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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