Introduction to Medical Parasitology PDF

Introduction To Medical Parasitology Prepared by: Dr; Mohamed Lashal Lecturer of medical Parasitology Introduction To Medical Parasitology What is Parasitology??? It is the study of parasites, their hosts, and the relationship between them. Loading… Medical Parasitology: Medical Parasitology is that...

Introduction To Medical Parasitology Prepared by: Dr; Mohamed Lashal Lecturer of medical Parasitology Introduction To Medical Parasitology What is Parasitology??? It is the study of parasites, their hosts, and the relationship between them. Loading… Medical Parasitology: Medical Parasitology is that branch of medical science deals with parasitic organisms which cause human infections and the diseases they produce. Parasites living organism that depends on its host for survival and protection -Parasite : is a living organism which depend on another organism (host) for their feeding, survival and protection then harming it and possibly causing death. -. An association between two living organisms (host organism relationship): Parasitism: one organism (Parasite) lives at an expense of (benefits) the other Host to obtain its nourishment and physical protection causing variable injuries to its host (harmed). Commensalism (Latin ward means eating at the same table) one partner is benefited (Commensale) and the other is neither benefits nor affected (Host). Mutualism: both organisms are benefited from association. Symbiosis: permanent association of two organisms that can not live independently, symbiosis means (Living together). Types of parasites There are various types of parasites, according to their location, including : Ectoparasite: when parasite lives on the outside (surface) of the host ,this is known as (Infestation). Lice Endoparasite: when parasite lives within the body of the host, this is known as (Infection), when infection causes clinical manifestations it is termed as a disease. (all protozoan and helminthes). Ticks Helminths Mosquito Protozoa Types of parasites Facultative Obligate parasite: parasite: may exist either an organism that in a free living can not survive in state or as a a free living i.e. parasite.i.e. completely Naegleria dependent upon Fowleri its host.i.e. plasmodium species Incidental parasite( Accidental parasite): Temporary parasite: free living but seeks its host intermittently to obtain nourishment. i.e. mosquitoes Loading… establish itself in a host in which it does not ordinarily live. i.e. hydated disease Permanent parasite: remains on or in its host until maturity or for its entire life Opportunistic (parasites) Infection: Certain parasites either fail to infect persons with normal immune mechanisms or cause asymptomatic to mild and self limited infection. In the other hand these parasites may cause devastating disease in persons with lowered immunity (Immunocompromised). Examples: 1-Entamoeba histolytica 2-Giardia lambilia 3-Isospora belli 4.T. Gondi 5-Leishmania sp. 6- pneumocystis jiroveci. 7-Srtongyloides stercoralis. 8.Crypotosporidium parvum. 9. Microspora These parasites (opportunistic) also may undergo reactivation after latent infection from a previously acquired infection if immune system of the human is suppressed by any cause like: neoplastic disease ,organ transplantation ,AIDS , use of immunosuppressive Types of Hosts Host : it an organism which harbour the parasites and provide feeding and protection Types of hosts; 1) Definitive Host: the final host harbours the adult or sexual stage of the parasite. 2)Intermediate 3)Reservoi 4)Accidental 5)Dead end 6)Paratenic Host: in r Host: Host: the Host: host Host : in which part or all of the larval or asexual stage of the parasite some may need 2 parasites for their life cycle, first and second intermediate host. an animal that harbours the same parasite as man ,thus acts as a source of human infection host in which the parasites is not ordinary life on or infect. which cannot transmit parasites to antother hosts. which parasite dose not undergo any developmen t , but remains a live and infective to another host. Vectors: the transmitter of the parasite. -MB Biological vectors transmit the parasites -MB to the host but it is Its usually Mechanical vector essential in the life arthropods transmit the parasites cycle of the parasite which play role to the host but it is not e.g. Yersinia pestis in essential in the life flea, and all type of in the cycle of the parasite, it transmission of is simply the transport bacteria and viruses, and rickettsia. of organisms from one disease agents place to another.e.g. propagative vector from human to housefly (Musca Cyclopropagative vector domustica) human and Cyclodevelopmental animal to vector Vectors human Types of life cycle of the parasite Direct life cycle, the parasite only requires one host to complete its life cycle. For example, the intestinal protozoan parasite Giardia lamblia has a direct life cycle involving only humans or other animals. Indirect life cycle, the parasite requires multiple hosts to complete its life cycle. For example, the tapeworm's life cycle involves both a definitive host, where the adult worm lives, and an intermediate host, where the larval stage of the worm develops Soil polluted with embryonated eggs (roundworm, whipworm) may be ingested or infected larvae in soil, may penetrate exposed skin (hookworm). Water; infective forms of parasites present in water may be ingested (cyst of amebae and Giardia). -penetrating exposed skin (cercariae of Schistosomes). - Free-living parasites in water may directly enter through vulnerable sites (Naegleria may enter through nasopharynx). Food: Ingestion of contaminated - food or vegetables containing infective stage of parasite (amoebic cysts, Toxoplasma oocysts, Echinococcus eggs). -Ingestion of raw or undercooked meat harbouring infective larvae (Cysticercus cellulose, the larval stage of Taenia solium). Vectors: A vector is an agent, usually an arthropod that transmits an infection from man to man or from other animals to man, e.g. female Anopheles is the vector of malarial parasite. Mode of parasite transmssion Direct Transmission: occurs when the parasite is spread directly from person to person or from animal to person through physical contact. This can happen through skin-to-skin contact, contact with bodily fluids, or through the air..Skin-to-skin contact (Scabies). Sexual contact (Trichomonas vaginalis & pubic lice). Contact with bodily fluids (blood transfusion, shared needle, lab accident). Indirect transmission: occurs when the parasite is spread through contaminated objects or surfaces..Contaminated objects (pinworm & head lice). Contaminated soil (Hook worms (skin penetration) & toxoplasmosis). Food and water (Giardiasis & cryptosporidiosis). Vector (Malaria, leishmania) Congenital transmission (vertical) from mother to fetus.. Factors affecting parasitic infection Depends on detection of specific antigen of the parasite, antibodies & nucleic acid sequence of the parasites Parasitic factors: Virulence of the infecting strain of the parasite. Intensity of infection Host factors: Immune status of the infected person Age Occupation Economic condition Genetic Health education Environmental conditions Zoonotic Infection: when parasitic disease normally transmitted only among animals and human infection is incidental, the disease in this case is referred to as Zoonosis. Man is known as dead-end host if the cycle for transmission of the parasite can not be transmitted further Classification of medically important parasites are... are insects ? Helminthes (worms) Protozoa Joef ] ] - Loading…