Diagnostic Parasitology PDF

Diagnostic Parasitology By Asst. Lec: Hanaa abdul Hussein Forth stage (Lec. 1 )  General term used in parasitology Parasitology: is a branch of the Biological Science, it deals with studying the organisms which have adapted to exist in or on another organism that h...

Diagnostic Parasitology By Asst. Lec: Hanaa abdul Hussein Forth stage (Lec. 1 )  General term used in parasitology Parasitology: is a branch of the Biological Science, it deals with studying the organisms which have adapted to exist in or on another organism that harbor them and give necessary food, so it being termed as the host. Parasite: living organism requiring intimate prolonged contact with another living organism to meet some of its basic nutritional needs. Host: organism harboring a parasite. A zoonosis: is any disease or infection that is naturally transmissible from vertebrate animals to humans. The parasites included in medical parasitology are protozoa, helminthes, and arthropods. Association Between Parasite and Host: 1-Symbiosis This type is seen when such association are useful to both organisms and their existence together is necessary, such as termites and some flagellates in their intestine. 2-Mutualism It is an association is useful to both organisms , benefit from the association if they found together which mean it is not necessary to be associated all the time such as lichens (fungi and algae). 3-Commensalism - an association in which the commensal takes the benefit without causing injury to the host. E.g. Most of the normal floras of the humans’ body can be considered as commensals. 4- Parasitism - an association where one of the partners is harmed and the other lives at the expense of the other. E.g. Worms like Ascaris lumbricoides reside in the gastrointestinal tract of man, and feed on important items of intestinal food causing various illnesses. Types of Parasites Parasites divided in general depending on: 1- Hosts number in the life cycle as: ** Monoxenous parasites As Eimeria sp. which has a direct life cycle. ** Heteroxenous parasites As Fasciola sp. Which has indirect life cycle. 2- As to their dependence on host: ** Obligatory parasites An organism that cannot survive in any other manner and died without its host, such as miracidium of Schistosoma and its peculiar snail and tape worm, Taenia saginata. ** Facultative parasites An organism that may exist in a free- living state or parasitic state when changeable conditions occurred, such as Strongyloides spp. ** Incidental parasites It is obligatory parasites invade a stranger host and complete their life cycle, such as Fasciola of sheep and it may be parasitic in human. 3-According to their habitat on the host as: A- Ectoparasites: Mostly from insects such as: ** Permanent parasites Which found attached continually on the surface of host, such as lice and ticks. ** Temporary parasites Which visits the host for feeding only, such as mosquitoes B- Endoparasites Lives inside the systems and tissues of host body, mostly from helminthes Types of host 1- Definitive host It is the host that harbors the adult or the sexual stages of parasite. 2- Essential host It the final host that the parasite preferred than the other hosts. 3- Carrier host It is an essential host which shows the infection symptoms clearly at first then disappear, and for the continuous re-infection, it has an acquired immunity that the symptoms doesn't appear visibly again, it mostly work as a parasite distributor. 4- Incidental host It is the host not preferable for the parasite and getting infection in incidental conditions. 5- Intermediate host It is the hosts carry the immature or asexual stages of parasite. 6-Vector host It is the host that transports the parasite stages helping to increase its prevalence, and it can be: ** Mechanical vector:That no changes happen to the parasite stages inside or outside the hosts, suchas house fly which carry eggs of parasites or cysts of protozoa through its legs. ** Biological vector: That some changes would happen to the parasite stages, such as mosquitoes carried the malaria parasite.  Life cycle Life cycle: The sequence of morphologic and environmental stages is referred to as the life cycle. for survival and reproduction reasons many parasites evolve through a number of morphologic stages and several environments or different hosts. Types of life cycle: 1-Indirect life cycle: require different type of host or vector (intermediate host) for various stages of their life cycle. 2-direct life cycle: in which a parasite is transmitted directly from one host to the next without an intermediate host or vector of another species.  Classification Of Medical Parasitology All parasites are classified within the taxonomic units: (kingdom, sub-kingdom, phylum, subphylum, supra-class, class , subclass, order, suborder, superfamily, family, genus and species). The scientific name of the parasite should written in Italic Letter or under lined, and begin with a capital letter for the genus name and a small letter for the name of the species, for example, Entamoeba histolytica. Medical Parasitology is generally classified into: Medical Protozoology - Deals with the study of medically important protozoa. Medical Helminthology - Deals with the study of helminthes that affect human. Medical Entomology - Deals with the study of arthropods which cause or transmit disease to human. Classification Of Parasites Pathogenesis : the origination and development of a disease. Degree of injury depends on several factors: 1) Potential virulence of the agent (i.e. its intrinsic pathogenecity). 2) A mount of inoculum & rapidity of multiplication. 3) The site of inculation. 4) Exposure is single or repeated. 5) General resistance of the host. 6) Type of damage caused by agent, which either: Mechanical, Lytic, Toxic & Allergic. Diagnosis: Diagnosis of parasitic diseases depends on 2 parts: 1) Clinical features: like fever, pain. 2) Laborator y diagnosis to: a) Detect the presence of eggs, larvae, cysts (in stool, urine, blood ,sputum). b) Distinguished these stages from each other. c) Find out whether it is the causative agent or coincidental. Epidemiology:Is the science concerned with factors which determine the prevalence of infection & incidence of disease. Prevalence: Is define as the number of infected individuals at a given time in a designated area. Incidence: Is the rate or frequency with which a disease (new infection) occurs. Parasitic disease may be grouped epidemiologically ( source of infection ) as follows: 1) Filth-borne or contaminative : Like intestinal protozoa, helminthes. 2) Contracted from soil or water: Like eggs of Ascaris. 3) Food-borne infections: Like Taenia spp. 4) Arthropods-borne infection: Like Malaria- Leishmania 5) Infestation by arthropods : Like the Lice. 6) Arthropod envenomation: Like the bite of Scorpion.