Introduction to MEDICAL PARASITOLOGY-1 PDF

Introduction to medical parasitology BMS 2.2 Ambrose Shabohurira (MLS,BMLS,PGD HSM, MSc.)  Introduction out line 1. Kay terms and Types of parasites. 2.Types of hosts. 3. Host- parasite relationship. 4. Pathogenesis of parasitic disease 5. Zoonoses 6. Classification...

Introduction to medical parasitology BMS 2.2 Ambrose Shabohurira (MLS,BMLS,PGD HSM, MSc.)  Introduction out line 1. Kay terms and Types of parasites. 2.Types of hosts. 3. Host- parasite relationship. 4. Pathogenesis of parasitic disease 5. Zoonoses 6. Classification of Medical Parasitology. 7. General characters of parasites.  Definitions of key terms Medical Parasitology: is the study of parasites of man and their medical consequences. Parasites: are organisms which live on or within its host (infestation & infection) , for nourishment and physical protection.  Types of parasites 1. Ectoparasite: lives on the surface or within the superficial tissue of the host (e.g. Pediculus, mites). 2. Endoparasite: lives within the host, (e.g. Hookworms). 3. Temporary or intermittent parasite: visits the host from time to time for food (e.g. soft ticks). 4. Permanent or obligate parasite:depends completely on its host for its entire life (e.g. Plasmodium, Enterobius). 5. Accidental parasites: free living organisms which enter the human body by mistake (e.g. larvae of house flies). 6. Facultative parasite: can exist in a free living or parasitic state under unfavorable environmental conditions (e.g. Strongyloides). 7. Specific parasite: affects only one species of host (e.g. Enterobius). 8. Coprozoic or spurious parasites: foreign parasites or stages of non human parasites which havebeen swallowed and  Types of hosts 1. Definitive host (D.H.): harbors the adult stage or sexually mature forms of the parasite e.g. man for Taenia saginata. 2. Intermediate host (I.H.): harbors the larval stages or asexually mature forms of the parasite e.g. man for Plasmodium. 3.Reservoir host (R.H.): carries the adult stage of parasite, and acts as a continuous source for human infection e.g. cats for Heterophyes. 4.Amplifier host: is an I.H. in which asexual multiplication takes place (e.g. snail is for Schistosoma sp.) 5. Paratenic host (transport host): in which the parasite doesn't undergo any multiplication or developmental changes (e.g. Carp fish for oar crustaceans, tadpoles for the trematode Alaria americana). 6. Vector: is an arthropod which transmits the parasites from one host to another (e.g. fleas transmit Pasteurella from rodents to man).  Host-parasite relationship Symbiosis: more or less permanent association of two organisms of different species. This relationship occurs in 4 forms: a.Parasitism: one of the two organisms benefits, on the expense of the other, that suffers from such association (Schistosoma). b.Commensalism: the parasite benefits c. Mutualism: the relationship is beneficial to both associates (flagellates in the intestine of ants that feed on wood). d.Phoresis: in which the phoront is usually the smaller organism and is mechanically transmitted by the other which is usually large (e.g. Dientameoba fragils on Entrobius egg).  Pathogenesis of parasitic infection a)Pathogenic parasite: These cause definite pathological lesions (Ancylostoma).(commensal) b)Non- pathogenic derives food parasite: and without protection from (Entamoeba causing host pathological c)coli). Opportunistic lesions parasite: causes immunologically mild disease in individuals, healthy severe and pathological lesions  Zoonosis Diseases and infections in which the causative agents are transmitted from animals to man.  Anthroponosis: parasitic infection is found in man alone as in trichomoniasis and Entrobiasis. Zooanthroponosis: parasitic infections mainly affect man and animals become infected in life cycle of a parasite as in taeniasis.  Anthropozoonosis: parasitic infection  Classification of zoonotic diseases: 1) According to the source of infection: A-Feral or sylvatic zoonosis: source of infection is a wild animal. Humans become infected when population move to infected B-Domestic area or parasit zoonosis: become exposed these during hunting es transmitted such in African trypanosomiasis. from manown domest ic 2) According to the method of transmission: A-Direct zoonosis: infection is directly transmitted from the vertebrate to man as in trichinosis. B-Saprozoonosis: infection is transmitted via a non developmental site as soil and water as in visceral larva migrans (VLM) and Fasciola. C-Metazoonosis: infection is THANK YOU