1. Suan Lui Teoh Danh Voong
Ascaris lumbricoides
Suan Lui Teoh
Danh Voong

2. Introduction
a common cream colored roundworm that is parasitic in the intestines of humans
Most common helminthic human infection
Largest nematode to infect the human intestine
An estimated 1 billion people are infected (1 out of 4 people in the world)

3. Geography
Worldwide
High prevalence in underdeveloped countries that have poor sanitation (parts of Asia, South America and Africa)
Occurs during rainy months, tropical and subtropical countries
Even occurs in rural areas in the United States

4. Host
Definitive host : Humans or pigs
Intermediate Host : -none-

5. Modes of transmission
Occurs mainly via ingestion of water or food (raw vegetables or fruit in particular) contaminated with A. lumbricoides eggs.
Occasionally inhalation of contaminated dust
Children playing in contaminated soil may acquire the parasite from their hands
Enhanced by the fact that individuals can be asymptomatically infected and continues to shed eggs for years
Prior infection does not confer protective immunity

6. Morphology Fertile egg mammillated thick external layer unembryonated
measures mm by mm

7. Morphology Cont. Infertile egg elongated and larger than fertile egg
thin shelled
shell ranges from irregular mammillations to a relatively smooth layer completely lacking mammillations
measures between mm by mm

8. Morphology Cont.
Infertile
Fertile

9. Egg Can survive for prolonged periods as long as warm, shade, moist conditions are available and can live up to 10 years Eggs are resistant to unusual methods of chemical water purification Eggs are removed by filtration and killed by boiling. Developing larvae are destroyed by sunlight and desiccation

10. Morphology Cont. Adult worm: tapered ends; length 15 to 35 cm
Female are larger in size and have a genital girdle

11. The 3 prominent “lips”

12. Life Cycle

13. Life Cycle Cont.
Females lay eggs in small intestine and eggs are passed out through feces.
After 14 days, L1 larvae develops in eggs
L2 larvae develops after one week
Ingestion of raw foods, fruits or vege contaminated with eggs will cause infection
Eggs hatch in small intestine, releases L2 rhabditiform larvae
L2 penetrate intestinal wall, enter portal blood stream, migrate to liver, heart and lungs in 1-7 days
Moults twice to become L4 larvae

14. Cont. Borrow out of blood vessels and enter bronchiols
Migrate through the lungs into the trachea
Enter throat and swallowed to end up in the small intestine
Mature and mate, where they complete their life cycle

16. Food Habits Feeds on semi-digested contents in the gut
Evidence show that they can bite the intestinal mucus membrane and feed on blood and tissue fluids

17. Symptoms Symptoms associated with larvae migration
Migration of larvae in lungs may cause hemorrhagic/ eosinophilic pneumonia, cough (Loeffler's Syndrome)
Breathing difficulties and fever
Complications caused by parasite proteins that are highly allergenic - asthmatic attacks, pulmonary infiltration and urticaria (hives)

18. Symptoms Cont.
Symptoms associated with adult parasite in the intestine
Usually asymptomatic
Abdominal discomfort, nausea in mild cases
Malnutrition in host especially children in severe cases
Sometimes fatality may occur when mass of worm blocks the intestine

19. HOST IMMUNE RESPONSE Innate Immune Response
Macrophage, neutrophils and most importantly eosinophils
The worms would be coated with IgG or IgE which would increase the release of eosinophil granules on the worm’s surface
Adaptive Immune Response
General consensus is a Th2 immune response with high IL-4 production, high levels of IgE, eosinophilia and mastocytosis

20. Diagnosis
Stool microscopy :eggs may be seen on direct examination of feces.
Eosinophilia: eosinophilia can be found, particularly during larval migration through the lungs
Imaging: In heavily infested individuals, particularly children, large collections of worms may be detectable on plain film of the abdomen.
Ultrasound: ultrasound exams can help to diagnose hepatobiliary or pancreatic ascariasis. Single worms, bundles of worms, or pseudotumor-like appearance, individual body segments of worms may be seen.
Endoscopic Retrograde Cholangiopancreatography (ERCP) :
A duodenoscope with a snare to extract the worm out of the patient

21. Treatment Mebendazole Albendazole Pyrantel pamoate Ivermectin
Piperazine citrate
Levamisole

22. Prevention
Prevention of reinfection poses a substantial problem since this parasite is abundant in soil – therefore good sanitation is needed to prevent fecal contamination of soil
Limit using human feces as fertilizer
Treatment can be done on contaminated soil although it is not highly advised
Mass treatments of children with single doses of mebendazole or albendazole – helps reduce transmission in community but can cause reinfection

23. Some cool pictures

26. How many people in the world are estimated to be infected with A
How many people in the world are estimated to be infected with A. lumbricoides ?

27. Who are the definitive host/s of this parasite?

28. Name 2 modes of transmission?

29. What morphological difference can be seen in fertile and infertile eggs?

30. Name the symptom caused by larvae migration in the lungs.

31. What is the drug of choice for this parasite?

32. What are some of the methods of prevention?