Introduction Introduction to Medical Parasitologyto Medical Parasitology

History, DefinitionsHistory, DefinitionsClassification and Taxonomy Classification and Taxonomy

ofof Human Parasites Human Parasites

Doç.Dr.Hrisi Bahar

ParasitologyParasitology

• Parasitology Parasitology – – science about science about parasitic animals and parasitic animals and relationships with their hosts.relationships with their hosts.

• Para + situ + logosPara + situ + logos = = conversation about those living conversation about those living nearby us nearby us

= parasitology.= parasitology.

HistoryHistory

The first written records of whatThe first written records of what

are almost certainly are almost certainly parasiticparasitic

infectionsinfections come from a period come from a period ofof

Egyptian medicineEgyptian medicine from 3000 to from 3000 to

400 BC, particularly the 400 BC, particularly the EbersEbers

papyruspapyrus of 1500 BC discovered of 1500 BC discovered

at Thebes.at Thebes.

A.lumbricoidesA.lumbricoides eggs have been eggs have been found in human coprolites from Peru found in human coprolites from Peru dating from 2277 BC.dating from 2277 BC.

Larval nematodes,possibly hook Larval nematodes,possibly hook wormsworms, have been found in fecal , have been found in fecal samples dated to about 200 BC samples dated to about 200 BC from the Colorado Plateaufrom the Colorado Plateau

In 1910, Marc Armand Ruffer found In 1910, Marc Armand Ruffer found S.haematobium S.haematobium eggseggs in two in two

Egyptian mummies dating from Egyptian mummies dating from the,1250 to 1000 BCthe,1250 to 1000 BC

A parasiteA parasite,, is an organism that lives is an organism that lives

on or inside another organism to the on or inside another organism to the detriment of the host organism. detriment of the host organism.

The parasiteThe parasite grows, feeds, or uses grows, feeds, or uses shelter of the host organism shelter of the host organism (including the host itself) contributing (including the host itself) contributing negatively to the relationship. negatively to the relationship.

• ParasitismParasitism: :

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

Obligate parasitesObligate parasites::All or most of their All or most of their life cycle are parasitic.life cycle are parasitic.

Temporary parasites:Temporary parasites:parasitic for parasitic for limited period for either feeding or limited period for either feeding or reproduction.reproduction.

Types of parasitismTypes of parasitism

Facultative parasites:Facultative parasites:organisms are organisms are not parasitic but can live parasitic for not parasitic but can live parasitic for a limited period.a limited period.

Accidental parasites:Accidental parasites:normally free normally free living organisms can survive within a living organisms can survive within a host when they are accidentally host when they are accidentally taken.taken.

The hostThe host is the organism that the is the organism that the parasite lives in.parasite lives in.

**A A definitive hostdefinitive host

* * An intermediate hostAn intermediate host **A A paratenic hostparatenic host **A reservoir hostA reservoir host

What is a Parasite Host?

A A definitive hostdefinitive host is an organism is an organism that the adult, or sexually that the adult, or sexually reproductive stage of the parasite reproductive stage of the parasite lives in.lives in.

Ex: When a human has an adult beeftapeworm in the intestine producing eggs,he or she is a “definitive host”

• An An intermediate hostintermediate host is an is an organism that hosts an immature organism that hosts an immature parasitic stage, or a stage that parasitic stage, or a stage that reproduces asexuallyreproduces asexually

Ex:Human are “intermediate hosts” to

malariae parasites which multiply

in human liver and blood cells.

• Reservoir hostsReservoir hosts, , with respect to human with respect to human parasites, are hosts that are infected with parasites, are hosts that are infected with a parasite and keep it alive even if the a parasite and keep it alive even if the parasite is wiped out in humans. parasite is wiped out in humans.

“ “Reservoir hosts can spread the parasite and reintroduce it Reservoir hosts can spread the parasite and reintroduce it

to human populations”to human populations”..

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

SYMBIOSISSYMBIOSIS

A biological relationship in which A biological relationship in which (usually) two species live in close (usually) two species live in close proximity to each other and interact proximity to each other and interact regularly in such a way as to benefit regularly in such a way as to benefit one or both of the organisms.one or both of the organisms.

**Symbiosis may exist between two or Symbiosis may exist between two or more individuals of the same species as more individuals of the same species as well as between two or more individuals well as between two or more individuals representing two different species representing two different species

The three principal varietiesThe three principal varieties of symbiosis are of symbiosis are

**mutualism, mutualism, **commensalism,commensalism,

** parasitism.parasitism.

MUTUALISMMUTUALISMMutualism is any relationship between two species ofMutualism is any relationship between two species oforganisms that benefits both species organisms that benefits both species

COMMENSALISM COMMENSALISM A symbiotic relationship in which one organism, theA symbiotic relationship in which one organism, thecommensal,benefits without causing any detriment tocommensal,benefits without causing any detriment tothe other organism which is the host.the other organism which is the host.

PARASITISM PARASITISM

A symbiotic relationship in which one organism, theA symbiotic relationship in which one organism, theparasite,benefit at the expense of the otherparasite,benefit at the expense of the otherorganism,which is the host. organism,which is the host.

Other Parasitology Other Parasitology DefinitionsDefinitions

*A*A cyst cyst is a stage of many protozoan is a stage of many protozoan

parasites that survives well in the parasites that survives well in the environment. Cysts of human environment. Cysts of human parasites are infective to humans.parasites are infective to humans.

**A trophozoiteA trophozoite is a moving, feeding, is a moving, feeding, and multiplying stage of protozoan and multiplying stage of protozoan life cycles. There are not male and life cycles. There are not male and female trophozoites: they multiply female trophozoites: they multiply asexually.asexually.

Other Parasitology Other Parasitology DefinitionsDefinitions

• Infective (=invasive) stageInfective (=invasive) stage The stage The stage of the parasite that invades the host . of the parasite that invades the host .

• VectorVector:An Arthropod which is carrying :An Arthropod which is carrying and transferring parasites from one host and transferring parasites from one host to an otherto an other

(Egg-larval stages-adult parasite-eggs) (Egg-larval stages-adult parasite-eggs)

Other Parasitology Other Parasitology DefinitionsDefinitions

• ReservoirReservoir== Non-human “host” Non-human “host” where the parasite can live.This term where the parasite can live.This term is only applied when the parasite can is only applied when the parasite can infect humansinfect humans . .

• Life CycleLife Cycle= Stages of development = Stages of development of a parasiteof a parasite

Essential features of the Essential features of the parasitismparasitism

**Parasite is smaller then the hostParasite is smaller then the host

**Parasite has a shorter life span Parasite has a shorter life span than it’s hostthan it’s host

**Parasite has a greater Parasite has a greater reproductive potential than it’s reproductive potential than it’s hosthost

Zoological ClassificationZoological Classification Living organismsLiving organisms Without cell With celularWithout cell With celular construction constructionconstruction construction (VIRUS)(VIRUS) Procaryotic cell Procaryotic cell Eucaryotic cellEucaryotic cell (= monera) (=protista /single cell)(= monera) (=protista /single cell)

RICKETSIA RICKETSIA PROTOZOAPROTOZOA

BACTERIABACTERIA (=metazoa) (=metazoa)HELMİNTSHELMİNTSARTHROPODSARTHROPODS

Classification of parasites

Ecological ClassificationEcological 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.

Different location of Different location of parasites into the host parasites into the host bodybody• Living in digestive systemLiving in digestive system - - coelozoiccoelozoic

parasites (tapeworms)parasites (tapeworms)

• Living in tissuesLiving in tissues – histozoic parasites– histozoic parasites

(trichinelliosis)(trichinelliosis)

●●Living in bloodLiving in blood – hemoparasites (Malaria – hemoparasites (Malaria etc.).etc.).

Methods of invasion and escape Methods of invasion and escape

INVASIONINVASION

- Via vectors- Via vectors

- Oral- Oral

- Penetration from the skinPenetration from the skin

ESCAPEESCAPE

• SputumSputum

• Via vectorsVia vectors

• Faeces or urineFaeces or urine

Pathologic effects of Pathologic effects of parasitesparasites

• Physical trauma (skin,mucosa)Physical trauma (skin,mucosa)

• MigrationMigration

• NutritionNutrition

• ToxinsToxins

• ImmunosupressionImmunosupression

Diagnosis of Parasitic InfectionsDiagnosis of Parasitic Infections::

• 11.. Clinical diagnosisClinical diagnosis

• 22.. Laboratory diagnosisLaboratory diagnosis

Methods for study and Methods for study and clinical analysisclinical analysis

• Parasitological analysis:Parasitological analysis:

tissue samples, excrements, surgical tissue samples, excrements, surgical methods (biopsy)…methods (biopsy)…

●● Radiological (Radiological (Rontgenoscopy Tomography Rontgenoscopy Tomography ...)...)

• Serodiagnosis (Serodiagnosis (Immunodiagnostics. ELISA test Immunodiagnostics. ELISA test

etc)etc)

Major Groups of Parasites

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

Treatment of Parasitic InfectionsTreatment of Parasitic Infections::

• 11. . Medical and surgical

• 22. . Chemotherapy

• 33. . Adequate nutrition

Prevention and Control:Prevention and Control:

• 11. . Reduction in sources

• 22. . Education

• 33. Destruction and/or control of reservoir hosts and vector