Presentation on theme: "GENERAL PROPERTIES OF PROTOZOA & HELMINTS"— Presentation transcript:
1 GENERAL PROPERTIES OF PROTOZOA & HELMINTS Doç.Dr.Hrisi BAHAR
2 GENERAL PROPERTIES OF PROTOZOONS Doç.Dr.Hrisi BaharDoç.Dr.Hrisi Bahar
3 General Characteristics ● Unicellular animal with full functions● Distribute widely: water,soil, etc.● Total species 65,000Free-living: majorityParasitic: about 10,000
4 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.
5 Medical Protozoa ● Pathogenic protozoa ● Opportunistic parasite Not normally pathogensBecome pathogenic due to impairment of host resistanceClinical importance of the AIDS epidemic
8 Mode of Reproduction ●Asexual reproduction ●Sexual reproduction Binary fission: results in 2 daughter cellsSchizogony: multiple fission, results in multiple cells●Sexual reproductionConjugation: exchange of nuclear materials of 2 cellsGametogony : sexually differentiated cells unit zygote
9 Life Cycle Patterns ● One stage form ● Two-stage form ● Two-host form Trophozoite ( =vegetatif form.Take food, be mobile, multiply)● Two-stage formTrophozoite & cyst (not mobile, with cyst wall. cyst=protective form)● Two-host formMammals – mammalsMammals - insect vectors
10 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)
11 A-The Sarcomastigophora (Amoeboflagellates) 1-Sub phylum Sarcodina(The amoebas)Motility via PseudopodaExtensions of the cell membraneinto which the cytoplasm flowsCyclosisNo cell wall; thus, no uniform shapeShape changes with movementReproduce asexually by mitosis;Sexually by meiosisTrophozoiteMotile vegetative stageCystLatent survival stage
12 Medically important species of this philum 1-Entamoeba histolytica which causes amoebic dysentery .The organism producesprotective cysts which passout of the intestines of theinfected host and areingested by the next host(fecal-oral route).
13 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.
14 2-Subphylum Mastigophora (Protozoa-flagellates)Motility via flagellaOne or more whip-like filaments move in counter-clockwise fashion creating rapid movementA flagellum is a complex organelle composed of many smaller tubulesFlagella attach to the cell membrane and derive energy from movement from this membraneMost numerous of the protozoan typesSeveral are pathogens of humansAll reproduce asexually; some reproduce sexually
15 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).
16 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.
17 Medically important species c. Trypanosoma brucei gambiens causes African sleeping sickness and is transmitted by the bite of an infected Tsetse fly.
18 B-The Ciliophora Protozoa-ciliates Uses energy from the cell membran Motility via ciliaCilia surround the cell; their coordinated movementUses energy from the cell membranTwo nuclei per cellSmall micronucleus governs sexually reproductionLarge macronucleus governs metabolism and growthBoth nuclei divide during asexual mitosisIntracellular organellesFunction in digestion and excretionOnly one ciliate pathogen affects humans
19 Pathogenic ciliateThe 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).
20 C. The Apicomplexans No established means of movement Thus, not motile All are intracellular parasites in a variety of hostsSeveral parasitic species affect humansThey possess a complex of organelles called apical complexesAll lack intracellular organellesAll have three things in commonNo motilitySexual and Asexual mode of ReproductionIntracellular parasites
21 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 gametesin the mosquito.
22 Medically important species Toxoplasma gondii causes toxoplasmosisIt 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.
23 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
27 Virulence Factors that Promote Colonization of Protozoans The ability to:1. Contact host cells; 2. Adhere to host cells and resist physicalremoval; 3. Invade host cells; 4. Compete for nutrients; 5. Resist innate immune defenses such asphagocytosis and complement; and 6. Evade adaptive immune defenses.
28 GENERAL PROPERTIES OF HELMINTES Doç.Dr.Hrisi Bahar
29 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 basedon the external and internal morphology ofegg, larval, and adult stages●Helminths are multicellular eukaryotes.
30 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.
31 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.
32 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
33 NEMATODES● Some species require an intermediate host to complete development.● Intestinal nematodes all mature into adults within the human intestinal tract.
34 NEMATODESThe 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.
35 NEMATODES● The males are usually smaller than the females and are equipped with copulatory organs that often show features specific to each species.
36 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
37 NEMATODESThree of the intestinal nematodes are acquired by the ingestion of nematode eggs:● Trichuris trichiura ("whipworm")● Ascaris lumbricoides● Enterobius vermicularis ("pinworm")
38 ● Necator americanus ("hookworm") NEMATODESTwo worms are acquired when their larvae penetrate through the skin, usually of the foot:● Necator americanus ("hookworm")● Strongyloides stercoralis
39 NEMATODESOne is acquired by the ingestion of the encysted larvae in muscle (pork meat):Trichinella spiralis
41 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.
42 Parasite and Lıfe Cycle Ascaris lumbricoidesParasite 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.
43 Enterobius vermicularis (Pinworm) Causative agent of enterobiosis(oxyuriosis)Occurrence. The pinworm occurs in all partsof the world and is also a frequentparasite in temperate climate zones and developed countries.The age groups most frequently infected are five- to nine-year-old children and adults
44 Enterobius vermicularis Parasite and Lıfe CycleEnterobius vermicularis which belongsto 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 givesthe pinworm its name.
46 Class Trematoda (Flukes) General characteristicsMost of the trematode species that parasitizehumans are dorsoventrally flattened with anoval to lancet shape, although others havedifferent shapes such as the threadlikeschistosomes.
47 Class Trematoda Most species are hermaphroditic. Snails are the first intermediate hosts;some species require arthropods or fish as second intermediate hosts
48 Schistosoma (Blood Flukes) Class TrematodaSchistosoma (Blood Flukes)Causative agents of schistosomosis or bilharziosis.Schistosomosis (bilharziosis) is one ofthe most frequent tropical diseases withabout 200 million infected persons.The occurrence of schistosomosisdepends on the presence of suitableintermediate hosts (freshwater snails).
49 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)
50 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, andS. mekongi are the causative agents of intestinal schistosomosis and other forms of the disease.
52 The lancet liver fluke (0.5–1.0 ! 0.2 cm) Fasciola hepatica F. hepatica is a flattened,leaf-shaped parasite about2–5 cm long and at most1 cm wide.Dicrocoelium dendriticumThe lancet liver fluke(0.5–1.0 ! 0.2 cm)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.
56 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.
57 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.