Parasitology Introduction Parasitology: It is the science that deals with organisms that live on or within other organisms (Hosts). Mainly in this course branch we study the parasites which live on the expense of man. The relationship between two living organisms may be one of the following:1 Mutualism 2 Symbiosis 3 Commensalisms 4 Parasitism Continue Mutualism:Mutual benefits is derived from the association of these organisms Benefit Benefit two Continue Symbiosis: Mutual benefit , and the two organisms can not live independently (physiological relationship). Benefit Benefit Continue Commensalisms:One partner benefits (commensal) while the other (host) is unaffected. It may be called a non-pathogenic parasite. Benefit No harm ,No benefit Continue Parasitism:One organism (parasite) lives at the expense of the other (host) which usually suffer from the association. It is called a pathogenic parasite. Benefit Harm Parasitism Parasite Host Types of Parasites Continue 1. Ectoparasite:- Live outside the body of the host (infestation). e.g. Lice 2. Endoparasite:Live inside the host (infection). e.g. most of human parasite Continue 3. Facultative Parasite:- Capable of leading both a free-living and a parasitic existence (live parasitically or none parasitically). 4. Obligate Parasite:- Completely dependent upon its host and can not lead a free life. Continue 5. Temporary Parasite:- Parasitic only during part of its life cycle. 6. Permanent Parasite:Live parasitically during the whole life cycle. Continue 7. Incidental Parasite:- Can establish itself in a host in which it does not ordinary (occur in abnormal host). 8. Pseudoparasite:- A certificate mistaken as a parasite. live Continue 9. Specific Parasite:- Occurs in one particular host. 10.Pathogenic Parasite:- Causing injury to the host. Continue 11. Coprozoic Parasite:- [copro= faeces] Parasite passes the alimentary canal without infection faeces after release. or contaminant Types of Hosts Continue 1. Definitive Host (final or terminal):- Harbours the adult or mature parasite. In which parasite sexually if it applicable. can reproduce Continue Definitive Host І Main Host ІІ Secondary Host ІІІ Accidental Host Continue I. Main Host:In which the parasite occur more frequently and reach maturity. II. Secondary Host:In which the parasite occur less frequently and growth is retarded. Continue III. Accidental Host:In which its occurrence and development is very difficult. Continue 2. Intermediate Host:- Harbours the immature stage of the parasite (larval stage) that reproduce asexually into infective stage. 3. Reservoir Host:- Animal that harbours the same species of parasites as man and constitute a source of infection to him. Factors Affecting Prevalence & Geographical Distribution of the Parasites Continue 1. Availability of suitable hosts and their habits. 2. Immune status of the hosts. 3. Easy entry & exit of the parasite to and from the host. 4. Regional habits. 5. Socio-economical status. Continue 6. Education [knowledge about parasites reduce the infections rates] 7. Environmental sanitation [water, food, waste disposal,…..] 8. Suitability of the environmental and climatic conditions. Continue 9. Control of intermediate hosts, treatment of infected cases….ect. 10. Nature of life cycle [e.g. parasites with simple life cycles have more distribution than with complicated cycles]. General Modes of Parasites Transmission Continue 1. Congenital (through placenta) e.g. malaria 2. Direct Leshmania, Contact. [e.g. Tichomonas & arthropods, Entamoeba gingivalis ]. 3. Indirect contact (in contaminated objects). [e.g. amoebic cyst, helminthes egg as of H. nana , Taenia , Entrobius]. Continue 4. In food as most parasites are intestinal and their infective stage reach food either: • In flesh: [e.g. T. saginata & T. solium]. • In contaminated water [e.g. vegetable with protozoa cyst & helminthes egg]. • Contamination by [e.g. mechanically by housefly]. • Contamination by food handler. insects Continue 5. In water: water drinking with helminthes containing contaminated protozoa egg the or cyst using intermediate or water host, infective stage [e.g. Schistosomiasis]. 6. Contaminated soil [e.g. Ancylostoma]. 7. Animals [e.g. Toxoplasmosis (cat)] dog worm (dog), Continue 8. Arthropods: - Transmission occurs either:• Mechanically [e.g. faecal cyst & eggs to food by house fly]. • Biologically [e.g. malaria & filariasis ( by mosquitoes), sleeping sickness (by Tsetse (by sand fly)] fly) & Leishmaniasis Continue Praziquantel is very safe, taken as a single or divided dose according to the worm type. Dose is calculated according to the patient weight. Praziquantel is swallowed, not chewed; as it is very bitter in taste.