Introductory Concepts of Parasitology 2 Flashcards by VERNARD DOMINIC ALOYON

Living together of unlike organisms

SYMBIOSIS

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Refers to the association of two species for food and shelter

SYMBIOSIS

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a symbiotic relationship in
which two species live together and one species benefits from the relationship without harming or benefiting the other

Symbiosis

Commensalism

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Denotes an association that is beneficial to one partner and
at least not disadvantageous to the other

Symbiosis

Commensalism

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Entamoeba coli lives in the lumen of the intestine

SYMBIOSIS

Commensalism

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Occurs when associations are beneficial to both organisms

Symbiosis

Mutualism

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a symbiosis in which two organisms
mutually benefit from each other

Symbiosis

Mutualism

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Termites and Flagellates in their digestive system, which
aids in the breakdown of ingested wood by synthesizing
cellulase

Symbiosis

Mutualism

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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

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Necessarily involves an intimate relationship between the two species (Close and prolonged contact)

Symbiosis

Parasitism

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Entamoeba histolytica, which derives nutrition from
the human host and causes amebic dysentery.

Symbiosis

Parasitism

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“To carry”

Phoresis

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In Phoresis, No physiologic interaction is involved between the ____ and _______

host and
phoront

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In Phoresis, host is a _____________

mechanical vector

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An area of biology that deals with the dependence of one
organism on another

PARASITOLOGY

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The study of parasites, its hosts, and their relationships

Parasitology

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concerned primarily with
parasites of humans and
their medical significance,
as well as their importance
in human communities

Medical Parasitology

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Where can you find parasites

Mostly in poor, developing countries

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Millions of people are affected worldwide

PARASITES

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NTDs meaning

Neglected tropical diseases

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Characteristics of Parasitic Disease

Prevalence in developing countries; in lower socioeconomic population
Low mortality and morbidity
Limited drug development
No current vaccines

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Species which harbors the parasite

HOST

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The organism that provides physical protection and nourishment to the parasite

HOST

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The organism that provides physical protection
and nourishment to the parasite

HOST

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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