[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 8 The Nematodes
rather than becoming dislodged. Infected individuals
may reinfect themselves, known as an
autoreinfection, if infective pinworm eggs are
ingested via hand-to-mouth contamination.
Epidemiology
E. vermicularis is found worldwide, particularly
in temperate areas. Pinworm is considered by
many to be the most common helminth known to
cause infection in the United States. White children
appear to be at the greatest risk of contracting
this parasite. Transmission of pinworm occurs
primarily by hand-to-mouth contamination.
As noted in Chapter 4, it is believed that E.
vermicularis may be responsible for the transmission
of Dientamoeba fragilis. This theory suggests
that the D. fragilis trophozoite may actually
take up residence inside the pinworm egg for
transmission. Infections with both organisms
have been reported.
Clinical Symptoms
Asymptomatic. Many cases of E. vermicularis
infection are asymptomatic.
Enterobiasis: Pinworm Infection. The most
common symptoms experienced by individuals
infected with pinworm include intense itching
and inflammation of the anal and/or vaginal
areas. These symptoms may be accompanied by
intestinal irritation, mild nausea or vomiting,
irritability, and difficulty sleeping. Additional
symptoms known to occur with much less frequency
consist of minute ulcers as well as mild
intestinal inflammation and abdominal pain.
Prevention and Control
Pinworm prevention and control measures include
the following: practicing proper personal hygiene,
particularly hand washing; applying an ointment
or salve to an infected perianal area to help
prevent egg dispersal into the environment; and
avoiding scratching the infected area. Furthermore,
thorough cleaning of all potentially infected
environmental surfaces, including linens, and
providing treatment to all household members
are important steps to help prevent future infections.
Because of the ease with which this parasite
is capable of being transmitted, total eradication
of pinworm is highly unlikely in the near future.
Quick Quiz! 8-4
The specimen of choice for the recovery of Enterobius
vermicularis is: (Objective 8-9)
A. Stool
B. Urine
C. Cellophane tape prep
D. Tissue biopsy
Quick Quiz! 8-5
The most likely individual to contract pinworm infection
is(are) a(an): (Objective 8-7)
A. Older adult
B. Child
C. Adult prisoner
D. Military personnel
Treatment
The treatment of choice for the eradication of
E. vermicularis is albendazole, mebendazole, or
pyrantel pamoate. It is important to note that
in many cases treatment is suggested for the
family members of an infected individual
because pinworm eggs spread readily into the
environment.
Quick Quiz! 8-6
The morphologic forms recovered in cases of pinworm
infection are which of the following? (Objective 8-6)
A. Eggs and adult females
B. Adult males and females
C. Eggs and larvae
D. Larvae and adult males