Lecture 4 2.2_ascaris
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1. Ascaris lumbricoides, or the common roundworm, infects over 1.4 billion people worldwide and causes up to 100,000 deaths annually. 2. It is a large, stout nematode that lives in the small intestine of infected individuals. The female worm can grow up to 40 cm long and lay up to 25 million eggs in her lifetime. 3. Infection causes a range of symptoms depending on the worm load, including intestinal obstruction, malnutrition, and in heavy infections pneumonia-like symptoms. Diagnosis involves finding eggs in stool or adult worms after treatment.
Lecture 4 2.2_ascaris
- 1. Intestinal nematodes ASCARIS LUMBRICOIDES Common round worm Umar Farooq, Ph.D Module 2.2
- 2. Objective • The students will be learn about Intestinal Nematodes which causes morbidity and mortality to human biengs
- 3. •Ascaris lumbricoides has world wide distribution. It is common in both temperate and tropical countries like China, India and other South-east Asian countries •1400 million infected persons in the world (23% of the world population), with about 60,000–100,000 deaths annually. Geographical Distribution
- 4. • Habitat • Adults are normally found in the lumen of the small intestine but do not attach to the mucosa • Morphology • Large, stout nematodes, tapering at both ends • Females (25 to 40 cm in length and 5 mm in diameter) • Males (15–30 cm in length and 2–4 mm in diameter) but may show great variation in size, depending on age and worm load
- 5. Morphology cont.. • Mouth: Three lips, each of which has a pair of sensory papillae on its lateral margin, and rows of small denticles or teeth. • Principal structural protein:Collagen, tabilized by disulphide bonds. • Female • Female: the paired, tortuous, tubular ovaries, oviducts, seminal receptacles and uteri lead into a vagina, which opens by a small vulva on the ventral surface . • Eggs: 200,000 per female and each may lay a total of 25 million during her lifetime
- 6. • Male • The posterior end of the male is curved ventrally and there are two almost equal copulatory spicules (measuring 2.0–3.5 mm) and numerous preanal and postanal papillae. Curtsy: Atlas Medical Helminthology and Protozoology
- 7. Eggs • Fertilized egg • Ovoid and measure 45–70 μm X 35–50 μm. • Shell is thick and transparent • outer albuminous coat • Stained light brown with bile pigments. • Ova are un-segmented when passed in the faeces. • Unfertilized egg • Longer and narrower 90 μm X 40 μm, • uncoated with a thin shell, more irregular outer covering . • Rapid production of eggs allows some to pass through unfertilized or because only female worms are present
- 8. Curtsy: Atlas Medical Helminthology and Protozoology
- 9. Clinical Manifestations • Incubation period: 60-75 days • Migrating larvae • Pneumonitis with cough, dyspnoea, substernal pain, fever and sometimes a blood stained sputum (which may contain larvae). • These symptoms begin 5 to 6 days after infection and usually last 10–12 days. • This is known as Loeffler’s syndrome and the X- ray findings often show dense pulmonary infiltrations, resembling acute tuberculosis. There is moderate eosinophilia.
- 10. Clinical Manifestations cont.. • Adult worm • Light worm load asymptomatic. Its cause malabsorption of protein, carbohaydrate and vitamins, in malnourished children, adult worm cause growth retardation. • Heavy worm load causes: vomiting, intestinal obstruction, fever, appendicitis, obstructive jaundice and acute hemorrhagic pancreatitis.
- 11. Laboratory diagnosis • Direct evidence • Finding of adult worm in stool or vomit. • X-Ray diagnosis: The presence of A. lumbricoides has been demonstrated by Radiography with barium emulsion, which being ingested by the worm within 4-6 hours, casts an opaque shadow. • By direct microscopy: Finding of eggs in stool • In Bile Juice: Bile aspiration examined by microscope. • Demonstration of larvae in sputum and bronchial aspirates. • Indirect evidence • Ascaris antibody can be detected by IHA and immuno- fluorescence antibody test. • Dermal reaction: “Scratch test” with powdered Ascaris antigens has often been found to be positive but the results are variable.
- 12. • Treatment • Pyrantal pamoate in a single dose of 11 mg/kg. • Mebendazole in a dose of 100 mg twice daily for 3 days • Piperazine citrate in a dose of 75 mg/kg daily 2 days. • Prophylaxis • Proper disposal of human faeces. • Avoidance of eating raw vegetable and salads. • Periodic treatment with an effective antihelminthic, in communities that lack sanitary facilities