Intro to Para Flashcards
Any organism that spends a portion or all of its life cycle intimately associated with another organism of a different species is considered as
Symbiont
The relationship is called Symbiosis (symbiotic relationships).
an association in which the one symbiont benefit from the other without causing injury.
Commensalism
an association in which both partners are metabolically dependent upon each other and one cannot live without the help of the other
None of the symbionts suffers any harm from the association.
Mutualism
an association where one of the symbionts 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.
Parasitism
is a living organism, which takes its nourishment and other needs through contact with another species
PARASITE
is an organism which supports the parasite which later develops diseases
HOST
Branch of science that is concerned with the study of the biology of parasites and parasitic diseases, including the distribution, biochemistry, physiology, evolution and clinical aspects of parasites, including the host response to these agents.
Parasitology
- is restricted to studying those parasites that are living in or on the body of human, their geographic distribution, the diseases caused by them, clinical picture and the response generated by human against them.
Medical parasitology or Human parasitology
a parasitic organism that lives on the outer surface of its host, e.g.lice, ticks, mites etc.
Ectoparasite
presence of ectoparasites in the body
Infestation
parasites that live inside the body of their host, e.g. Entamoeba histolytica.
Endoparasites
presence of endoparasites in the body
Infection
a parasitic organism that requires a host to survive and reproduce
Obligate Parasite
Without a host, obligate parasites cannot complete their life cycle and will die.
organism that exhibits both parasitic and non-parasitic (free-living) stages of living and hence does not absolutely depend on the parasitic way of life, but is capable of adapting to it if placed on a host.
Facultative parasite
is one that wanders in to an organ in which it is not usually found.
Ascaris lumbricoides
Erratic or Aberrant parasite
parasites that only visit the host from time to time for feeding
Intermittent/Temporary parasites
organisms that have been swallowed and passed through the alimentary tract without causing any effect
Spurious/Coprozoic parasite
parasite that parasitizes other parasites
Hyperparasite
an object or organism that resembles or is mistaken for a parasite.
Pseudoparasite
a host that harbors a parasite in the adult (sexual) stage or where the parasite undergoes a sexual method of reproduction.
Definitive host
harbors the larval (asexual) stages of the parasite or an asexual cycle of development takes place.
Intermediate host
True or False?
In some cases, larval development is completed in two different intermediate hosts, referred to as first and second intermediate hosts.
True
True or False?
In some cases, larval development is completed takes place in soil and water and there is no need for an intermediate host
True
is when parasites complete their developmental cycle in a single host species
monoxenous life cycles
when parasites require multiple host species
* Definitive hosts
* Intermediate hosts
heteroxenous life cycles
parasite does not require intermediate host to complete its life cycle
Direct life cycle
parasite requires the presence of an intermediate host to complete its life cycle
Indirect life cycle
a host that serves as a temporary refuge and vehicle for reaching an obligatory host, usually the definitive host, i.e. it is not necessary for the completion of the parasites life cycle.
Paratenic host
a host that makes the parasite available for the transmission to another host and is usually not affected by the infection.
Additional sources of infection
Reservoir host
a host that is naturally infected with certain species of parasite.
Natural host
a host that is under normal circumstances not infected with the parasite.
Accidental host
What are the Direct Effects of parasites to the Host?
-Mechanical Injury
-Deleterious effect of toxic substance
-Deprivation of nutrients, fluids, and metabolites
What are the Indirect Effects of parasites to the Host?
-Excessive proliferation of certain tissues due to invasion of parasites
Modes of Transmission of parasites?
-Peroral (Mouth)
-Nasal Passage
-Skin Penetration
-Insect Vectors (Mosquitoes)
-Vertical Transmission (Mother to Baby)
-Sexual Intercourse
-Air-borne
is the stage in the life cycle at which the parasite is able to initiate an infection to it’s host is called the
Infective stage
is the life cycle that exits the definitive host
Diagnostic stage
Time between infection and evidence of symptoms.
Clinical incubation period
Time between infection and acquisition of the parasite as demonstration of the infection
Biologic incubation period
occurs when an infected individual becomes his direct source of infection.
Autoinfection
Happens when the already infected individual is further infected with the same species leading to massive infection with the parasite
Superinfection
Form of reproduction in which an egg can develop into an embryo without being fertilized by a sperm.
is derived from the Greek words for “virgin birth,”
Parthenogenesis
are Y-shaped proteins that recognize unique markers (antigens) on pathogens.
Antibodies or immunoglobulins (Ig)
5 Types of Antibodies
-IgA
-IgD
-IgE
-IgG
-IgM
An antibody that is secreted into mucous, saliva, tears, colostrum. Tags pathogens for destruction.
IgA
An antibody that acts as a B-cell receptor. Stimulates release of IgM.
IgD
An antibody that binds to mast cells and basophils. Allergy and antiparasitic activity.
IgE
An antibody that binds to phagocytes. Main blood antibody for secondary responses. Crosses placenta.
IgG
An antibody that fixes complement. Main antibody of primary responses. B- cell receptor. Immune system memory.
IgM
bind to IgE’s on the surface of the parasite and causes antibody-dependent cell cytotoxicity (ADCC)
Eosinophils
release MAJOR BASIC PROTEIN which is toxic to parasites (larva and adults)
Eosinophils
causes naïve T-cells to differentiate into T helper 2 cells (causes B-cells to become IgE producing plasma cells)
causes increased gut motility to cause expulsion of worms from the GIT
IL-4 (Interleukin 4)
causes goblet hyperplasia with leads to mucus hypersecretion. Parasites will be trapped in mucus.
IL-13 (Interleukin 13)
is produced by T helper 2 cells to increase production of eosinophils in bone marrow.
IL-5 (Interleukin 5)
parasites shed their surface antigens that can neutralize the antibodies away from them
Surface turnover
Parasites such as Schistosoma species cover themselves with host proteins for them to be considered as self and will not be attacked by the immune system
Host mimicry
Some parasites can change their antigenic compositions of their surfaces.
Antigenic variation
Cuticle covering of worms can prevent phagocytosis and protect them from cytokines and complement proteins
Resistance to Intestinal enzymes
Entamoeba histolytica produces suppressor factor which inhibits movement of phagocytes (monocyte locomotion inhibitory factor)
Immune suppression
Toxoplasma, Trypanosoma and Leishmania parasites multiply within the cytoplasm of macrophages thus they can evade phagocytosis
Plasmodium falciparum can make the infected red cells display surface knobs
Intracellular sequestration
The ways that parasites can evade immune responses
-Surface turnover
-Host mimicry
-Antigenic variation
-Resistance to Intestinal enzymes
-Immune suppression
-Intracellular sequestration
Use of antihelminthic drugs in an individual or a public health program
Deworming
Refers to the number of previously positive subjects found to be egg negative on clinical samples using standard procedure
Cure rate
Refers to the percentage fall in the egg counts on clinical samples after deworming
Egg reduction rate
Individual-level deworming with selection for treatment based on diagnosis of infection and severity
Selective treatment
Group level deworming where the group to be treated (w/out prior diagnosis) may be defined by age, sex or other social characteristics irrespective of infection status.
Targeted treatment
Population-level deworming in which the community is treated irrespective of age, sex, infection status or other social characteristics
Universal treatment
Regular, systematic, large scale intervention involving the administration of one or more drugs to selected population with the aim or reducing morbidity and transmission
Preventive chemotherapy
Unicellular eukaryotes
Has nucleus, cytoplasm, membrane and organelles. Some have locomotory apparatus
Protozoans
What are the types of helminthic parasites
*Roundworms (Nemahelminths)
-NEMATODA
*Flatworms (Platyhelminths)
-Flat and Segmented - CESTODA (tapeworms)
-Flat and Unsegmented - TREMATODA (flukes)
Ways of treatment for parasites?
-Deworming
-Cure rate
-Egg reduction rate
-Selective treatment
-Targeted treatment
-Universal treatment
-Preventive chemotherapy
