PRINCIPLES AND DEFINITIONS Chap. 1

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PRINCIPLES AND DEFINITIONS (Chap. 1)
Parasitology is a division of ___________________
_____ - two organisms living together
(__________________________).   Categories of
symbiosis are based on the effects of one
organism on the other.   1. _____________________
_____ 2 organisms traveling together
Example bacteria carried on the legs of a
housefly to a drinking glass   2.
___________________________ 2 organisms living
together in which both benefit from the
association both are metabolically dependent on
one another.   Example flagellates in
termite gut provide cellulase for breakdown
wood termite provides habitat for
flagellates.
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Symbiosis cont

• 3. _____________________________ relationship
  in which the commensal benefits from an
  association with a host which is passive to the
  relationship (not harmed or benefited)
•   Example Remora fish associated with
  sharks feeds on leftover food.
• ____________________________ - 4 definitions
• Original meaning from the Greek is a relationship
  in which
• _______________________________________________."
  
•  
•  

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Symbiosis cont

• Roberts and Janovy - Foundations of Parasitology
  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.
• Problem The ameba Entamoeba invadens is
  harmless in turtles but causes 100 mortality in
  snakes.
• Is it then a commensal (when its in
  turtles) or is it a parasite (when its in
  snakes)?
•   This definition implies ________________________
  _____ which is not always the case.

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• The true nature of parasitism involves an
  ecological relationship between
  the parasite and its host. A parasite is
  metabolically dependent on its host.
• 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."
•  
• Dogiel Parasitology 
• "Parasitism is a relationship in which a parasite
  uses another living animal as its environment and
  source of food and relinquishes to its host the
  task of regulating its relationship with the
  external environment."

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• Dogiel's definition indicates the true essence of
  parasitism - metabolic and ecological
  relationships between a parasite and its host and
  do not imply injury to the host. 
• We can then further define parasitism based on
  injury to the host
• If a parasite does cause injury to a host, it
  is a _________________________________________.
•   If the parasite causes no injury, it is a
  _________________________________________.
• Thus, in our example of Entamoeba invadens, this
  ameba is a parasite in both turtles and snakes,
  as both hosts provide an environment for the
  ameba and the ameba is metabolically dependent
  upon either host. The parasite may be
  differentiated as being non-pathogenic in turtles
  and pathogenic in snakes.

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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. ______________
____________ host in which the parasite reaches
sexual maturity and undergoes reproduction. The
definitive host is usually a vertebrate. ________
__________________ - non-human definitive host
which maintains the parasite for possible human
infection. Example a dog, the definitive
host of a mature parasite, could infect a human
with this parasite through contact
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Definitions of Hosts cont.
__________________________ - host in which the
parasite undergoes larval development but does
not reach sexual maturity. Typically, the
intermediate host must be eaten to transmit the
parasite to the next host. Example a larval
parasite occurs in a fish that is eaten raw by a
human __________________________- a host,
usually an arthropod, in which the parasite
undergoes a significant change and is actively
transmitted to the next host, usually by a
bite.  Example a mosquito picks up malaria
from a bite, parasite undergoes

reproduction, and is transmitted in a new bite
of a human host
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Definitions of Hosts cont.
____________________________ - host in which
there is no parasite development but the parasite
continues to live and is infective to the next
host. A paratenic host bridges an ecological gap
in the life cycle. Example larval parasite in
insect adult parasite in
an owl
little chance larval parasite
in insect adult parasite
in an owl
shrew paratenic host ____________________
__ an inanimate object that may be contaminated
by a parasite and serve as a means of
transmission to the next host. Example eating
utensil or washcloth shared by 2 people
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Types of Parasitic Diseases
______________________ - endoparasite lives
within its host   ______________________-
ectoparasite lives on the surface of its
host   ______________________- parasitic disease
that occurs in non-human animals that is
transmissible to humans   ______________________
- parasitic disease of humans that is
transmissible only to other humans
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Types of Parasitic Diseases cont.
_______________________ a parasite is present in
the human population at a stable rate of
prevalence in a certain geographical
area  Example Malaria is endemic in central
Africa. _______________________- a parasite is
present in the non-human population at a stable
rate of prevalence in a certain geographical
area  Example Heartworm is enzootic in
Wisconsin dogs.
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Types of Parasitic Diseases cont.
________________________ a parasite is present
in the human population at an unusually high rate
of prevalence in a certain geographical
area  Example An epidemic of trichinosis
occurred in Milwaukee from sausage purchased at
Ottos Sausage Shop. ________________________ -
a parasite is present in the non-human population
at an unusually high rate of prevalence in a
certain geographical area Example An epizootic
of bee mites in Wisconsin has killed many
honeybees resulting in decreased honey production.
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Types of Parasitic Diseases cont.
If a parasite shows ________________________, the
parasite can use only 1 or 2 animal species as a
host   Example the beef tapeworm uses only 1
animal as its definitive host
the human If a
parasite shows ________________________, the
parasite can use many animal species as a host
Example the trichina worm can use almost any
carnivore as its host
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METHODS BY WHICH A PARASITE CAN INFECT A HOST

• 1. _______________________ containing an
  infective stage of the parasite
• 2. _______________________________________
  containing an infective stage of a parasite
• ___________________of an arthropod vector
• 4. _____________________________________
  resulting in fecal contamination and ingestion of
  an infective stage of the parasite

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METHODS BY WHICH A PARASITE CAN INFECT A HOST
cont.

• 5. ________________ carrying an infective stage
  of the parasite
• ______________________________infected with a
  parasite
• 7. _____________________ by one's self

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HOW DOES A PARASITE ENTER ITS HOST?
1. ___________________________ 2.
___________________________ - by the parasite
itself - through the bite of a vector 3.
___________________________ 4.
___________________________ 5.
___________________________ 6.
___________________________
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WHAT ARE THE EFFECTS OF A PARASITE ON ITS HOST?

• 1. ______________________________
• 2. ______________________________
• 3. ______________________________
• 4. ______________________________
• 5. ______________________________
• 6. ______________________________
• ______________________________
• All of these effects result in the pathology
  caused by the parasite.

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Introduction to the Parasitic Protozoa Chapter 4

• Characteristics
• 1. Protozoan parasites are ______________________
  ______ in which all activities of life occur
  within the limits of a single plasma membrane.
• 2. Protozoan cells are __________________________
  ___ - contain a distinct nucleus and numerous
  organelles which perform specific functions.
• 3. Most protozoa are ____________________________
  __ - commonly ranging in size from 3 to 300 µm.
• First protozoa were described by Leeuwenhoek in
  the late 1600's using his newly invented
  microscope.

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• 3. Protozoa are found whereever life can exist
  but are dependent upon ___________________________
  
• Moisture is generally not a problem for
  parasitic protozoa as water is a major
  component of cells.
• Should drying occur, many parasites have the
  ability to ________________________ - secrete a
  resistant cyst wall around themselves to survive
  harsh conditions away from a host.
• 4. _____________________________- Protozoa move
  by use of flagella, cilia, or pseudopodia
  (roughly used as basis of classification)

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5. Three types of NUTRITION occur in the
Protozoa (1) ___________________________________
____ (autotrophic) - protozoan produces its own
nutrients (carbohydrates) by photosynthesis in
chloroplasts - not used by parasitic
forms (2) _______________________________________
(holozoic) - ingestion of other organisms or
particles of organic molecules as food
- some protozoa have mouths - cytostomes - to
ingest food materials - other protozoa
utilize phagocytosis - heterotrophic nutrition
is used by many parasitic protozoa (3)
_______________________________________
absorption of water-soluble organic molecules
through the cell membrane, usually by
pinocytosis - used by several parasitic
protozoa - Note text considers saprozoic
nutrition to be the same as heterotrophic
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• REPRODUCTION - may be either asexual or sexual
  some parasitic protozoa may alternate types in
  their life cycle
• (1) ASEXUAL REPRODUCTION - involves mitosis and
  fission
• - ___________________________________is most
  commonly used by parasitic protozoa 
• - ___________________________________(schizo
  gony) used by some involves repeated divisions
  of the nucleus before cytokinesis to produce many
  daughter cells.
• (2) SEXUAL REPRODUCTION - involves meiosis
  formation of gametes
• - if gametes join to form new cell, process
  is ___________________________
• - if gamete nuclei are exchanged between two
  existing cells, process is _______________________
  _______________ (occurs only in the ciliates)

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Taxonomy of the Protozoa
The number of named species of protozoan is
_______________ Of these, about 10,000 species
are parasitic.   - These numbers represent only a
fraction of the number of
species, as many species remain undescribed.   In
the 5 kingdom classification scheme commonly used
today, the protozoans are placed in the KINGDOM
_________________________
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Taxonomy of the Protozoa
Several taxonomic schemes have been devised for
the protozoa. One was developed in 1980. The
classification scheme divides the protozoa into
______________________ 3 Major Phyla (contain
parasites of medical and veterinary importance)
Phylum Sarcomastigophora - flagellates and
amebae   Phylum Ciliophora - ciliates 
Phylum Apicomplexa - sporozoan parasites 4
Minor Phyla (none of medical or veterinary
importance) 
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Taxonomy of the Protozoa
New taxonomic scheme published in your text
(2005) divides the parasitic protozoa into
___________________ Some of these are Phylum
Retortamonada Phylum Axostylata
Phylum Euglenozoa Phylum Parabasalia Phylum
Sarcodina - ___________________________ Phylum
Apicomplexa ____________________________ Phylu
m Ciliophora __________________________

_______________
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