SBM 2022 Medical Parasitology

1
SBM 2022Medical Parasitology Entomology

• Lecturer Sr. Norazsida Ramli

2
Course assessment

• Mid semester 40
• Quiz/ assignment 10
• Final examination 50

3
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.

4

• 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.

5

• 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.

6

• 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.

7

• 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.

8

• 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.

9
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.

10

• 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.

11

• Moisture is essential for the development of
  free-living larvae and propagation of
  intermediate hosts. Example arthropods, snails
  and fishes.

12
Types of host

• Definitive host
• Intermediate host
• Paratenic host
• Incidental host
• Dead-end host
• Reservoir host

13
Definitive host

• The final host harbors the adult or sexual stage
  of the parasite.
• Example human for the Scistosome sp.

14
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.

15
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)

16
Incidental host

• Host that refer to the situation in which the
  infected individual is not necessary for the
  parasites survival or development.
• -example the human being in the case of
  trichinosis.

17
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.

18
Reservoir host

• Animal that harbor the same parasite.
• These hosts ensure continuity of the parasites
  life cycle and act as additional sources of human
  infection.
• Example The rabbit as new reservoir host of
  enterohemorrhagic Escherichia coli.

19
Life cycle

• Directly simple , only need a host.
• Indirectly complicated, need more than a host.

20
Vector

• Biological vector
• -act as transportation and host as well
• -example mosquito
• Mechanical vector
• -act as transportation only.
• -example fly