Transcript Miles_Fletcher_Pinworm

ENTEROBIUS VERMICULARIS
Accounts of pinworm infestation have existed in medical literature since the beginning of
recorded time. A worm causing intense pruritus ani (perianal itch) was described in early
Chinese, Indian, Arabic-Persian, and Greco-Roman populations, and even Hippocrates recorded
his experience with the sleep disturbances caused by infestation with E. vermicularis.
Direct evidence of enterobiasis in ancient populations emerged with the discovery of E.
vermicularis eggs in dried fecal specimens (known as coprolites) found in archaeological sites.
The oldest known eggs were recovered from the Danger Cave and Hogup Cave in western
Utah from a 10,000-year old coprolite. Described by Fry and Moore in a 1969 article
published in Science, the coprolites were positively identified as belonging to the prehistoric
humans who inhabited the caves. The eggs reported in that article still represent the earliest
recorded samples of E. vermicularis, although subsequent discoveries have been reported in
many ancient populations around the world, including a recent discovery among ancient
Egyptian mummies.
Recovery of eggs from various prehistorical human coprolites has allowed researchers to trace
the migratory patterns of the humans carrying the worm. Because the pinworm life cycle occurs
entirely within humans and does not rely on specific soil or climatic conditions, it is likely that E.
vermicularis was carried over by human migrations across the Bering Strait. Such an early spread
of the worm in human populations helps explain its wide geographic distribution today.
Pinworms are helminthic pathogens.
The worms are white and spindle-shaped
with a large, bulbar esophagus. Eggs are
ovoid, thin-shelled, and flat on one side.
Females are approximately 1 cm long and
males are half that size. The curved posterior
end of male worms has a single copulatory
spicule. The males are rarely seen because
they die shortly after copulation and are
expelled.
Eggs will not embryonate at temperatures
below 23°C, but embryonated eggs can
remain viable for several weeks under moist
and cool conditions.
Little is known about immune responses to
pinworm infection. Infections are more
common in children than in adults,
suggesting that acquired immunity or some
other type of age-related resistance develops.
Infections affect about
200 million worldwide.
40 million cases in the
U.S. and Canada.
Most common worm
infection in the U.S.
Enterobius ova (Scotch tape prep)
Humans become infected by ingestion of infected
embryonated eggs which reach the mouth by
inhalation, hand to mouth transport, or in
contaminated food or drink. Infections many times
involve families living under crowded conditions.
Sometimes the entire family may be infected.
Enterobiasis (pinworm disease) is caused by the
nematode worm Enterobius vermicularis. This
organism has a worldwide distribution and can infect
horses, mice and primates (man and monkeys). It
does not infect cats and dogs.
Pinworms reach maturity in the lower GI tract within
2 to 6 weeks. The female worm migrates to the
perianal region (usually at night) to deposit ova. The
sticky, gelatinous substance in which the ova are
deposited and the movements of the female worm
cause perianal pruritus. The ova can survive on
fomites as long as 3 weeks at normal room
temperature. Intestinal lesions are reported, but the
worms usually cause little intestinal pathology. The
parasite has been found in diseased appendices but is
not necessarily the cause of the pathology. Pinworms
can make their way to extraintestinal locations and
cause complications. For example, the parasites may
carry bacteria into other organs, resulting in abscess
formation.
Children suffering sleepless nights because of
perianal itching often have pinworms. Eggs
are rarely found in the feces, and the
diagnosis is made by finding eggs on perianal
swabs made of Scotch tape. The tape is
pressed first onto the perianal region and then
onto a microscope slide, and is examined
microscopically. Perianal specimens are best
obtained in the morning before bathing or
defecation. Three specimens should be taken
on consecutive days before pinworm infection
is ruled out.
The medications used for the treatment of pinworm are mebendazole, pyrantel pamoate, and
albendazole. All three of these drugs are to be given in 1 dose at first and then another single dose
2 weeks later. Pyrantel pamoate is available without prescription. The second dose of medication
is to eliminate possible re-infection since the first dose of medication. Health practitioners and
parents should weigh the health risks and benefits of these drugs for patients under 2 years of age.
Repeated infections should be treated by the same method as the first infection. In households
where more than one member is infected or where repeated, symptomatic infections occur, it is
recommended that all household members be treated at the same time. In institutions, mass and
simultaneous treatment, repeated in 2 weeks, can be effective.
Wash in the morning. Because pinworms lay their eggs at night, washing the
anal area in the morning can help reduce the number of pinworm eggs on your
body. Showering may help avoid possible recontamination in bath water.
Change underwear and bed linen daily. This helps remove eggs. Launder in hot
water. Wash bed sheets, nightclothes, underwear, washcloths and towels in hot
water to help kill pinworm eggs.
Don't scratch. Avoid scratching the anal area. Trim your child's fingernails so
there's less space for eggs to collect. Discourage nail biting.
Clean toilet seats daily. This helps remove eggs.
WHEN?
-Before, during, & after preparing a
food and also before consumption.
-Before and after caring for someone
who is sick.
-Before and after treating a wound or
cut.
-After using the toilet.
-After blowing nose, sneezing, or
coughing.
-After touching an animal, animal
feed, or waste.
-After touching garbage.
HOW?
-Wet hands with clean running water
(hot or cold) and apply soap.
-Rub your hands together to make a
lather and scrub them well; be sure
to scrub the back of your hands,
between your finger, & under nails.
-Continue rubbing your hands for at
least 20 seconds. (HINT)
-Rinse hands well under running
water.
-Dry your hands using a clean towel
or air dry.
*Hint- Need a timer? Try humming
Happy Birthday to yourself two
times.
What about hand sanitizer?
Washing hands with soap and water is the best way to reduce the number
of germs on them. If soap and water are not available, use an alcoholbased hand sanitizer that contains at least 60% alcohol. Alcohol-based
hand sanitizers can quickly reduce the number of germs on hands in
some situations, but sanitizers DO NOT eliminate all types of germs.
How?
 Apply the product to the palm of one hand (read the label to learn the
✔
correct amount).
 Rub your hands together.
✔
✔
 Rub the product over all surfaces of your hands and fingers until your
hands are dry.
Infection
Sally became unknowingly infected by ingesting infective pinworm eggs. (Possibly
from contaminated fingers, clothing, bedding, or by eating food that was prepared
by an infected host who failed to perform proper sanitary practices after defecating.)
After about a month and a half, Sally went to her physician complaining about
difficulty sleeping due to an itchy rectum, particularly at night.
Diagnosis
After reporting her symptoms to her physician, he instructed her to touch her
perianal skin with transparent tape first thing in the morning, to collect possible
pinworm eggs. She was then to repeat this process for three consecutive days. Upon
confirmation of a pinworms diagnosis, Sally’s physician prescribed the following
treatment plan.
Treatment
Sally was advised to take Combantrin @ 125mg, 6 tablets (750mg) immediately and
then repeat 2 weeks later to eliminate possible reinfection. She was then advised to
take nonpharmacological steps to prevent reinfection.
Will helminths be responsible for the zombie apocalypse?
Even though the current symptoms of pinworms are relatively harmless, future
evolution of the helminths could possibly result in more harmful symptoms.
A second species, Enterobius gregorii has already been found in Europe,
Africa, and Asia.
CDC (2013). Parasites-Enterobiasis. Retrieved from www.cdc.gov/parasites/pinworm/. (wash your
hands/treatment/prevention/stats)
Cross, John H. (2000). Enteric Nematodes of Humans. Retrieved from
http://www.ncbi.nlm.nih.gov/books/NBK8261/. (pathophysiology/description/transmission)
Dowshen, Steven (2009). Pinworms. Retrieved from http://wesleymc.com/yourhealth/kidshealth/22282/pinworms?mainCatergory=3. (pinworm soap image)
Evaneko (2007). Avalace the Demon Worm. Retrieved from evaneko.deviantart.com.art.Avalace-theDemon-Worm-59478396. (Imaginary worm and zombie images)
Kiche, Anne O. (2011). Microbiology in the Physicians Laboratory. Retrieved from
http://www.healthcare.uiowa.edu/cme/clia/modules.asp?testID=11. (diagnosis/tape
procedure image/egg slide)
Stanford (2006). History. Retrieved from http://www.
Stanford.edu/class/humbio103/ParaSites2004/Enterobius/history.htm. (pinworm history)
Thompson, Jason (2010). Attack of the Pinworms. Retrieved from
www.theartofdad.blogspot.com/2010/05/attack-of-pinworms.html. (Pinworms image)