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1- Genus: Trichuris Trichura.
Also known as whipworm causes trichuriasis.
Distribution:
It has a world wide distribution, but most commonly found in worm arias.
Habitat: large intestine.
Transmission:
1- T. trichura spread by faecal (ingestion) pollution of the soil and water,
2- Unclean vegetables.
3- Contaminated fingers especially children.
Morphology:
1 -The infective stage is the EGG which is yellow-brown in colour and
measures about 50x 25µm. has a characteristic barrel shape with a colorless
mucoid plug at each end and unsegmented ovum.
2- Adult:
- called the whip because of its shape.
- Female: 35-50 mm in length.
- Male: 30-45 mm in length, with posterior spiracle (male sex organs).
Infection and pathology:
1- Usually early infection causes abdominal pain and chronic watery
diarrhea.
2- Heavy infection can lead to muscle wasting, oedema.
Diagnosis:
By finding the T. trichura egg in faeces
2- Enterobius Vermicularis.
Called the thread worm and pinworm, causes enterobiasis.
Distribution:
World wide.
Habitat:
Adult worm in small intestine.
Egg deposited in the peri-anal skin.
Infective larvae: during night when eggs hatch on the buttock.
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Transmission and life cycle:
1234-
Ingestion of infective egg.
Infection is easily transmitted by contaminated bed or clothes.
Autoinfection when egg hatches on the buttocks.
Infective larvae migrate back to the intestine.
Pathology:
Rarely causes serious disease, usually intense irritation around the anus. In
female infection of urinary and genital tract may occur. Worms in appendix
may cause appendicitis.
Morphology:
Adult: male measures about 4 mm in length with curved tail and spicules.
Female: measures about 10 mm in length, with straight and pointed tail.
Egg: asymmetric colorless and flattened from one site, measures about 55-25
µm.
Diagnosis:
1- By finding the egg in samples collected from perianal skin using
adhesive tape, or recovered from clothing during the night.
2- Egg can also be found in stool but this is less commonly.
3- By finding the adult (female only) worm in faeces or during clinical
examination (occasionally less that 10% of cases).
3-Hook worm.
Ancylostoma duodenale.
Necator americanus.
Distribution:
Tropics and sub-tropics, worm areas. Necator americanus is more common
than Ancylostoma duodenale.
Habitat:
Adult worm in small intestine.
Egg in faeces but not infective.
Infective larvae: free in soil and water.
Transmission and life cycle:
1- Infection occurs when infective filariform larvae penetrate the skin.
2- Then larvae follow heart-lung migration.
3- Adult in small intestine.
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4- Egg passed in faeces.
5- Larvae hatches from egg under favorable condition.
6- Develop into rhabditiform larvae, which develop into infective filariform
larvae.
Pathology:
1- The first sign is skin reaction at the site of penetration.
2- Mild respiratory symptoms.
3- Adult hookworm causes chronic blood loss leading to developing iron
deficiency anaemia in prolonged infection.
Morphology:
Egg: oval 60X40 µm. colorless with thin shell.
Adult:
1- Cylindrical white in color.
Diagnosis:
1- Finding hookworm egg in faeces by direct or concentration technique.
2- In old stool sample larvae may hatch.
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