[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 9 The Filariae
235
Quick Quiz! 9-13
Which of the following filarial drugs is effective
against Mansonella ozzardi if therapy is necesary?
(Objective 9-9)
A. Albendazole
B. Diethylcarbamazine
C. Doxycycline
D. Ivermectin
Mansonella perstans
(man”so-nel’ah/per’stans)
Common name: Perstans filaria.
Common associated disease and condition
names: None (considered as a nonpathogen).
Morphology
Microfilariae. The average Mansonella perstans
microfilaria measures about 200 µm in
length (Fig. 9-10; Table 9-6). The organism does
not have a sheath and the body is filled with
nuclei that extend all the way to the tip of the
tail. The anterior or tail end is rounded and blunt.
TABLE 9-6
Parameter
Size range
Sheath
Arrangement of nuclei in
tail
Mansonella perstans
Microfilaria: Typical
Characteristics at a Glance
Description
about 200 µm in length
Absent
Numerous; extend to tip of
tail
Adults. The typical adult female worm measures
82 mm in length, whereas the adult male
measures a little over half that, 43 mm in length.
They reside in peritoneal and pleural cavities as
well as the mesentery.
Laboratory Diagnosis
Blood is the specimen of choice for the recovery
of M. perstans. The sample may be collected at
any time because there is no known peak time
for the circulating microfilariae to be present,
that is, the organism is non-periodic.
Life Cycle Notes
The life cycle of M. perstans is similar to that of
M. ozzardi. The only known vector is the Culicoides
sucking midge. In this life cycle, the insects
usually settle in areas in and around the eye. As
in the life cycle of M. ozzardi, humans are the
primary definitive hosts in the life cycle of M.
perstans. The incubation period of this organism
once inside the host is unknown.
Epidemiology
Infection rates are high in areas endemic to the
Culicoides sucking midge. These include parts of
Africa, selected areas in the Caribbean Islands,
Panama, and northern South America. Primates
are thought to harbor M. perstans or a closely
related species as reservoir hosts.
Clinical Symptoms
Because adult M. perstans worms usually appear
singly, damage to affected tissue is minimal. As
Nuclei in tip of tail
No sheath
Average length: 93 m
FIGURE 9-10 Mansonella perstans microfilaria.