Principles and Definitions (R and J Chs 1

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Principles and Definitions (R and J Chs 1 2)

• Parasitology is a division of Symbiosis - two
  organisms living together.
• Categories of symbiosis are based on the effects
  of one organism on the other.

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Phoresis-2 organisms traveling together
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Mutualism- 2 organisms living together in which
both benefit from the association both are
metabolically dependent on one another
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Commensalism- Relationship in which the symbiont
benefits from an association with a host which
is passive to the relationship (not harmed or
benefited)
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Parasitism- definitions

• Original meaning from the Greek is a relationship
  in which "one eats at another's table or lives at
  another's expense.
• RJ page 4 - "Parasitism is a relationship in
  which one of the participants, the parasite,
  either harms its host or in some sense lives at
  the expense of the host.

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Entamoeba invadens
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Entamoeba invadens
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Parasitism- definitions

• Noble and Noble Parasitology The Biology of
  Animal Parasites
•  "Parasitism is an obligatory association between
  two distinct species in which the dependence of
  the parasite upon its host is a metabolic one
  involving mutual exchange of substances."

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Our Definition Parasite-an organism which lives
at least part of its life cycle on or within
another organism (the host) upon which it is
physiologically dependent and to which it causes
harm in some way. In a parasitological or
medical context, it is restricted to animal
agents, i.e., protozoa, helminths, and arthropods.
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Where are Parasites Found?
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A brooding Glossiphonid leech with its young
feeding on my wifes leg!
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Where are Parasites Found?

• Ectoparasite- a parasite which lives on the body
  surface of the host.

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Where are Parasites Found?

• Endoparasite- a parasite which lives within the
  body of the host.

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Definitions of Hosts
Many parasites have more than one host in their
life cycle. These hosts have different roles and
are given specific names.
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Definitions of Hosts
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Definitions of Hosts

• Definitive host a host in which the parasite
  reaches sexual maturity and undergoes
  reproduction.

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Definitions of Hosts

• Definitive host a host in which the parasite
  reaches sexual maturity and undergoes
  reproduction.
• Intermediate a host in which the parasite
  undergoes larval development but does not reach
  sexual maturity.

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Definitions of Hosts

• Definitive host a host in which the parasite
  reaches sexual maturity and undergoes
  reproduction.
• Intermediate a host in which the parasite
  undergoes larval development but does not reach
  sexual maturity.
• Paratenic host (Transport host) a host in which
  a parasite survives without undergoing further
  development. A paratenic host accumulates and
  maintains stages of a parasite, and although
  beneficial, is not essential to the life cycle.

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Definitions of Hosts

• Vector- any agent, either animate or inanimate
  (such as wind, water, or arthropod) that
  transmits an infectious organism.

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Definitions of Hosts

• Vector- any agent, either animate or inanimate
  (such as wind, water, or arthropod) that
  transmits an infectious organism.
• Biological Vector- a vector in which a parasite
  lives or develops. The parasite undergoes
  morphologic change and/or multiplication, and the
  vector is usually essential for the life cycle.

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Definitions of Hosts

• Vector- any agent, either animate or inanimate
  (such as wind, water, or arthropod) that
  transmits an infectious organism.
• Biological Vector- a vector in which a parasite
  lives or develops. The parasite undergoes
  morphologic change and/or multiplication, and the
  vector is usually essential for the life cycle.
• Mechanical Vector- a vector which transmits a
  parasite by mechanical means only. It may be
  living or non-living and is not essential for the
  parasites life cycle.

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Host-Parasite Relationships

• Like other living organisms, parasites have basic
  need in order to survive and be successful.

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Host-Parasite Relationships

• Habitat or substrate
• Energy source (food)
• Reproduction of own kind
• Dispersal

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Host-Parasite Relationships

• Living animals present special problems as
  habitats or environments.

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Host-Parasite Relationships

• They move around and disperse
• They have non-specific defense mechanisms
• They mount specific immune responses
• They age and change physiologically
• They die

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Host-Parasite Relationships

• Some of the most important factors influencing
  parasite transmission and infection are related
  to host behavior.

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Echinococcus Tapeworms
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Echinococcus species
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Echinococcus multilocularis
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Echinococcus granulosus
 
Surgical removal of 3 unilocular hydatid cysts
from a Kenyan woman.
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Host-Parasite Relationships

• Innate behaviors
• Learned behaviors
• Ethnic and cultural practices
• Local customs or habits
• Religious practices

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Your Areas of Responsibility

• Lectures
• Any specific assignments given
• A set of facts/info about selected species of
  parasites (A-I)

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9 topics

• A- Morphology (structure)-size

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9 topics

• B- Taxonomy Largely based on morphology. Know
  where to place organism in the scheme of things.

Phylum ????? (Sarcodina)
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9 topics

• C Life cycle, including the ontogenetic
  (developmental) stages and their size.

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9 topics

• C Life cycle, including where found
  environmentally.

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Be more specific! Habitat
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9 topics

• C Life cycle, including prepatent period The
  period of time from infection of a host with a
  parasite until one can demonstrate that the host
  is infected by finding a stage of the parasite
  (cyst, egg, larva, etc.) in or from the host.

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9 topics

• D Geographic distribution Where in the world
  would you find it?

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Trypanosoma gambiense
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9 topics

• E Symptoms Aspects which you observe
  (headaches, fever, jaundice, etc.)

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9 topics

• F Pathology Damage from infection. Physical
  damage/changes done to body which you can see.
  Otherwise know as the consequences of the
  infection.

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9 topics

• G Diagnosis How to look for the parasite,
  where to look, and what do you expect to see. Do
  not base on symptoms.

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9 topics

• H Epidemiology How does it spread thru a
  population?

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9 topics

• I Drug of Choice and Prognosis Treatment and
  what you expect to happen/prospects.