SECTION 2B Flashcards
Most common intestinal roundworm
Ascaris lumbricoides
Synonym: Oxyuris vermicularis
Enterobius vermicularis
Giant Intestinal roundworm
Ascaris lumbricoides
Pin worm, seat worm
Enterobius vermicularis
embryonated ova
Ascaris lumbricoides
Filariform larva
HOOKWORMS
embryonated egg
Enterobius vermicularis
Rhabditiform larva
HOOKWORMS
Types of eggs:
a) Unfertilized: longer and narrower
b) fertilized: broadly avoidal and thick
Ascaris lumbricoides
2 layers of the egg shell
✓ albuminoid layer (absent in old specimens)
✓ chorionic layer or true shell
Ascaris lumbricoides
➢ filled with amorphous mass
Ascaris lumbricoides unfertilized
➢ lack the cresentric clear area
Ascaris lumbricoides unfertilized
Ascaris lumbricoides fertilized egg 3 layers:
✓ Chorionic/true shell
✓ Vitelline layer
✓ Protein coat/Albuminous layer
: chitinous layer
✓ Chorionic/true shell
secretory product of the egg
✓ Chorionic/true shell
: fertilization membrane
✓ Vitelline layer
highly impermeable membrane that protects the inner embryo
✓ Vitelline layer
: outermost mamillated layer with a tanning action
✓ Protein coat/Albuminous layer
: same as fertilized but contains the larva of the embryo
➢ Embryonated
: lacks the albuminous mamillated shell
➢ Decorticated
usually seen in old specimens;m
➢ Decorticated
it may be fertilized or unfertilized
➢ Decorticated
Ova
- ovoidal, colorless/hyaline and thin shelled
HOOKWORMS
Ova
- 4-8 cell stage when passed in the feces (surrounded by a clear zone)
HOOKWORMS
- Feeding stage, short and stout
Rhabditiform larva
- Has a long narrow buccal cavity
Rhabditiform larva
- Flask shaped esophagus
Rhabditiform larva HOOKWORMS
- Very small genital primordium
Rhabditiform larva
- 250u long
Rhabditiform larva
-Non-feeding
Filariform larva
-Mouth is close with a protecting sheath
Filariform larva
-Longer and slender with a pointed posterior end
Filariform larva
-500-600u long
Filariform larva
-Oesophagus fills anterior ½ of larva
Filariform larva HOOKWORMS
-Notched tail end
Filariform larva
-small, cylindrical, fusiform, grayish white
Adult hookworms
-relatively stout with a cervical curvature
Adult hookworms
-with a well-developed buccal capsule
Adult hookworms
: -9-13 mm by 0.35 to 0.6 mm
Adult hookworms ✓ Females
: -5 – 11 mm by 0,3-0,45 mm
Adult hookworms ✓ Males
Ova
-Double lined chorionic shell, transparent and colorless; elongated and ovoidal with one side flattened
Enterobius vermicularis
Ova
-With inner embryonated layer and outer albuminous shell
Enterobius vermicularis
Ova
-Embryonated when laid at the perianal area
Enterobius vermicularis
Ova
-Remain viable up to 13 days, rarely seen in the stool
Enterobius vermicularis
Adult
-white, creamy or pinkish yellow when freshly expelled
Ascaris lumbricoides
Adult
-head is provided with three conspicuous lips which are finely denticulated
Ascaris lumbricoides
Adult
each lip has minute twinned sensory papillae.
Ascaris lumbricoides
✓ Females:
-35 cm long x 3-6 mm
Ascaris lumbricoides
✓ Females:
-straight posterior end
Ascaris lumbricoides
✓ Females:
-paired reproductive organs located in the 2/3 of the body
Ascaris lumbricoides
✓ Females:
-oviparous
Ascaris lumbricoides
✓ Females:
-gravid uterus : 200,000 eggs
Ascaris lumbricoides
✓ Males:
-10-31 cm
Ascaris lumbricoides
✓ Males:
-Usually shorter and slender
Ascaris lumbricoides
✓ Males:
-ventrically curved posterior end with 2 spicules
Ascaris lumbricoides
Males
-genitalia: composed of a single, long tortuous tubule
Ascaris lumbricoides
Lumen of the SI
Ascaris lumbricoides
Cecum and appendix
Enterobius vermicularis
12-17 months
Ascaris lumbricoides
Definitive host: Man (no intermediate host needed)
Ascaris lumbricoides
Definitive host: Man
Enterobius vermicularis
Reservoir host: Dogs and cats
Enterobius vermicularis
Ascariasis
Ascaris lumbricoides
Dooryard or Backyard Infection
Ascaris lumbricoides
Uncinariasis:
Necator americanus
Ancylostomiasis:
Ancylostoma species
Enterobiasis
Enterobius vermicularis
Oxyuriasis
Enterobius vermicularis
✓ Ascaris pneumonitis: Damage to the pulmonary tissue (petechial hemorrhage) when larvae break out of the lung capillaries into the air sacs
Due to larval migration
✓ Symptoms manifested: asthmatic type of respiration; cough; bronchial rales (abnormal respiratory sound); urticarial rash (hives, vascular reaction of the upper dermis; eosinophilia in the circulatory blood)
Due to larval migration
✓ Diarrhea, vague abdominal pain, nausea and loss of appetite
Due to adult worms
✓ Due to its erratic behavior: vomiting; suffocation; intestinal obstruction, appendicitis; acute pancreatitis; peritonitis (perforation of the bowel)
Due to adult worms
✓ Dermatitis at the site of entrance of filariform
Ground itch/Coolie itch/Dew itch
✓ Intense itching, edema and erythema and later papulovesicular eruption
Ground itch/Coolie itch/Dew itch
✓ Due to the exposure of the skin to the filariform larvae of A. braziliense and A caninum, occasionally of N. americanus and A duodenale.
Creeping eruption/Cutaneous larval migrans/Plumber’s itch/ Duck Hunter’s itch
✓ “Serpiginous tunnel” in the stratum germinativum of the skin
Creeping eruption/Cutaneous larval migrans/Plumber’s itch/ Duck Hunter’s itch
✓ Petechial hemorrhages with eosinophilic and leukocytic infiltration that induces cough and pyrexia
Pumonary lesions: Wakana disease
✓ Chronic blood loss due to continuous mechanical suction of blood from the intestinal mucosa and the presence of bleeding areas left by the adult as they transfer to new areas
Hookworm anemia
✓ Blood loss:
N. americanus:
A duodenale:
0.03-0.05 ml/day
0.16 – 0.34 ml/day
✓ Blood picture: “Mycrocytic Hypochromic Anemia”
Hookworm anemia
✓ Loss of protein due to a combined loss of blood and lymph and the protein loss is as well in excess of the loss of RBC
Hypoalbuminemia
✓ Some are asymptomatic; rarely causes serious lesions
Enterobius vermicularis
✓ Other symptoms
- Nocturnal perianal itching
Enterobius vermicularis
- Vulva irritation; vulvovaginitis, salpingitis
Enterobius vermicularis
- Cardinal feature: hypersensitivity
Enterobius vermicularis
- Mild nausea or vomiting
Enterobius vermicularis
- Loss of sleep, irritability
Enterobius vermicularis
- Slight irritation to intestinal mucosa
Enterobius vermicularis
✓ By anus to mouth via contaminated fingers and fomites
Enterobius vermicularis
✓ Through contaminated food and drinks especially if the food handler is the carrier
Enterobius vermicularis
✓ Via inhalation- viable ova can float in the air
Enterobius vermicularis
✓ Retro infection: gravid female after laying their eggs in the perianal area goes back through the anus to the large intestine. The larvae upon hatching migrate back to the large intestine
Enterobius vermicularis
DFS, KTS, Concentration Technique, ELISA
Ascaris lumbricoides
Stool examination may give negative results due to the following
- During the early stage of infection (worms are still immature)
- During larval migration through the blood stream
- When only male worms are present in the intestines
Ascaris lumbricoides
a) Ground itch and creeping eruption – characteristic of the lesion and the history of skin contact with soil
HOOKWORMS
b) Recovery of eggs – DFS, KTS, Brine flotation and FECT
HOOKWORMS
c) Harada Mori culture technique
HOOKWORMS
a) Graham Scotch Tape Technique/Cellulose Acetate Technique
Enterobius vermicularis
b) NIH Swab Technique
Enterobius vermicularis
c) Schuffner and Swelling Rebel Method
Enterobius vermicularis
✓Sanitary disposal of human excreta
Ascaris lumbricoides
✓ Personal hygiene
Ascaris lumbricoides
✓ Avoid the use of night soil fertilizer
Ascaris lumbricoides
✓ Thorough cooking of food particularly vegetables and washing of fruits
Ascaris lumbricoides
✓ Washing solution: aqueous iodine solution (200 parts/million)
Ascaris lumbricoides
✓ kills infective egg and larva in 15 minutes
Ascaris lumbricoides
a) Sanitary disposal of feces
A. lumbricoides
HOOKWORMS
b) Avoid sites where infected dogs and cats may defecate
HOOKWORMS
c) Eradicating the infection in dogs and cats by periodic antihelminthic treatment
HOOKWORMS
d) Personal hygiene such as use of shoes or slippers
HOOKWORMS
e) Avoiding ingestion of raw vegetables
HOOKWORMS
extremely difficult once infection sets in the household
Enterobius vermicularis
✓ Home and community sanitation
Enterobius vermicularis
✓ Better personal hygiene; fingernails should be cut short
Enterobius vermicularis
✓ Use showers rather than bath tubs
Enterobius vermicularis
✓ Infected persons should sleep alone
Enterobius vermicularis
Mebendazole (500mg)
Ascaris lumbricoides
Pyrantel pamoate (10 mg/kg (maximum of 1 g))
Ascaris lumbricoides
Hookworms
Albendazole (400 mg)
Ascaris lumbricoides
Mebendazole, Pyrantel pamoate, Oxantel
HOOKWORMS
Severe anemia- raise the hemoglobin level to about 70-80 g/l
HOOKWORMS
Iron therapy (Ferrous sulfate, 200 mg 3x a day for 3 months)
HOOKWORMS
Human Hookworms:
Animal Hookworms:
: (cause skin lesions or larval migrans in man)
Animal Hookworms
: American hookworm/American murderer
a) Necator americanus
New World Hookworm
a) Necator americanus
: Old world hookworm
b) Ancylostoma duodenale
(cat hookworm)
d) Ancylostoma braziliense
(dog hookworm)
e) Ancylostoma caninum
- 1 pair of semilunar cutting plates, dorsal median tooth, deep pair of triangular subventral lancets
Necator americanus
- fused spicules; deep cleft
Necator americanus
- bipartite dorsal rays
Necator americanus
- 2 pairs of fused ventral teeth
Ancylostoma duodenale
- unfused spicules; shallow cleft
Ancylostoma duodenale
- tripartite dorsal rays
Ancylostoma duodenale
- 3 pairs of ventral teeth
Ancylostoma caninum
- bursa is supported by long, slender rays
Ancylostoma caninum
- 1 pair of larger outer teeth and 1 pair of very inconspicuous median teeth
Ancylostoma braziliense
- bursa is supported by short stubby rays
Ancylostoma braziliense
Ova 56-60 µ x 34-40µ
Hookworms
2 species:
S. stercoralis, S. fuellerborni
Threadworm
- Ova
not found in feces except in diarrhea and hyperistalsis
- Ova
contains a fully developed embryo
- Ova
ovoidal thin shelled, transparent, resembles a Chinese lantern
- Rhabditiform larva
Flask-shaped & stout esophagus
- Rhabditiform larva
Short buccal cavity
- Rhabditiform larva
Conspicuous genital primordium
- Filariform larva
Non-feeding stage with a long and delicate esophagus
- Filariform larva
Forked or notched tail
- Adult
well – developed buccal capsule
- Adult
no teeth, no cutting plates
- Adult
but bears a crown of chitinous, leaf-like processes
2 PHASES of development
- Parasitic
- Free-living
✓ inhabits the intestine of host
✓ female is a delicate filiform worm
✓ L: 2.2 mm
✓ esophagus: occupies 1/3 of the anterior part (longer)
✓ Parthenogenetic
✓ Parthenogenetic
✓ Parthenogenetic
