• NEMATODA
─ “roundworms”
─ Long, cylindrical, and elongated
─ Anterior end → can have hooks, teeth, plates, and papillae
▪ Used for attachment, abrasion, or for sensory response
─ Has alimentary tract (GI tract), no circulatory system
─ BODY
1. Hyaline cuticle outer layer
2. Subcuticular epithelium
3. Inner muscle cells
─ REPRODUCTION
▪ Occur with separate sexes; some are parthenogenic
▪ With Amphids and phasmids
▪ Aphasmid worms (no amphids): TTC
o Trichuris
o Trichinella
o Capillaria
• Phasmid – located in posterior end of nematode ; responsible for sensing
chemicals/chemoreception
o Hookworm
o Brugia
o Strongyloides
o Bancrofti
• Amphid – chemoreception; sensory organ located anterior end
─ LIFE CYCLE
1. Egg stage
2. Larval Stage
3. Adult Stage
─ REPRODUCTION HABIT
o Oviparous – Ascaris Lumbricoides
o Ovoviviparous – Enterobius Vermicularis
o Viviparous/larviparous – Trichinella Spiralis; Filaria
Note: WRITING PARASITES
Ex; Ascaris lumbricoides
Ascaris – genus (Starting with a capital letter)
lumbricoides – species (written with a small letter)
1. ASCARIS LUMBRICOIDES
─ “Giant/Large Intestinal Roundworm”
─ 1 billion are infected
─ Size comparable to mongol pencil
─ A parasite specific for man (definitive host) that Resembles earthworm
─ Ascaris Infection in ANIMALS (can be incidental to man but no development in
man, but can sometimes cause visceral larva migrans)
o Toxocora canis – Ascarid of DOGS
o Toxocora cati – Ascarid of CATS
o Ascaris suum – Ascarid of PIGS
Habitat: Small Intestine
Transmission: soil-transmitted helminth; geohelminth
Appearance:
─ Polymyarian type (many rows of longitudinal muscle cells)
─ ADULT: white-cream or pinkish-yellow when fresh
─ ADULT MALE: curved tail (10-31 cm / 3mm) (l x w)
─ ADULT FEMALE: straight pointed posterior end, larger
(22-35 cm / 5mm)]
─ Anterior end (head) has THREE LIPS
o Has triangular cavity
Reproduction
✓ Adult female can produce 200,000 – 240,000 eggs / day
✓ 65 million fertilized eggs
THREE LAYERS of a FERTILIZED EGG
1) INNER VITELINE – absent in unfertilized egg
2) GLYCOGEN LAYER
3) ALBUMINOUS MAMMILATION - (+) corticated, (-) decorticated
▪ ASCARIS LUMBRICOIDES EGGS
1) FERTILIZED EGG (product of repeated copulation)
─ 45 – 70 / 35 – 50 micrometers (um)
─ Ovoidal, golden brown
─ Very thick eggshell, inside is a set of organized germ cell
2) UNFERTILIZED EGG / INFERTILE (never undergo further development)
─ 88 – 94 / 39 – 44 micrometers (um)
─ Irregularly ovoidal, larger, longer, and narrower
─ thin eggshell
─ irregular mammilated coating
o Albuminous mammilation
▪ (+) corticated
▪ (-) decorticated
─ No vitteline membrane but has glycogen layer
─ Has LECITHIN granules
Egg Characteristics
1. Dryness – unfavorable to survival (susceptible to dessication)
2. Eggs are destroyed by direct sunlight (9-13 hours)
3. Killed at temperature ABOVE 40C
➢ few weeks/months in tropical countries
➢ 1-2 years in temperature climate (not hot, not cold)
4. Can survive in freezing temp
5. Resistant to chemical disinfectant
6. Can Withstand temporary immersion in strong chemicals
Infection Characteristics
1. If Male and female ascaris is present in SI, they will copulate
2. Female is pregnant with egg
3. Eggs will come out of the feces
4. If eggs are defecated in the soil
5. Embryonation – 2-3 weeks in the soil
6. After embryonation (infective stage of parasite) (if not embryonated-not
infected/will not hatch when ingested)
i. Note: Eggs will NEVER HATCH in the soil
7. Transmission could happen when child/person plays with the soil and
happens to ingest without cleaning hands
8. After ingestion, egg will hatch in the host
9. Larva will reach lungs and molt twice (larval migration)
10. Rise the passages and ascend to respiratory tree, then swallowed again
11. Descend to Small intestines and mature there
Note: Repeated copulation – fertilized egg is produced, if di masipag mag copulate – unfertilized
PATHOLOGY of Ascaris Lumbricoides
• Ascariasis
─ Infection of 10-20 worms: may not show symptoms
─ Note: neither number or size of parasite provides a criterion for damage they produce
─ Causes Ascaris Pneumonitis [CDAC-FEI)
o Lung infiltration
o Chest pain
o Difficulty in breathing
o Asthmatic attacks
o Coughing
o Fever
o Edema of the lips
o Increased EOSINOPHIL (with heart to lung migration)
• Other Correlated Pathological Characteristics
─ May invade appendix (LARVAE are the one that migrates, not eggs)
─ May block/seen in
o pancreatic duct,
o bile duct,
o liver parenchyma,
o gall bladder
─ Can perforate the bowel which causes (hole in bowel)
➢ Acute peritonitis
➢ Chronic Granulomatous peritonitis
─ Can also be found in
o Brain
o Spinal Membranes
o Spinal Cord
o Eyeball
o Kidneys
─ Causes
✓ Decreased fat and Nitrogen Absorption
✓ Increase nitrogen loss in feces
✓ Malaabsorption
✓ Intolerance of Lactose
✓ Decrease growth in children
✓ Heavy infection can cause
o Obstruction
▪ Note: May irritate NERVE ending in the mucosa and result to
Intestinal Spasms leading to > intestinal obstruction
o Intussusception (part of the small intestines folds into adjacent part of
large intestine)
o Volvulus (twisting of intestine)
• PHYSICAL effects [ Louie is Nauseated in DiVVisoria ]
o Loss of appetite
o Nausea
o Diarrhea
o Vague Abdominal Pain
o Vomited ascaris
o Pulmonary Gangrene (if lungs)
o Otitis media (eustachian tube)
DIAGNOSIS OF ASCARIS LUMBRICOIDES INFECTION
• DIRECT FECAL SMEAR (DFS) – common but kato katz is more accurate
─ Add 1 drop of NSS (Normal Saline Solution) in slide; but if stool is watery no need to add
NSS
─ Spread fecal Sample on slide
─ Microscopic exam; observe for presence of ascaris egg and quantitate the ova
─ Counting: different fields → 10,15,30 (result: 10-30 Ascaris Lumbricoides per LPO)
❖ NEGATIVE FINDINGS is given if patient are any of the ff. (PELO)
o Patient is free from infection
o Early stage of infection
o Larval migration
o Only male worms are present in intestine (since no eggs)
• KATO KATZ TECHNIQUE – recommended
─ Place 50-60g of stool in slide
─ Cover with cellophane (soaked in “glycerine malachite green” for 24 hours)
─ Press with rubber stopper
─ Leave for 10-20 minutes
─ Examine
Note: There is enough evidence that FECT/Kato is better than > DFS, but need adequate training and
proficiency of laboratory staff
EPIDEMIOLOGY
─ “Endemic” in many countries with warm-moist climate
o Southeast Asia, Africa, Central and South America
─ Cosmopolitan distribution: 1.2 billion have ascariasis, 2000 die annually
─ ¼ of the world is infected
─ High prevalance in 5-15 years old
─ In the Philippines,
o Prevalance rate is 80-90% in RURAL AREAS, poor slum sections
o 8/10 public school children are positive of A. lumbricoides
TREATMENT, PREVENTION AND CONTROL
─ Deworming
o 3x a year for 3 years (PALP DeworMing) – antithelmintic drugs
▪ Pyrantel Pamoate
▪ Albendazole
▪ Levamisole
▪ Piperazine salts
▪ Mebendazole
─ Sanitary disposal of feces
─ Personal hygiene
─ Avoid use of feces as fertilizer
─ Thorough cooking of food
─ WA-S-HE-D
o Water
o Saniation
o Hygiene Education
o Deworming framework
─ WOW in Binan, Laguna
o War on Worms
