Ascaris Lumbricoides

lecture include: introduction, morphology, life cycle, pathology, lab diagnosis, treatment, prevention and control methods.

1. Ascaris lumbricoides Lecture by: Maha Gamal Eldein Ali

2. Introduction Ascaris lumbricoides is the largest intestinal nematode found in human Inhabit human small intestine. Causing the disease known as Ascariasis. It is soil transmitted infection It is most common in children ( young children , school and preschool children) 2

3. Geographical distribution: About 1 billion people are infected with A. lumbricoides The infection occurs throughout most of the world; Africa countries, Philippines, India, Middle East , Europe, Central & South America, Indonesia The infection is spread is more common in villages & Rural communities. 3

4. A scaris infection is more common in discussion ) ) rural areas 4

5. Morphology (worm& eggs) 5

6. Morphology (the worm) Shape: round or cylindrical, tapered at both ends Color : pink- creamy Size: Male=15 -31cm in length x 2-4 mm in diameter Female=20-35 cm x 3-6 mm, it may reach up to 46 cm in length. 6

7. Mouth: provided with 3 lips 7

8. Morphology (worm) Sex is separate Males are smaller than the female worms The male : is curved at the posterior end. 8

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10. Ascaris female are oviparous, produce 2 types of eggs 1- fertilized eggs Shape: round to oval Size: 60-75 x 50-60 µm Color: golden brown Content: unembryonated contain a round compact mass of granules Shell: thick composed of 3 layers; inner vitelline, middle transparent layer, outer irregular albuminoid layer. 10

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12. 2 - u nfertilized eggs Shape: oval elongate Size: 90 x45µm Color: brown Content: diffuse mass of large refractile granules Shell: thin composed of 3 layers; inner vitelline, middle transparent layer, outer irregular albuminoid layer. 12

13. At times both eggs (fertilized or unfertilized) has no outer albuminoid layer: so it is known as decorticated eggs. 13

14. Development of Ascaris eggs 14 1cell stage 2cell stage morula L1 L2 L2 – L5

15. How man become infected? Man become infected by ingestion of infective Ascaris eggs; contain second stage larva L 2 . The larva hatch in the small intestine, and penetrate the wall of the intestine enter the portal circulation , carried to heart, then to lungs (Heart lung migration) Within 9-15 days In lungs the larva develop to L 3 , which migrate up through the bronchial tree, reach the throat then swallowed and enter the intestine. 15

16. In the intestine the Ascaris larva grow into L4 then L5 which then mature into worm within 2-3 month. The mature female will be fertilized by the male worms (mating). Each worm uteri may contain up to 27 million eggs at a time, but it produce about 200,000 eggs /day which deposit in feces. . 16

17. How life cycle continue? The life cycle continue when the eggs reach the soil when infected h uman defecate in soil the eggs will reach the soil. 2- under certain soil conditions; Oxygen, Shad, Moisture, Temperature 22-30 ᵒC, the fertilized eggs develop into infective eggs. 3-Ingestion those of infective eggs by other (contamination of hands, foods, drinks with soil contain the eggs) While the infertile eggs don't develop; has no role in the life cycle 17

18. Life cycle 18

19. Factor help spreading of Ascariasis The worm produce large numbers of eggs The eggs resistant to strong chemicals, desiccation , and low temperatures. The eggs can remain viable in the soil for several months or even years. 19

20. Pathology & Symptomatology Lung phase : The early phase due to larva development in lungs, cause Ascaris pneumonitis coupled with asthma like symptoms ( loffler’s syndrome) Usually the symptoms last for 14 days and disappear spontaneously. usually the severity of symptoms depends on the number of larvae. 20

21. Intestinal phase: Due to p resence of Ascaris worm in the intestine associate with: Colic pain Loss of appetite Fullness Impaired carbohydrate absorption Impaired fat absorption ( steatorrhea ) Long term infection associate with malnutrition & impaired growth in children. Large number of worm cause obstruction of bowel. 21

22. Obstruction of bowel by Ascaris worms 22

23. Extra intestinal effect of the worm: Due to migration of worm from intestine to other sites obstructive jaundice due to obstruction of bile duct by the worms liver abscess (hepatic Ascariasis) when worm force its body through gallbladder and inter the liver. The worms may inter the liver veins then carried to (brain, heart, lungs) causing serious complications. Pancreatitis when the worms migrate up enter and block the pancreatic duct . Appendicitis when the worm migrate down enter and block the appendix . 23

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25. Laboratory Diagnosis 1- what is /are suitable sample/s? 2- what is are suitable diagnostic test/s or technique/s? 3- what is/are the diagnostic stage/s? 25

26. Summary : Ascaris lumbricoides worms inhabit human small intestine The worm release large number eggs(200,000 egg/each worm daily which deposit in feces. Eggs in stool found as (fertilized & unfertilized) they may be d ecorticated The adult worm may pass through the anus, mouth, or nose specially in febrile illness( fever). 26

27. Ascaris worm coming through anus, nose and mouth, 27

28. 1- Stool is the best sample to diagnose Ascariasis 2- suitable diagnostic technique: Eggs of A. lumbricoides can be easily found in direct wet mount with saline because the worm produce large number of eggs. 3 - diagnostic stages: A- In stool eggs ( fertilized/ unfertilized/ decorticated) B-adult worm if come out through mouth, nose, or anus 28

29. How to identify Ascaris worms?? The worm should be washed with water Then fixed with hot 10% formalin for 10 minutes Remove the worm from the fixative and measure the length of the worm Use hand lens to see the 3lips 29

30. Treatment Several anthelmintics drugs of choice: Pyrantel pamoate Mebendozle Piperazine citrate Prognosis The prognosis is excellent (intestinal) In surgical conditions( extraintestinal) it depends on the location 30

31. E pidemiology Ascaris lumbricoides one of the highly spread helminthes infection Factors helps disease spreading Defecation if infective persons in soil Favorable condition of soil which is required for egg development. The worm produce very large number of eggs Ability of eggs to resist the unfavorable conditions. Coprophagous animals; young dogs & pigs ( eat fresh human feces) and transport the eggs to different sites. 31

32. Prevention & control why the soil become contaminated?? 32

33. construction of feces where people need to prevent defecation in soil . Prevent use of human feces as soil fertilizer (night soil) If night soil used should be treated ( by chemical or physical methods) to destroy the eggs 33

34. Mass treatment for all age groups once or twice a year (specially in rural communities) Washing hands Washing vegetables & fruits 34