Introductory Concepts of Parasitology 2 Flashcards
Living together of unlike organisms
SYMBIOSIS
Refers to the association of two species for food and shelter
SYMBIOSIS
a symbiotic relationship in
which two species live together and one species benefits from the relationship without harming or benefiting the other
Symbiosis
Commensalism
Denotes an association that is beneficial to one partner and
at least not disadvantageous to the other
Symbiosis
Commensalism
Entamoeba coli lives in the lumen of the intestine
SYMBIOSIS
Commensalism
Occurs when associations are beneficial to both organisms
Symbiosis
Mutualism
a symbiosis in which two organisms
mutually benefit from each other
Symbiosis
Mutualism
Termites and Flagellates in their digestive system, which
aids in the breakdown of ingested wood by synthesizing
cellulase
Symbiosis
Mutualism
symbiotic relationship where one organism, the parasite, lives in or on another, depending on the latter for its survival and usually at the expense of the
host
Symbiosis
Parasitism
Necessarily involves an intimate relationship between the two species (Close and prolonged contact)
Symbiosis
Parasitism
Entamoeba histolytica, which derives nutrition from
the human host and causes amebic dysentery.
Symbiosis
Parasitism
“To carry”
Phoresis
In Phoresis, No physiologic interaction is involved between the ____ and _______
host and
phoront
In Phoresis, host is a _____________
mechanical vector
An area of biology that deals with the dependence of one
organism on another
PARASITOLOGY
The study of parasites, its hosts, and their relationships
Parasitology
concerned primarily with
parasites of humans and
their medical significance,
as well as their importance
in human communities
Medical Parasitology
Where can you find parasites
Mostly in poor, developing countries
Millions of people are affected worldwide
PARASITES
NTDs meaning
Neglected tropical diseases
Characteristics of Parasitic Disease
- Prevalence in developing countries; in lower socioeconomic population
- Low mortality and morbidity
- Limited drug development
- No current vaccines
Species which harbors the parasite
HOST
The organism that provides physical protection and nourishment to the parasite
HOST
The organism that provides physical protection
and nourishment to the parasite
HOST
Different Types of Hosts:
- Final / Definitive Host
- Intermediate Host
- Vectors
- Accidental Host
- Paratenic Host (Transfer Host)
- Dead-end Host (Incidental Host)
- Reservoir Host
Harbors the adult or sexually mature stage of the parasite
Different Types of Hosts
Final / Definitive Host
usually the Definitive Host
Different Types of Hosts
Man
Human is the _________ for lymphatic
filarial worms that cause elephantiasis and
trypanosomes that cause African trypanosomiasis
Different Types of Hosts
definitive host
Harbors the larval stages or asexual forms of the parasites
Different Types of Hosts
Intermediate Host
Ex. Lower animals, vegetation
Different Types of Hosts
Intermediate Host
Harbors the early larval
stage of the parasites
Different Types of Hosts
First Intermediate Host (1st IH)
Harbors the infective
larval stage of the parasite
Different Types of Hosts
Second Intermediate Host (2nd IH)
Responsible for transmission; may also become hosts
Different Types of Hosts
Vectors
morphologic change or
transformation of the parasite before transmission to another host
Ex: Aedes
Different Types of Hosts
Biologic Vector
no morphologic change occurs on the parasite
Ex: Cockroaches and Flies
Different Types of Hosts
Mechanical Vector
Harbors a parasite that usually does not infect it
Different Types of Hosts
Accidental Host
Not part of the life cycle; parasite does not completely mature
Different Types of Hosts
Accidental Host
one in which the parasite does not develop further to later stages but remains alive
and can infect other hosts
Different Types of Hosts
Paratenic Host (Transfer Host)
Harbors the parasite in an underdeveloped or in arrested
state of development; part of the parasite’s life cycle
Different Types of Hosts
Paratenic Host (Transfer Host)
It will only continue the life cycle if the paratenic host is consumed by a susceptible definitive host
Different Types of Hosts
Paratenic Host (Transfer Host)
Example of Paratenic Host (Transfer Host)
Different Types of Hosts
Wild boar
What is the 2nd Intermediate host of Paragonimus westermani
Different Types of Hosts
Fresh water prawn/crab
Wild boar is the paratonic host for ___________
Different Types of Hosts
Paragonimus westermani
Host that does not allow the life cycle of the parasite to
continue
Different Types of Hosts
Dead-end Host (Incidental Host)
Humans consume food that contains the larvae of the parasite (pig) are the dead end host for _____________
Different Types of Hosts
Trichinella spiralis
Host other than the parasite’s usual hosts that allows the
life cycle to continue
Ex: Pigs, field rats, cats, beavers
Different Types of Hosts
Reservoir Host
allow the parasite’s life cycle
to continue and become additional sources
of human infection
Different Types of Hosts
Reservoir host
Alternative host to a parasite that is harbored normally by
humans
Different Types of Hosts
Reservoir Host
Acts as an additional source of infection
Different Types of Hosts
Reservoir Host
no human cases; ongoing transmission
Eliminate
no human cases; no ongoing transmission
Eradicate
Organisms that depend on the host for survival
PARASITE
Parasite that always require a host for it to survive
TYPES OF PARASITES
Obligate
Cannot survive in any other manner in the absence of a
host
TYPES OF PARASITES
Obligate
Example of obligate parasites
TYPES OF PARASITES
- Ascaris
- Hookworms
- Trichuris
May exist in a free-living state or as a commensal and that,
if opportunity presents itself, may become parasitic
TYPES OF PARASITES
Facultative
Has a free-living and a parasitic phase
TYPES OF PARASITES
Facultative
Example of Facultative parasite
TYPES OF PARASITES
Threadworms (Strongyloides stercoralis)
The smallest faucultative nematoda
TYPES OF PARASITES
Strongyloides stercoralis
Non pathogenic
TYPES OF PARASITES
Commensal
Example of commensals
TYPES OF PARASITES
Entamoeba coli
Parasites found on the surface of the body
Types of parasites according to habitat
Ectoparasite
presence of an ectoparasite in a host
Types of parasites according to habitat
Infestation
Presence of endoparasite in the host
Types of parasites according to habitat
Infection
Parasites living within the host
Types of parasites according to habitat
Endoparasite
Parasite not living in its natural habitat
Types of parasites according to habitat
Erratic Parasite
Example of Erratic Parasite
Types of parasites according to habitat
Ascaris lumbricoides
Natural habitat of Ascaris lumbricoides
Types of parasites according to habitat
small intestine
VLM meaning
Types of parasites according to habitat
Visceral larva migrants
goes to the other parts of the body
Types of parasites according to habitat
Erratic
Parasite that does not live in its usual host; counterpart to
the accidental host
Types of parasites according to habitat
Accidental / Incidental Parasite
Accidental in humans
Types of parasites according to habitat
- Toxocara cati
- Toxocara canis
Free-living organism that passes through the GI tract
without infecting the host
(Just passes through)
Types of parasites according to habitat
Spurious Parasite
Present in the host for a long time
Types of parasites according to habitat
Permanent parasite
remains on or in the body of the host for its entire life
Types of parasites according to habitat
Permanent parasite
a parasite that
establishes itself in a host in which it does not
usually live
Types of parasites according to habitat
Accidental/ incidental parasite
lives on the host only for a short period of time
| Types of parasites according to habitat
Temporary parasite
Can be obligatory at one or more stages of their life cycles
but free-living at others
Types of parasites according to habitat
Temporary Parasite
- Produces immature eggs
- Larva is not yet developing
- Not yet infective
Parasites according to egg laying capacity (helminths)
Oviparous
Produces mature / segmented / embryonated eggs
Parasites according to egg laying capacity (helminths)
Ovoviviparous
Produces larva
Parasites according to egg laying capacity (helminths)
Larviparous
Example of Oviparous
Parasites according to egg laying capacity (helminths)
- Ascari
- Trichuris
Example of Ovoviviparous
Parasites according to egg laying capacity (helminths)
- Schistosoma
- Clonorchis,
- Opisthorchis
- Taenia
Example of larviparous
Parasites according to egg laying capacity (helminths)
Trichinella
Hermaphroditic; no male or female
Parasites according to sexes
Monoecious
Both reproductive organs are found in one parasite
Parasites according to sexes
Monoecious
Example of moecious
Parasites according to sexes
- Flukes, except Schistosoma
- Cestodes
Separate sexes
Parasites according to sexes
Dioecious
Female parasites are capable of self-fertilization
Parasites according to sexes
Parthenogenetic
In unfavorable conditions, larvae become parasitic and all become female in the host
Parasites according to sexes
Strongyloides stercoralis
Example of Parthenogenetic
Parasites according to sexes
Strongyloides stercoralis
Example of dioecious
Parasites according to sexes
- Nematodes
- Schistosoma
PARASITE STAGES OF HELMINTHES
PARASITE STAGES
- Adult
- Larva
- Egg/ovum
Immature stage
Parasite stages of larva
Larva
Specific names of the stages differ between
species
Parasite stages of larva
Larva
Highly resistant stage
Parasite stages of larva
Egg / Ovum
May be an infective stage
Parasite stages of larva
Egg / Ovum
Parasite stages of Protozoans
- Trophozoite
- cyst
Motile / Feeding / Vegetative stage
Parasite stages of Protozoans
Trophozoite
Fragile, easily dies
Parasite stages of Protozoans
Trophozoite
Non-motile / Non-feeding stage
Parasite stages of Protozoans
Cyst
Usually the infective stage
Parasite stages of Protozoans
Cyst
Soil is important to the life cycle
TRANSMISSION
Soil Transmitted Helminths
Example of soil transmitted helminthes
TRANSMISSION
- Hookworms
- Ascaris lumbricoides
- Trichuris trichuria
- Strongyloides stercoralis
Types of Hookworms
TRANSMISSION
- Ancylostoma duodenale
- Necator americanus
MOT of Necator americanus
TRANSMISSION
Skin penetration of larva
MOT of Ascaris lumbricoides
TRANSMISSION
Ingestion of embryonated eggs
MOT of Trichuris trichuria
TRANSMISSION
Ingestion of embryonated egg
MOT Strongyloides stercoralis
TRANSMISSION
Skin penetration of larva
Example of parasites with biological vectors
TRANSMISSION
- Plasmodium
- Hemoflagellates
- FIlarial worms
BIological vector of plasmodium
TRANSMISSION
Anopheles mosquitos
BIological vector of Hemoflagellates
TRANSMISSION
- Tse tse
- Kissing bug
- sand fly
BIological vector of Filarial worms
TRANSMISSION
Mosquito
Ingestion; undercooked or raw food with larva
TRANSMISSION
Food Borne
Fasciola is transmitted from _________
TRANSMISSION
Water plants; kangkong
Opisthorchis is transmitted from _________
TRANSMISSION
freshwater fish
Clonorchis is transmitted from _________
TRANSMISSION
freshwater fish
Echinostoma is transmitted from _________
TRANSMISSION
snail
Heterophyes is transmitted from _________
TRANSMISSION
freshwater fish
Taenia is transmitted from _________
TRANSMISSION
Pork, beef
Haplorchis is transmitted from _________
TRANSMISSION
freshwater fish
Paragonimus is transmitted from _________
TRANSMISSION
freshwater crab; crayfish
Associated with outbreaks of diarrhea
TRANSMISSION
Water Borne
Water borne trannsmission assoc. w/ “traveller’s diarrhea”
TRANSMISSION
Giardia
Water borne trannsmission assoc. with AIDS infection,
severe diarrhea, and contaminated water supply
TRANSMISSION
Cryptosporidium
Can cross placenta
TRANSMISSION
Vertical Transmission/Congenital
Vertical transmission parasite which Oocyst in cat feces, can cause congenital defects
TRANSMISSION
Toxoplasma gondii
Breastfeeding
TRANSMISSION
Transmammary
Larva in breast milk
TRANSMISSION
Ancylostoma
Example of trasmammary parasites
TRANSMISSION
Strongyloides
Egg is inhaled
TRANSMISSION
Inhalation
Most common nematode infection worldwide
TRANSMISSION
Enterobius vermicularis
Reproduces in the anal area; nocturnal
TRANSMISSION
Enterobius vermicularis
TRANSMISSION
Fast to embryonate (4 hrs)
Enterobius vermicularis
Sexual contact
TRANSMISSION
Intimate Contact
Most common non-viral STD worldwide
TRANSMISSION
Trichomonas vaginalis
Types of LIFE CYCLES
- Direct Life Cycle
- Indirect Life Cycle
No intermediate host needed
Types of LIFE CYCLES
Direct Life Cycle
Has intermediate host/s
Types of LIFE CYCLES
Indirect Life Cycle
Infective stage: egg
Types of LIFE CYCLES
Direct Life Cycle
Infective stage: larva
Types of LIFE CYCLES
Indirect Life Cycle
Causative agent, causes harm
EXPOSURE AND INFECTION
Pathogen
Establishment of the organism in the host
EXPOSURE AND INFECTION
Infection
Harbors the organism but is asymptomatic; shows no signs
and symptoms
EXPOSURE AND INFECTION
Carrier
Period between infection and appearance of signs
and symptoms
EXPOSURE AND INFECTION
Incubation Period
Period between infection and evidence / demonstration of infection (can test positive)
EXPOSURE AND INFECTION
Pre-patent Period
Infected individual becomes his/her own source of infection
EXPOSURE AND INFECTION
Autoinfection
Larva becomes infective inside the host and can infect the host again
EXPOSURE AND INFECTION
Autoinfection
Example of parasites that can cause Autoinfection
EXPOSURE AND INFECTION
- Capillaria
- Strongyloides
- Enterobius
- Cryptosporidium
- Hymenolepis nana
Infected individual is further infected with the same parasite
EXPOSURE AND INFECTION
Superinfection / Hyperinfection
May spread to other parts of the body
EXPOSURE AND INFECTION
Superinfection / Hyperinfection
Exaple of parasites that can cause Superinfection / Hyperinfection
EXPOSURE AND INFECTION
Strongyloides
Study of patterns, distribution, and occurrence of the
disease
EPIDEMIOLOGY
All total cases
EPIDEMIOLOGY
Prevalence
% of individuals in a population with at least 1 parasite
EPIDEMIOLOGY
Cumulative Prevalence
Rate of occurrence of new cases
EPIDEMIOLOGY
Incidence
Constant presence and/or prevalence of a disease or an
infectious agent in the population within a geographic area
EPIDEMIOLOGY
Endemic
Ongoing local transmission
EPIDEMIOLOGY
Endemic
A disease that occurs infrequently and irregularly
EPIDEMIOLOGY
Sporadic
Often above what is normally expected in that population in that area
EPIDEMIOLOGY
Epidemic
Refers to an increase, often sudden, in the number of cases
of a disease
EPIDEMIOLOGY
Epidemic
Sudden increase → outbreak
EPIDEMIOLOGY
Epidemic
Number of patients who
died of the disease.
EPIDEMIOLOGY
Mortality
Refers to an epidemic that has spread over several countries
or continents
EPIDEMIOLOGY
Pandemic
Worldwide epidemic
EPIDEMIOLOGY
Pandemic
Related to the number of worms/eggs per infected person
EPIDEMIOLOGY
Intensity of Infection / Worm Burden
no human cases, no transmission
EPIDEMIOLOGY
Eradication
Refers to the burden of infection
EPIDEMIOLOGY
Intensity of Infection / Worm Burden
Number of diseased
individuals.
EPIDEMIOLOGY
Morbidity
no human cases, ongoing transmission
EPIDEMIOLOGY
Elimination
Parasites can:
EFFECTS OF THE PARASITES TO HUMAN HOSTS
o Cause injury by release of metabolites/enzymes
o Cause invasion and tissue destruction
o Deprive certain nutrients from hosts
The use of anthelminthic drugs in an individual or a public
health program
EPIDEMIOLOGY
Deworming
Example of Tissue damage
EFFECTS OF THE PARASITES TO HUMAN HOSTS
- Fatty degeneration
- albuminous degeneration
- necrosis (tissue/cell death)
Example of Tissue changes
EFFECTS OF THE PARASITES TO HUMAN HOSTS
- Hyperplasia
- Hypertrophy
- Metaplasia
- Neoplasia
- Tumors
Can become resistant
EFFECTS OF THE HOST ON THE PARASITE
Genetic makeup of host
EFFECTS OF THE HOST ON THE PARASITE
- Genetic makeup of host
- Nutrition and Diet
- Immunity and Immune Response
Resistant to Plasmodium
vivax
EFFECTS OF THE HOST ON THE PARASITE
Duffy Blood Group Fy(a- b-)
Example of Genetic makeup of host
EFFECTS OF THE HOST ON THE PARASITE
- Duffy Blood Group Fy(a- b-)
- Sickle cell disease
Resistant to Plasmodium falci
EFFECTS OF THE HOST ON THE PARASITE
Sickle cell disease
Usually found in Africans
EFFECTS OF THE HOST ON THE PARASITE
Duffy Blood Group Fy(a- b-)
High protein diet can inhibit intestinal
protozoans
EFFECTS OF THE HOST ON THE PARASITE
Nutrition and Diet
Types of HOST IMMUNE RESPONSE
EFFECTS OF THE HOST ON THE PARASITE
- Innate Immune Response
- Acquired Immune Response
Body detects and eliminates pathogens through nonspecific mechanisms
EFFECTS OF THE HOST ON THE PARASITE
Innate Immune Response
3rd line of defense
EFFECTS OF THE HOST ON THE PARASITE
Acquired Immune Response
Specific response
EFFECTS OF THE HOST ON THE PARASITE
Acquired Immune Response
2nd line of defense
EFFECTS OF THE HOST ON THE PARASITE
Innate Immune Response
EFFECTS OF THE HOST ON THE PARASITE
Host exposed to the parasite antigens → stimulate an
immune response
Acquired Immune Response
Example of Innate Immune Response
EFFECTS OF THE HOST ON THE PARASITE
Phagocytosis by macrophage and dendritic
cells
Example of Acquired Immune Response
EFFECTS OF THE HOST ON THE PARASITE
T and B cells
Permits survival of parasites upon entering blood and tissues
PARASITE EVASION MECHANISM
Resistance to Infection
Intrcellular → immune system won’t recognize
the parasites
PARASITE EVASION MECHANISM
Resistance to Infection
Used by helminths to resist macrophages
PARASITE EVASION MECHANISM
Cuticle and integument
Parasites can reduce the immune function of macrophages
→ Lower action of macrophages and defective processing
of antigen
PARASITE EVASION MECHANISM
Immune Suppression
Macrophages are inhibited
PARASITE EVASION MECHANISM
Immune Suppression
Parasites that causes Antigenic Variation
PARASITE EVASION MECHANISM
- Trypanosoma brucei infection
- Plasmodium
African sleeping sickness
PARASITE EVASION MECHANISM
Trypanosoma brucei
Used by Trypanosoma brucei for antigenic variation
PARASITE EVASION MECHANISM
Variant surface glycoproteins (VSG)
Parasite that uses antigenic diversity
PARASITE EVASION MECHANISM
Plasmodium
Surface / antigens are changed
PARASITE EVASION MECHANISM
antigenic diversity
Replaces self’s antigen and mimics host antigens
PARASITE EVASION MECHANISM
Host Mimicry
Body can’t differentiate self from non-self
PARASITE EVASION MECHANISM
Host Mimicry
larval stages carry P blood group
antigens
PARASITE EVASION MECHANISM
Echinococcus granulosus
can acquire antigenic molecules from the
host
PARASITE EVASION MECHANISM
Schistosoma sp.
Parasites that uses Host Mimicry
PARASITE EVASION MECHANISM
- Echinococcus granulosus
- Schistosoma sp
Parasites that uses Intracellular Sequestration
PARASITE EVASION MECHANISM
- Leishmania
- Plasmodium
Lives in host cells
PARASITE EVASION MECHANISM
Intracellular Sequestration
monocytes, macrophages,
endothelial cells (lines blood vessels) intracellular sequestration
PARASITE EVASION MECHANISM
Leishmania
Liver cells, red cells intracellular sequestration
PARASITE EVASION MECHANISM
Plasmodium
Exist as motile trophozoite stage and the nonmotile
infective cyst
PROTOZOANS (KINGDOM PROTISTA)
Locomotor apparatus serves as one of the bases of
classification
PROTOZOANS (KINGDOM PROTISTA)
Equipped with pseudopods (“false feet”)
MEDICALLY IMPORTANT PARASITES
Subphylum Sarcodina – Ameba
Equipped with flagellum (whip-like structure)
MEDICALLY IMPORTANT PARASITES
Subphylum Mastigophora – Flagellates
PHYLUM SARCOMASTIGOPHORA:
MEDICALLY IMPORTANT PARASITES
- Subphylum Sarcodina – Ameba
- Subphylum Mastigophora – Flagellates
Equipped with cilia (hair-like structures)
MEDICALLY IMPORTANT PARASITES
PHYLUM CILIOPHORA
Some are multinucleate
MEDICALLY IMPORTANT PARASITES
PHYLUM CILIOPHORA
Two nuclei of PHYLUM CILIOPHORA
MEDICALLY IMPORTANT PARASITES
A large macronucleus and a small micronucleus
Only ciliate parasite in humans
MEDICALLY IMPORTANT PARASITES
Balantidium coli
May produce severe intestinal symptoms
MEDICALLY IMPORTANT PARASITES
Balantidium coli
Not equipped with definite locomotor apparatus
MEDICALLY IMPORTANT PARASITES
PHYLUM APICOMPLEXA
Contains apical complex
MEDICALLY IMPORTANT PARASITES
PHYLUM APICOMPLEXA
causative agent of malaria
MEDICALLY IMPORTANT PARASITES
Plasmodium spp
causative agent of
Toxoplasmosis
MEDICALLY IMPORTANT PARASITES
Toxoplasma gondii
Examples of PHYLUM APICOMPLEXA
MEDICALLY IMPORTANT PARASITES
- Plasmodium spp
- Babesia microti
- Toxoplasma gondii
Gametocytes develop independently
MEDICALLY IMPORTANT PARASITES
Suborder Haemosporina
causative agent of Nantucket fever
MEDICALLY IMPORTANT PARASITES
Babesia microti
Now classified as fungi
MEDICALLY IMPORTANT PARASITES
PHYLUM MICROSPORIDIA
Possess polar tube
MEDICALLY IMPORTANT PARASITES
PHYLUM MICROSPORIDIA
Spore forming
MEDICALLY IMPORTANT PARASITES
PHYLUM MICROSPORIDIA
Class Nematoda
MEDICALLY IMPORTANT PARASITES
PHYLUM ASCHELMINTHES / NEMAHELMINTHES
Elongate and cylindrical organisms
MEDICALLY IMPORTANT PARASITES
PHYLUM ASCHELMINTHES / NEMAHELMINTHES
Roundworms
MEDICALLY IMPORTANT PARASITES
PHYLUM ASCHELMINTHES / NEMAHELMINTHES
Dioecious
MEDICALLY IMPORTANT PARASITES
PHYLUM ASCHELMINTHES / NEMAHELMINTHES
Male is typically smaller than the female
MEDICALLY IMPORTANT PARASITES
PHYLUM ASCHELMINTHES / NEMAHELMINTHES
Parasites of humans: intestinal and tissue inhabiting species
MEDICALLY IMPORTANT PARASITES
PHYLUM ASCHELMINTHES / NEMAHELMINTHES
PHYLUM PLATYHELMINTHES classes:
MEDICALLY IMPORTANT PARASITES
- Class Trematoda
- Class Cestoda
Trematodes, Flukes
MEDICALLY IMPORTANT PARASITES
Class Trematoda
Leaf-shaped or elongate, slender organisms
MEDICALLY IMPORTANT PARASITES
Class Trematoda
Possess suckers
MEDICALLY IMPORTANT PARASITES
Class Trematoda
Order of class trematoda that Contains all species parasitic to humans
MEDICALLY IMPORTANT PARASITES
Order Digenea
Order of class trematoda that Inhabits: small intestine, lungs, liver, pancreas, blood
vessels
MEDICALLY IMPORTANT PARASITES
Order Digenea
Physical barriers (1st line of defense against pathogens):
MEDICALLY IMPORTANT PARASITES
- Skin
- Mucous membranes
- Components of body fluids
- Physiologic functions of the body
Elongate, ribbon-like, segmented body
MEDICALLY IMPORTANT PARASITES
Class Cestoda
Inhabit the small intestine
MEDICALLY IMPORTANT PARASITES
Class Cestoda
Tapeworms
MEDICALLY IMPORTANT PARASITES
Class Cestoda
Specialized anterior attachment organ: scolex
MEDICALLY IMPORTANT PARASITES
Class Cestoda
