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CHAPTER 9 The Filariae
a result, symptoms, such as a minor allergic reactions,
or no symptoms at all, are experienced by
the infected individual. These individuals may
exhibit moderate eosinophilia. The presence of
Calabar swellings, similar to those of Loa loa
headache, edema, and lymphatic discomfort are
also associated with this infection. There is evidence
to suggest that this organism may be
responsible for joint and bone pain, as well as
enlargement and associated pain in the liver.
Treatment
Asymptomatic infections are often not treated.
However, it has been suggested that treatment in
some cases may be of benefit. The treatment of
choice, when deemed necessary, is diethylcarbamazine
(DEC). It may require multiple treatments.
An effective alternative is mebendazole.
Ivermectin has not been proven effective.
Prevention and Control
The use of insecticides targeted against the vector,
as well as other measures of controlling the
vector population, is crucial to the prevention of
M. perstans infection. Personal protection is also
necessary to prevent the insect bites.
Quick Quiz! 9-14
If a physician suspects an individual has the potential
for infection with Mansonella perstans, what specimen
type would you suggest for recovery of the
organism? (Objective 9-8)
A. Skin snips
B. Lymphatic fluid
C. Blood
D. Infected nodules
Quick Quiz! 9-15
What type of periodicity does Mansonella perstans
exhibit? (Objective 9-8)
A. Nocturnal
B. Diurnal
C. Subperiodic
D. None
LOOKING BACK
When examining specimens for microfilariae or
adult filarial worms, it is important to keep
several points in mind. First, noting the specimen
source is helpful in determining which organisms
and morphologic forms may be found. Because
the appearance of almost all adult filarial worms
is similar, careful examination of microfilariae
for the presence of a sheath and for arrangement
of nuclei in the tail are necessary to ensure
proper identification. Organism size may be
helpful in some cases when screening adult
worms as well as microfilariae. However, because
of overlapping of sizes among the species, an
identification based solely on size is not
recommended.
Microfilariae are the typical forms recovered
in blood and tissue specimens submitted for diagnosis
of infection with the filiarial nematodes.
This morphologic form is the focus of the comparison
drawings in this chapter.
TEST YOUR KNOWLEDGE!
9-1. You live by a fast moving river in Eastern
Africa. Which of the following filarial
nematodes poses the greatest risk of infection
for you? (Objective 9-5)
A. Brugia malayi
B. Onchocerca volvulus
C. Wuchereria bancrofti
D. Loa loa
9-2. Which of the following filarial nematodes
is known as the blinding filaria? (Objective
9-3)
A. Brugia malayi
B. Onchocera volvulus
C. Loa loa
D. Mansonella ozzardi
9-3. The microfilariae of Brugia malayi are recognized
by the: (Objective 9-11)
A. presence of a sheath and two distinct
terminal nuclei in the tail
B. presence of a sheath and absence of
nuclei in the tail
C. absence of a sheath and nuclei continuous
to the tip of the tail