BMS1-13. Parasitic Cell Structure and Classification - Doç. Dr.Emrah Ruh.ppt

Parasitic Cell Structure and Classification Assoc. Prof. Emrah Ruh NEU Faculty of Medicine Department of Medical Microbiology and Clinical Microbiology E-mail: [email protected] Learning objectives  At the end of this course, the...

Parasitic Cell Structure and Classification Assoc. Prof. Emrah Ruh NEU Faculty of Medicine Department of Medical Microbiology and Clinical Microbiology E-mail: [email protected] Learning objectives  At the end of this course, the students;  Will be able to classify parasites.  Will learn important terms related to parasitology.  Will learn the cell structures of protozoa and how they reproduce.  Will be able to distinguish helminth groups from each other.  Will be able to classify arthropods and understand the importance of these vectors for human health.  There are three types of symbiosis. These are: Mutualism, commensalism and parasitism.  Mutualism (+/+): ◦ Reciprocal benefit  Commensalism (+/0): ◦ One organism gets benefit; the other organism gets neither benefit nor harm  Parasitism (+/-): ◦ One organism gets benefit; the other organism gets harm Medical parasitology is the study of parasites and parasitic diseases includes the methods for diagnosing and identifying parasites Parasite: “is a living organism that acquires some of its basic nutritional requirements through its intimate contact with another living organism”. Parasites are eukaryotes: they have a well defined chromosome in a nuclear membrane. Protozoa Arthropods Helminths Endoparasite A parasite that lives within another living organism. Examples: Plasmodium, Giardia Ectoparasite A parasite that lives on the external surface of another living organism. Examples: lice, ticks Obligate parasite An organism that cannot survive in any other manner. Example: Plasmodium Facultative parasite An organism that may exist in a free-living state or as a commensal. In a suitable condition it may become parasitic. Example: Naeglaria fowleri Accidental parasite When a parasite attacks an unnatural host and survives. Example: Hymenolepis diminuta (rat tapeworm) Intermittent parasite Arthropodes, such as mosquitoes, which periodically feed on larger organisms. Monoxen parasite A parasite that completes its life cycle in or on one host. Heteroxen parasite A parasite that completes its life cycle in or on more than one host. Host: is the organism where the parasite lives and causes harm.  Definitive host (final host): In which the sexual or adult form of parasite is found.  Intermediate host: In which the asexual or immature, or larval form of the parasite is found. The host  Patient: Persons who have parasites in their body and show clinical symptoms.  Carrier: Persons who have parasites in their body, but do not show symptoms.  Reservoir host: Animals that harbor the same species of parasites as man. Sometimes, the parasites in animals can be transmitted to humans. Parasites  Non-pathogenic parasites: live in/on the body of the host and do not cause disease.  Pathogenic parasites: are disease causing parasites.  Opportunistic parasites: do not generally produce disease in healthy (immunocompetent) individuals but they cause illness in individuals with impaired immunity. Pathogen A parasite which is able to produce disease. Virulence Refers to the degree of pathogenecity. Infection The presence of parasite in or on the tissues of the host. Infestation The presence of arthropods on the skin of the host.  Human-to-human transmission  Animal-to-human transmission  Food-borne transmission  Water-borne transmission  Blood-borne transmission  Vector-borne transmission  Sexual transmission  Congenital transmission Human-to-human transmission and animal-to-human transmission: A reservoir/carrier of a parasite may be human or animal. If a disease is transmitted by animals to humans it is called zoonosis. zoonosis Here, the animal is normally the host, but the parasite can also infect the human. Food-borne transmission: Directly transmitted by eating undercooked seafood/meat; raw aquatic plants  Consumption of food contaminated by human or animal feces Many of these organisms can also be transmitted by water, soil, or person-to-person contact  Some foods are contamined by food service workers who practice poor hygiene or who work in unsanitary facilities Food-borne transmission: Water-borne transmission: People become infected; when they swallow or have contact with water  when they drink water when they swim in or have contact with freshwater lakes Blood-borne transmission:  Some parasites can be found in the bloodstream of infected people.  These parasites can be transmitted to other people by blood transfusion, or by sharing needles or syringes contaminated with the infected blood. Vector-borne transmission: Vector: is a living carrier (an arthropod) that transports a pathogenic organism from an infected person to a non-infected host. Biological vector: is absolutely necessary for the evolution and life cycle of the parasite. Example: Female Anopheles mosquito that transmits malaria Mechanical vector: just carries the parasite. Example: House fly (Musca domestica) Vector-borne transmission: Also:  Sexual transmission  Congenital transmission ◦ From infected mother to her baby during pregnancy Diagnosis of the parasitic diseases:  A history of exposure and the clinical pattern of illness in the patient  Identification of parasite in the excreta (stool, urine), blood or specific tissue of the host  Indirect evidence of parasite by testing the patient’s blood for antibodies  Detection of parasite antigens  Detection of parasite DNA&RNA Preventive measures for the parasitic diseases  Controlling the source of the infection Treatment of the patients, carriers and reservoir hosts.  Intervention at the routes of transmission Managing feces and water resource, controlling or eliminating vectors and intermediate hosts.  Protecting the susceptible hosts Paying attention to personal hygiene, changing bad eating habit, taking medicine.  Medical parasitology Amoeba Medical Flagellates Protozoology Ciliates Sporozoa Nematodes Medical Trematodes Helminthology Cestodes Medical Insecta Entomology Arachnida Medical Protozoology Amoeba Flagellates Ciliates Sporozoa  Small microscopic eukaryotes  Unicellular organisms  Wide range of sizes and shapes  Contains nucleus and functional organelles  Reproduce quickly ◦ May have asexual and/or sexual phase in the host and/or vector Protozoa Cyst nonfeeding, nonmotile, infective stage Trophozoite vegetative stage, active, feeding  Most protozoa are motile  Protozoa move by locomotion (motility) organelles Organism Class Organelles of Explanation Locomotion Amoeba Pseudopods Temporary projections of the cytoplasm, ingestion of food Flagellates Flagella Filamentous extensions of the cytoplasm Ciliates Cilia Elongated hair-like organelles, ingestion of food, sensory organ Sporozoa None Gliding motility Locomotion organelles of protozoa Pseudopod Flagella Cilia Sporozoa (Apicomplexa) have apical complex that help the organism enter the host cell  Flexible cell membrane; no cell wall  Non-photosynthetic  Common in moist environments, including the intestinal tracts of animals  Live either as free entities or as parasites  Reproduction is sexual or asexual  Protozoa Asexual reproduction A) Binary fission individual parasite divides transversely or longitudinally into two daughter cells. B) Multiple fission (schizogony) nucleus of parent cell undergoes multiple divisions, which is surrounded by cytoplasm. C) Endodyogeny internal budding.  Protozoa Sexual reproduction A) Syngamy sexually A different cells unite to form a zygote. B) Conjugation 2 cells attach to each other, and B exchange of nuclear material occurs. After this, they detach. The number of cells does not increase. Terms used in protozoology Protoplasm: body of protozoa Ectoplasm: the external hyaline portion of the cytoplasm Endoplasm: the internal granular portion of the cytoplasm Pseudopods: false feet  Protoplasm Cytoplasm Nucleus Vesicular or sac-like, Endoplasm Ectoplasm massive nutrition movement reproduction ingestion excretion respiration protection Terms used in protozoology Endocytosis: a process in which a particle or a macromolecule is taken intact into a cell. Phagocytosis: particulate matters are ingested. Pinocytosis: macromolecules are ingested by a drinking type of action. Medical Helminthology Nematodes Trematodes Cestodes  Nematodes Trematodes Cestodes (Roundworms) (Flukes) (Tapeworms)  Multicellular  Adult forms Macroscopic  Eggs Microscopic  Complex life cycle: ◦ Egg, larva, adult forms  Possess specialized organ systems  Some are human and/or animal parasites  Can be transmitted by water, food & soil or by arthropods  Nematodes Trematodes Cestodes (Roundworms) (Flukes) (Tapeworms)  Unsegmented  Cylindrical body tapered at each end  Body is covered by tough cuticle that resists drying and crushing.  Posses developed digestive & excretory organs.  Have a complete digestive system: contain mouth, intestine & anus.  Separate males and females.  Reproduction: oviparous, ovoviviparous or viviparous.  Oviparous: Produce eggs.  Ovoviviparous: Lay embryonated eggs.  Viviparous: Directly produce live larvae.  Nematodes Trematodes Cestodes (Roundworms) (Flukes) (Tapeworms)  Unsegmented Leaf-like (except Schistosoma) Have two suckers (oral and ventral), which they use to attach within the host Oral sucker contains the mouth Have blind digestive tract Adult form is covered by a tegument (skin)  Generally hermaphroditic (except Schistosoma) Minimum two hosts, one is snail Miracidia and cercariae are infective (invasive) stages Eggs contain lids (except Schistosoma) Adults in liver, intestine, lung & blood Snail:  Nematodes Trematodes Cestodes (Roundworms) (Flukes) (Tapeworms)  Segmented, a ribbon-like structure  Hermaphrodites  Have suckers / teeth that grasp the host  No mouth, no digestive system  Entire uptake of nutrients occurs through the tegument  Adults live in intestine scolex  Adult’s body includes a neck scolex (looks like the “head”), a neck and * strobila *  Strobila consists of segments (proglottids) strobila  Hermaphrodites * ◦ Each proglottid carries a set of female and (*proglottids) male reproductive organs  Most worms are very long: occupying the entire length of small intestine  Gen. eggs have hooks, no lids Medical Entomology  Include ◦ Insects: lice, fleas, flies, mosquitos ◦ Arachnids: mites, ticks, spiders, scorpions ◦ Crustaceans: crabs, etc.  Some of them are parasitic to human  Some of them are important in transmitting infective stages of microorganisms Class: Insecta Class: Arachnida Body division: Head, Body division: Only one thorax & abdomen part Thorax& abdomen Nothorax & abdomen segmentation segmentation One pair of antenna No antenna 3 pairs of legs 4 pairs of legs 0, 1 or 2 wings No wings Lice, fleas, flies, Mites, ticks, spiders, mosquitos scorpions  Direct tissue invasion  Envenomation (exposure to a poison or toxin resulting from a bite of an arthropod)  Vesication (formation of vesicles/blisters in the skin)  Blood loss  Transmission of disease  Mechanical vector  Biological vector  Hypersensitivity reactions  Psychological manifestations  Infestation: is the presence of arthropods on the skin of the host.  Vector: is a living carrier (an arthropod) that transports a pathogenic organism from an infected person to a non- infected host. Biological vector: is absolutely necessary for the evolution and life cycle of the parasite. Example: Female Anopheles mosquito that transmits malaria Mechanical vector: just carries the parasite. Example: House fly (Musca domestica) References:  Medical Microbiology, Ninth Edition, Patrick R. Murray PhD, Ken S. Rosenthal PhD, Michael A. Pfaller MD. Elsevier, 2020.  Sherris Medical Microbiology, Seventh Edition. Kenneth Ryan, Nafees Ahmad, J. Andrew Alspaugh, et al. McGraw- Hill Education / Medical, 2018.  Jawetz, Melnick & Adelberg’s Medical Microbiology, 28th Edition. Stefan Riedel, Stephen Morse, Timothy Mietzner, Steve Miller. McGraw-Hill Education / Medical, 2019.