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