Introduction to Parasitology (Protozoa & Helminths) PDF

‫كلية الطب‬ Introduction to Parasitology (Protozoa & Helminths) (Lectures 17 & 18) Dr. Sozan Mohamed Fadl Head of Microbiology & Immunology Unit  Definitions Parasites: Protozoa, helminths, and arthropods. Types of hosts: Defini...

‫كلية الطب‬ Introduction to Parasitology (Protozoa & Helminths) (Lectures 17 & 18) Dr. Sozan Mohamed Fadl Head of Microbiology & Immunology Unit  Definitions Parasites: Protozoa, helminths, and arthropods. Types of hosts: Definitive host: Sexual cycle Intermediate host: Asexual cycle. Infective stage: The stage that enters the human body to cause the infection. Diagnostic stage: The stage found in the samples Protozoa Loading…  Protozoa Protozoa are unicellular, eukaryotic organisms. Protozoa are measured in microns (2-150 µm). Reproduction: mostly asexual (binary fission) or sexual. Most protozoa have two stages: – Cyst: dormant, immotile, survive in the environment. – Trophozoite: motile, actively feeding, and reproducing. Classification:  Amoeba Flagellates Ciliophora Sporozoa motile by motile by Flagella motile by Obligate pseudopodia cilia intracellular parasites. Forms: Cyst Forms: Cyst and Forms: Cyst Forms: Many & trophozoite trophozoite & trophozoite Entamoeba Giardia lamblia: Balantidium Plasmodium histolytica Disease: Loading… GIT (diarrhea) Trichomonas coli: Balantidial Malaria Transmission: Amoebic vaginalis: urethritis dysentery Anopheles dysentery & vaginitis. Mosquitoes bite. Trypanosoma: Transmission Transmission: Blood & tissue: : Fecal-oral Toxoplasma Fecal-oral (sleeping sickness) Definitive host: Leishmania: cats (cutaneous  Entamoeba histolytica Mode of transmission: Fecal-oral Giardia lamblia Mode of transmission: Fecal-oral Trichomonas vaginalis Mode oof transmission sexual contact Trypanosoma Leishmania. Transmission: Transmission: Arthropod-born: Arthropod-born: Sand-fly tsetse fly  Balantidium Mode of transmission: Fecal-oral  Plasmodium falciparum Transmission: Arthropod-borne Female Anopheles mosquito Loading…  Toxoplasma gondii Definitive host: Cats 4 5 1 2 3 Helminths  Helminths Multicellular organisms. Stages of life: – Adult worms – Larvae Larvae Adult worms Eggs – Eggs Routes of transmission: – Ingestion of eggs (fecal-oral). – Ingestion of larvae in undercooked meat. – Skin penetration by the larvae. Definitive host: harbors the adult worm with/without  larvae Helminths Flat Round Cestodes Trematodes Nematodes (Flukes)  Cestodes (Tapeworms) Flat, segmented, hermaphrodites Length range 2 mm-15 meters. Body parts: – Scolex: carry organ of fixation (suckers +/-hooks). – Neck – Segments: contain male and female sexual organs. Examples: o Taenia saginata (beef tapeworm) o Taenia solium (pork tapeworm) o Diphyllobothrium latum (fish tapeworm) Infective stage: larvae Diagnostic stage: eggs a Larvae in cow’s meat T. saginata & T. solium Eggs Adult worms in intestine Diphyllobothrium Latum  Diphyllobothrium Cestode Taenia saginata Taenia solium latum Consumption of Consumption of Consumption of Transmission larvae in larvae in larvae in undercooked undercooked undercooked beef pork freshwater Disease Vitamin B12 GIT symptoms deficiency Diagnostic stage Definitive host Intermediate host  Trematodes (flukes) Flat, leaf-shaped, non-segmented, unisexual. Examples: Schistosoma mansoni: intestinal bilharziasis Schistosoma haematobium: urinary bilharziasis Infective stage: larvae. Diagnostic stage: eggs Intermediate host: snails  Nematodes Cylindrical, unisexual worms. Infectious Example Diagnostic stage stage Ascaris lumbricoides Eggs Enterobius vermicularis Ancylostoma duodenale Larvae Eggs (hook worms) Trichinella spiralis Larvae Ascaris lumbricoides: Site of infection: small intestine Infective & diagnostic stage: egg. Enterobius vermicularis: Pin Worm Site of infection: Large intestine Infective & diagnostic stage: egg. Disease: perianal itching in children. D-shaped Egg (diagnostic stage) Hookworm: Infective stage: Larvae (skin penetration). Complication: blood loss→ anemia. Trichinella spiralis: Transmission: eating encysted larvae in undercooked pork.  Infectious Diagnostic Classification Example stage stage Taenia saginata Cestodes Diphyllobothrium latum Taenia solium Larvae Eggs Trematodes Schistosoma Ascaris lumbricoides Enterobius vermicularis Ancylostoma duodenale Larvae Eggs Nematodes Eggs Trichinella spiralis Eggs Larvae Larvae  Reference Essentials of Medical Microbiology, 3rd edition, chapter 45&46; pages 427-469, chapter 49; pages 491-500. Lippincott Illustrated Microbiology 4th Loading… edition, Chapters: 22.