[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 13 The Arthropods
13-12. Given a case study, including pertinent
patient information and laboratory data,
correctly name the arthropod responsible.
13-13. Given prepared laboratory specimens, and
with the assistance of this manual, the
student will be able to identify and
differentiate the arthropods discussed in
this chapter based on their key
characteristics.
CASE STUDY 13-1
UNDER THE MICROSCOPE
Ed and Sue went for a romantic walk in a heavily wooded
area. After completing their excursion, Sue looked down at
her watch to check the time and noticed a small black
object partially buried under her skin on her right forearm.
The area had already become red and irritated. Ed drove
her home immediately, where he attempted to remove the
unwelcomed guest with a pair of tweezers. Thinking that
this procedure was successful, Ed bandaged the area.
Sue went about her business for the next couple of days
convinced that it was gone. However, every time she changed
the bandage, she noticed that the site was still red and
irritated. She chose to ignore it, thinking that it would get
better soon. Several days later, when Sue removed the
bandage to change it, the irritated site showed signs of
edema and was bleeding. She immediately went to her physician
and showed him the infected area. On questioning by
her physician, Sue explained the events leading up to the
initial symptoms. The physician, now suspicious of the presence
of a parasite in the wound, made a small incision and
removed the mouthpiece of the organism. The entire parasite
responsible for Sue’s discomfort is shown in the diagram.
Questions and Issues for Consideration
1. Which parasite is suspected? (Objective 13-12)
2. What types of adult forms can be seen with this parasite?
(Objective 13-6)
3. Name one method of prevention of infection with this
parasite. (Objective 13-10)
4. Name at least two types of diseases that are notably
transmitted by this organism. (Objective 13-9)
FOCUSING IN
Members of the phylum Arthropoda that affect
humans as ectoparasites consist of a group of
arthropods known as arachnids, including ticks,
mites, spiders, and scorpions, and insects, including
fleas, flies, lice, mosquitoes, and bugs. There
are over four times as many species of arthropods
as there are species in the remainder of the
entire animal kingdom. Arthropods are of particular
interest to parasitologists because they
are responsible for the transmission of parasites,
bacteria, viruses, and rickettsial organisms, as
well as directly causing disease in humans. This
chapter introduces the reader to what some
might consider the most commonly encountered
arthropods of interest that relate to human parasitology.
It is important to note that the organization
and structure of this chapter vary somewhat
from that of the other parasite chapters.
MORPHOLOGY AND LIFE
CYCLE NOTES
At some time in their life cycle, every arthropod
shows each of the following three distinguishing
characteristics: (1) pairs of jointed appendages;