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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.
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