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Blood (Intracellular) and Other Tissue Protozoa 115

Laboratory Diagnosis Symptoms
The diagnosis of infections with M. ozzardi is primarily Most victims of this infection are asymptomatic or ex-
based on recovery of the unsheathed and nonperiodic perience rather mild symptoms. Calabar-like swellings
microfilariae from blood specimens and skin snippings have however been found in some cases. Where mature
or biopsies for identification of the species. Thick and worms live in serous cavities, mild inflammatory changes
thin blood smears or centrifugal procedures for concen- may be noted in the host.
trating the parasites are also collected at any time of the
day and prepared for examination. Life Cycle
Microfilariae of this species have nuclei that do not
cover the entire length of the body to the tip of the tail, The mature worms of M. ozzardi inhabit the serous cavi-
and they must be differentiated from the other blood- ties of the pleural, pericardial, and peritoneal regions of
borne microfilariae. the body. The microfilariae (190 to 200 μm in length) are
found in the circulating blood and are ingested by the
Treatment and Prevention feeding midge (genus Culicoides) and are not periodic in
their times of activity or appearance.
Asymptomatic patients are not given therapy for the
condition. Administration of the drug diethylcar- Disease Transmission
bamazine is given three times per day for 10 days and
has proven to be effective in eliminating larval mi- M. perstans infection rates are high in endemic areas. The
crofilaria in patients who present with more serious disease is acquired when bitten by an infected midge.
clinical signs. In endemic area, insect repellent may
prevent a great number of the bites. Again, bed net- Laboratory Diagnosis
ting to prevent bites from the infected midges is not
very effective as the midges are so small they can pass Infections with M. perstans may be accomplished through
through the netting. Eradication of breeding grounds examination of blood or serosal effusions from body cavities.
in swampy areas and some other vector control pro- Blood samples are collected at any time of the day and pre-
cesses have not proven effective in reducing the vector pared from skin snips or biopsies that are soaked in saline.
populations. Size is a chief criterion in differentiating the various species
of bloodborne microfilaria along with other morphological
characteristics. Because the disease may produce no symp-
MANSONELLA PERSTANS toms or mild symptoms, the only clues for the infection by
M. perstans may be an elevated serum antifilarial titer per-
Mansonella perstans was previously known as Dipeta- haps accompanied by considerable eosinophilia.
lonema streptocerca, and is found in both humans and
apes as a filarial infection. The infectious organism is Treatment and Prevention
found in most of central Africa and in the northeastern
portion of South America. The organism resides primar- Administration of the drug diethylcarbamazine is stan-
ily in the serous cavities of humans and apes. dard treatment, but appears to be ineffective. Ivermectin
also shows no activity against this infection. Metronida-
Morphology zole has been shown to be successful and is given for
30 days twice daily. In endemic areas, vector control
The adult worms of M. perstans are similar to those of would be advisable, but is rarely practiced. Insect repel-
M. ozzardi. The microfilariae are unsheathed but larger lent may prevent a great number of the bites but bed net-
than M. perstans, measuring 190 to 200 μm and have ting to prevent bites form the infected midges is not very
body nuclei that extend to the tail’s tip. The larvae are effective as the midges are so small they can pass through
nonperiodic and appear at any time of the day. They the netting. Impregnation of protective clothing with per-
have nuclei that extend to the tip of the tail. methrins appears to discourage bites from the midges.