1. Morphology
1.1. Unfertilized Egg
1.1.1. Shape: Narrow & Elliptical Size: 80 X 55 μm (bigger) Bile stained Outer layer: Thinner Irregular albuminous coating Carries an atrophied ovum It does not develop further Sinks in a saturated solution of salt
1.2. Fertilized Egg
1.2.1. Shape: Round / oval Size: 60 X 40 μm Colour: Brown/ yellow (Bile stained) Outer layer: thick albuminous coat (mamillations) Yolk granules cover the ovum Unsegmented ovum is present It undergoes maturation in soil Floats in a saturated solution of salt as it carries (air) empty spaces at 2 poles
1.3. Adult Male
1.3.1. size: 15-25 cms in length and 3-4 mm in diameter Morphology is same as that of a typical nematode with a complete intestine (from mouth to anus) Posterior end of the male worm is coiled. Cloaca is a common opening for anus and ejaculatory duct 2 spicules are present at the posterior end of the male worm. These act as accessory copulatory organs and assist in fertilizing the female worm.
1.4. Adult Female
1.4.1. size: 22-35 cms in length and 5 mm in diameter Female worm is long and slender. Posterior end is straight and not coiled Vulvar waist is a narrowed part of the body where vulva is present and is located at the junction of anterior1/3rd and posterior 2/3rd. Female worms produces nearly 200,000 eggs/day. Eggs: are of 2 kinds: Unfertilized and Fertilized
2. Transmission
2.1. Ingestion of fertilized embryonated eggs with uncooked vegetables (especially from gardens or farms where human stool is used as fertilizer) or contaminated drinking water. Flies and paper money may rarely disseminate embryonated eggs.
3. Habitat
3.1. Adult worms inhabit the small intestine (jejunum & ileum)
4. disease
4.1. Ascariasis
5. Clinical features
5.1. Symptoms are related to the worm burden
5.1.1. Asymptomatic: 10-20 worms: stool examination is +ve in most cases for eggs
5.1.2. Commonest symptom: Vague abdominal pain
5.1.3. Pulmonary stage symptoms: During migration of Larvae through alveoli. (called as Loeffler’s syndrome)
5.1.4. Brief period of Fever, cough, wheezing, dyspnoea (difficulty in breathing) & sub-sternal discomfort. Sometimes rash develops on skin.
5.1.5. Intestinal stage symptoms: Due to presence of adult worms in intestine.
5.1.5.1. Listlessness (restlessness) Weight loss (loss of Protein/vitamins), retarded growth in children Anorexia (Loss of appetite) Distended abdomen, intermittent loose stool, diarrhoea Biliary blockage, jaundice (rise in bilirubin above 1 mg%) Vomiting
5.1.6. Ectopic Ascariasis
5.1.6.1. Presence of Ascaris worms in stomach, oesophagus, nose, mouth, respiratory passages etc. away from the normal habitat of small intestine.
5.1.6.2. Occurs due to migration or movement of adult worms up the intestinal tract