Parasitology Pt 1

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Questions and Answers

What is the primary function of a paratenic host in a parasite's life cycle?

To maintain the parasite's life cycle in nature

To provide a habitat for parasite development

To act as a transportation medium for the parasite (correct)

To serve as a definitive host for the parasite

What is the term for the specificity of parasites for particular hosts?

Parasite predilection

Definitive host preference

Host specificity (correct)

Intermediate host selection

What is the primary difference between biological and mechanical vectors?

Biological vectors transmit parasites unchanged, whereas mechanical vectors do not

Biological vectors are always animals, whereas mechanical vectors are not

Biological vectors are always insects, whereas mechanical vectors are not

Biological vectors multiply or develop the parasite, whereas mechanical vectors do not (correct)

What is the term for an animal that serves to maintain a parasite's life cycle in nature?

Reservoir host Signup and view all the answers

Which of the following is an example of an incidental host?

Human for Trichinella spiralis Signup and view all the answers

What is the term for an organism responsible for transmitting a parasite from one host to another?

Vector Signup and view all the answers

What is the term for the host in which the parasite undergoes asexual stages of development?

Intermediate host Signup and view all the answers

What is an example of a biological vector that acts as a definitive host?

Mosquito for Malaria Signup and view all the answers

What is the term for the association of two organisms that cannot exist independently, and therefore are living together?

Symbiosis Signup and view all the answers

Which type of host harbors the adult (sexual) stage of a parasite?

Definitive host Signup and view all the answers

What is the term for a disease of animals that is transmissible to humans?

Zoonosis Signup and view all the answers

What is the primary mechanism by which helminths infect hosts?

Re-exposure to the parasite Signup and view all the answers

What determines the severity of disease in helminth infections?

Worm load introduced into the host Signup and view all the answers

Which condition is not required for endemic parasitism?

Host immune response Signup and view all the answers

What is the primary characteristic that distinguishes obligate parasites from other types of parasites?

They are fully physiologically dependent on a host to complete their life cycle Signup and view all the answers

Which of the following is an example of an ectoparasite?

Pediculus humanus Signup and view all the answers

What is the characteristic of parasites that are best adapted to their hosts?

Low pathogenicity Signup and view all the answers

What is the term for organisms that live close in association with each other?

Symbionts Signup and view all the answers

What is the characteristic feature of cestodes?

They have a flat body with no coelom Signup and view all the answers

What is the function of the scolex in cestodes?

It is used for attachment to the host Signup and view all the answers

Which of the following is an example of an endoparasite?

Ascaris suum Signup and view all the answers

What is a characteristic feature of trematodes?

They are hermaphroditic and have a ventral sucker. Signup and view all the answers

What is a common feature of arachnid nymphs and adults?

They have 4 pairs of legs. Signup and view all the answers

What is a characteristic of acari (mites)?

Their body has scales, spines, setae (hairs), and their legs may have claws or sucks used to attach to hosts. Signup and view all the answers

What is a characteristic feature of trophozoites?

They are 50-150 micrometers in size, are ciliated, and have a kidney-bean shaped nucleus. Signup and view all the answers

What is a characteristic feature of cysts?

They are up to 60 micrometers in size, and their cilia is sometimes evident inside. Signup and view all the answers

Study Notes

Symbiosis and Parasitology

Symbiosis: the association of two organisms that cannot exist independently, living together.
Types of symbiosis:
- Phoresis: two organisms travel together.
- Mutualism: both organisms benefit.
- Commensalism: one partner benefits, the other is unaffected.
- Parasitism: one partner (parasite) benefits, the other (host) is harmed.
Symbionts: organisms that live close in association with each other.
Zoonosis: any disease of animals that is transmissible to humans.

Parasites and Hosts

Parasites adapt to every niche in the host.
Parasite-host relationships are typically long-term/chronic/"intimate".
Conditions required for endemic parasitism:
- Reservoir of infection.
- Means of transmission to susceptible hosts.
- Ability to invade and establish in new hosts.
- Ability to reproduce.
Host types:
- Definitive host (DH): harbors the adult (sexual) stage of a parasite.
- Intermediate host (IH): harbors the larval (asexual) stage of a parasite.
- Paratenic host (PH): harbors a parasite that does not undergo any required development, and is solely used for transportation.
Reservoir host: an animal (definitive) host that serves to maintain the parasite's life cycle in nature.
Incidental host: an unusual host, unnecessary for the maintenance of the parasite in nature.

Vectors

Vectors: organisms responsible for transmitting a parasite from one host to another.
Types of vectors:
- Biological vectors: the parasite multiplies or develops.
- Mechanical vectors: the parasite is transmitted unchanged from one host to another.

Parasite Types

Obligate parasites: fully physiologically depend on a host (to complete its life cycle).
Temporary parasites: parasitic for a limited period for either feeding or reproduction.
Facultative parasites: organisms that are not normally parasitic but can survive for a limited period when they accidentally find themselves within another organism.
Ectoparasites: live on the host, typically causing infestations.
Endoparasites: live inside of the host, typically causing infections.

Veterinary Parasitology

3 groups of eukaryotic organisms that affect the health and wellbeing of animals:
- Protozoa (protozoology).
- Helminths (helminthology).
- Arthropods (entomology).

Parasites: Specific Info

Cestodes:
- Flat body with no coelom (body cavity).
- No alimentary canal.
- Hermaphroditic.
- Scolex (head) with 4 suckers or bothria.
- Strobila (body) with a head, neck, and proglottids (segments).
Trematodes:
- Dorso-ventrally flattened, leaflike body.
- Incomplete alimentary canal.
- Hermaphroditic.
- Use ventral and oral suckers for attachment.
Arthropods:
- Insects: flies (order Diptera), fleas (order Siphonaptera), lice (order Phthiraptera), and Hemiptera.
- Arachnids: ticks, and mites.
- Acari (mites): microscopic, with scales, spines, setae (hairs), and their legs may have claws or sucks used to attach to hosts.
Protozoa:
- Unicellular, prokaryotic organisms.
- Classified based on their mode of locomotion.
- Locomotion methods: pseudopodia, flagella, gliding movement (no locomotion organelle), or cilia.
- Trophozoites: 50-150micrometers in size, ciliated, and have a kidney-bean shaped nucleus.
- Cysts: up to 60micrometers in size, and their cilia is sometimes evident inside.