Specimen Section 2

1. Ascaris lumbricoides – Round Worm

• It is a specimen of Ascaris lumbricoides .
• Agent – Ascaris lumbricoides ( Nematode)
• Distribution of the worm – Worldwide, prevalent in India
• Habitat – Small intestine (Jejunum)
• Largest intestinal nematode
• Morphology of adult worm 
• Colour – Light brown or pink when fresh, changes to white
• Shape – Rounded and tapering at both ends, Anterior end is thinner than posterior
• Mouth opens at anterior end and possesses 3 finely toothed lips
• Pathogenecity: 
  • Due to adult:
    • About 80% infections are asymptomatic
    • Mild infection-intestinal disorder, malnutrition,+/- abdominal pain
  • Due to migrating larva:
    • Loeffler’s syndrome
    • Allergic reaction     

2.Hydatid cyst

• Hydatid disease is a parasitic infestation by a tapeworm of the genus Echinococcus.
• Hydatid cyst It is a fluid-filled bladder-like cyst, unilocular, subspherical in shape and average size measure up to 5-8 cm.
• Cyst wall consists of three layers: outer pericyst (host derived), middle ectocyst and inner endocyst
• Brood capsule: The inner side of the endocyst gives rise to brood capsule, and also secretes the hydatid fluid. The brood capsule contains number of protoscolices (futurehead)
• Hydatid fluid: It is clear, pale yellow colored fluid, which is antigenic, toxic and anaphylactic
• Hydatid sand: Some of the brood capsules and protoscolices break off and get deposited at the bottom as hydatid sand
• Fate: The hydatid cyst may undergo-(1) spontaneous res olution, or (ii) rupture of the cyst, which may lead to either formation of secondary cysts (carried to other organs) or anaphylactic reaction to the hydatid fluid antigens.
• site: Most common site of the cyst is liver (60-70%, right lobe) or lung (20%), followed by kidney, muscle, spleen,soft tissue, brain, bone and others 

laboratory diagnosis

• Hydatid fluid microscopy (direct mount or staining with acid fast staini-detects brood capsules and protoscolices
• Histological examination (H&E-demonstrates cyst wall and attached brood capsules 
• Antibody detection ELISA (using 821 antigen), DIGFA (dotimmunogold filtration assay) and western blot
• Imaging methods-X-ray, USG (demonstrates Water lily sign CT scan MRI
• Molecular methods-PCR, PCR-RFLP and molecular typing