Transcript Medical Parasitology & Entomology

SBM 2022
Medical Parasitology
&
Entomology
Lecturer: Sr. Norazsida Ramli
Course assessment
Mid semester: 40 %
Quiz/ assignment: 10%
Final examination: 50%
What is Parasitology?
Parasite: a live organism living in, or on ,
and having some metabolic dependence
on another organism known as a host.
A weaker organism that obtains food and
shelter from the association.
It may be a pathogen, causing disease in
a host or it maybe nonpathogenic (causing
no harm).
Host: the harboring species.
THE NATURE OF HOST-PARASITE
INTERACTIONS
Symbiosis interaction– a permanent association of
two organisms that cannot exist independently.
Mutualism – both organisms are benefited.
Comensalism – one partner is benefited, the
other is unaffected.
Parasitism: any reciprocal association in which a
species depends upon an other for its existence.
Ectoparasite: parasite that lives on the
outside of the host (infestation).
-Example: tick, mite.
Endoparasite: parasite that lives within the
body of the host (infection).
-Example: Plasmodium sp.
Facultative parasite: parasites that
capable of leading both a free and a
parasitic existence. For example,
Halicephalobus (Micronema) deletrix , a
saprophytic soil nematode that is found
free-living in nature, has been reported to
produce pathology in the CNS of horses.
Obligate parasite: parasites that take up a
permanent residence in and are
completely dependent upon the host.
Example: Plasmodium sp.
Incidental parasite: parasite that
establishes itself in a host which it does
not ordinarily live. For example,
Parelaphostrongylus (Pneumostrongylus)
tenuis normally is found in neurologic sites
within the definitive host, white-tailed deer
Temporary parasite: is free living during
part of its existence and seeks its host
intermittently to obtain nourishment.
Permanent parasite: remains on or in the body
of the host from early life until maturity,
sometimes for its entire life.
Pathogenic parasite: parasite that cause injury to
the host by its mechanical, traumatic, or toxic
activities.
Pseudoparasite: an artifact mistaken for a
parasite.
Coprozoic parasite: a foreign species that has
passed through the alimentary tract without
infecting the host.
Zoonosis: a disease that caused by zoonotic
infection. Can be transmitted from animal to
human not from human to animal.
Geographic distribution
Tropical countries are most favorable
places for the survival, larval development,
and transmission of parasites.
WHY?????? Bcoz…….
Optimal conditions of temperature and
humidity are present.
Short summer season (temperate zones)
prevents the development of many
species that required high temperatures
during their larval stages.
Intense dry heat/direct sunlight may
destroy the larval forms.
Low temperatures arrest the development
of eggs and larvae and may even destroy
them.
Freezing temperatures/snow force
humanity to use privies and prevent
general soil pollution.
Moisture is essential for the development
of free-living larvae and propagation of
intermediate hosts. Example: arthropods,
snails and fishes.
Types of host
Definitive host
Intermediate host
Paratenic host
Incidental host
Dead-end host
Reservoir host
Definitive host
The final host harbors the adult or sexual
stage of the parasite.
Example: human for the Scistosome sp.
Intermediate host (IH)
Host that part or all of the larval or asexual
stage may take place in another animal.
Example: snail for the schistosome.
It can be, 2 intermediate hosts for a
parasite life cycle: primary and secondary
intermediate host.
Example: Diphyllobothrium latum, 10 IH is
copepod, 20 is fish.
Paratenic host
An animal that harbors the parasite in an
arrested state of development;
However the parasite is capable of
continuing its cycle in a subsequent
suitable host.
Act as a transportation for parasite.
Example: Shrew (tupai tanah)
Incidental host
Host that refer to the situation in which the
infected individual is not necessary for the
parasite’s survival or development.
-example: the human being in the case of
trichinosis.
Dead-end host
Human or incidental host is called as
dead-end host if the cycle for transmission
of the parasite is such as that it cannot be
transmitted further.
Reservoir host
Animal that harbor the same parasite.
These hosts ensure continuity of the
parasite’s life cycle and act as additional
sources of human infection.
Example: The rabbit as new reservoir
host of enterohemorrhagic Escherichia
coli.
Life cycle
Directly –simple , only need a host.
Indirectly –complicated, need more than a
host.
Vector
Biological vector
-act as transportation and host as well
-example: mosquito
Mechanical vector
-act as transportation only.
-example: fly