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Enterobius vermicularis
Chad ClarkKelli Rogers
Introduction
Kingdom: Animalia Phylum: Nematoda Family: Oxyuridae Known more commonly as the “Human
Pinworm” Enterobius gregorii is considered a “sister”
species and synonymy between E. gregorii and E. vermicularis has been proven via molecular biology
Infects at least 400 million people worldwide!!!
Geographic Area
Geographic distribution• Worldwide (mainly affects children)• Originated in Africa, but also thrives in
temperate zones• Greatest area of risk are
institutionalized areas such as an orphanage or a school.
Hosts
Definitive host • Humans Intermediate host• None (Direct Life Cycle)
Morphology
Both males and females have 3 lips surrounding their mouth
Males are 1-4 mm in length with a posterior end that strongly curves to the ventral side and have a single spicule which is 100-141 um in length
Females are 8-13 mm in length and have a posterior end that extends into a long, slender point and they contain 2 uteri that can store thousands of eggs
Eggs are elongated-oval and completely flat on one side and measure 50-60 um by 20-30 um
Eggs
Male Female
Cross Section
Epidemiology
Disease is transmitted from person to person
Fabric (IE clothing, bedding, towels, etc) is a perfect reservoir for eggs and spreads rapidly this way
Can also be found on curtains, walls carpet and even in dust
Another rapid mode of transmission is by placing soiled fingers or other objects in mouth
Life Cycle
Pathogenesis
Damage from the intestine is the result of adult attachment to the mucosa and can lead to mild inflammation and bacterial infection
Damage from eggs results in female movement out of the anus to deposit eggs causing a tickling sensation of the perianus causing a person to scratch (usually occurs while a person is sleeping)
Clinical Signs
About 1/3 of all infections are completely asymptomatic
If symptoms due arise, commonly perianal pruritus occurs
Other symptoms…• Anorexia• Irritability• Abdominal pain• Nightmares• Bed Wetting
Diagnosis
Ordinary fecal exams are unproductive In order to get accurate diagnosis the
area of the perianus must be reached• A short piece of cellophane (scotch) tape
is held against a flat wooden applicator or similar object sticky side out
• Tape is then pressed against the junction of the anal canal and the perianus
Treatment
Pyrantel pamoate How does it work?
• Pyrantel pamoate acts as a depolarizing neuromusclar blocking agent. It causes sudden contraction, followed by paralysis, of the helminths. This has the result of causing the worm to "lose its grip" on the intestinal wall and be passes out of the system by natural processes (defecation).
Control
Personal hygiene Laundering of beddingand other cloth materials
Public Health Concern
May cause….• Intestinal obstruction• Intestinal perforation• Granulomas and abcesses• Urinary tract infections
References
http://www.stanford.edu/group/parasites/ParaSites2006/Enterobius/Enterobius%20vermicularis.htm
http://www.dpd.cdc.gov/dpdx/HTML/Enterobiasis.htm
Foundations of Parasitology • Eighth Edition• Gerald D. Schmidt & Larry S. Roberts &
John Janovy, Jr
Egg Comparisons