intro parasitology 2013
TRANSCRIPT
05/03/2023 Even semester 2012/2013
INTRODUCTION TO PARASITOLOGY
ISNA INDRAWATIDEPARTMENT OF PARASITOLOGY
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Medical Parasitology
• science that deals with the study of the dependence of organism (parasite) on another (host) without making any useful return.
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Parasite • organism that lives on or within
another organism for survival• usually cannot exist as free –
living, except Strongyloides stercoralis
• dependent on the host for existence.
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• An endoparasite: a parasite that lives within
another living organism; invade deep and internal organs of the body e.g. : Ascaris lumbricoides, Giardia lamblia
• An ectoparasite: a parasite that lives on the
external surface of another living organism, e.g. : lice (Pediculus), ticks
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05/03/2023 Even semester 2012/2013
• Obligate organism which are completely
dependent on the host for existence.e.g. : Nematodes
• Facultative when a parasite is capable of living
even without a host can exist as free – living or as parasite, e.g. Strongyloides stercoralis
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Life cycle of Strongyloides stercoralis
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• Permanent parasite that remains on or in the
body of the host from early life until maturity or for its entire life , e.g. Ascaris , Pediculus humanus capitis
• Temporary visit their host only for a short period of time, e.g : bugs, ticks
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HOST• Definitive
where the parasite lives & complete their life cycle /completion of sexual reproduction
• Intermediate completion of larval stage , asexual
reproduction, and for transmission to the definitive host, e.g: Snail for Schistosoma
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• Reservoir host other animal that harbors the
same parasite & act as additional source of human infection, e.g : rat fro Schistosoma
• Paratenic host one which incidentally carries
the infective stage of parasite in an arrested state ( no continuity of life cycle )
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Vectors:• Intermediate host playing an
active role in the transmission of the parasite.
• Usually arthropodes that harbors infective stage of parasite
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Helminthes
Protozoa
Arthropodes
• Class Nematoda• Class Trematoda• Class Cestoda
• Class Rhizopoda• Class Mastigophora• Class Sporozoa• Class Ciliophora
• Class Insecta • Class Arachnida• Class Crustacea• Class Chilopoda• Class Diplopoda
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INFECTION• Autoinfection
infection acquired by an individual resulting from their own direct source of exposure.
• Reinfection when a person is infected with a parasite after months of cure gets reinfected with the same specie of parasite.
• Superinfectionwhen a host is harboring more than one parasite at a time.
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Source of exposure to parasitic infection
1. Contaminated water and soil2. Food containing immature
infective stage of parasite3. Blood – sucking insects as
vectors.
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Source of exposure (cont’d)
5. Domestic Animals harboring the parasite, e.g : dog flea contained infective stage of D. caninum
6. Another person, his clothing or bedding
7. One’s self
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Portal of Entry:1.Mouth/oral : most common2.Skin : penetration of infective
stage larva3.Airborne : parasite inhaled
nose nasopharynx intestine, e.g : E. vermicularis
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4.Transplacental : parasite from mother transmitted to the fetus in utero, e.g. : T. gondii
5. Sexual : acquired through sexual contact
e.g : T. vaginalis
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05/03/2023 Even semester 2012/2013
Nomenclature of animal parasite
• binomial scientific names are assigned to each parasite which are LatinA. Genus name : begin with capital letterB. Species : small letter
e.g: Ascaris lumbricoides A. lumbricoides
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Diagnosis of parasitic infection:• Clinical diagnosis– easy when the doctor familiar
with the symptom/ in endemic area/ specific manifestation of infection.– problem if disease is uncommon
in the community or with migrants in the community.
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• Laboratory–purpose is to make specific
diagnosis– collect proper specimen like stool, urine, blood, sputum, aspirate from body orifices, tissue scrapings
–know how & when specimen is to be obtained
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• Other laboratory method used:
• 1) X – ray/ USG•2) Serology•3) Biopsy