Introduction to Medical Parasitology PDF

INTRODUCTION TO MEDICAL PARASITOLOGY Dr. Özge YILMAZLI Medical Microbiology Dept. PARASITE • In a part or all of it’s life, it lives on or in host cell (body cavities, tissues or cells, …) - and it is able to grow and reproduce in there • They always harmful pathogens PARASITISM PARASITISM is...

INTRODUCTION TO MEDICAL PARASITOLOGY Dr. Özge YILMAZLI Medical Microbiology Dept. PARASITE • In a part or all of it’s life, it lives on or in host cell (body cavities, tissues or cells, …) - and it is able to grow and reproduce in there • They always harmful pathogens PARASITISM PARASITISM is a relationship which a host provides benefit to parasite; parasite causes harm to host A branch of science that investigates parasite, host and parasite-host relationship is called PARASITOLOGY SYMBIOSIS • Symbiosis means coexistence of different life forms and is seperated in 3 different groups: • Parasitism: -It is a situation which a pathogen lives on or in a host with harming it. • Mutualism: -It is a situation which two life forms live in common benefit from this relationship. • Commensalism: -It is a situation that one of the two partners benefit from another, but the other one is not affected positively or negatively from this relationship. EXAMPLES… • Entamoeba hartmannii lives in human large intestine (Commensalism) • Bacteria that live in human gastrointestinal tract (Mutualism) • Ascaris lumbricoides that lives in human small intestine (Parasitism) PARASIT-HOST RELATION • Monoxene Parasite: - A single host is enough for them to complete their life cycles - Giardia intestinalis, Ascaris lumbricoides • Heteroxene Parasite: - Requires multiple hosts to complete it’s life cycle - Taenia saginata (in humans and cows) • Absolute Host; • It is the host which adult form of parasite lives PARASITHOST RELATION • Human is the absolute host for Taenia saginata • Intermediate Host; • The host that carries immature form of parasite • Human intermediate host for Echinococcus granulosus PARASIT-HOST RELATION • Vector; • It is an invertebrate that carries the causative agent from sick vertebrate to non-sick. • Female Anopheles for malaria • Polyheteroxene; • Parasites that require different intermediate hosts of different species to complete their life cycles • Mollusc and fish are intermediate hosts for Diphyllobothrium latum PARASIT-HOST RELATION • Hyperparasitism; • It is the case that parasite in host also has a parasite • The blood-sucking Anopheles also contains the Plasmodium parasite. • Ectoparasite; • They live under the skin and it is not called as an infection; it is called as a infestation • Sarcoptes scabiei (scabies) PARASIT-HOST RELATION • Parasite Infection; • It is the infection caused by endoparasites • Entamoeba histolytica (amoebic dysentery) infection • Superinfection; • The condition of being infected with a parasite and being re-infected with a parasite of the same species. • Enterobius vermicularis infection • Autoinfection; • Infection of host with parasite present in it • • • • Protozoa Helminths Amoebaes Flagellates Sporozoons Ciliates • Nematodes • Trematodes • Cestodes Arthropods • • • • • • Mosquitoes Fleas Lice Ticks Scorpions Scabies PROTOZOA • They are unicellular, non-photosynthetic eukaryotic microorganisms. • There are some that live freely in seas, fresh waters and moisture places. • Some of them are intracellular parasites and some of them are extracellular parasites in blood, urogenital tract or digestive tract. • Reproduction is usually achieved by division into two (mitosis). • Many have a rigid membrane around them. Thus, they become more resistant to environmental conditions. These forms of protozoa are called CYSTS. • Shapes that do not have a wall structure, are mobile, can take nutrients from external environment are called TROPHOZOID. • Cyst form is responsible from infectivity and trophozoid form is from disease CLINICAL CLASSIFICATION Gastrointestinal Tract • Entamoeba histolytica (amoebae) • Giardia intestinalis (flagellated) • Cryptosporidium parvum (sporozoon) • Balantidium coli (Ciliates) Urogenital • Trichomonas vaginalis (flagellated) Blood and Tissue • Plasmodium species (sporozoon) • Babesia species • Toxoplasma gondii (sporozoon) • Trypanosoma cruzi (flagellated) • Leishmania donovani (flagellated) • Free living amoeba MICROBIOLOGICAL CLASSIFICATION • I. Sarcomastigophora: • A) Sarcodina: The protozoans with pseudopods • E.g.; Entamoeba, Acanthamoeba ve Naegleria species • B) Mastigophora: Flagellated protozoans • E.g.; Giardia, Leishmania, Trypanosoma ve Trichomonas MICROBIOLOGICAL CLASSIFICATION • II. Ciliophora: • Ciliates E.g.; Balantidium coli • III. Apicomplexa: • They are spore-forming protozoa of class Sporozoa • E.g.; Plasmodium, Babesia,Toxoplasma, Isospora ve Cryptosporidium HELMINTHES Helminths that cause diseases in humans and animals (worms), Multicellular and eukaryotic organisms 2 filums Platyhelminthes (flatworms): Trematoda (flukes) and Cestoda (tapeworms) Nematyhelminthes (roundworms) PLATYHELMINTHES (FLATWORMS) • This filum consist of Trematoda (flukes) and Cestoda (tapeworms) • All obligate parasite • Except Schistasoma genus (Trematode class), they are hermaphrodites. • Respiratory and circulatory systems are absent • The bodies of trematodes are one-piece leaf-shaped. • Cestodes have 3 different regions: head (scolex), neck and rings (proglottid). PLATYHELMINTHES (FLATWORMS) • Cestodes (tape worms) • Taenia saginata • Taenia solium • Echinococcus granulosus • Echinococcus alveolaris • Diphyllobothrium latum • Hymenolepis nana Trematoda (fluke worms) Schistosoma Fasciola hepatica • Cestodes generally have a mammalian intermediate host and a final host. • 2 exceptions; Diphyllobothrium latum has multiple intermediate hosts CESTODES • Hymenolepis nana does not use intermediate host. • The final host for Taenia saginata is only humans • Eggs of Taenia. solium are infective for humans. When an intermediate host ingests egg, in tissues, cysticercus (young taenia) develops. Taen ia sag in at a Ech in ococcu s g r an u losu s • Mostly seen in Far East and tropical countries • Cestode infections are more common than trematodes in community. TRE M ATO DA ( F L UK E WORM S ) • Trematodes other than schistosomes are hermaphrodite. • Oval eggs are yellowish brown and capped. Schistosoma eggs do not have a cap. Fasciola hepatica Schistoma haematobium NEMATYHELMINTHES (ROUND WORMS) • They are long, filamentous and cylindrical parasites. • Fully differentiated males and females • They have a full digestive tract consisting of mouth to anus! • Females are longer than males • Adults have an acellular cuticle layer that provides resistance to external factors on their bodies. NEMATYHELMINTHES (ROUND WORMS) • İntestinal tract The adult is in gut, the larvae is in tissue. • Ascaris lumbricoides • Enterobius vermicularis • Necator americanus • Trichuris trichuira Tissue Wuchereria bancrofti Loa loa Dranculus medinensis Toxocara canis ve T. cati Strongyloides stercoralis Trichinella spiralis Ascaris lumbricoides Enterobius vermicularis • Myriapoda • Pentastomida A RT H RO P O D S • Crustacea – such as crabs • Chelicerata (Arachnida) – mites, ticks, spiders and scorpions • Insecta – fly, mosquito, midge, flea, lice and ant • Taenia saginata is the most common causative agent of cestode infection SPOT INFORMATION • Longest cestode : Diphyllobothrium latum (25m) • Smallest cestode : Hymenolepis nana (2-5cm) • The longest nematode in gut : Ascaris lumbricoides (15-35m)