Medical parasitology studies parasites that infect humans, their hosts, and associated diseases, focusing on diagnosis, treatment, and prevention. Key terms include types of parasites, hosts, transmission routes, and their life cycles, along with the effects parasites have on hosts. The document outlines the importance of controlling infections and highlights the classification and nomenclature of parasites.

1. INTRODUCTION TO MEDICAL
PARASITOLOGY

2. INTRODUCTION
• Human and other living things on earth
live in closed relationship with each
other.
• They don’t exist in an isolated fashion.
• They are interdependent; each forms a
strand in the web of life.
• Parasitology is the study of parasites,
their hosts, and the relationship
between them.

3. • Medical parasitology is the subject
which deals with the parasites that
infect human being, the diseases caused
by them, clinical feature and the
response generated by human being
against them.
• It's also concerned with the various
methods of their diagnosis, treatment
and finally their prevention & control.

4. Definitions of keys terms
• A parasite: a living organism that acquires some
of its basic nutritional requirements through its
intimate contact with another living organism.
• Parasites may be simple unicellular protozoa or
complex multicellular metazoa.
All parasitic organisms are eukaryotes

5. • Protozoa: unicellular organisms.
• Metazoa: multicellular organisms, e.g.
worms and arthropods.
• An endoparasite: a parasite that lives within
another living organism.
• An ectoparasite: a parasite that lives on the
external surface of another living organism
e.g. lice, ticks.

6. • Zoonosis: a parasitic disease in which an
animal is normally the host - but which also
infects man
• Vector: a living carrier (e.g.an arthropod) that
transports a pathogenic organism from an
infected to a non-infected host.

7. There two types of vectors:
mechanical and biological

8. Epidemiology
• Although parasitic infections
occur globally, the majority occur
in tropical regions, where there is
poverty, poor sanitation and
personal hygiene.

9. Notes: Non-pathogenic parasites: live
in/on the body of the host do not
cause disease
• Opportunistic parasites: cause illness
in individuals with impaired defense
mechanism, is becoming of
paramount importance because of
the increasing prevalence of
HIV/AIDS.

10. DIFFERENT KINDS OF HOSTS
• Definitive host: harbors a parasite in the adult
stage or where the parasite undergoes a sexual
method of reproduction.
• Intermediate host: harbors the larval stages of the
parasite or an asexual cycle of development takes
place.

11. Paratenic host:
An intermediate host whose presence may be
required for the completion of a parasite's life
cycle but in which no development of the
parasite occurs

12. Host cont...
• Reservoir host : makes the parasite available for
the transmission to another host and is usually not
affected by the infection. /animals harboring the
same species of parasites as man. Potential sources
of human infection.

14. Life cycle and type of life cycle
• Life cycle : The whole process of parasite growing
and developing.
• The direct life-cycle : Only one host (no
intermediate host).
• The indirect life cycle : Life cycle with more than
one host (intermediat host and final host).

15. Symbiotic relationships
• Organism that spends a portion or all of its life
cycle intimately associated with another
organism of a different species is considered
as Symbiont.
• This relationship is called symbiosis (symbiotic
relationships).

16. The basic factor of transmission
of parasitic diseases
• The source of the infection
• The routes of transmission
• The susceptible host

17. The source of the infection
• Patient: Persons who have parasites in their
body and show clinical symptoms.
• Carrier: Persons who have parasites in their
body, not show symptoms.
• Reservoir host: Animals that harbors the
same species of parasites as man.
Sometimes, the parasites in animals can
transmit into human.

18. The routes of transmission
• Congenital transmission: From mother to infant.
Eg: Toxoplasmosis
• Contact transmission:
• Direct contact (E.g:Trichomonas vaginalis);
• Indirect contact (E.g:Ascaris lumbricodes)
• Food transmission: The infectious stage of
parasites contaminated food / The meat of the
intermediate hosts containing infectious stage of
parasites.

19. • Water transmission: Drink or contact the
water contaminated the infectious stage
of parasites.
• Soil transmission: Contamination of the
soil by feces containing the certain stage
of parasites.
• Arthropod transmission: Vectors of
certain parasitic diseases.

20. The susceptible host
In general, most people is the
susceptible host. The parasite
reaching a susceptible host must
gain entrance and set up a favorable
residence in order to complete its
life cycle and cause the transmission
of parasitic diseases.

21. The avenues of invasion
• Digestive tract: Most common avenue of
entrance. (Food/ Water transmission)
• Skin: Infective larvae perforate skin and
reach to body and establish infection. (soil/
water transmission)
• Blood: Bloodsucking insects containing
infective parasites bite the skin and inject
parasites into human blood. (Arthropod
transmission---malaria).

22. The prevention measures of the
parasitic diseases
• Controlling the source of the infection.
Treatment of the patients, carriers and reservoir
hosts.
• Intervention at the routes of transmission
Managing feces and water resource, controlling or
eliminating vectors and intermediate hosts.
• Protecting the susceptible hosts.
Paying attention to personal hygiene, changing bad
eating habit, taking medicine.

23. EFFECT OF PARASITES ON THE HOST
• Mechanical injury: may be inflicted by a
parasite by means of pressure as it
grows larger, e.g. Hydatid cyst causes
blockage of ducts such as blood vessels
producing infraction, e. g. , biliary
e. g. , biliary
ascariasis and larva migrans, Ascaris
ascariasis and larva migrans, Ascaris
Perforate/Obstruction
Perforate/Obstruction

24. • Deleterious effect of toxic substances: in
P. falciparum production of toxic
substances may cause rigors and other
symptoms.
• e. g., mosquitoes, spiders and ticks
e. g., mosquitoes, spiders and ticks
introduce venom when they insert their
introduce venom when they insert their
mouth parts into the skin.
mouth parts into the skin.

25. • Deprivation of nutrients, fluids and
metabolites -parasite may produce
disease by competing with the host for
nutrients. e.g. hookworms suck blood.
e.g. hookworms suck blood.

26. • Immunological reaction: Tissue damage may
be caused by immunological response of the
host, e.g. schistosoma liver cirrhosis; when
e.g. schistosoma liver cirrhosis; when
hydatid fluid is released from the rupture of
hydatid fluid is released from the rupture of
a hydatid cyst anaphylaxis often results.
a hydatid cyst anaphylaxis often results.
• nephritic syndrome following Plasmodium
nephritic syndrome following Plasmodium
infections.
infections.

27. Classification
• The classification of parasites is controversial
- there is no universally accepted system.
• Parasites form part of the animal kingdom
which comprises some 800,000 identified
species categorised into 33 phyla.
• The parasitic organisms that are of
importance for human health are eukaryotes

29. Nomenclature of parasites
• Each parasite possesses two names, a
generic and a specific
• the former begins with an initial capital
and the latter with an initial small letter,
after which comes the designator’s
name, followed by punctuation and
finally the year.
• The generic and specific names are in
italics but not the designator’s name.

30. • for example, the common intestinal
roundworm of man is named Ascaris
lumbricoides Linnaeus, 1758. This
means that it belongs to the Genus
Ascaris and the name of the species
lumbricoides was given by Linnaeus
in the year 1758.