Nematode

parasitology ppt

1. NEMATODENEMATODE
Dr. Naresh
E-mail: [email protected]

2. Fluke: flat,
leaf-shaped worm
Tapeworm: long,
ribbon-like segments
hermaphrodite
dioecious
Nematode: elongate,
cylindrical , tapered
at both ends

3. Part ⅠGeneral Information about
Nematode
Nematode belong to
Phylum Nemathelminthes
Class Nematoda
Most nematodes are free living in fresh water, sea
water and soil.
A few are parasitic in humans, animals and plants.

4. A. adult
 elongate,cylindrical,bilaterally symmetrical and
tapered at both end.
 dioecious, malefemale. At the curved,posterior
﹤
end of male is a copulatory organ.
Ⅰ.MORPHOLOGY
roundwormpinworm

5.  pseudocoelom
nematode consists of an outer tube(the body wall) enveloping
an inner tube(the digestive tract). between the tubes is the fluid-
filled pseudocoelom, in which the reproductive system and
other structures are found.
no peritoneal lining ,
containing transport of
solution, electrolytes,
proteins, fats
 function: protecting
the internal organs,
helping the movement
and excretion of the
worm
Body
wall
Digestive
tract
pseudocoelom

6. 1.body wall
cuticle
Three layer hypodermis
muscles
Dorsal cord
Lateral cord
Ventral cord
hypodermis
muscles
cuticle
Fig. cross section of nematodes

7. The arrangement of the somatic muscles is of
value in the systematic grouping of nematodes
Polymyarian HolomyarianMeromyarian
roundworm Hookworm whipworm

8. 2.Digestive System
Complete Complete
mouth, esophagus , intestine, rectum(F)/cloaca(M)
and anus

9. 3.Reproductive system
SeparateSeparate
femalefemale
pseudocoelom
uterus
oviduct
ovary

10. testis
Vas deferens
Seminal vesicle
male

11. 4.excretory system4.excretory system
Two lateral excretory ducts running inside the Two lateral excretory ducts running inside the
lateral cordslateral cords
5.Nervous system5.Nervous system
A nerve ring encircling the esophagus,from which A nerve ring encircling the esophagus,from which
trunks radiated anteriorly and posteriorly.trunks radiated anteriorly and posteriorly.
Lateral
excretory
duct

12. B.Egg
Three layers:Three layers:
1. outer layer : embryo membrane1. outer layer : embryo membrane
2. Middle layer: chitinous layer 2. Middle layer: chitinous layer
3. Inner layer: lipid layer/ascaroside3. Inner layer: lipid layer/ascaroside
Protein
membrane
chitinous layer
embryo membrane
lipid layer
Inside the egg, there is an embryo that may range from a
few blastomeres to a completely formed larva

13. Stages in life cycle of nematodes includeStages in life cycle of nematodes include : :
egg egg larvaelarvae adultsadults
Under favorable conditions larvae undergoUnder favorable conditions larvae undergo
four four moltsmolts
Two types of nematodesTwo types of nematodes
soil-transmittedsoil-transmitted nematodes: nematodes: Ascaris,Ascaris,
pinworm, whipwormpinworm, whipworm, , hookwormhookworm
bio-sourcebio-source nematodes: nematodes: Filaria,Filaria,
Trichinella spiralisTrichinella spiralis (intermediate host)(intermediate host)
Ⅱ.LIFE CYCLE

14. Infections is transmitted by:
1) Ingestion of eggs (Ascaris lumbricoides )
2) Penetration of larvae through surfaces
(Hookworm)
3) Insect bite (Filaria)
4) Ingestion of encysted larvae (Trichnella
spiralis)

15. The effect depends on the species, worm The effect depends on the species, worm
burden,development stage, parasitic burden,development stage, parasitic
site,physiological condition and site,physiological condition and
immunological response of hostsimmunological response of hosts
Species vary in their ability to produce Species vary in their ability to produce
mechanicalmechanical or or toxic damagetoxic damage and in their and in their
selective affinity for vital organselective affinity for vital organ
III. Pathogenesis and symptomatology

16. Trichinella spiralis
Microfilaria
Hookworm
Ascaris lumbricoides

17. Epidemiology
WidespreadWidespread
Common in warm climateCommon in warm climate
Close relation with social Close relation with social
economic statuseconomic status

18. Common humman parastic nematodes
Ⅳ. Classification

19. One worm means many wormsOne worm means many worms

21. Ascaris lumbricoides
(Roundworm)

22. Introduction

﹡

﹡
““round worm of manround worm of man””

﹡

﹡
It is the largest of the intestinal It is the largest of the intestinal
nematodes nematodes

﹡

﹡
It is the most common worm found in It is the most common worm found in
humanhuman

﹡

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adult worm parasitize in the intestinal adult worm parasitize in the intestinal
tract of human ,and cause tract of human ,and cause AscariasisAscariasis..

23. A.Adult: A.Adult:
shape: shape: cylindrical, fusiform body,similar to cylindrical, fusiform body,similar to
earthworm.earthworm.
Color:Color: pink(alive) and white(dead). pink(alive) and white(dead).
Length:Length: female: 20-30cm; male:15-31cm female: 20-30cm; male:15-31cm
Special structure:Special structure:
On the tip of the head there are On the tip of the head there are three lipsthree lips, ,
arranged as a Chinese word “ arranged as a Chinese word “ 品 ”品 ”..
 Cross veins and lateral lines are paired on the Cross veins and lateral lines are paired on the
surface of the bodysurface of the body
The typical curled tail with a pair sickle like The typical curled tail with a pair sickle like
copulatory copulatory spinesspines. .
Ⅰ.MORPHOLOGY

24. Adult worm of
A. lumbricoides
♀
♂

25. The lips of Ascaris lumbricoides
The three lips are seen at the anterior end.
The margin of each lip is lined with minute teeth

26. Copulatory spines of male

27. There are three kinds of the eggs: There are three kinds of the eggs: fertilized fertilized
eggs, unfertilized eggseggs, unfertilized eggs and and decorticated decorticated
eggs. eggs.
We usually describe an egg in We usually describe an egg in 5 aspects5 aspects: :
size, color, shape, eggshell and contentsize, color, shape, eggshell and content
B.Egg

28. Fertilized egg:
 size: 45-75 × 35-50 μm.
 Shape:elliptic.
 color:brown.
 shell:thick and protein
membrane
outside of the shell
 content: one embryo cell.

29. Fertilized
Ascaris Egg

30. Fertilized Ascaris Egg
The ova begin fission

31. Freshly Passed Ascaris Eggs From
faeces
The eggs may The eggs may
appear from light appear from light
to dark brown in to dark brown in
color.color.

32. Embryonated Eggs of Ascaris
Egg contains a larva, which will be
infective if ingested.

33. Fertilized egg
Embryonated
egg Infective egg
2w 1w
molt once

34. unFertilized egg:
 Measure: 88-94 × 39-44 μ m.
 Shape:longer and slender than
fertilized egg.
 color:brown.
 shell:thin protein membrane
without ascaroside.
 content: a mass of refractile
granules

35. Unfertilized egg

36. Unfertilized egg

37. Unfertilized and Fertilized Egg

38. Both fertilized and unfertilized eggs sometimes Both fertilized and unfertilized eggs sometimes
may lack their outer protein coats and are colorless.may lack their outer protein coats and are colorless.
Decorticated egg

39. • Human to human
adult worm
egg
larva (four times molts)
adult worm
Ⅱ.LIFE CYCLE

40. Development of ovaDevelopment of ova
temperature, moisture, oxygentemperature, moisture, oxygen
fertilized eggs Infective eggs
25-30℃
2-4w
Enclosed larva has undergone
its first molt
Survive viable in the soil for two years or longer

41. Life cycle
Adult worms live in the lumen of small intestine,
feeding on the intestinal contents, where the
fertilized female lays eggs.
After the ingestion of infective eggs in contaminated food or
drink or from contaminated fingers, host digestive juices
acts on the egg shell and liberate the larva into the small
intestine
These larvae penetrate the intestinal mucosa
and enter circulatory system ,
They are carried by circulation to the
liver, right heart and finally to the
lungs
where they penetrate the capillaries into the alveoli in
which they molt twice and stay for 10-14days
then they are carried up the bronchioles, bronchi, and trachea to the epiglottis. When
swallowed, the larvae pass down into the small intestine where they develop into adults.

42. duodenum
intestinal wall
liver
heart
lungs
alveolibronchi
trachea
esophagus
adult worm
Intestine
Eggs with larva
Migrating of larva
60-75 days

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44. summary
1. Site of inhabitation:1. Site of inhabitation:
2. Infetive stage:2. Infetive stage:
3. Route of infection:3. Route of infection:

small intestine
infective eggs
by mouth
4. No intermediate and reservoir hosts
5. Life span of the adult: about 1 year
6.Female can produce up to 200,000eggs/day

45. The varied The varied
pathologypathology
of Ascaris of Ascaris
infectioninfection
The reaction of the invading
larvae
The irritation of the intestine
by the mechanical and toxic
action of adult
The complication arising from
its extra-intestinal migrations
III. Pathogenesis and symptomatology

46. Pathogenesis and SymptomsPathogenesis and Symptoms
1. Migrating larvae1. Migrating larvae
The pathological
reaction to the
invading larvae
depends upon
The number of invading larvae
The histological nature of the
organ involved. Liver, lung

47. The pathogenesis in
human consist of
Eosinophilic infiltration
Granuloma formation
around and in the path of
migrating larvae
Inflammation along the portal
tract with infiltration of
eosinophils in the acute phase
Later fibrosis of the periportal and interlobular space occurs

48. Pathogenesis and SymptomsPathogenesis and Symptoms
The pathologic process
in the lung is known as
Ascaris pneumonitisAscaris pneumonitis
The symptoms of ascaris pneumonitis
Dyspnea ；bronchial asthma
A dry or productive cough
Moderate fever; transient eosinophilia

51. 2. Adult worms2. Adult worms
The varied symptoms of adult ascaris infection
depend upon the location and to a lesser extent
upon the number of the worms
Intaking nutrimentsIntaking nutriments and negatively affect the and negatively affect the
absorption, poor nutritional statusabsorption, poor nutritional status
AllergyAllergy
ComplicationComplication

52. Intestinal ascariasisIntestinal ascariasis
Adult worm usually cause no acute symptoms
ChildrenChildren
Intermittent colicky
Loss of appetite
Abdominal distension
Malnutrition
Impairment of growth, stunted growth

53. Allergy Allergy
Exposure to ascaris allergen may cause
hypersensitivity reactions in lungs,skin and
intestinal mucosa
Itch
Urticaria
Angioneurotic edema
Skin
change

54. ComplicationsComplications
When disturbed
by fever (usually
a temperature
over 38.9℃ or
other abnormal
conditions)
The worms migrate outward in
both direction
The worms congregate in a
closely mass that may tend to
obstruct the bowel causing
mechanical ileus
The migrating worm have a
proclivity for probing and force
themselves into any cavity

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Most commonly they simple expelled or crawl
from the mouth
They enter the nasal meatus via the nasopharynx
and exit through a naris
They may penetrate to the middle ear and through
the tympanic membrane to the external auditory
meatus
They enter and block the biliary or pancreatic
duct, resulting acute biliary or acute pancreatitisacute pancreatitis
They may loged in the appendix and cause
obstructive appendicitisobstructive appendicitis
They may reach other site such kidney via
fistula formed after intestinal perforationintestinal perforation

57. Biliary ascariasisBiliary ascariasis
The most common complicationThe most common complication
Symptoms:Symptoms:
Right upper abdominal pain,a sudden onset, a very strong Right upper abdominal pain,a sudden onset, a very strong
intensity,nausea, vomiting and extremal nervous.intensity,nausea, vomiting and extremal nervous.

58. Mechanical ileus
The usual site of obstruct:
Ileocecal region
Symptoms:
Start suddenly with
vomiting and colicky,
recurring abdominal pain.
Intestinal perforation

59. 
finding the egg in the fecesfinding the egg in the feces
(1) Direct fecal film: It is simple and effective. The
eggs are easily found due to a large number of the
female oviposition, So this method is the first
choice.
(2) Recovery of adult worms

therapeutic test and clinical manifestationtherapeutic test and clinical manifestation
Ⅳ Laboratory Diagnosis

60. World wide distribution, very common in World wide distribution, very common in
China, especially in the countryside.China, especially in the countryside.
Factors favoring the spread of the transmission:Factors favoring the spread of the transmission:
1. 1. Simple life cycle. Simple life cycle.
2. Enormous egg production 2. Enormous egg production
3.3.Eggs are highly resistant to ordinary disinfectantsEggs are highly resistant to ordinary disinfectants
4. Social customs and living habits.4. Social customs and living habits.
5. Disposal of feces is unsuitable.5. Disposal of feces is unsuitable.
ⅤEpidemiology

61. Distribution of Ascariasis in world
100 million persons have been affected by ascarisis

62. Ascariasis is most prevalent in the area with
warmer climates, moister and poor sanitation

63. Treatment of infected patients: Treatment of infected patients:
Mebendazole,Mebendazole, AlbendazoleAlbendazole and and
LevamizoleLevamizole are effective. are effective.
Sanitary disposal of feces.Sanitary disposal of feces.
Hygienic habits such as cleaning of hands Hygienic habits such as cleaning of hands
before meals.before meals.
Health education.Health education.

Ⅵ
Prevention & Treatment

64. Thank you Thank you