[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 13 The Arthropods
(Dermatobia spp). The skin lesion resembles a
boil, with a small opening at the top. The patient
may feel movement of the larval form within the
lesion, which is usually pruritic and may also be
painful.
Treatment
Treatment is often not necessary for a typical fly
bite. Topical ointments are available to help
reduce minor discomfort. Treatment for myiasis
is complete excision of the lesion with treatment
to prevent secondary bacterial infection.
Prevention and Control
Education regarding the fly’s ability to transmit
disease, wearing of protective clothing, use of
screening, and use of insect repellents are essential
to prevent and control the spread of disease
via flies. Chemically treating fly breeding areas
may also be helpful but is difficult to achieve
successfully.
Quick Quiz! 13-19
Flies are identified and speciated based on which of
the following characteristics? (Objective 13-5)
A. Two body sections, three pair of legs, one pair of
antennae, two sets of wings
B. Three body sections, four pair of legs, one pair of
antennae, two sets of wings
C. Two body sections, three pair of legs, no pair of
antennae, no wings
D. Three body sections, three pair of legs, one pair
of antennae, two sets of wings
Quick Quiz! 13-20
The process that flies undergo in development characterized
by distinct larval stages is known as which
of the following? (Objective 13-1)
A. Myiasis
B. Vertical transmission
C. Metamorphosis
D. Nymphosis
Quick Quiz! 13-21
The major symptom most often experienced by individuals
who have been bitten by a fly is which of the
following? (Objective 13-9)
A. Fever and chills
B. Allergic reaction
C. Irritated and painful bite site
D. Difficulty breathing
Lice
Morphology
Head and body lice (the singular form of lice is
louse) are wingless ectoparasites that have threesegmented
bodies consisting of a head, thorax,
and abdomen (Figs. 13-10 and 13-11; Table
13-9). In general, lice are equipped with three
pairs of legs with clawlike feet that extend from
the thorax region. This feature allows lice to
grasp body hair. A pair of antennae is located on
the head of the typical louse. The louse head is
narrower than the balance of its body. The mouth
parts are well adapted for piercing the human
skin and sucking blood. Both the head louse
(Pediculus humanus capitis) and body louse
(Pediculus humanus humanus) are hairless and
appear long and narrow, measuring 2 to 3 mm
long. The crab louse, Phthirus pubis, is smaller
and plump, measuring up to 2 mm long, and
contains hair over much of its extremities. The
thorax and abdomen appear as one section.
Life Cycle Notes
Adult lice lay their eggs, also known as nits, on or
very near their respective specific hosts. Head lice
eggs may be found in the hair shafts of the head
and neck, whereas body lice eggs are typically
found in clothing fibers and occasionally on chest
hairs. Pubic lice lay their eggs mainly in the pubic
hair region. The young lice resemble their parents
in appearance. It takes 24 to 27 days from the
time the lice eggs are laid to pass through three
nymph stages and transform into young adult lice.
The typical adult louse lives for only 30 days.