Parasitology Intro

A kind of symbiosis + a relationship which one organism lives at the expense of another

Parasitism

One who eats at the table of another

Paraitos

If the parasite lives on the hosts surface _____

Ectoparasite

If the parasite lives inside the host _____

Endoparasite

An average mammalian host harbors ____ cestodes, ____ trematodes, _____ nematodes, and an acanthocephalan in every ____ mammalian species examined

2, 2, 4, 4

Each bird species harbors ____ cestodes, ____ trematodes, _____ nematodes, and _____ acanthocephalan

3, 2, 3, 1

What are cestodes, trematodes, nematodes, and acanthocephalans?

parasitic worms (helminthes)

What are the 3 factors that contribute to the development of parasitic disease?

1. Age and health status

2. Host density

3. Aberrant hosts

What contributes to host density?

sanitation and housing, changes in environment (stress), human development

What is the main abiotic factor that can influence and distribute parasites?

Climate

How are parasites classified?

morphology and life cycle similarities

What are the 5 major groups of parasites?

1. protozoa (single cell eukaryotes)

2. trematodes (helminths)

3. cestodes (helminths)

4. nematodes (helminths)

5. arthropods (surface)

suffix’s: a condition or state; a disease is produced by

-osis, -iasis

parasite lives on/in its host for only short periods

temporary or intermittent

parasite lives entire life (or long periods of it) on/in host

permanent or stationary

parasite in an unusual host or location in the host

aberrant

organism must lead a parasitic way of life in order to complete its life cycle

obligate

organism can either be parasitic or free-living as part of its normal life cycle

facultative

the host in which the parasite reaches sexual maturity

definitive

the host in which some portion of parasite development occurs (expect sexual maturity) - develops or changes stages

intermediate

varies by parasite, often affects severity of disease (e.x. tissue specificity)

host specificity

a host within which a parasite can survive and be infective to a definitive host but complete parasite development does NOT occur (sits and waits)

paratenic

a host (population that serves to maintain a particular parasite species which can then be transmitted to other animals or humans

reservoir

a host that becomes infected with a parasite that have evolved a tropism (changes disease state) for a different host species

aberrant, incidental, accidental

transmission from one animal to another (ingestion of eggs, protozoa, free-living larvae, migration through skin)

direct

larval states or cysts in an intermediate host. definitive host ingests intermediate host and parasite (parasite transmitted through a vector)

indirect

time between infection and production of progeny by parasite

prepatent period

the parasite life stage that allows for transmission to the definitive or intermediate host

infective stage

the stage that can be detected by sampling appropriate tissues or excreta in a live, infected host.

diagnostic stage

which parasite stage often (but not always) leaves the definitive host to continue its development?

diagnostic stage

What type of life cycle does the hookworm have when there is no intermediate host required?

direct

what is the prepatent period for the hookworm

14 days

what type of lifecycle does heart worm have?

indirect

what is the prepatent period for heart worm?

6 months

pathogenesis: what are the 2 types of competition for absorption and essential nutrients intended for the host?

1. general debilitation and/or interference with normal development (decreased weight gain or loss)

2. interference with normal activities due to annoyance

pathogenesis: what is an examples of interference with proper absorption of nutrients by the host?

Giardia - GI absorption interference causing loss of body fluids (diarrhea)

pathogenesis: what are 3 types of production of anemia

1. parasitic destruction of RBC’s (plasmodium, trypanosomes, babesia)

2. Blood-sucking arthropods

3. consumption of blood in GI tract

pathogenesis: what are examples of feeding on host tissue

screwworm (fly) larvae and other maggots

pathogenesis: What is an example of mechanical obstruction of hollow organs

Ascarids in small intestine, filarids in lymphatic vessels or heart

pathogenesis: what are 2 ways for physical damage to host tissues?

1. damage to organs via pressure necrosis

2. physical and chemical damage to tissues during larval migration (making their own way through)

pathogenesis: what are 2 examples of secretion/production of toxins

1. secretion of toxins causing tick paralysis (metabolic waste products = neurotoxic)

2. Hemozoin by malaria parasites (limits phagocytosis)

pathogenesis: creating wounds

predisposes the host to secondary infections due to wound, where infections can be bacterial, viral, or fungal

vector that is required for the completion of the parasitic life cycle (malaria and mosquitos)

Biological vector

vector not required in the life cycle but serves as a source of physical transmission

mechanical vector

pathogenesis: examples of damage secondary to immune response

high fever and malaria, onchocerciasis (immune system cause)