Introduction to Medical Parasitology History, Definitions Classification and Taxonomy of Human Parasites Doç.Dr.Hrisi Bahar Parasitology • Parasitology – science about parasitic animals and relationships with their hosts. • Para +

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Transcript Introduction to Medical Parasitology History, Definitions Classification and Taxonomy of Human Parasites Doç.Dr.Hrisi Bahar Parasitology • Parasitology – science about parasitic animals and relationships with their hosts. • Para +

Slide 1

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


Slide 2

Parasitology
• Parasitology – science about

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


Slide 3

History
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.


Slide 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


Slide 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.


Slide 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).


Slide 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.


Slide 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.


Slide 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


Slide 10

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”


Slide 11

• 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.


Slide 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”.


Slide 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.


Slide 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


Slide 15

The three principal varieties
of symbiosis are

*mutualism,
*commensalism,
* parasitism.


Slide 16

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

A symbiotic relationship in which one organism, the
parasite,benefit at the expense of the other
organism,which is the host.


Slide 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.


Slide 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)


Slide 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


Slide 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


Slide 21

Classification of parasites
Zoological Classification
Living organisms

Without cell
construction
(VIRUS)
Procaryotic cell
(= monera)

RICKETSIA
BACTERIA

With celular
construction

Eucaryotic cell
(=protista /single cell)

PROTOZOA
(=metazoa)

HELMİNTS
ARTHROPODS


Slide 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.


Slide 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.).


Slide 24

Methods of invasion and escape
INVASION
- Via vectors
- Oral
- Penetration from the skin

ESCAPE
• Sputum
• Via vectors
• Faeces or urine


Slide 25

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


Slide 26

Diagnosis of Parasitic Infections:

• 1. Clinical diagnosis
• 2. Laboratory diagnosis


Slide 27

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


Slide 28

Major Groups of Parasites











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


Slide 29

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


Slide 30

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