If there is more than one intermediate host, this could be classified as first and second and so on.
Introduction to parasitology
• Phoresis, commensalism, mutualism, andparasitism• If we consider the degree of theassociation, then phoresis andcommensalism represent “loose”associations, where as mutualism andparasitism indicate “intimate” associations
1 .Phoresis (Phoresy)• Phoresis means “to carry.”• A type of symbiotic relationship in which oneorganism (the smaller phoront) is mechanically carriedon or in another species (host).
2. Commensalism• Means “eating at the same table”• Occurs when one member of the associatingpair, usually the smaller, receives all the benefit and theother member is neither benefited nor harmed Branchiobdelid worm attached to a crayfish
3. Mutualism• Occurs when each member of the associationbenefits the other• Mutuals are metabolically dependent on oneanother; one cannot survive in the absence ofthe other• Often included as a special subcategory ofmutualism is cleaning symbiosis • In this relationship, certain animals known as cleaners, remove ectoparasites, bacteria, diseased and injured tissue from cooperating hosts Honeybee bringing pollen to a desert shrub
4. Parasitism• Parasitos (para: beside; sitos: grain or food)•Definitions of parasitism have traditionally focusedupon some ecological aspect of the parasite-hostinteraction Anterior end of a hookworm
Parasite -refers to organism thatlives in or on other livingorganisms (Hosts), at whoseexpense the parasite gain someadvantages of obtaining shelterand food.
In this course we willconcentrate on 3 major groupsof parasites: 1. Protozoa-flagellates, amebas, malarial organisms2. Helminths - parasitic wormssuch as the flukes, tapeworms, androundworms 3. Arthropods - insects andarachnids that are ectoparasitesand carriers (vectors) of diseases
Human parasites are either unicellular(protozoa)or multicellular (helminthes andarthropods. Accdg. to their habitat: Endoparasites: Parasites that live within (inside) the body of other organisms. Ectoparasites: Parasites that exist on the body surface (outside the host`s body) of other organisms Erraticparasites– a parasite found in an organ which is not its usual habitat.
Accdg. to their mode of development: • OBLIGATE PARASITES – needs a host at some stage of their life cycle to complete their development and to propagate their species. *Tapeworms which depend entirely upon their host for existence. • FACULTATIVE PARASITE – capable of free-living existence and may become parasitic when the need arises.
• ACCIDENTAL/INCIDENTAL PARASITE – establishes a relationship to a host where it does not normally live.• PERMANENT PARASITE – spends most or the rest of its adult life cycle on or in its host.• TEMPORARY/INTERMITTENT PARASITE – lives on or in the parasite only when the need arises.• CUPROZOIC/SPURIOUS PARASITE – free- living parasite which passes thru the alimentary tract without infecting the host.
HOST AND TYPES OF HOST Hosts: The organisms that harbor the parasites and may suffer a loss such asdiseases caused by the harbored parasite. A host is determined and differentiated according to their role in the life cycleof the parasite.
TYPES OF HOST Definitive host: The host in which the parasite survives its adult andsexual stages. Intermediate host: The host in which a parasite lives a larval or asexualstage as apart of its life cycle. Paratenic/ transport host– bridges the gap between intermediate anddefinitive host. Reservior host – hosts that allow the parasite’s life cycle to continue andbecome an additional source of human infection.
causes injury PARASITES ----- harbour in -------- HOST produce an immune response
E F F E C T S O F PARASITE T O T H E H O S T PATHOLOGICAL EFFECTS: Deprives the Host of its Esential Nutrition Hookworms Suck blood Anemia Mechanical Effects of the Parasite on the Host Ascaris Perforate/Obstruction Toxic and Immunological Effects Protozoa Proteolytic Enzymes Necrosis OTHER EFFECTS: Causes Social “stigma” and inconvenience
EFFECTS OF THE HOST TO THE PARASITE Immune Response Damages the Parasite Auto-antibodies serve as protective barriers • Sicke-cells and Duffy Blood Groups Nutrition of Host Affects Parasite Growth