Enterobiusvermicularis Chad Clark Kelli Rogers
Introduction • Kingdom: Animalia • Phylum: Nematoda • Family: Oxyuridae • Known more commonly as the “Human Pinworm” • Enterobiusgregorii is considered a “sister” species and synonymy between E. gregorii and E. vermicularishas 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
Cross Section Eggs Male Female
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
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 perianalpruritus 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 bedding and 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