human intestinal tract.

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NEMATODES

• The nematodes (nema thread) are threadlike,
  nonsegmented parasites.,
• A few mm to 1m in length, with separated sexes.
• They possess a complex tegument and a digestive
  tract.

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NEMATODES

• ? The males are usually smaller than the
  females and are equipped with copulatory organs
  that often show features specific to each
  species.

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NEMATODES

• ? Development from the egg includes four larval
  stages andv four moltings before the adult stage
  is reached.
• ? The larval forms of many of these roundworms
  may be distributed widely throughout the body

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NEMATODES

• Three of the intestinal nematodes are acquired by
  the ingestion of nematode eggs
• ? Trichuris trichiura ("whipworm")
• ? Ascaris lumbricoides
• ? Enterobius vermicularis ("pinworm")

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NEMATODES

• Two worms are acquired when their larvae
  penetrate through the skin, usually of the foot
• ? Necator americanus ("hookworm")
• ? Strongyloides stercoralis

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NEMATODES

• One is acquired by the ingestion of the encysted
  larvae in muscle (pork meat)
• Trichinella spiralis

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NEMATODES

• Ascaris lumbricoides
• (Large Roundworm)
• Causative agent
• of
• ascariosis

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Ascaris lumbricoides

• Occurrence
• ? The human large roundworm occurs worldwide.
• ? The main endemic regions, with prevalence rates
  of approx. 1090, include countries in Southeast
  Asia, Africa, and Latin America.
• ? Autochthonous infections are rare in central
  Europe.

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Ascaris lumbricoides

• Parasite and Life Cycle
• ? The adult ascarids living in the small
  intestine are 1540cm in length, about as thick
  as a pencil and of a yellowish pink color.

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Enterobius vermicularis(Pinworm)

• Causative agent of enterobiosis
• (oxyuriosis)
• Occurrence. The pinworm occurs in all parts
• of the world and is also a frequent
• parasite in temperate climate zones and developed
  countries.
• The age groups most frequently infected are five-
  to nine-year-old children and adults

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Enterobius vermicularis

• Parasite and Life Cycle
• Enterobius vermicularis which belongs
• to the Oxyurida has a conspicuous white color.
• The males are 25mm long,
• The females 813 mm.
• The long, pointed tail of the female gives
• the pinworm its name.

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Enterobius vermicularis
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Class Trematoda(Flukes)

• General characteristics
• Most of the trematode species that parasitize
• humans are dorsoventrally flattened with an
• oval to lancet shape, although others have
• different shapes such as the threadlike
• schistosomes.

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Class Trematoda

• Most species are hermaphroditic.
• Snails are the first intermediate hostssome
  species require arthropods or fish as second
  intermediate hosts

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Class Trematoda

• Schistosoma (Blood Flukes)
• Causative agents of schistosomosis or
  bilharziosis.
• Schistosomosis (bilharziosis) is one of
• the most frequent tropical diseases with
• about 200 million infected persons.
• The occurrence of schistosomosis
• depends on the presence of suitable
• intermediate hosts (freshwater snails).

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Schistosoma (Blood Flukes)

• ?Schistosomosis is also known as bilharziosis
  after the German physician Th. Bilharz, who
  discovered Schistosoma hematobium in human blood
  vessels in 1851.
• ? Schistosomosis occurs endemically in 74
  tropical and subtropical countries of Africa,
  South America, and Asia .
• ? The number of persons infected with
  schistosomes is estimated at 200 million(WHO 2008)

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Schistosoma (Blood Flukes)

• ? Human infections result from contact with
  standing or slow-moving bodies of water
  (freshwater) when Schistosoma cercariae penetrate
  the skin.
• ? Schistosoma hematobium causes urinary
  schistosomosis.
• ? S. mansoni, S. japonicum,S. intercalatum, and
• S. mekongi are the causative agents of
  intestinal schistosomosis and other forms of the
  disease.

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Trematodes

• Fasciola hepatica
• Dicrocoelium dendriticum
• Clonorchis spp
• Paragonimus spp

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Fasciola hepatica and F. gigantica are bile duct
parasites of domestic ruminants.In their life
cycle freshwater snails act as intermediate host
Humans become accidentally infected when they eat
plants to which infectious parasite stages
(metacercariae) adhereDicrocoelium dendriticum
is a bile duct parasite in sheep,cattle, and
other herbivores, Its life cycle includes two
intermediate hosts (terrestrial snails and ants).
Humans become infected accidentally when they
ingest ants containing infective metacercariae of
the lancet liver fluke.

• Fasciola hepatica
• F. hepatica is a flattened,
• leaf-shaped parasite about
• 25 cm long and at most
• 1 cm wide.

• Dicrocoelium dendriticum
• The lancet liver fluke
• (0.51.0 ! 0.2 cm)

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Dicrocoelium dendriticum egg
Fasciola hepatica egg
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Cestoda (Tapeworms)

• Taenia saginata
• Taenia solium
• Echinococcus granulosus

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Cestoda (Tapeworms)

• ? General characteristics
• Parasitize in the small intestine of humans.
• They are hermaphrodites and consist of the
  head (scolex), followed by an unsegmented
  germinative section (neck) and a posterior chain
  of segments (proglottids).
• There are no digestive organs, so nutrients are
  taken up through the absorptive integument.

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Cestoda (Tapeworms)

• The life cycle of cestodes include one or two
  intermediate hosts.
• Humans can also be infected by larval stages of
  various tapeworm species (cysticerci,
  metacestodes).
• These stages develop in body tissues and
  generally cause considerably greater pathological
  damage than the intestinal cestode stages.

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Taenia saginata
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Echinococcus granulosus