1. Introduction to the medical parasitology
and protozoology
7th theory lecture
Dentistry 2023
2. Parasitology: Is the study of parasites, their hosts, and the relationship between
them.
Parasite: Organism living in, or on , and having some metabolic dependence on
another organism known as a host.
Host: Its an organism , animal or mans which harbors a parasite, its always larger
then parasite.
Medical parasitology: Is a science that deals with parasite that have medical
importance on human.
What is ?
3. The releationship between two living organisms (parasite and host) that coexist and provide
protection or other benefits to one or both partners called symbiosis.
Types of Symbiotic Association.
Host -parasite relations:
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5. • According to the nature of the host- parasite interaction and the environmental factors, the parasite may be one of
the following
1. According to the habitat in/on host:
A- Ecto-parasite: Parasite found on the surface of the body host.
B- Endo-parasite :Parasite found inside the body host.
2. According to the degree of parasitism
A-Facultative parasite: Are those don’t absolutely depend on the parasitic life.
B-Obligatory parasite :Are those which completely depend on parasitic mode of the life.
3. According to the transmission to man or animal:
A- Zoonotic parasite: Are those transmissible from the animal to man
B-Non-zoonotic parasite: Are those transmissible from animal to another animal or from man
to another man.
C- Accidental parasite: This parasite infect an unusual host are known as accidental parasites
Types of parasites:
6. • According to the nature of the host- parasite interaction and the environmental factors, the parasite may be one of the
following
4. According to the size of the parasite
A-Macroparasite: Those can see by eye
B-Microparasite: Can see by using microscope
5. According to the laying stages by the parasites
A-Oviparous parasite: Female lay eggs
B-Viviparous parasite: The eggs hatched and the larvae passed out
C-Ovo-viviparous parasite :Female lay eggs which are containing fully developed larvae to hatch
6. According to the life cycle
A- Direct life cycle: Not require intermediate host
B-In direct life cycle: require intermediate host
Types of parasites:
Life cycle: Is the
process of parasite
growth, development
and reproduction.
7. 1-Definitive host: The host which harbour the adult parasites or in which parasites
undergo sexual method of reproduction.
2-Intermediate host: The host in which the larval stages of the parasite live or in which
asexual reproduction of parasite takes place.
Types of hosts :
9. Sources of parasitic infection
1.Contaminated soil and water
2-Raw or undercooked meat
3-Blood sucking insects
4-Autoinfection
Self-infection by direct contagion, as with pinworm
(Enterobius vermicularis) eggs passed in the infectious
state and transmitted by fingernails (anal-oral route).
10. Role of vector in parasites life cycle
Vector :Are those transmitted parasite from one vertebrate to another.
Type of vectors
2-Biological vector :the parasite remain
for undergoing of development stage
and then traferred to the host
1-Mechanical vector :Trsaferring
infective stage of parasite without
development stage
11. Routes by which humans acquire parasitic infections?
Infection route: Is the specific entrance through which the parasite invades
the body
