Ascaris Lumbricoides Taxonomy n Kingdom Animalia Phylum Nematoda

Ascaris Lumbricoides

Taxonomy n Kingdom : Animalia Phylum : Nematoda Class : Rhabditea Order : Ascaridida Family : Ascarididae Genus : Ascaris Species : lumbricoides

Introduction § Common name : Round worm § Largest of intestinal nematodes. § causative agent of ‘Ascariasis’. § Distribution: - world wide § Habitat: - small intestine, mainly jejunum.

Morphological forms n § § Adult worms : male female Eggs : fertilised unfertilised decorticated Rhabditiform larva.

MORPHOLOGY n n Adult worms : cylindrical in shape with tapering ends. Creamy white or pinkish. Mouth of the worm is surrounded by 3 lips (1 dorsal and 2 ventral) with minute teeth. Life span is <1 yr.

Adult worms Lips of ascaris

Adult male n n n smaller than female. Size : 15 -30 cm in L 3 -4 mm in D. Curved tail contains a pair of ‘copulatory spicules’. Adult male Copulatory spicules

Adult female n n Size : 20 -40 cm in L 2 -6 mm in D. Post. end is straight and conical. ‘vulvar waist’ Eggs : 240, 000/day. Adult female

Egg n 3 kinds : Fertilised, Unfertilised and Decorticated. n Fertilised egg : - oval in shape measures 45 x 70 mc in L 35 x 50 mc in B. Golden brown , Bile stained. Shell is thick with mammillated albuminous outer coat. Contains an unsegmented ovum with clear crescentic space at each pole. Floats in sat. salt solution. § §

n Unfertilised egg : - ellipsoidal in shape measures 78 x 105 mc in L 38 x 50 mc in B. § Brown coloured , Bile stained , Thin shelled. § Heaviest of all helminthic eggs , hence it doesn’t float in sat. salt solution. § Decorticated egg : - Both fertilised and unfertilised eggs sometimes may lack their albuminous coat and are colourless.

Egg shell Ovum Albuminous layer Fertilised egg Unfertilised egg

Decorticated egg

n Rhabditiform larva : size : 250 mc in L 14 mc in D actively motile larvae hatch out in duodenum penetrates the intestinal mucosa Hatching out larva

Pathogenesis n n n Source : soil , water , food contamined with eggs. Route : ingestion Infective form : embryonated eggs Host : man No intermediate and reservoir hosts.

Life cycle

Manifestations due to of migrating larva : § Inflammatory and hypersensitvity reactions. § Granuloma and eosinophilic infiltration. § Eosinophilic pneumonia Loeffler’s syndrome. § Symptoms : fever cough dyspnea urticaria.

Manifestations due to adult : Sporiative action : § Mechanical action : n § Allergic reaction : release of ascaron malnutrition growth retardation. abdominal pain intestinal obstruction intestinal perforation fever urticaria Angioneurotic edema conjunctivitis

Intestinal obst. by adult worms Peritonitis by intest. perforation

n Ectopic ascariasis : appendicitis obst. jaundice haemorrhagic pancreatitis liver abscess Ascaris in common bile duct Adult worms in liver

Lab diagnosis n Parasitic diagnosis : § demo. of eggs in feaces –direct microscopy formalin ether conc. demo. of larvae – in sputum , bronchial aspiration demo. of adult worms – barium meal. Sero diagnosis : Ab’s detected by IHA , IFA. used for diagnosis of loeffler’s syndrome. Imaging methods : x – ray , ct scan , ultrasound §

Epidemiology n World wide distibution through out temperate and tropical areas. n ¼th of the world population. n 40% population in africa and asia. n Poor sanitary conditions.

Treatment n Mebendazole pyrantel pamoate piperazine citrate. Prophylaxis § Proper disposal of human faeces § Avoid eating raw vegetables and salads § Periodic treatment with antihelminthics.