1. Introduction to Medical Parasitology History, Definitions Classification and Taxonomy of Human Parasites
Doç.Dr.Hrisi Bahar
Doç.Dr.Hrisi Bahar

2. Parasitology
Parasitology – science about parasitic animals and relationships with their hosts.
Para + situ + logos = conversation about those living nearby us
= parasitology.

3. History infections come from a period of
The first written records of what
are almost certainly parasitic
infections come from a period of
Egyptian medicine from 3000 to
400 BC, particularly the Ebers
papyrus of 1500 BC discovered
at Thebes.

4. A.lumbricoides eggs have been found in human coprolites from Peru dating from 2277 BC.
Larval nematodes,possibly hook worms, have been found in fecal samples dated to about 200 BC from the Colorado Plateau
In 1910, Marc Armand Ruffer found
S.haematobium eggs in two Egyptian mummies dating from the,1250 to 1000 BC

5. A parasite, is an organism that lives on or inside another organism to the detriment of the host organism.
The parasite grows, feeds, or uses shelter of the host organism (including the host itself) contributing negatively to the relationship.

6. Parasitism:
A symbiotic relationship in which the symbiont (parasite) benefits at the expense of the host by living either within the host (endoparasite) or outside the host (ectoparasite).

7. Types of parasitism
Obligate parasites:All or most of their life cycle are parasitic.
Temporary parasites:parasitic for limited period for either feeding or reproduction.

8. Facultative parasites:organisms are not parasitic but can live parasitic for a limited period.
Accidental parasites:normally free living organisms can survive within a host when they are accidentally taken.

9. What is a Parasite Host?
The host is the organism that the parasite lives in.
*A definitive host
* An intermediate host
*A paratenic host
*A reservoir host

10. Ex: When a human has an adult beef tapeworm in the intestine producing
A definitive host is an organism that the adult, or sexually reproductive stage of the parasite lives in.
Ex: When a human has an adult beef
tapeworm in the intestine producing
eggs,he or she is a “definitive host”

11. Ex:Human are “intermediate hosts” to malariae parasites which multiply
An intermediate host is an organism that hosts an immature parasitic stage, or a stage that reproduces asexually
Ex:Human are “intermediate hosts” to
malariae parasites which multiply
in human liver and blood cells.

12. Reservoir hosts, with respect to human parasites, are hosts that are infected with a parasite and keep it alive even if the parasite is wiped out in humans.
“Reservoir hosts can spread the parasite and reintroduce it to human populations”.

13. ●A paratenic host is an organism that is infected with a parasite and can pass it on to another host, but in which the parasite does not develop further.

14. SYMBIOSIS
A biological relationship in which (usually) two species live in close proximity to each other and interact regularly in such a way as to benefit one or both of the organisms.
*Symbiosis may exist between two or more individuals of the same species as well as between two or more individuals representing two different species

15. The three principal varieties
of symbiosis are
*mutualism,
*commensalism,
* parasitism.

16. parasite,benefit at the expense of the other
MUTUALISM
Mutualism is any relationship between two species of
organisms that benefits both species
COMMENSALISM
A symbiotic relationship in which one organism, the
commensal,benefits without causing any detriment to
the other organism which is the host.
PARASITISM
parasite,benefit at the expense of the other
organism,which is the host.

17. Other Parasitology Definitions
*A cyst is a stage of many protozoan parasites that survives well in the environment. Cysts of human parasites are infective to humans. *A trophozoite is a moving, feeding, and multiplying stage of protozoan life cycles. There are not male and female trophozoites: they multiply asexually.

18. Other Parasitology Definitions
Infective (=invasive) stage The stage of the parasite that invades the host .
Vector:An Arthropod which is carrying and transferring parasites from one host to an other
(Egg-larval stages-adult parasite-eggs)

19. Other Parasitology Definitions
Reservoir= Non-human “host” where the parasite can live.This term is only applied when the parasite can infect humans .
Life Cycle= Stages of development of a parasite

20. Essential features of the parasitism
*Parasite is smaller then the host
*Parasite has a shorter life span than it’s host
*Parasite has a greater reproductive potential than it’s host

21. Classification of parasites
Zoological Classification
Living organisms
Without cell With celular
construction construction
(VIRUS)
Procaryotic cell Eucaryotic cell
(= monera) (=protista /single cell)
RICKETSIA PROTOZOA
BACTERIA (=metazoa)
HELMİNTS
ARTHROPODS

22. Ecological Classification
Endoparasite:a parasite that inhabits the
internal organs or tissues of an animal
or plant
Ectoparasite:any parasite that lives on
the outer surface of an animal.

23. Different location of parasites into the host body
Living in digestive system - coelozoic
parasites (tapeworms)
Living in tissues – histozoic parasites
(trichinelliosis)
●Living in blood – hemoparasites (Malaria etc.).

24. Methods of invasion and escape
- Via vectors
- Oral
Penetration from the skin
ESCAPE
Sputum
Via vectors
Faeces or urine

25. Pathologic effects of parasites
Physical trauma (skin,mucosa)
Migration
Nutrition
Toxins
Immunosupression

26. Diagnosis of Parasitic Infections:
1. Clinical diagnosis
2. Laboratory diagnosis

27. Methods for study and clinical analysis
Parasitological analysis:
tissue samples, excrements, surgical methods (biopsy)…
● Radiological (Rontgenoscopy Tomography ...)
Serodiagnosis (Immunodiagnostics. ELISA test etc)

28. Major Groups of Parasites
PROTOZOANS
-- Single-celled eukaryotes
– Malaria, Giardia, Trichomonas vaginalis
HELMINTS (The Worms)
– Multicellular animals
– Flukes, Tapeworms, Roundworms
ECTOPARASITES
– Live outside the host
– Ticks, Lice, Fleas

29. Treatment of Parasitic Infections:
1. Medical and surgical
2. Chemotherapy
3. Adequate nutrition

30. Prevention and Control:
1. Reduction in sources
2. Education
3. Destruction and/or control of
reservoir hosts and vector