Page 106 - Medical Parasitology_ A Textbook ( PDFDrive )
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Filarial Worms Causing Lymphatic Filariasis 99
2. Xenodiagnosis
Biopsy bits of infected muscle are fed to laboratory rats, which are sacrificed
about 1 month later. The larvae can be demonstrated in the muscles of such
infected rats.
3. Serodiagnosis
4. Radiological examination
Calcified cysts may be demonstrated on X-ray examination.
5. Molecular diagnosis
PCR on clinical specimens.
Treatment
Supportive treatment consisting of bed rest, analgesics and antipyretics. Albendazole
(400 mg twice/day orally for 8–14 days) or mebendazole (200–400 mg 3 times/day
orally for 3 days, then 400–500 mg 3 times/day for 10 days) may also be useful for
intestinal stage of the parasite. These drugs have not been shown to be effective
against the encysted larva. Steroids are sometimes required in more severe cases.
Prevention and Control
1. Proper cooking of pork
2. Do not feed pigs with raw meat
3. Control of rats in pig farms
Filarial Worms
The filarial worms reside in the subcutaneous tissues, lymphatic system, or serous
cavities of humans. The female worms are ovoviviparous and release larvae known
as microfilariae. The microfilariae can be detected in the peripheral blood or cutane-
ous tissues, depending on the species. Presence of microfilariae in peripheral blood
can exhibit nocturnal periodicity, diurnal periodicity or no periodicity at all. The
basis of periodicity is unknown but it may be an adaptation to the biting habits of the
vector. The life cycle of filarial nematodes is completed in 2 hosts: definitive host
(human) and intermediate host (blood-sucking arthropods). The microfilariae com-
plete their development in the arthropod host to produce the infective larval stage.
Adult worms have a lifespan of many years in the human body whereas microfilar-
iae survive for a few months.
Filarial Worms Causing Lymphatic Filariasis
Wuchereria bancrofti
Distribution
Wuchereria brancofti is distributed widely in the tropics and subtropics.