By
Assist. Prof. of Parasitology,
Zoology Department,
Damietta Faculty of Science, Mansoura University
Topics
NO. of hours
Date
1
Parasitology and Parasitism
1
22 Sept.
2
Protozoan Parasites
1
29 Sept.
3
Protozoan Parasites
1
6 Oct.
4
Protozoan Parasites
1
13 Oct.
5
Protozoan Parasites
1
20 Oct.
6
Worm Parasites
1
27 Oct.
7
Worm Parasites
1
3 Nov.
8
Revision
1
10 Nov.
9
Worm Parasites
1
17 Nov.
10
Worm Parasites
1
24 Nov.
11
Worm Parasites
1
1 Dec.
12
Worm Parasites
1
8 Dec.
13
Worm Parasites
1
15 Dec.
14
Revision
1
22 Dec.
15
Final Exam
1
*Dr. Ola Abdell Halim Abu Samak
*Office hours:
*Phone: 0572403981-168
*Email: olasamak@mans.edu.eg
*Lecture: 1 hour
*Labs: 2 hours
Parasites and Parasitism
Lecture 1
Aim of the lecture
Increasing the familiarity with the
parasites and host relations
Recognizing the parasitism among the
other biological relationships
Comparing between different biological
relationships and monitoring in the
surrounding environment
Identifying the biological relationships
Do Parasites Rule the World?
Parasites are often occupying the 3rd great
environment (aquatic-terrestrial-parasitic)
*Traditionally, only considered to be protists,
worms, and arthropods.
*Now known to encompass everything from
prokaryotes up to the diversity of metazoans.
*One of the most common lifestyles in existence, with
an estimate 1/3 of life being parasitic (Price 1980).
*In fact, of the 35 animal phyla, only echinoderms,
chordates, and a few minor phyla do not have
representative parasitic members.
Organismal Associations
Any association more or less permanent is called a
symbiosis, with each member a symbiont.
Symbiosis is used as a n umbrella term for organisms
that live together
Symbiosis
Phoresis
Commensalism
Mutualism
Parasitism
Phoresis
Two organisms simply
travel together
Neither organism is
helped or harmed
Usually one is
transporting the other
Examples of Phoresis
Barnacles on a whale
Burrs attached to fur of mammals
Or your socks and shoe laces
Dematobia (bot fly) eggs on mosquito
Female bot fly lays eggs on female mosquito
Eggs drop off when mosquito feeds
Fungal spores on legs of house fly
Commensalism
One benefits but the other isn’t harmed
and receives no benefits
Usually one feeds off the “wastes” of the
other partner.
Commensalism Examples
Remoras and sharks
*Feed on scraps left by shark
Humans have many commensals
*Intestinal protozoans and bacteri
*Entamoeba Gingivalis Amoeba in the mouth
*Eyelash mites
Mutualism
Both organisms benefit from the relationship
Usually obligatory
Both partners realy on the relationship and can’t live
without the other.
Mutualism Examples
Coral and Zooxanthelle
Termites and bacteria
Bacteria digest wood
Cleaner fish and the fish they
clean
Leeches and bacteria
Bacteria digest blood
Humans and bacteria
Bacteria make vitamins out
of our wastes
Parasitism
One organism benefits while the other organism is
harmed
The amount of harm can vary
-Mosquito bite causes minor irritation
-Some parasites steal nutrients
-Some cause major damage that can result in death
of other organism
Parasite is in wrong host
Parasites in large numbers
Symbiosis
The line between some the categories may
be difficult to draw.
A parasite in one organism may be a
commensal in another organism.
How much “harm” is necessary before a
commensal becomes a parasite?
Predation
Predation is frequently viewed as a
symbiosis
Interaction between two organisms
One organism dies at the end of the
interaction.
The interaction occurs over a very short
time
Predation vs. Parasitism
Predation and parasitism may seem to be the
same.
One organism benefits, other is harmed
Both can result in an evolutionary arms race
The host/prey gets better at avoiding the
parasite/predator so the parasite/predator must adapt
But there are significant differences.
Predation results in the death of one of the
organism.
Parasites usually try to keep host alive.
Predator is larger than the prey.
Parasites are usually smaller than host.
Predator preys on many individuals in a lifetime.
Parasite usually spends entire life in one or two host
Parasitology
Usually restricted to protozoans and
multi-cellular animals that are parasitic
on other animals, particularly humans.
Does not include
bacteria and viruses
parasites on plants
Our Focus in Parasitology
Learn the taxonomic groups of parasites
Recognize life cycles for important parasites
Identify diseases associated with particular
parasites, and how to recognize them
Parasites or not?
If an animal lives inside another, but is not
actively causing harm, is it a parasite?
If an animal temporarily feeds upon
another, but leaves its prey alive, is it a
parasite?
If an animal lays its eggs in another, and the
young consume the host from the inside-out,
is it a parasite?
A simple view
In a straight forward situation a small
organism (Parasite) has the potential to
harm a larger organism (Host), and relies on
said host for nutrients and shelter (a Niche).
The parasite generally has a much higher
reproductive capability compared to its host.
Unfortunately, parasitism is seldom this
clear cut.
Types of Parasites
Endoparasite vs Ectoparasite
Living inside or outside the host
What about Pneumonyssus simicola
that infest nasal passages and lungs?
Temporary vs Permanent
Only on host to feed or only off the host to
disperse
Obligate vs Facultative
Must have the host to complete life cycle or freeliving organism capable of infesting a host under
the right conditions.
Types of Parasites
1- Location
Endoparasite
Lives inside the body of the host may be just
under the surface or deep in the body
Tapeworms, flukes, protozoans
Ectoparasite
Stays on outside surface of the host
Mosquitoes, leeches, ticks, fleas, brood
parasites
Types of Parasites
2 – Required or not
Obligate Parasite
Requires finding and invading the
host to complete its life cycle
Most of the parasites we will cover
are obligate parasites
Facultative Parasite
May become parasitic if it is given
the chance but does not require a host.
Types of Parasites
3- Amount of time spent
Permanent Parasite
Lives entire adult life stage on or in a
host
Usually endoparasites
One exception is eyelash mite
Temporary Parasite
Spends only a short time on a host
Usually ectoparasites
Types of Hosts
Definitive Host
Host where sexual reproduction (or
any other gene shuffling) takes place.
In the few parasites with only asexual
reproduction, it is the host most
important to humans.
Intermediate Host
Required in the life cycle of parasite.
No reproduction or asexual
reproduction takes place.
Types of Hosts
Paratenic or Transport Host
No development occurs but parasite
remains alive
May go dormant
May cause damage
Accidental or Incidental Host
Parasite is in the “wrong” species.
Parasite usually wanders around and
causes great damage because it doesn’t know
where to go then dies.
Types of Hosts
Reservoir Host
Any animal that carries a parasite that can cause
infections in humans.
Even if it is the normal host for that parasite.
Related to the medical perspective of parasitology
 Vector
Any organism that transmits infections to humans.
Broader because it includes organisms that carry
parasites, bacteria, and viruses.
Frequently, it is an obligate host for a parasite.
Life Cycles
Direct life cycle
Transmitted from one
host to another through the
air, by a fomite, or in
contaminated food or
water.
Indirect life cycles
requires a vector or
intermediate host to
reproduce or grow in.
Tritrichomonas foetus
Direct life cycle
Indirect life cycle
How are Parasites Studied?
Need to be familiar with invertebrate and
vertebrate zoology
Taxonomy and systematics
Histology and cytology
Immunology
Molecular biology
Vector Biology and the study of life cycles
Our Focus in Parasitology
Learn the taxonomic groups of
parasites
Recognize life cycles for important
parasites
Identify diseases associated with
particular parasites, and how to
recognize them