August 2025
INTRODUCTION —
Filariasis is caused by nematodes (roundworms) that inhabit the lymphatics and subcutaneous tissues. Three species cause lymphatic filariasis: Wuchereria bancrofti, Brugia malayi, and Brugia timori. Infection is transmitted by mosquito vectors; humans are definitive hosts. Lymphatic filariasis is a major cause of disfigurement and disability in endemic areas, leading to significant economic and psychosocial impact.
Treatment of lymphatic filariasis requires an understanding of the microfilaricidal and macrofilaricidal activity of therapeutic agents.
In regions where loiasis and onchocerciasis may coexist with lymphatic filariasis, additional consideration is important for minimizing the likelihood of adverse effects. Prior to treatment of lymphatic filariasis, patients should be evaluated for coinfection with onchocerciasis and/or loiasis.
Most of the studies regarding the efficacy of available treatment regimens are derived from data from mass chemotherapy programs. These data are helpful in determining the relative efficacy of the drugs and combinations in terms of microfilaricidal and macrofilaricidal activity, but do not necessarily provide optimal data on the management of infected individuals.
The treatment and prevention of lymphatic filariasis will be reviewed here. The epidemiology, diagnosis, and clinical features of lymphatic filariasis and other filarial infections (including onchocerciasis, loiasis, and mansonellosis) are discussed separately. (See "Lymphatic filariasis: Epidemiology, clinical manifestations, and diagnosis" and "Onchocerciasis" and "Loiasis (Loa loa infection)" and "Mansonella infections".)
TREATMENT OF MONOINFECTION —
Prior to treatment of lymphatic filariasis, patients should be evaluated for coinfection with onchocerciasis and/or loiasis. (See "Loiasis (Loa loa infection)", section on 'Diagnosis' and "Onchocerciasis", section on 'Diagnosis'.)
Treatment is warranted for all patients with lymphatic filariasis, regardless of whether clinical symptoms or microfilaremia are present; regimens are summarized in the table (table 1) [1-3]. Early lymphatic changes may be present before the onset of symptoms, and reversal of early lymphatic dysfunction has been observed following treatment [4].
Diethylcarbamazine (DEC) as preferred regimen — The preferred regimen for treatment for lymphatic filariasis monoinfection is DEC for 12 days [5]. Dosing is summarized in the table (table 1).
●Activity – DEC, a piperazine derivative, is a potent microfilaricidal and macrofilaricidal agent with activity against W. bancrofti, B. malayi, and B. timori [6]. The mechanism of action is uncertain; it is thought to alter microfilarial surface membranes or inhibit filarial release of immunomodulatory eicosanoids, thereby enhancing destruction via host immune responses [7,8]. DEC also has macrofilaricidal activity, likely via hyperpolarization leading to immobilization of adult worms.
●Adverse effects – Adverse effects of DEC include fever, headache, anorexia, nausea, and arthralgias. These effects are likely attributable to the host response following the death of microfilariae (systemic reactions) and damage to adult worms (local reactions). Dying microfilariae probably release lipopolysaccharide-like proteins from endosymbiotic Wolbachia organisms within the filariae [9,10].
DEC reactions can be severe, and even life-threatening, in the setting of coinfection with onchocerciasis and/or loiasis; evaluation for these conditions should be pursued prior to treatment with DEC.
Management of mild to moderate adverse effects during treatment of lymphatic filariasis consists of administration of antipyretic and/or anti-inflammatory agents.
●Efficacy – There are few studies on the microfilaricidal efficacy of DEC monotherapy. In one study, including 14 patients in South India with lymphatic filariasis treated with DEC for 13 days, complete microfilarial clearance by day 12 was achieved in 78 percent of cases [11]. Efficacy of DEC against adult worms has been demonstrated based on ultrasonography (disappearance of worm nests) and lymphoscintigraphy (demonstrating restoration of lymphatic flow) [4,12]. Estimates suggest DEC kills approximately 50 percent of adult worms, and its effect on adult worms in turn leads to sustained decreases in the microfilarial burden [13].
●Availability – DEC is not commercially available in the United States but can be obtained from the United States Centers for Disease Control and Prevention (CDC) under an Investigational New Drug protocol (CDC Drug Service, Atlanta, GA 30333; telephone 404-718-4745) [14].
Alternative regimens
Doxycycline — For cases in which DEC is not available or contraindicated, doxycycline may be used; dosing is summarized in the table (table 1).
●Activity – An alternative approach to attacking the adult worm directly is to focus treatment against Wolbachia, an intracellular bacterial symbiont of filarial parasites that is present in microfilariae and adult worms of W. bancrofti, B. malayi, and B. timori [15]. Doxycycline targets Wolbachia; it has activity against adult W. bancrofti worms but no effect on Loa loa. (See "Lymphatic filariasis: Epidemiology, clinical manifestations, and diagnosis", section on 'Wolbachia'.)
●Efficacy – Doxycycline has both microfilaricidal and macrofilaricidal activity and has demonstrated efficacy in W. bancrofti and B. malayi infections [16,17]:
•In a randomized trial including 72 patients in Tanzania with bancroftian filariasis, patients who received doxycycline (200 mg daily for eight weeks) had reduced microfilaremia and diminished detectability of adult worms compared with patients who received a placebo (22 versus 88 percent, respectively) [18].
•In a randomized trial including 161 patients in Indonesia with brugian filariasis, a six-week course of doxycycline reduced the prevalence of microfilaremia compared with placebo (77 versus 27 percent) [19].
Subsequent trials have demonstrated the efficacy of shorter regimens (four or six weeks may also be sufficient) [20-22], and that the addition of albendazole may enhance microfilarial clearance by doxycycline [23].
Doxycycline treatment has also been shown to reduce lymph vessel dilation and hydrocele [24,25]. In a trial including 162 patients with lymphedema in Ghana, administration of doxycycline (200 mg/day for six weeks) was associated with improvement in filarial lymphedema [26].
The efficacy of doxycycline compared with DEC for the treatment of lymphatic filariasis is not known.
Albendazole — Albendazole is an acceptable alternative regimen for patients who cannot take doxycycline; dosing is summarized in the table (table 1).
●Activity – Albendazole is a benzimidazole antihelminthic that binds beta-tubulin leading to impaired intestinal function in a wide variety of parasitic worms. Albendazole has macrofilaricidal activity in lymphatic filariasis, but no direct effect on microfilariae. Its effect against adult worms leads to a slow decline in microfilaremia.
Albendazole may be used in patients with concomitant loiasis or onchocerciasis since there are no adverse effects related to rapid killing of microfilariae (as seen with DEC or ivermectin).
●Efficacy of monotherapy
•In a community-based trial in the Democratic Republic of Congo, biannual administration of single-dose albendazole (400 mg) led to microfilarial clearance in 37 percent of individuals at 12 months [27] and a 94 percent reduction in the prevalence of microfilaremia after three years [28].
•In two cohort studies of repeated albendazole administration in Central Africa, a correlation between treatment adherence and clearance of microfilaria was observed [29].
●Efficacy of combination therapy – Many studies have demonstrated enhanced suppression of microfilaremia with albendazole and ivermectin (relative to ivermectin alone) [30].
Albendazole does not appear to enhance the microfilaricidal efficacy of DEC; in a small study evaluating the effects of albendazole and DEC on adult worm killing (as assessed by scrotal ultrasound), combination therapy was less effective than DEC alone [31].
TREATMENT OF COINFECTION
With onchocerciasis — Administration of diethylcarbamazine (DEC) for treatment of lymphatic filariasis is contraindicated in patients with onchocerciasis coinfection, due to the potential for severe adverse events related to killing of onchocercal microfilariae in the eye and/or skin (Mazzotti reaction) [32,33]. (See "Onchocerciasis".)
Preferred regimen — For patients with lymphatic filariasis and onchocerciasis, adult worms (for lymphatic filariasis as well as onchocerciasis) may be treated with doxycycline (200 mg orally once daily for six weeks) with the addition of ivermectin (150 mcg/kg single dose) for rapid microfilarial reduction and morbidity reduction in onchocerciasis.
Alternative regimens — Alternative regimens include (table 1):
●Ivermectin plus albendazole
•Ivermectin
-Activity – Ivermectin is a macrocyclic lactone belonging to the avermectin subfamily; it binds glutamate-gated chloride channels, leading to worm paralysis and death. Ivermectin has microfilaricidal activity [34-36], but does not have significant macrofilaricidal activity [37-40]. Therefore, reduction in microfilaremia is not sustained without repeat dosing.
The clinical benefit of ivermectin for the treatment of lymphatic filariasis is uncertain, given the lack of activity against adult worms, which play an important role in the pathogenesis of lymphangitis and lymphedema. Ivermectin may have some effect in reducing the fertility of worms.
-Efficacy – Ivermectin is at least as effective as DEC in reducing microfilaremia due to bancroftian filariasis [41,42]; a single dose has been shown to reduce microfilaremia by approximately 90 percent, even one year after treatment [34,35].
One study in South India demonstrated that a single dose of ivermectin (150 microgram/kg) was approximately equivalent to a 12-day course of DEC in suppressing microfilaremia for three to six months [11].
•Albendazole – Albendazole is discussed above. (See 'Albendazole' above.)
●Moxidectin plus albendazole or doxycycline
•Moxidectin
-Activity – Similar to ivermectin, moxidectin is a macrocyclic lactone that binds glutamate channels. Moxidectin has a longer half-life than ivermectin with rapid microfilaricidal activity, but does not have significant macrofilaricidal activity.
-Efficacy – In a randomized trial evaluating two moxidectin-based regimens and two ivermectin-based regimens among 164 adults in Cote d'Ivoire with microfilaremia due to lymphatic filariasis, patients who received a moxidectin-based regimen (8 mg single dose) were more likely to be amicrofilaremic at 12 months (95 versus 32 percent; adjusted risk ratio 2.79 (95% CI 1.59-4.90) [43]. At 24 months, the efficacy of an ivermectin versus moxidectin-based regimen for amicrofilaremia was comparable (91 percent).
•Albendazole – Albendazole is discussed above. (See 'Albendazole' above.)
•Doxycycline – Doxycycline is discussed above. (See 'Doxycycline' above.)
With loiasis — The treatment of coinfection due to lymphatic filariasis and loiasis is the same as the treatment for loiasis monoinfection. (See "Loiasis (Loa loa infection)", section on 'Treatment of monoinfection'.)
With onchocerciasis and loiasis — The treatment of coinfection due to lymphatic filariasis, loiasis, and onchocerciasis is the same as the treatment for coinfection with loiasis and onchocerciasis. (See "Loiasis (Loa loa infection)", section on 'With onchocerciasis'.)
MANAGEMENT OF CHRONIC COMPLICATIONS —
The most common chronic complications of lymphatic filariasis are recurrent lymphangitis or cellulitis, lymphedema, elephantiasis, and hydrocele. Chyluria is relatively infrequent.
Lymphedema
●Routine care – Individuals with lymphedema should wash affected areas twice daily, use antibacterial creams on small abrasions, keep nails clean, and wear shoes. The affected limb should be exercised regularly to promote lymph flow and should be elevated at night. Complex decongestive physiotherapy can also be effective in some cases. (See "Management of peripheral lymphedema".)
The National Lymphedema Network provides a listing of certified lymphedema therapists in the United States who have expertise in treating chronic lymphedema.
●Secondary infection – Secondary infections (especially bacterial) are contributing determinants of worsening lymphedema and elephantiasis, particularly in individuals with late-stage disease. Aggressive treatment of secondary infections and close attention to hygiene is critical. Antibiotic prophylaxis should be considered in patients who experience recurrent infections despite appropriate local care. (See "Acute cellulitis and erysipelas in adults: Treatment".)
Hydrocele — A hydrocele is a sac of fluid that forms inside the scrotum around one of the testicles (figure 1). The role of surgery for management depends upon the individual anatomy and local surgical expertise. Drainage may give some relief, but is almost always followed by fluid reaccumulation. Hydrocelectomies can be helpful; among 301 patients with filariasis in Nigeria, hydrocelectomy was performed successfully [44]. (See "Nonacute scrotal conditions in adults", section on 'Hydrocele'.)
Chyluria — Chyluria refers to the discharge of lymph into the urine. It may lead to secondary nutritional deficiency; in such cases, low-fat, high-protein diets supplemented with medium-chain triglycerides can be helpful.
PREVENTION —
Tools for prevention include mass drug administration and vector control.
Mass drug administration — W. bancrofti has been designated as a target for elimination since there are no animal hosts. Elimination of brugian filariasis is not feasible since this infection has a large domestic and wild animal reservoir. (See "Lymphatic filariasis: Epidemiology, clinical manifestations, and diagnosis", section on 'Epidemiology'.)
Mass drug administration reduces the bloodborne reservoir of microfilariae to a level below that required for sustained transmission by local mosquito vectors (figure 2 and figure 3). The period of microfilaremia has been estimated to be four to six years, corresponding with the reproductive lifespan of the adult parasite.
Mass drug administration using various regimens of diethylcarbamazine (DEC), ivermectin, and albendazole had been in place in some countries for more than 20 years prior to 2000, when the Global Program for the Elimination of Lymphatic Filariasis was launched with drug company donations of ivermectin and albendazole. Since that time, mass drug administration programs have been implemented in more than 60 countries, with more than 5 billion doses of antifilarial therapy administered [45,46]:
●In areas where lymphatic filariasis is endemic (in the absence of onchocerciasis or loiasis), management consists of a three-drug combination regimen consisting of ivermectin, DEC, and albendazole (single dose) or a two-drug combination regimen of DEC plus albendazole (administered once yearly for three years) [47-49].
This approach is supported by a randomized trial including more than 180 adults in Papua New Guinea with W. bancrofti microfilaremia treated with a single dose of the three-drug regimen, a single dose of the two-drug regimen, or the two-drug regimen administered once a year for three years [48]. Administration of the three-drug regimen was associated with clearance of microfilaremia for three years in 98 percent of participants; it was superior to the two-drug regimen administered once and noninferior to the two-drug regimen administered once a year for three years. There were no serious adverse events.
●In areas where lymphatic filariasis and onchocerciasis are coendemic (in the absence of loiasis), management consists of combination therapy with yearly ivermectin and albendazole; the presence of onchocerciasis precludes the use of DEC [50,51].
●In areas where lymphatic filariasis and loiasis are coendemic, management consists of albendazole monotherapy twice yearly [47,52]; unless onchocerciasis is hyperendemic, in which case the benefits of ivermectin for onchocerciasis are felt to outweigh the risk of serious adverse events from ivermectin treatment of loiasis, and combination therapy with yearly ivermectin and albendazole is recommended.
Suppression of transmission to <1 percent (the predicted threshold for elimination) has been achieved in several countries, including Egypt, Togo, and 12 countries in Asia and the Pacific Islands.
A number of challenges remain; these include the availability of funds for drug distribution and monitoring, the persistence of hot spots of transmission [53], difficulties reaching populations in remote areas and areas of conflict, and the occurrence of treatment-related encephalopathy in areas endemic for loiasis [54,55].
Human immunodeficiency virus (HIV) coinfection does not appear to affect response to mass therapy with ivermectin and albendazole [56].
Vector control — Tools for vector control include the use of insect repellents and insecticide-treated bed nets. (See "Prevention of arthropod bites: Repellents and other measures" and "Malaria: Epidemiology, prevention, and elimination", section on 'Insecticide-treated nets (ITNs)'.)
SUMMARY AND RECOMMENDATIONS
●Treatment of monoinfection – We treat all patients with lymphatic filariasis, regardless of whether clinical symptoms or microfilaremia are present. Dosing is summarized in the table (table 1). (See 'Treatment of monoinfection' above.)
•Preferred regimen – For patients with lymphatic filariasis, we suggest treatment with diethylcarbamazine (DEC) (Grade 2C). (See 'Diethylcarbamazine (DEC) as preferred regimen' above.)
•Alternative regimens – Alternative regimens include doxycycline or albendazole. (See 'Alternative regimens' above.)
●Treatment of coinfection
•With onchocerciasis – DEC should be avoided in patients with onchocerciasis due to the risk of severe adverse effects.
-Preferred regimen – For patients with lymphatic filariasis and onchocerciasis, we suggest treatment with ivermectin plus doxycycline (Grade 2C).
-Alternative regimens – Alternative regimens include ivermectin plus albendazole, moxidectin plus albendazole, or moxidectin plus doxycycline.
•With loiasis – The treatment of coinfection due to lymphatic filariasis and loiasis is the same as the treatment for loiasis monoinfection. (See "Loiasis (Loa loa infection)", section on 'Treatment of monoinfection'.)
•With onchocerciasis and loiasis – The treatment of coinfection due to lymphatic filariasis, onchocerciasis, and loiasis is the same as the treatment for coinfection with onchocerciasis and loiasis. (See "Loiasis (Loa loa infection)", section on 'With onchocerciasis'.)
●Management of chronic complications – Individuals with lymphedema should wash affected areas twice daily, use antibacterial creams on small abrasions, keep nails clean, and wear shoes. The affected limb should be exercised regularly to promote lymph flow and should be elevated at night. Aggressive treatment of secondary infections and close attention to hygiene is critical. (See 'Management of chronic complications' above.)
●Mass drug administration for prevention – Mass drug administration reduces the bloodborne reservoir of microfilariae to a level below that required for sustained transmission by local mosquito vectors. Programs use various combinations of albendazole, ivermectin, and DEC, leading to suppression of transmission in several countries; many challenges remain. (See 'Mass drug administration' above.)
ACKNOWLEDGMENT —
The UpToDate editorial staff acknowledges Dr. Karin Leder, MBBS, FRACP, PhD, MPH, DTMH, who contributed to earlier versions of this topic review.
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