[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 13 The Arthropods
317
adult stage. Similarly, some species of cockroaches
may have fully developed wings in the adult stage.
Life Cycle Notes
Most bugs go through a series of growth stages,
with approximately six moltings from nymph to
adult. Adult stages may or may not have fully
developed wings.
Epidemiology and Geography
Cockroaches (order Blattaria) are primarily
linked to human disease as mechanical carriers
of filth. They are potential carriers of fecal pathogens
since they are frequently known to move
from sewers to food preparation areas. Cockroaches
are found throughout the world. Organisms
of the order Hemiptera are also called the
true bugs, including bedbugs (e.g., Cimex lectularius)
and the triatomid bugs that are a concern
for human health management. Bedbugs can be
found in tropical and subtropical climates around
the world. Their migration with humans is primarily
that of a pest, but they have been known
to produce small red marks or hemorrhagic
lesions. The presence of these marks or lesions is
dependent on the individual’s sensitivity to the
bedbug’s saliva. They live in bedding and clothing,
coming out at night to take a blood meal.
Triatomid bugs, on the other hand, are responsible
for transmitting the parasite Trypanosoma
cruzi, the cause of Chagas’ disease. The triatomid
bugs are sometimes called kissing bugs because
of their tendency to bite sleeping victims on the
face, especially around the mouth. The bugs discussed
here transmit disease while taking a meal
through defecation, which in turn may result in
infection of the wound with bacteria or T. cruzi.
Clinical Symptoms
The most notable symptom of a bug bite is an
irritating dermatitis at the bite location. Excessive
scratching may also result in a secondary bacterial
infection of the bite wound. Cockroaches do
not directly cause symptoms. Triatomid bug bites
may cause similar dermatitis reactions in their
victims. T cruzi and the symptoms of Chagas’
disease are discussed in Chapter 5.
Treatment
OTC lotions and ointments, such as calamine
and Benadryl lotion, are available to relieve the
itching associated with bug bites. Other bactericidal
ointments may be needed for those with
secondary bacterial infections.
Prevention and Control
Because these bugs exist in the environment and
in human dwellings, it is almost impossible to
eliminate exposure. At best, we can minimize
the potential for exposure to cockroaches and
bedbugs through relevant hygiene practices.
Eliminating garbage and increased sanitation
will minimize materials that attract cockroaches
to an area. Similarly, vigilant surveillance for the
presence of bedbugs and subsequent treatment
and removal will minimize their spread in a residence.
Treatment with pesticides in endemic
areas of South America can minimize the occurrence
of triatomid bugs in tribal dwellings but
will not eliminate it entirely.
Quick Quiz! 13-28
Which of the following features are found in all
bugs at some point during their development? (Objective
13-5)
A. Three pairs of legs and wings
B. Wings and rudimentary mouth
C. Three pairs of legs and webbed feet
D. Rudimentary mouth and webbed feet
Quick Quiz! 13-29
The most notable symptom humans experience as a
result of encounters with bugs is which of the following?
(Objective 13-9)
A. Breathing difficulties
B. Nausea and vomiting
C. Diarrhea and abdominal cramping
D. Intense itching at bite site