Presentation on theme: "GENERAL PROPERTIES OF PROTOZOA & HELMINTS Doç.Dr.Hrisi BAHAR."— Presentation transcript:
GENERAL PROPERTIES OF PROTOZOA & HELMINTS Doç.Dr.Hrisi BAHAR
GENERAL PROPERTIES OF PROTOZOONS Doç.Dr.Hrisi Bahar
General Characteristics ● ● Unicellular animal with full functions ● Distribute widely: water,soil, etc. ● Total species 65,000 Free-living: majority Parasitic: about 10,000
General Characteristics ● ● Size micrometers ● Parasitic protozoa are most facultative anaerobes; ● Mostly heterotrophic,chemoorganotrophs ● Nutrients assimilated via phagocytosis, pinocytosis, diffusion ● Digestion may be both extracellular and intracellular.
Medical Protozoa ● ● Pathogenic protozoa ● Opportunistic parasite Not normally pathogens Become pathogenic due to impairment of host resistance Clinical importance of the AIDS epidemic
Basic Structures ● ● Plasma membrane ● Cytoplasm Ectoplasm: locomotion, ingestion, etc Ectoplasm: locomotion, ingestion, etc Endoplasm: metabolism Endoplasm: metabolism ● Nuclear Vesicular form or compact form Vesicular form or compact form ● Locomotive organelle Pseudopodium, flagellum, cilia Pseudopodium, flagellum, cilia
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
Life Cycle Patterns ● One stage form Trophozoite ( =vegetatif form.Take food, be mobile, multiply) Trophozoite ( =vegetatif form.Take food, be mobile, multiply) ● Two-stage form Trophozoite & cyst (not mobile, with cyst wall. cyst=protective form) Trophozoite & cyst (not mobile, with cyst wall. cyst=protective form) ● Two-host form Mammals – mammals Mammals – mammals Mammals - insect vectors Mammals - insect vectors
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) Naegleria sp,Acanthamoeba sp)
A-The Sarcomastigophora (Amoeboflagellates ) 1-Sub phylum Sarcodina 1-Sub phylum Sarcodina (The amoebas) Motility via Pseudopoda Motility via Pseudopoda Extensions of the cell membrane Extensions of the cell membrane into which the cytoplasm flows into which the cytoplasm flows Cyclosis Cyclosis No cell wall; thus, no uniform shape No cell wall; thus, no uniform shape Shape changes with movement Shape changes with movement Reproduce asexually by mitosis; Reproduce asexually by mitosis; Sexually by meiosis Sexually by meiosis Trophozoite Trophozoite Motile vegetative stage Motile vegetative stage Cyst Cyst Latent survival stage Latent survival stage
Medically important species of this philum 1-Entamoeba histolytica which causes amoebic dysentery. 1-Entamoeba histolytica which causes amoebic dysentery. The organism produces The organism produces protective cysts which pass out of the intestines of the infected host and are ingested by the next host ingested by the next host (fecal-oral route).
Medically important species of this philum 2-Acanthamoeba. 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.
2-Subphylum Mastigophora 2-Subphylum Mastigophora (Protozoa-flagellates) (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
Medically important species a. Giardia lamblia : giardiasis. 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).
Medically important species b-Trichomonas vaginalis. 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.
Medically important species c. c. Trypanosoma brucei gambiens causes African sleeping sickness and is transmitted by the bite of an infected Tsetse fly.
B-The Ciliophora Protozoa-ciliates 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
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).
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
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.
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.
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
Virulence Factors that Promote Colonization of Protozoans The ability to: 1. Contact host cells; 2. Adhere to host cells and resist physical removal; 3. Invade host cells; 4. Compete for nutrients; 5. Resist innate immune defenses such as phagocytosis and complement; and 6. Evade adaptive immune defenses.
GENERAL PROPERTIES OF HELMINTES
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 ● The definitive classification is based on the external and internal morphology of on the external and internal morphology of egg, larval, and adult stages egg, larval, and adult stages ●Helminths are multicellular eukaryotes. ●Helminths are multicellular eukaryotes.
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.
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.
There are three classes of helminths Cestodes – pig and cattle "tapeworms" ● Adult tapeworms are elongated, segmented, hermaphroditic flatworms that inhabit the intestinal lumen. ● Adult tapeworms are elongated, segmented, hermaphroditic flatworms that inhabit the intestinal lumen. ● Larval forms, which are cystic or solid, inhabit extraintestinal tissues ● Larval forms, which are cystic or solid, inhabit extraintestinal tissues
NEMATODES ● Some species require an intermediate host to complete development. ● Some species require an intermediate host to complete development. ● Intestinal nematodes all mature into adults within the human intestinal tract. ● Intestinal nematodes all mature into adults within the human intestinal tract.
NEMATODES The nematodes (nema: thread) are threadlike, nonsegmented parasites., The nematodes (nema: thread) are threadlike, nonsegmented parasites., A few mm to 1m in length, with separated sexes. A few mm to 1m in length, with separated sexes. They possess a complex tegument and a digestive tract. They possess a complex tegument and a digestive tract.
NEMATODES ● The males are usually smaller than the females and are equipped with copulatory organs that often show features specific to each species. ● The males are usually smaller than the females and are equipped with copulatory organs that often show features specific to each species.
NEMATODES ● Development from the egg includes four larval stages andv four moltings before the adult stage is reached. ● 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 ● The larval forms of many of these roundworms may be distributed widely throughout the body
NEMATODES Three of the intestinal nematodes are acquired by the ingestion of nematode eggs: Three of the intestinal nematodes are acquired by the ingestion of nematode eggs: ● Trichuris trichiura ("whipworm") ● Ascaris lumbricoides ● Enterobius vermicularis ("pinworm") ● Enterobius vermicularis ("pinworm")
NEMATODES Two worms are acquired when their larvae penetrate through the skin, usually of the foot: Two worms are acquired when their larvae penetrate through the skin, usually of the foot: ● Necator americanus ("hookworm") ● Strongyloides stercoralis
NEMATODES One is acquired by the ingestion of the encysted larvae in muscle (pork meat): One is acquired by the ingestion of the encysted larvae in muscle (pork meat): Trichinella spiralis
Ascaris lumbricoides Occurrence ● The human large roundworm occurs worldwide. ● The main endemic regions, with prevalence rates of approx. 10–90%, include countries in Southeast Asia, Africa, and Latin America. ● Autochthonous infections are rare in central Europe.
Ascaris lumbricoides Parasite and Lıfe Cycle ● The adult ascarids living in the small intestine are 15–40cm in length, about as thick as a pencil and of a yellowish pink color.
Enterobius vermicularis (Pinworm) Causative agent of enterobiosis (oxyuriosis) (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
Enterobius vermicularis Parasite and Lıfe Cycle Enterobius vermicularis which belongs to the Oxyurida has a conspicuous white color. The males are 2–5mm long, The females 8–13 mm. The long, pointed tail of the female gives the pinworm its name.
Class Trematoda (Flukes) General characteristics 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.
Class Trematoda hermaphroditic. Most species are hermaphroditic. Snails arthropods or fish Snails are the first intermediate hosts;some species require arthropods or fish as second intermediate hosts
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).
Schistosoma (Blood Flukes) ●Schistosomosis is also known as bilharziosis after the German physician Th. Bilharz, who discovered Schistosoma hematobium in human blood vessels in ● 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)
Schistosoma (Blood Flukes) Schistosoma cercariae ● 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. ● Schistosoma hematobium causes urinary schistosomosis. S. mansoni, S. japonicum,S. intercalatum, and ● S. mansoni, S. japonicum,S. intercalatum, and S. mekongi are the causative agents of intestinal schistosomosis and other forms of the disease. S. mekongi are the causative agents of intestinal schistosomosis and other forms of the disease.
Dicrocoelium dendriticum metacercariae 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) adhere Dicrocoelium 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 2–5 cm long and at most 1 cm wide. Dicrocoelium dendriticum The lancet liver fluke (0.5–1.0 ! 0.2 cm) (0.5–1.0 ! 0.2 cm)
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.
Cestoda (Tapeworms) * The life cycle of cestodes include one or two intermediate hosts. * 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.