LEC 5 - Ente-Dracu Flashcards
Enterobius Vermicularis Common Name`
pinworm, seatworm, society worm, social worm
E. vermicularis is also called
Oxyuris vermicularis
E. vermicularis causes
Enterobiais and Oxyuriasis
Greek word that means bowel
Enteros
Greek word that means life
bios
Latin word for small worm
vermicularis
E. vermicularis morphology
Tail end pointed, sharp like a tailor’s pin
- It is an exclusive human parasite – it does not need intermediate host
- Other species may infect animals (like horse, dogs) - But also insects – cockroach
Enterobius vermicularis
- High risk groups of E. vermicularis
- School children 5-10 yrs./old
- Family members
- Institutions: schools, daycare, camps, hostels
The prognosis of enterobiasis is good except that this parasitic disease is easily spread within the family, hence it may be described as
Family disease
The pattern of distribution is globally. It can be found anywhere in the world.
Cosmopolitan Parasite
Why does E. vermicularis prefer Temperate Climate?
They disintegrate if exposed sila sa direct heat like heat, kasi sa mainit na countries namamatay ung parasite.
- The most prevalent helminth in USA and Western
Europe - Commonly found in school aged children
- Also seen in adult
- Prevalence in children communities
E. vermicularis
Percent of Prevalence per country
- 61% India
- 50% England
- 39% Thailand
- 37% Sweden
- 29% Denmark
Natural host of Sitworm
Human
First report of pinworm in naturally occurring
___________ (Chan et.al., 2004)
cockroaches
Existence of pinworm and Trichinella in cockroaches from hospitals and schools in
______
Hawaii
In 2005, Tatfeng et.al isolated pinworm ova from
what specific cockroach specie
Diplotera punctata
Infective stage of sitworm
egg
The female parasite of sitworm lays eggs in the ____________, not in the intestinal lumen. That is why the eggs of this parasite cannot be seen in the feces.
perianal region
Methods Used for E. vermicularis examination
1.Graham’s Scotch Tape/ Cellulose Tape
2. Anal Swab Penetration Technique
The egg of pinworm contains what type of layer that makes the egg stick to the perianal region?
albuminoid layer
The pinworm egg needs ________ to develop
Oxygen
It is the only intestinal nematode infection that
cannot be controlled through sanitary disposal of
human feces because eggs are deposited in the
perianal region instead of the intestinal lumen
Enterobius vermicularis
Adult worms size
Male worm smaller 2-5mm
Female worm 8-13 mm
Anterior end of adult pinworm has ____________ (wing like expansions both sides of anterior end)
cervical alae
Adult pinworm structure
Posterior 1/3 body
- Curved in males
- Straight and very thin (pin-like in female)
Pinworm lays ____ eggs and dies
11,000
Pin worm eggs Morphology
- Planoconvex
- Size: 30-50 um
- Very sticky (adhesive) – albuminoid
- Mature egg may contain larva
- Very hardy in cold climate, high humidity
- Easily destroyed by dry heat, sunlight
- It can be seen in the naked eye if in clumps of
thousand, dislodged from clothing, very light and is
easily airborne!!
Enterobius vermicularis eggs
are inanimate objects that can carry and spread
diseases and infectious agents
Fomites
Fomites of Enterobius
Beddings
Blanket
Underwear
– intense chronic itching affecting peri-anal skin
Pruritus ani
Do not need to rely on a vector
Horizontal transmission
ROT of sitworm
- Ingestion of infectious eggs
- by direct anus-to-mouth transfer by fingers –
anus to mouth - perianal itch (pruritis ani) induced by the
presence of pinworm eggs in the perianal folds - as a result of nail biting, poor hygiene, or
inadequate hand-washing
mother to son transmission
Vertical Transmission
son to mother, generic term which denotes the ROT is unusual, not common
Retroinfection
person to person transmission
Horizontal Transmission
According to Belizario, the route of infection of pinworms are:
- through the mouth
- the respiratory system (by inhalation of dust
containing Eneterobius eggs - through anus (wherein the hatched larvae
enter the anus and cause retroinfection
when they go back into the large intestine
pinworm larvae which hatch on the anus return to the gastrointestinal tract of the original host, ensuring continued infestation
Retroinfection
eggs ‘fly’ from shaken bedsheets, towels →
inhalation
Airborne
Same person scratch anus → egg stick to hand → mouth
Autoinfection
: eggs stick to legs of cockroaches and ants, dog / cat fur
Mechanical vectors
LIFE SPAN OF ENTEROBIUS VERMICULARIS
- External environment (outside human host): viable for 3 weeks in cool temperature, moist areas
- In (1 moulting) upper small intestine: hatched into infective larva → lower small intestine, undergo 2
moultings (Egg – Juvenile 1 – Juvenile 2 – Juvenile 3) - In large intestine (cecum, appendix): Become adult worms.
- In the large intestine the male worm fertilizes, female worm and dies, expelled in stool
- 5 weeks after fertilization, female worms migrate to perianal to lay eggs and die, eggs stick to clothes, not in stool
Life span of adult E. vermicularis
Male 50 days, Female 37-93 days → natural death
Mild to intense itching at night (peak activity of female worms) only
Nocturnal pruritis ani
frequent irritability and waking up at night
disturbed normal day activities
Insomnia
SYMPTOMS of Enterobiasis
- Causing appendicitis (as high as 2.39% of cases in
developing countries) - Intestinal obstruction
- Intestinal perforation
- Eosinophilic ileocolitis
- Extra-intestinal infections also possible (Extra-intestinal enterobiasis)
- Most involve the female genital tract
Dianosis of E. vermicularis
Pinworm Tape Test (Graham Scotch Tape Method)
Pinworm Tape Test
- Morning sample is the best before washing, toilet
- Take samples on successive days (worms do not lay eggs every night)
- Sticking scotch or cellophane tape to anal area
- Place sticky side of tape to glass slide
- View under x10 - x40 magnification
Best time for collection on Pinworm Tape Test
Collect madaling araw kasi kakatapos mangitlog nung mga gravid female and di pa naligo si patient
Other options when collecting samples for E. vermicularis
o Look for worm at the perianal region 2-3 hours
after sleep
o Analyze sample from under fingernails under
microscope to look for pinworms eggs
diagnosed via colonoscopy followed by confirmation via microscopy was documented by Petro et. al. in 2005
Extra-Intestinal Infections
usually require laparotomy and excision of granulomas for a conclusive diagnosis
Infections of the female genital tract
via cervical smears, vaginal wet mounts, and vaginal pooled specimen is possible but difficult
Pre-operative diagnosis
- 100 mg by mouth
- repeated for two weeks to prevent reinfection,
- safest and most efficient therapy (96%)
- Drug targets adult worms, blocking glucose uptake asubsequently causing death
Mebendazole
- 100 mg doses for patients under two years okd
- 400 mg for older patients
- Repeated for two weeks
- Also targets adult worms, decreasing their ATP
production and causing energy depletion,
immobilization, and ultimately death
Albendazole
- Given at 11 mg/kg not to exceed 1g
- Can cause side effects, which include GI distress,
neurotoxicity and transient increases in liver enzymes - Serves as depolarizing neuromuscular blocking agent, inhibiting cholinesterase and resulting in paralysis of the adult worms
Pyrantel pamoate
Other Therapy/Treatment for Enterobiasis
- piperazine citrate, pyrvinium pamoate, oxantel,
oxantel-pyrantel, fenbendazole, and nitrazoxamide - For pinworm infections of the genitourinary tract
mebendazole, ivermectin - Topical insecticides containing malathion or
ivermectin may also be applied to the skin of the
perineum to eliminate pinworm eggs
Other Therapy/Treatment for Enterobiasis
- Treatment of the entire household is strongly
suggested whether or not symptoms are present. - Pinworms are easily transmitted among members of the household.
- Strict handwashing – after using the toilet/changing the diaper of an infected baby, also before and after eating, for two weeks
- Bedding cleaned every 3-7 days for three week
- Underwear and pajamas washed daily
According to Belizario,
The drug of choice for Enterobiasis is
pyrantel pamoate
PREVENTION
- Keep fingernails short
- Dry bedlinen, clothes in sunlight / dryer
- Wash dogs and cats
- Frequent handwashing before meals, after toilet
- Change underwear daily
- Apply petroleum jelly to anal area to block oxygen uptake, larva hatching / re-entering and lessen itchiness
- Bath when you wake up to help reduce the egg
contamination. - Frequent changing of night clothes are recommended.
- Eggs are sensitive to sunlight, open blinds or curtains in bedrooms during the day.
- Discourage nail-biting and scratching bare anal areas.
These practices help reduce the risk of continuous self reinfection.
an arthropod borne nematode disease
Dracunculiasis
For Dracunculus medinensis, Vector serves as the _______ host while human serves as the _________ host
intermediate; definitive
Common Name for Dracunculus medinensis
Guinea Worm, Fiery Serpent of Israelites
Disease caused by D. medinensis
Dracunculiasis/Guinea Worm Disease/Disease of the Empty Granary
Intermediate host of D. medinensis
Cyclops/ Copepod
- Mesocyclops spp.
- Thermocyclops vermifer
- Encyclops serrulatus (Eucyclops serrulatus)
- The female worms could reach _______ in length and _______ in diameter. Male worms are rarely seen and die off after mating
50 cm; 1.55 mm
Color of D. medinensis
Slender, milky white
T or F
Dracunculus is ovoviviparous, the larvae is discharge into the water
False, Dracunculus is viviparous
According to Panikers,
The adult females of D. medinensis are usually found in the__________________ of the legs, arms and back in man.
subcutaneous tissue
D. medinensis - Definitive Host
Man
D. medinensis - Intermediate Host
Cyclops, in which embryos undergo developmental changes. There is no animal reservoir.
D. medinensis - Infective Form
Third-stage larva present in the hemocele of infected cyclops.
D. medinensis - MOT
Humans get infected by drinking unfiltered water containing infected cyclops.
Incubation period of D. medinensis
1 year
Guinea worm infections in animals:
- Animals infected with some species of nematode, Dracunculus medinensis
- Found in domestic dogs and cats
- Therefore, eradication program requires stopping infections in both humans and animals
Currently there is no cure, however for the removal of the Guinea worm the best method is the ancient technique of patiently twisting it around a stick called
Stick therapy
If nahila = _________. The worm dies inside the body.
putrefication
PREVENTIVE MANAGEMENT OF DRACUNCULIASIS
- Ensuring wider access to safe drinking water supplies
- Filtration of drinking water to prevent infection
- Intense surveillance and control to detect every case within 24 hours of the emergence of worm
- Treatment of ponds with larvicide temephos that kills the water fleas and
- Promoting health education and behavior change.
Clinical features of D. medinensis
Pruritus, uticarial rash, blister formation in skin, and cellulitis.
Diagnosis of D. medinensis
Detection of adult worm and larval form in ulcer. Demonstration of deadworm by X-ray. Serology-ELISA and IFA.
Treatment for D. medinensis
Antihistaminics and steroids in initial stage. Metronidazole and niridazole are useful. Surgical removal of the worm.
