2. CLASS NEMATODA
General characters

3. 1- Bilaterally symmetrical.
2- Unsegmented.
3- Elongated.
4- Cylindrical, round in cross section.
5- Separate sexes. Males are smaller than females.
6- Has a body cavity containing body fluid within which lie the digestive and reproductive systems.

4. 7- The oesophagus takes different shapes in different species:
i) Club-shaped e.g. Ascaris lumbricoides.
ii) Double bulbed e.g. Entrobius vermicularis, anterior part club shaped and posterior spherical.
iii) Rhabditiform e.g. Strongyloides stercoralis, anterior cylindrical and posterior pyriform parts.
iv) Filariform (cylindrical): short narrow anterior muscular part and long wide post glandular part e.g. Filariae.
v) Cellular: shows one raw of cells e.g. Trichinella.

5. 1- Intestinal Nematodes
These don't require an intermediate host Ascaris lumbricoides
Enterobius vermicularis
Hookworms (Ancylostoma duodenale and Necator americanus)

6. 2- Tissue Nematodes
These require an intermediate host which is usually an arthropod. These include:-
Filariae.

8. INTESTINAL NEMATODES ASCARIS LUMBRICOIDES

9. Morphology
1- Adult: White or pink worm identified by: Large size, smooth finely striated cuticle.
Male is cm in length and has ventrally curved posterior end with two spicules.
Female is 20-35cm in length with straight posterior end.

10. 1- Fertilized egg: The egg is oval, 60 x 45 μm with brownish inner thick shell and outer coarsely mammillated, albuminous covering; immature.

11. 2- Unfertilized egg: These are eggs laid by unfertilized females, 90 x 45 μm, long and narrow, brownish with retractile granules and have less developed mammillated layer and thin inner egg shell.
3- Decorticated egg: When the mammillated layer is lost, the fertile or infertile egg is said to be decorticated.

12. Disease: Ascariasis.
Geographical distribution: Cosmopolitan.
Life cycle
Habitat: Small intestine.
Definitive host: Man.
Infective stage: Eggs containing second stage larvae.
Mode of infection: Man is infected by swallowing water or raw vegetables polluted with embryonated eggs containing larva or through contaminated hands by polluted soil or via Pica phenomenon.

13. Eggs hatch in the intestine and the rhabditiform larvae penetrate the intestinal wall entering the circulation to the right side of the heart to the lungs where they break out of the pulmonary capillaries into the alveoli
Here they remain for some days and undergo their second and third moults (Filariform larvae). They then pass up The bronchioles to the bronchi, the trachea, the epiglottis where they are swallowed to reach their final habitat in the small intestine.
Here they moult for the fourth time and become adults. Eggs appear in feces about 2 months after infection.

17. Loeffler's syndrome
a- Allergic manifestations as asthma and oedema (angioneurotic).
b- Fever, cough and expectoration of blood-stained sputum.
c- Eosinophilia.
d- Minute haemorrhages and pneumonitis (verminous pneumonia).

19. 3- If the worm migrates into unusual sites (e
3- If the worm migrates into unusual sites (e.g ampula of vater, bile duct-appendix) or even penetrates the intestinal wall it may case some complications. Migration may be stimulated by fever, anaesthetics or some drugs e.g. tetrachloroethylene.

22. Diagnosis
• Finding the characteristic eggs in the feces.
• During the pulmonary phase there may be eosinophilia and larvae may be found in sputum.
• Finding adult worm in feces. (Egyptian people called it abdomen snakes or toilet seat's worm)
• Radiological detection of adult by X-ray.

23. Treatment
•Mebendazole (Vermox, Antiver) or Flubendazole (Fluvermal): One tablet (100 mg) twice daily for 3 days.
Prevention and control
•Proper washing of vegetables eaten raw.
•Health education & Sanitary disposal of human feces.
•Washing hands before meals.
*Mass treatment.

24. ENTEROBIUS VERMICULARIS (PINWORM OR SEAT WORM)
Morphology
1- Adult: The worm has 2 anterior circular wings like expansions (alae), 2 lateral thickenings along the length of the worm, three retractile lips, double bulbed esophagus
The Female is 10 mm in length, the posterior end is straight with long pointed tail.
The male is 5 mm in length; the posterior end is curved ventrally with one spicule.

25. 2- Egg:, 20x50 μm .The egg is Plano-convex, the egg shell has 2 layers covered by a third outer thin albuminous translucent sticky layer. contains full developed larva. Its colour is translucent

26. Disease: Enterobiasis, oxyuriasis.
Distribution: Cosmopolitan.
Life cycle
Habitat: The caecum and adjacent portions of small and large intestine.
Definitive host: Man.
Infective stage: Embryonated eggs laid by gravid females that migrate to perianal and perianal regions.

27. Gravid females migrate to the perianal region (especially during night) where mature eggs are laid. The gravid ♀ contains from to eggs. Eggs are infectious 4 to 6 hours after passage. Man is infected by swallowing the eggs by one of the following ways:a-
Autoinfection(hand to mouth).
b-In food or drink.
c-Handling contaminated clothing or bedding.
d-Inhalation of eggs
e-Retro infection

28. Pathogenicity Clinical Picture
1- Pruritus ani is the main symptom. It may be severe causing fatigue and insomnia. Loss of appetite, loss of weight.
2- Children may suffer from nervous irritability and enuresis.
3- The presence of the worms in the appendix may give a picture of appendicitis.
4- Worms may migrate to the vagina, uterus, tubes and even the urinary bladder leading to irritation and inflammation.

29. Diagnosis:
1- Eggs are seldom found in the faeces except when the uterus of a gravid female ruptures during its migration to the perianal region.
2- Adult worms may be seen in stools.
3- Eggs are best obtained by swabbing the perianal region (in the morning before bathing or defecation) by:

30. a- N.I.H. Swab (National Institute of Health);
A cellophane paper is folded and tied to the tip of a glass rod and inserted in a test tube. The cellophane end is applied to the perianal region, then removed and spread on a glass slide.

31. Treatment
1- Mebendazole (Antiver) or Flubendazole (Fluvermal): one tablet (100 mg) = one teaspoonful single dose.
2- A mercurial ointment (white precipitate ointment) is applied to the perianal region especially by night. It relieves itching, kills females coming out to lay eggs and prevents dispersal of eggs.

32. Prevention and control
1- Personal cleanliness is essential.
2- Fingernails should be cut short.
3- Hands should be washed thoroughly after using the toilet and before meals
4- Application of ointment to perianal region will prevent the dispersal of eggs.
5- Infected children should wear tight-fitting cotton pants.

34. Morphology
1- Adult: Hookworms are small, cylindrical, fusiform and grayish white Nematodes.
The mouth is well developed, with a pair of teeth on either Side of the median line and a smaller pair in the depths of the buccal Capsule.

35. 3. Hookworms
Ancylostoma duodenale Old World hookworm Necator americanus New world hookworm

36. Ancylostoma duodenale
0.2 mm
teeth
0.2 mm

37. Ancylostoma duodenale
The male measures nearly 10 x 0.5 mm
and its posterior end Has a broad
translucent membranous caudal bursa with rib-like rays, used for copulation.
2mm

38. Ancylostoma duodenale posterior end
broad translucent membranous caudal bursa with rib-like rays

39. Hookworm Eggs
2- Egg: 60 μm x 40 μm, rounded ends and a thin shell. Translucent contains immature ovum; 4 cell stage..

40. Disease
Ancylostomiasis.
Geographical distribution
This species is found in the northern part of the world including Middle East, countries around the Mediterranean, China, Japan, Europe, North Africa and Ethiopia
Necator americanus
Far East, South Asia, Tropical Africa, Central and South America

41. Life Cycle
1- Adults live in the small intestine of man (no reservoir host) attached to the wall by sucking part of the mucosa into their mouth parts.
2- Immature eggs pass in the feces (20,000 eggs/female/day).
3- Under favorable environmental conditions in the soil (moist shaded areas – sandy or loam soil, alkaline and free of salinity – of suitable temperature and sufficient oxygen) a rhabditiform larva (250 u) develops and hatches in about 2 days (development does not occur in undiluted stool being acidic).

43. 4- It feeds and moults in about 3 days giving another rhabditiform larva (500 u). This moults again after about 7 days (keeping its skin) to become a filariform larva. This ensheathed filariform larva is the infective stage. 5- Infection occurs when infective filariform larva penetrates the skin especially when a person is walking bare foots on infected ground attracted to man by histo- thermotrpism.
6- Following penetration of the skin, the larvae enter small blood vessels and follow a heart – lung migration during which they moult for the third time. Moult the fourth time in the small intestine and they become adults

44. • Adult ingests mucous membrane and blood from their host.
The worms especially A. duodenale, migrate in the intestine in search of new sites from which to suck blood. The abandoned sites continue to bleed for some time.

48. • The protein loss is caused by
• Loss of protein is an important feature of hookworm anaemia, which is a cause of protein – losing enteropathy and the oedema of hookworm disease which does not respond to diuretics.
• The protein loss is caused by
a limited capacity for albumin synthesis
as well as loss caused by anaemia
and other factors such as liver disease.
• It is closely related to the hookworm load.

49. Diagnosis 1- Clinical picture and anaemia in endemic areas.
2- Finding hookworm eggs in feces.
3- Stoll’s egg counting technique to detect worm burden (intensity of infection).
4- Baermann’s apparatus to recover larvae from soil.
5- Stool culture.
6- Barium meal studies will not reveal the worms but radiological abnormality of the duodenum is closely related to haemoglobin levels in hookworm patients.
7- Blood picture shows eosinophilia.

50. Treatment I. Elimination of adult parasite.
• Mebendazole (vermox) or flubendazole: One tablet (100 mg) twice daily for 3 days. It is highly effective against both A. duodenal & N. americanus.
II. Treatment of anaemia.
By oral administration of iron in the form of ferrous sulphate or gluconate, 200 mg three times daily for 3 months.

51. Prevention and control
1- Personal prophylaxis: wearing shoes and other protective clothes as gloves for people handling mud or working in mines, gardening pottery and brick-making.
2- Health education: stress on:
a. Abstinence from walking bare footed.
b. Abstinence from defecation on the ground.
3- Sanitary disposal of human feces:
a. Avoid using human feces as fertilizer except after storage or chemical disinfection.
b. Construction of public w.cs.