Genital Filariasis (Bancroftian Filariasis)

Diagnosis

  • In early stages, microfilariae are usually present in smears of blood obtained at night
  • In long-standing, chronic disease, blood smears are usually negative
    • Look for eosinophilia
    • Look for microfilariae in hydrocele fluid or chylous urine
    • Filarial complement fixation tests are useful for the detection of disease.
      • Specific serodiagnostic tests for W. bancrofti are available
      • ELISA test for IgG4 antibody against recombinent filarial antigen is also useful
  • Differential diagnosis includes:
    • Nonfilarial congenital lymphatic defects and obstructions
    • Tuberculous
    • Inguinal lymphadenitis
    • Schistosomiasis
    • Lymphatic obstruction from malignancy

Medical Management

  • Even though chemotherapy is effective in eliminating W. bancrofti, structural changes may not be reversible. Treatment goals are the elimination of adult worms and microfilarae.
  • Diethylcarbamazine (Hetrazan)
    • Mainstay of the treatment. known to be effective against adult worms and microfilarae
    • Mechanism of action unknown
    • Dose: 6 mg/kg per day. Total course: 72 mg/kg. Some recommend lower doses initially; 3 mg/kg/day and increasing gradually. Repeat at 3- to 6-month intervals.
    • Toxicity (anorexia, nausea, vomiting, pruritis) may be due to dying microfilaria
  • Ivermectin
    • Effective against microfilarae, but has no effect on the adult worms
    • Single dose of 20 to 25 ug/kg is usually well-tolerated with fewer side effects. Like Hetrazan, it needs to be repeated to prevent recurrent filaremia
  • Suramin (Antrypol, Moranyl)
    • Complex derivative of urea
    • Intrapelvic instillations of silver nitrate 1 to 2 percent solutions
    • Rarely, surgical interruption of renal pedicle lymphatics
  • Desideratum: a new anti-adult filarial drug that has shown promise

References


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