CDC Health Parasites

1. PHYLUM
NEMATODA

2. PHYLUM NEMATODA
• Nematodes or true roundworms
• Unsegmented, elongated and cylindrical in shape
• Sexes are separate and the females are larger than
males
• Life cycle includes: 1) the egg stage 2) four larval
stage and 3) the adult stage

3. CLASS APHASMIDIA
A. Species which parasitize the small
intestines
1. Trichinella spiralis
2. Capillaria philippinensis
B. Species which parasitize the large
intestines
1. Trichuris trichiura

4. CLASS PHASMIDIA
A. Species which parasitize the small
intestines
1. Ascaris lumbricoides
2. Necator americanus
3. Ancylostoma duodenale
4. Ancylostoma ceylanicum
5. Strongyloides stercoralis

5. CLASS PHASMIDIA
B. Species which parasitize the large
intestines
1. Enterobius vermicularis
C. Species which parasitize the tissues
1. Wuchereria bancrofti
2. Brugia malayi

6. CLASS PHASMIDIA
D. Species which cause larva migrans
in man
1. Ancylostoma braziliense
2. Ancylostoma caninum
3. Angiostrongylus cantonensis

7. Ascaris lumbricoides
Common Name: Giant Intestinal Roundworm
Final Host: Man
Habitat: Small Intestine
Diagnostic Stage: Ova (fertilized or unferilized)
Infective Stage: Embryonated Ova
Sources of Infection: Soil Transmitted Helminthes
Mode of transmission: Ingestion
Portal of Entry: Mouth

8. Ascaris lumbricoides
Morphology:
The adult worms are creamy-white to pinkish
yellow when freshly expelled. The head is provided
with 3 lips and a small triangular buccal cavity
Female: female worm is tapered at both ends and
large (20 to 35 cm long, up to 45cm)
Male: smaller and slender, curve posteriorly and
equip with copulatory spicule

9. 1. Cuticle and hypodermis
2. Longitudinal muscle layer
3. Vas deferens
4. Testis
5. Lateral line with excretory canal
6. Intestine
7. Pseudocoelom
Ascaris lumbricoides – male (cross section)

10. 1. Cuticle and hypodermis
2. Longitudinal muscle layer
3. Ovary
4. Oviduct
5. Uterus
6. Intestine
Ascaris lumbricoides – female (cross section)

11. The three lips are seen
at the anterior end. The
margin of each lip is lined
with minute teeth which
are not visible at this
magnification.
Ascaris lumbricoides - lips

12. A fertilized corticated Ascaris egg, still
at the unicellular stage, as they are
passed in stool. All membranes are
present. The outer *mamillary coat,
the middle gycogen and the
innermost vitelline layer.
* Lacking in decorticated ova.
Ascaris lumbricoides - egg

13. The chitinous layer and
albuminous coat are thinner
than those of the fertilized
eggs without ascaroside and
fertilizing membrane. The
content is made of many
refractile granules various in
size.
Ascaris lumbricoides - egg

14. Ascaris lumbricoides – life cycle

15. Adult worms live in the lumen of the small intestine.
A female may produce up to 240,000 eggs per day, which are passed with the feces
Fertile eggs embryonate and become infective after 18 days to several
weeks , depending on the environmental conditions (optimum:
moist, warm, shaded soil).
After infective eggs are swallowed , the larvae hatch , invade the
intestinal mucosa, and are carried via the portal, then systemic
circulation to the lungs .
The larvae mature further in the lungs (10-14 days), penetrate the
alveolar walls, ascend the bronchial tree to the throat, and are
swallowed .
Upon reaching the small intestine, they develop into adult worms .
Between 2 and 3 months are required from ingestion of the infective eggs to
oviposition by the adult female. Adult worms can live 1 to 2 years
Ascaris lumbricoides – life cycle

16. Pathology:
Larva:
- Ascaris pneumonitis/ Loeffler’s syndrome
- difficulty in breathing, coughing, fever, lung infiltration
- larva may become ERATIC
Adult:
- diarrhea
- malnutrition
- villi atrophy
- worm bolus/obstruction
Treatment: Mass treatment or Selective Treatment
Drug of choice: Mebendazole or Pyrantel pamoate
Ascaris lumbricoides

17. Ascaris lumbricoides
Diagnosis:
1. Direct Fecal Exam
2. Kato (qualitative) and Kato-katz technique (quantitative)
3. Stool exam
4. Concentration Techniques (Floatation, Sedimentation)
Prevention and Control

18. Trichuris trichiuria
Common Name: Whipworm
Final Host: Man
Habitat: Large Intestine - attached
Diagnostic Stage: Ova
Infective Stage: Embryonated Ova
Sources of Infection: Soil Transmitted Helminthes
Mode of transmission: Ingestion
Portal of Entry: Mouth

19. ADULT MORPHOLOGY
 Flesh colored or pinkish slender
worm
Anterior 2/3 of the worm is
attenuated and thin in contrast to
the remaining posterior 1/3 which is
fleshy and robust
“Whip like appearance”

20. FEMALE MALE
Trichuris trichiuria

21. Trichuris trichiuria - ova
-With mucoid, bipolar plug
-Foot ball - shaped
-Lemon-shaped
-Barrel-shaped
* Diagnostic stage

22. Trichuris trichiuria – life cycle

23. The unembryonated eggs are passed with the stool .
In the soil, the eggs develop into a 2-cell stage , an advanced cleavage
stage , and then they embryonate ; eggs become infective in 15 to 30 days.
After ingestion (soil-contaminated hands or food), the eggs hatch in the small
intestine, and release larvae that mature and establish themselves as adults in
the colon .
The adult worms (approximately 4 cm in length) live in the cecum and ascending
colon. The adult worms are fixed in that location, with the anterior portions threaded into
the mucosa. The females begin to oviposit 60 to 70 days after infection. Female worms
in the cecum shed between 3,000 and 20,000 eggs per day. The life span of the adults
is about 1 year.
Trichuris trichiuria – life cycle

24. Trichuris trichiuria
Diagnosis: * same with Ascaris lumbricoides
Pathology:
- diarrhea
- Iron Deficiency Anemia
- rectal prolapse
To declare free from A. lumbricoides and T. trichiuria
- three specimens are negative
- stool negative for egg
- all male parasite
- female worms are still immature (migration stage)
- unfetilized egg (all females or males are still immature)
Drug of choice: Mebendazole

25. The Hookworms
1. Necator americanus
2. Ancylostoma duodenale
3. Ancyiostoma braziliense
4. Ancylostoma caninum

26. Ancylostoma duodenale Necator americanus
Common name: Old world Hookworm New world Hookworm
Body Curvature: “C” shaped “S” shaped
Dental pattern: 2 pairs of teeth Semi lunar cutting plate
Bursa: Dorsal ray, tridigitate or
tripartite
Dorsal ray bidigitate or bifid
Spicule: Plain, bristle-like Barbed, fused
Habitat: Small intestine Small intestine
Diagnostic stage: Ova Ova
Infective stage: L3 (filariform) L3 (filariform)
MOT Skin penetration,
transmammary
Purely percutaneous

27. Ancylostoma duodenale Necator americanus
two pairs of teeth Semi lunar cutting plate
Dorsal ray, tridigitate or
tripartite
Dorsal ray, bifid

28. The Hookworms – life cycle

29. The Hookworms – life cycle
Eggs are passed in the stool , and under favorable conditions
(moisture, warmth, shade), larvae hatch in 1 to 2 days.
The released rhabditiform larvae grow in the feces and/or the soil ,
and after 5 to 10 days (and two molts) they become become filariform
(third-stage) larvae that are infective
These infective larvae can survive 3 to 4 weeks in favorable environmental
conditions. On contact with the human host, the larvae penetrate the skin
and are carried through the veins to the heart and then to the lungs. They
penetrate into the pulmonary alveoli, ascend the bronchial tree to the
pharynx, and are swallowed .
The larvae reach the small intestine, where they reside and mature
into adults. Adult worms live in the lumen of the small intestine,
where they attach to the intestinal wall with resultant blood loss by
the host

30. The Hookworms
Ova: Thin-shelled
2-4-8 cell stages (blastomeres)
*No species identification
Pathology: anemia
pneumonitis (Wakana Disease)
creeping eruption – cutaneous larva migrans (CML)
Lab test: Stool Exam
Harada Mori Technique
Rx of choice: Albendazole
Mebendazole

31. COMPARATIVE STUDY ON HOOKWORM AND
STRONGYLOIDES STERCORALIS LARVA
 Hookworm L1 Strongyloides
long = buccal capsule= short
small = genital primordium= prominent
L3
shorter = esophagus = longer
pointed = tail end = notched
both sheathed

32. Strongyloides stercoralis
Common Name: Threadworm, smallest nematode of man
Final Host: Man
Habitat: Small Intestine
Diagnostic Stage: Rhabditiform Larva
Infective Stage: Filariform Larva
*causative agent of Cochin China Diarrhea
Pathology:
Diarrhea
Honey Comb Ulcer
Lab Test:
Stool Exam
Duodenal Aspirate
Entero Test

33. Strongyloides stercoralis

34. Strongyloides stercoralis
rhabditiform larva of Strongyloides stercoralis. The rhabditiform larva
are usually mistaken from that of the hookworms rhabditiform.

35. egg capsule of Strongyloides stercoralis from free-living female. The
larvae is well formed with transparent capsule.
Strongyloides stercoralis

36. Capillaria philippinensis
Common Name: Pudoc worm
Final Host: Man/ other vertebrae
Intermediate host: glass fish
Habitat: Small Intestine
Diagnostic Stage: Ova in stool
Infective Stage: Larva in IH
Sources of Infection: Food borne
Mode of transmission: Ingestion
Portal of Entry: Mouth

37. Capillaria philippinensis

38. Capillaria philippinensis – life cycle
(1) Unembryonated eggs deposited in the intestinal lumen of either the avian or
human host are expelled in the feces, whereupon the eggs are released into the
external (usually aqueous) environment.
(2) The unembryonated eggs become embryonated while in the fresh- or brackish-
water.
(3) The embryonated eggs are ingested by fresh- or brackish-water fish. which serve
as the intermediate host for the Capillaria philippinensis. Inside the intestinal lumen of
the fish, the larvae hatch, burrow through the intestinal mucosa, and permeate the
fish's mesenteric and peripheral tissues.
(4) The parasite enters the intestinal lumen of humans, fish-eating birds, and other
animal hosts upon ingestion of raw or undercooked C. philippinensis infected fish.
(5) The adult worms of Capillaria philippinensis burrow into the intestinal mucosa (most
typically of the jejunum).
(6)While in the intestinal lumen of the human or avian host, the female worms deposit
unembryonated eggs, which are subsequently expelled in the host's feces. (Albeit a
rare occurence, the eggs of Capillaria philippinensis may become embryonated within
the intestine of the human host. The subsequent release of infective larvae leads
autoinfection and hyperinfection.

39. Capillaria philippinensis
Morphology:
Female: 2.5-4.4mm
1. Typical Female –egg in uterus (8-10) in single row
2. Atypical Female – viviparous, larvivapous, 40-45 eggs
arranged in 2-3 rows
Male: 2.2-3.2mm
- with chitinized spicule and a long spicule sheath
Female Male

40. Capillaria philippinensis
Morphology:
Ova: Produced by typical female
-moderately thick striated egg sheath
-with flattened bipolar plugs
- 1-2 segmentation
*Diagnostic stage

41. Capillaria philippinensis
-Can cause microulceration, depression of intestinal villi
-Borborygmi
-Abdominal pain
-Diarrhea
-Weight loss
-Malabsorption
-Low plasma electrolyte concentration
Pathology:
Laboratory test:
- DFS
- Concentration techniques (FECT)
- examination of duodenal aspirate
Rx of choice:
Albendazole, Mebendazole

42. Enterobius vermicularis
Common Name: Pinworm, seatworm, society
worm
Final Host: Man
Habitat: Large Intestine
Diagnostic Stage: Ova
Infective Stage: embryonated ova
Sources of Infection: Contact borne
Mode of transmission: Ingestion, inhalation

43. Enterobius vermicularis

44. Enterobius vermicularis
Eggs are deposited at night by the gravid females.
Eggs are ingested via person-to-person transmission through the handling of
contaminated surfaces (such as clothing, linen, curtains, and carpeting), or airbourne
eggs may be inhaled and swallowed. Self-infection may also occur if eggs are
transferred from to the mouth by fingers that have scratched the perianal area.
After ingestion, larvae hatch from the eggs in the small intestine. The adults then
migrate to the colon. The life span of the adults is about two months. Adults mate in
the colon, and the males die after mating.
Gravid females migrate nocturnally to the anus and ovideposit eggs in the perianal
area. The females die after laying their eggs. The time period from ingestion of
infective eggs to the ovideposition of eggs by females is approximately one month.
The larvae develop and the eggs become infection within 4-6 hours. Newly hatched
larvae may also migrate back into the anus, and this is known as retroinfection.

45. Enterobius vermicularis - morphology
Adult Female: E. vermicularis have a
long, pointed tail (arrow) leading to the
common name of pinworm. They are
about 8-13 mm in length.
Adult Male: The adult male is about
2-5 mm in length and has a curved,
relatively blunt posterior end (arrow).

46. Enterobius vermicularis - morphology
Adult Male: This image shows a
closeup of the male. Note the esophageal
bulb, characteristic of the species, in the
anterior end (black arrow) and the curled
posterior tail with a spicule, characteristic
of the male (red arrow).
Egg: The egg of E. vermicularis is
approximately 25 x 60 um in size. It has a
thin shell and one of the sides is
flattened. Eggs are collected by swabbing
the perianal area during the early morning
with an adhesive tape and then examining
the tape with a microscope.

47. Enterobius vermicularis
Pathology:
- Itchiness
- Secondary bacterial infection
- Nocturnal pruritus ani
Lab diagnosis:
-Scoth tape swab
-Swellengrebel
-Petrolatum Coated Swab
Rx of choice: Mebendazole

48. Angiostrongylus cantonensis
Common Name: Rat lung worm
Final Host: Rattus norvegicus
Rattus rattus rattus
Intermediate Host: Achanita fulica

49. Angiostrongylus cantonensis
FEMALE MALE
-Intestine fille with blood
-Interwinding uterus
-‘barber’s pole”
- Bean shaped bursa

50. Angiostrongylus cantonensis

51. PATHOLOGY
Angiostrongylosis
- Eosinophilic meningoencephalitis
- Increasing confusion, incoherence,
impaired memory
- Marked tissue necrosis

52. DIAGNOSIS
CSF examination with moderate to high white
blood cell count
- Pleocytosis
Patient history of eating any possible intermediate
host is important
Large numbers of Charcot-Leyden crystals are
present in the meninges

53. FILARIAL WORMS
Family Filariidae
Slender filarial worms
Arthropod-transmitted parasite of the circulatory
and lymphatic system
Medically important species in the Philippines
are Wuchereria bancrofti and Brugia malayi

54. Wucheria bancrofti Brugia malayi
Common name Brancroft’s Filarial
Worm
Malayan Filarial Worm
Final Host Anopheles, Aedes, Culex Mansonia bonneae , M.
uniformis
Host – adult Lower lymphatic Upper lymphatic
Diagnostic Stage Microfilaria Microfilaria
Infective Stage L3 filariform L3 filariform
Mode of
Transmission
Skin penetration Skin penetration
Periodicity Nocturnal Periodic-nocturnal
subperiodic

55. Wucheria bancrofti Brugia malayi
Cephalic space 1:1 2:1
Sheath affinity to
Giemsa
Unstained Stained- pink
Body nuclei Regularly shaped Overlapping/
irregular
Terminal nuclei None Two nuclei
Appearance Graceful curve Kinky/ stiff
Pathology Bancroftian Filariasis Malayan Filariasis

56. Wucheria bancrofti Brugia malayi
Microfilaria

57. Microfilariae – life cycle

58. DIAGNOSIS
1. Blood smear examination
Sample obtained between 10:00 PM – 2:00 AM
2. Knott’s concentration technique
(2ml blood:10ml of 2% formalin)
3. RDT- ICT- antigen detection (CFA)

59. TREATMENT, PREVENTION AND CONTROL
1. Single dose
- Diethylcarbamazine(DEC)
- Ivermectin
2. DEC-medicated table salt

60. TREATMENT, PREVENTION AND CONTROL
Educate communities about :
- The value of intensive local hygiene
- Awareness on etiology, prevention
and control of filariasis
Personal protective measures may help
prevent contact with mosquito vectors