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Parasitic Helminths and Arthropod Agents and
Vectors of Diseases
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Classification of Parasites
Helminths Protozoa
Mulicellular Specialized cells Unicellular Single cell for all function
A-Round worms (Nematodes) cylindrical, unsegmented B-Flat worms 1-Trematodes leaf-like, un-segmented. 2-Cestodes tape-like, segmented Amoebae move by psudobodia. Flagellates move by flagella. Ciliates move by cilia Apicomplexa (sporozoa) Tissue parasites

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• Location of helminths in the body
• Intestinal helminths
• Tissue helminths

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• Nematodes
• General features
• Elongated worm, cylindrical, unsegmented and
  tapering at both ends.
• Variable in size, measure from less than lt1 cm
  to about 100cm.
• Sex separate and male is smaller than female

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Ascaris lumbricoides
(roundworm)
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Ascaris lumbricoides
(roundworm)

• The commonest human helminthes infection.
• Found in jejunum and upper part of ileum.
• Female about 20 cm which is longer 10 cm than
  male.
• Feed on semi digested food
• In the small intestine.

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Ascaris lumbricoides
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The Trematodes Leaf- like un-segmented
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Taenia saginata Example of a tapeworm (cestodes,
tape like ,segmented)
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MEDICAL IMPORTANCE OF ARTHROPODS

• 1)As aetiologic agents (causes) of diseases.
• Tissue damage
• Induction of hypersensitivity reactions.
• Injection of poisons
• Entomophobia (acarophobia)
• 2) As vectors of diseases
• I Mechanical transmission - simple carriage
  of pathogens.
• II Biological transmission
• - cyclical
• - propagative
• - cyclo-propagative
• III Trans-ovarian transmission

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Scabies as etiological agent of the disease (
????? )tissue damage
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(No Transcript)
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HOUSE FLY

World-wide distribution Body with 3 visible
parts, 3 pairs of legs 1 pair of visible
wings. Retracted mouth parts Breeds in soil and
dirt Not a blood sucker. Mechanical transmission
of many diseases viruses, bacteria and
parasites
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Myiasis ((???????
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Ophthamo-myiasis
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Mosquitoes
Cosmopolitan , more than 3000 species.. Genus and
species distinguished by morphology of adult and
developmental stages.
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Phlebotomus ( sand fly)
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Flea ????????
Rat flea
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LICE ?????
Louse(singular) , Lice (pleural)
Pediculus humanus
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Bed bugs ???? (Cimex lectularius)
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Bee
BEES  Venoms of bees are a mixture of enzymes and
several polypeptides some of which are
pharmacologically active e.g. histamine or
neurotoxic. Some people are hypersensitive to
venoms and suffer anaphylactic reaction , death
might result in 1 hour.
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Scorpions

• Highly venomous
• Thick-tail scorpions (family Buthidae). They have
  thick tails and thin pincers.

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Scabies mites )?????)
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Scabies
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(The Spider) This spider is commonly found
outdoors and around human habitation. It's often
called The Red-back spider. .
Hobo or Brown Recluse Spider A venomous bite
from a can cause severe necrotic arachnidism
results from envenomation (venom poisoning). It
occurs due to the venom's ability to clot blood
that results in an area of tissue receiving
inadequate blood flow and thus dying secondary to
oxygen starvation.
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TICKS
Body 1 segment
4 pairs of legs no antennae
no
wings
Soft ticks Vector for Relapsing fever

• Hard Ticks
• Vector for
• Babesiosis,
• Q fever, Rocky Mountain spotted fever

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Important arthropod vectors for human diseases
House fly (Musca domestica) Mechanical transmission of many viruses, bacteria and parasites.
Mosquitoes ?????? Anopheles malaria, filariasis Culex filariasis, viruses Aedes yellow fever, dengue fever, Rift Valley Fever
Lice ????? Body louse vector for Relapsing fever, typhus and trench fever.
Fleas ???????? Rat flea is vector for plague due to Yersinia pestis.
Ticks ?????? Soft ticks , some are vestors for Borrela duttoni Hard ticks Include vectors for Babesiosis (protozoa), Q fever, and Rocky mountain spotted fever
Tse tse fly (Glossina) ????? ????? Vector for African Trynanosomiasis (African sleeping sickness)
Black fly (Simulium)??????? ??????? Vector for Onchocerca (river blindness)
Sand fly (Phlebotomus) ????? ????? Vectors for leishmania and sandfly fever virus.
Cyclops Vector for Dracunculus medinensis
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Parasitic Helminths and Arthropod Agents and
Vectors of Diseases

• Objectives
• By the end of this lecture the student should be
  able to
• Name the three main groups of parasitic helminths
  and their characteristic morphological features
  .
• Describe the life cycle of Ascaris lumbricoides
  as an example of parasitic heminths .
• Discuss the role of arthropods as agents and as
  vectors of diseases in humans.
• Give examples of the main arthropod vectors of
  diseases.